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PROCEEDINGS OF ONE-DAY SEMINAR 11/12/2014 The energy future of existing buildings in Brussels: between preservation and performance

A PUBLICATION OF BRUSSELS URBAN DEVELOPMENT 2015

Thanks This publication is the result of the proceedings of the one-day seminar “The energy future of existing buildings in Brussels: between preservation and performance”, held in Brussels at the Royal Library on 11 December 2014. Organised by Brussels Urban Development/Regional Public Service of Brussels, the project’s steering committee was made up of Grégoire Clerfayt, Sven De Bruycker, Caroline Mulkers, Benoit Périlleux, Marie-Laure Roggemans, Anne Van Loo and Manja Vanhaelen. We would like to thank everyone who provided their advice, participation and experience, especially Boris D’or, Michael de Bouw, Francois Dewez, Celine Jeanmart, Benoit Priod and Claudine Houbart. We would also like to thank all those involved, either directly or indirectly, in the organisation and smooth running of the event and the publication of these proceedings.

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A PUBLICATION OF BRUSSELS URBAN DEVELOPMENT 2015 3

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BRUSSELS HERITAGE – ONE-DAY SEMINAR – 11/12/2014

CONTENTS

P.006 EDITORIAL P.008 A WORD OF WELCOME Arlette VERKRUYSSEN

P.009 A WORD OF INTRODUCTION Bety WAKNINE

P.010 WHAT ARE THE REQUIREMENTS FOR THE ENERGY PERFORMANCE OF BUILDINGS WHEN RENOVATING? Michaël GOVAERT

P.016 ARCHITECTURAL HERITAGE AND ENERGY PERFORMANCE: COMPATIBILITY CHALLENGES?

Manja VANHAELEN

P.024 URBAN FORMS, TYPOLOGY AND IMPROVING THE ENERGY EFFICIENCY OF OLD BRUSSELS BUILDINGS Julien BIGORGNE

P.036 THE LISTED HOUSES OF THE LE LOGIS AND FLORÉAL GARDEN CITIES ADAPTATIONS TO CURRENT ENERGY AND COMFORT NEEDS

Guido STEGEN

P.048 FINANCIAL IMPACT OF ENERGY EFFICIENCY MEASURES IN LE LOGIS AND FLORÉAL Jonathan FRONHOFFS 4

THE ENERGY FUTURE OF EXISTING BUILDINGS IN BRUSSELS: BETWEEN PRESERVATION AND PERFORMANCE

P.056 ANALYSIS OF UNCERTAINTIES IN DYNAMIC THERMAL SIMULATIONS FOR OLD HOUSING: A CASE STUDY OF ONE APPARTMENT AND ONE HOUSE IN THE PARIS REGION

Julien BORDERON

P.064 RISK ANALYSIS FOR APPLYING INTERIOR INSULATION IN HISTORICAL BUILDINGS: A CASE STUDY OF THE FORMER VETERINARY SCHOOL IN ANDERLECHT Roald HAYEN

P.076 IEDER ZIJN HUIS: THE RENOVATION OF A MODERNIST SOCIAL HOUSING TOWER BLOCK Charlotte NYS

P.094 PRESENTATION AND RESULTS OF THE “PLAGE” PROJECTS LOCAL ACTION PLANS FOR ENERGY MANAGEMENT

Emmanuel HECQUET

P.100 THE BELGIAN BUILDING RESEARCH INSTITUTE: A CONTRIBUTION TO HERITAGE MAINTENANCE EXPLORING THE TRAINING OF HERITAGE ADVISORS SPECIALISING IN ENERGY

Michael DE BOUW and Sandrine HERINCKX

P.106 SUSTAINABLE RENOVATION OF A BRUSSELS HOUSE: A CHALLENGE FOR BUILDING TRADESMEN

Jérôme BERTRAND

P.118 CONCLUSION

Benoît PÉRILLEUX

P.086 THE BRUNFAUT TOWER: PRESENTATION OF THE CONCEPTUAL DESIGN CHALLENGES OF A RENOVATION

P.120 COLOPHON

Vincent DEGRUNE 5

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EDITORIAL Brussels Heritage online is the first digital edition of the periodical of the same name. Devoted to the proceedings of the symposium on “The energy future of existing buildings in brussels: between preservation and performance”, it contains the contributions presented during the one-day seminar organised by Brussels Urban Development, which was held in the Royal Library of Belgium on 11th December 2014. The purpose of this seminar was to lay the groundwork for a collective examination by all administrations and actors in the heritage and energy sector to find solutions, over the long term, to achieve a better balance between the necessary preservation of Brussels’ buildings and the no less necessary search for energy efficiency in these buildings. In order to identify the issues and determine the key elements for future projects, we invited specialists from Brussels and abroad and from a variety of backgrounds (including energy engineers, architects, art historians and engineers) to share their experiences and thoughts and compare their perspectives. The seminar opened with a general outline of the issues, examined in turn by Michael Govaert and Manja Vanhaelen via the regulatory texts and a questioning of the practitioners concerning their implementation and objectives. Case studies also featured prominently in the programme for the seminar. The issue of improving energy performance was first tackled at regional level as the reduction in consumption that we are aiming for must be considered in relation to the urban form, as emphasised by Julien Bigorgne, and not only based on a particular building in isolation. This broad context is reflected in the management plan for Logis-Floréal, presented by Guido Stegen and Jonathan Fronhoffs. This regulatory text, which takes an innovative approach to the management of Brussels’ heritage, sets out the general conservation guidelines for the biggest collection of listed buildings in the Region while also clearly defining the works that are permitted. In this way, the Region has developed a clear framework in which conservation objectives can be identified by working on the buildings on a case-by-case basis, while giving due consideration to concerns relating to energy, economics, maintenance and comfort. Specialised topics concerning the assessments to be carried out prior to any work on a building were also 6

addressed via presentations by Julien Borderon and Roald Hayen; the former examining the uncertainties associated with thermal simulations applied to old buildings and the latter reporting on the risks of problems inherent to the use of interior insulation, using the listed former veterinary school in Anderlecht as an example. As the notion of heritage has broadened over the years, we chose to present examples of renovation involving two social housing tower blocks. This provided an opportunity to explore the future of these buildings (the heritage value of which is often disputed) which are at risk of demolition even though they contain a number of tangible advantages from a renovation point of view. Using these two examples, the underlying issues of embodied energy, sustainability of fittings and the cultural value of these structures were explored. Finally, presentations were delivered addressing actions on the ground and projects concerning better management of energy in these buildings, as well as raising awareness among residents and training of trades. This was an opportunity to learn about the positive impact of the Local Action Plan for Energy Management (PLAGE) coordinated by Brussels Environment, the Belgian Building Research Institute’s joint energy engineer/restorative architect training project and, finally, to highlight the new challenges facing craftspeople working on the renovation of Brussels’ houses to improve energy efficiency and also preserve their architectural and structural characteristics. Through all these themes and the different interpretative frameworks applied to the issues raised, a number of important points of agreement emerged: the certainty that there is no magic solution; that uncertainties are unavoidable; that the complexity of the objects on which we work is real and must be better taken into account; that it is essential for experimentation and evaluations to be carried out; and, over and above all, that the resident must be the prime focus of any approach. This analysis can only encourage us to work together to respond to the challenges of the city of tomorrow.

Thierry Wauters Director. Direction des Monuments et Sites.


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A WORD OF WELCOME It is my pleasure to welcome participants, on behalf of the Regional Public Service and, in particular, Brussels Urban Development, to this one-day seminar on the energy future of Brussels’ buildings. This seminar arose from an observation that we share with many other conurbations and towns: thermal insulation improvement works have become one of the major issues in projects to renovate and restore existing buildings. These works are often complicated, the can be documentation complex and varied, and works are sometimes carried without professional advice. There is a real risk of such work damaging the architectural value of buildings and the urban landscape without necessarily achieving the expected results. However, we are responsible for the management of a city that has a heritage character and our duty is to preserve this character- preserve the heritage that we have inherited - while making sure that we do not transform the city into a museum. On the contrary, we must make sure that it will be capable of responding to the challenges and changes that await it - demographic boom, energy dependence, mobility, etc. - without spoiling it. It is a significant challenge. The energy future of our existing buildings is therefore a crucial issue which concerns the management of the city today as well as its future development. This oneday seminar is just one step lead by the desire to conduct a joint debate on the issue, within Brussels Urban Development on the one hand, and between Brussels Urban Development and Brussels Environment on the other.

efficiency; preserving the heritage value of buildings and the urban landscape; economic and social constraints; etc. Let’s not bury our heads in the sand; this is a difficult process and the subjects are complex, which is why it is becoming urgent and essential to conduct a joint reflection rather than examining the issues separately. It is also important that this process of reflection involves the experts - the operators in the field - from the energy, environment, architecture, heritage conservation, construction, urban planning and urban sociology sectors. This is why I have been delighted to see so many colleagues from this sectors in attendance. I hope that points of view will be compared, that knowledge, practices and experience will be shared and that this discussion fuels a joint debate so that we can develop operational policies and tools in future in consultation together. Before handing over to Mrs Bety Waknine from the Minister-President’s office, I would like to thank all the departments from Brussels Urban Development and, in particular, the Monuments and Sites Department (which coordinated this project), Brussels Environment, as well as the Royal Commission of Monuments and Sites (which participated in the preparation of this seminar). I would also like to thank the speakers for having responded to our invitation.

We all have to confront these problems and difficulties in our role as public managers and we are obliged to provide solutions to our fellow citizens and advise them in these complex and costly matters. These solutions must be aimed at reconciling the various issues of sustainable development: energy

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Arlette Verkruyssen General Director of Brussels Urban Development of the Brussels Regional Public Service


A WORD OF INTRODUCTION On behalf of the Minister-President, I’d like to thank all the participants for taking part in this seminar in such large numbers. The government’s adoption of the Brussels Air, Climate & Energy Code in May 2013 demonstrated its firm intention to take action to reduce greenhouse gas emissions and gaseous pollutants while ensuring affordable access to energy for households in the Region. This code, based on the Air-Climate-Energy Plan, includes among other things the measures to be implemented to improve energy efficiency in public buildings and achieve targets for reducing energy consumption, namely a 30% reduction in greenhouse gas emissions by 2025 compared to 1990 levels. The issue of energy efficiency is generally associated with buildings (both residential and non-residential), tertiary activities and transport. Insofar as buildings are concerned, housing is one of the biggest consumers of energy. There are obviously a variety of reasons for this: lack of building maintenance, obsolete technical installations, poor insulation, inappropriate occupation or use of buildings, etc. The combination of these factors can result in energy insecurity with significant financial and health implications, particularly among already economically disadvantaged populations. The issue of energy efficiency in existing buildings is fundamental. The Region already has a range of tools available to it to take action and improve the situation: four-year plans by the Brussels-Capital Region Housing Company; Sustainable or Renovation Neighbourhood Contracts; building façade improvement grants; subsidised works and mobility plans. Nevertheless, increasing the number of such mechanisms does not always make them effective. The onerousness of the procedures involved, the waiting time, the complexity of the mechanisms and the lack of monitoring of results has not always enabled the expected outcomes to be achieved. This is why the Government wanted, at this opening session of parlia-

ment “to assess and amend the system of renovation grants so that they are primarily aimed at those who really need them (...) and reassess the system for renovation and energy grants (...) with a view, in particular, to uniting the two mechanisms”. The government also wanted to shift the focus of current energy grants from new passive and low energy construction to energy saving works. This reassessment should also enable just consideration to be given to the architectural and heritage quality of our City and Region. The balance between conserving heritage and energy must be achieved. Our actions must be aimed at finding this balance between building performance and preservation; such a balance can only be found if we take into account the specific characteristics of the old fabric in order to work on buildings in an intelligent manner and reduce energy costs without creating structural problems that would endanger the long term objectives being pursued. By renovating the city, enhancing our heritage, working on the urban fabric and improving living conditions, we are looking towards the long term. Clearly, the efforts required are significant, the project complex, the parties involved numerous and the resources limited. However, it is possible to reconcile heritage and energy; there are numerous links between the two issues and by encouraging discussion, by bringing together the different trades, by posing issues and debating what’s at stake, common lines of thought can be mapped out. Faced with such complex challenges, a cross-disciplinary effort to raise awareness and advise our fellow citizens will have to be carried out. The administrations and associations will have an essential role to play. Thank you and I hope you have a day filled with intense discussion and ideas!

Bety Waknine Deputy Minister-President Rudi Vervoort.

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WHAT ARE THE REQUIREMENTS FOR THE ENERGY PERFORMANCE OF BUILDINGS WHEN RENOVATING? MICHAËL GOVAERT

ENERGY DIRECTORATE, BRUSSELS ENVIRONMENT

SINCE 2 JULY 2008, THE ENERGY PERFORMANCE OF BUILDINGS (EPB) WORKS REGULATION, WHICH IMPOSES VARIOUS ENERGY PERFORMANCE REQUIREMENTS, HAS APPLIED TO RENOVATION PROJECTS SUBJECT TO PLANNING PERMISSION IN THE BRUSSELS-CAPITAL REGION The purpose of this presentation is to outline the energy performance requirements applicable to renovation projects and demystify the regulations. Indeed, there are numerous fears circulating within the sector that are often the result of miscommunication.

THE CONTEXT BEHIND THE ENERGY PERFORMANCE OF BUILDINGS (EPB) REGULATION As the audience is likely already aware, we currently face the dual dilemma of global warming and increasing energy prices. The issues that we have to deal with are therefore both environmental and social. In Brussels, buildings account for 70% of energy consumption; they are therefore the main source of greenhouse gas emissions and one of the main

sources of atmospheric pollution in the city. Since 2008, the Brussels-Capital Region has had a legal instrument at its disposal for improving the energy performance of buildings, namely the Ordinance on Energy Performance and the Internal Climate of Buildings. This ordinance transposes into Brussels law the 2002 European Directive on the Energy Performance of Buildings, the measures of which were strengthened in 2010 in light of the deteriorating situation. In this respect, the second draft of this directive provides for new buildings to be almost zero-energy by 2021. The Brussels Air, Climate and Energy Code (COBRACE) has incorporated these new European provisions in its EPB section. They come into force on 1st January 2015. There are multiple objectives: reducing primary

10 | What are the requirements for the energy performance of buildings when renovating?

energy needs to preserve natural resources; reducing CO2 emissions to combat climate change; improving the energy efficiency, internal climate and the technical installations of buildings; as well as informing any future owner or tenant about the energy rating of the desired property via the EPB certificate. As part of the rewriting of the ordinance with a view to its incorporation within COBRACE, the “EPB Works” administrative procedure has been redesigned and simplified. I will therefore explain the “EPB Works” Regulation as it works in practice from 1st January 2015. It is worth noting that this designation refers to the section of the EPB regulation devoted to the energy performance requirements imposed within the context of a construction or renovation project.


THE SCOPE OF APPLICATION OF THE “EPB WORKS” REGULATION

school. It is on the basis of the unit that the nature of the works and the occupancy are determined.

As a first step, it is important to highlight that the EPB does not apply to all buildings and to all occupancies. The European Directive specifies exceptions, including places of worship, industrial or craft workshops, and temporary structures, among others. Only buildings occupied on a continuous basis and in which energy is used for people’s comfort come within the scope of the EPB. What’s more, the “EPB Works” regulation only applies within the context of an application for planning permission. It does not therefore apply to works that involve only renovations that are identical to the original building. It concerns all new buildings and, in buildings undergoing renovation, only buildings on which works are being carried out on the envelope and that may potentially influence the energy efficiency of the building. It does not therefore concern maintenance, painting or application of rendering without insulation.

The EPB Regulation defines four distinct categories of work (table 1): 1° New units (NU) which correspond to new-build projects, e.g. a house constructed on a greenfield site. 2° Units considered as new (UCN). These have caused the most ink to be spilled. This category is the result of an amalgamation between units that have been extensively renovated and units considered as new. Units considered as new are defined as units where works are carried out on at least 75% of their heat loss surface and by the replacement of all the technical installations. This category is only encountered very rarely: it concerns, for the most part, buildings that are completely stripped and of which only the

THE EPB UNIT, NATURE OF WORKS AND OCCUPANCIES It is the nature of the works and the occupancy that determines the EPB requirements applicable to a project. In order to find out what these requirements are, the project is split into buildings and EPB units. While the meaning of building is clear to everyone, that of unit needs to be explained as it is specific to the EPB. An EPB unit is a part of a building or a building complex. It is formed by a group of adjoining premises which are used for a single occupancy and which could be sold or rented separately. It typically concerns an apartment, a house, an office building or a

Nature of worksaccording to COBRACE

structure is retained. It should be specified that the heat loss surface corresponds to all of the thermal envelope, that is to say the façades, roof, floor slab, etc. 3° Extensively renovated units (ERU) which are defined as units where works are carried out on at least 50% of their heat loss surface and on at least one or two technical installations, depending on the occupancy. 4° Finally, simply renovated units (SRU) which are defined as units where works are carried out on the heat loss surface and on technical installations that are not covered under the other definitions. Extensively renovated units and simply renovated units can be distinguished from each other by different procedures. However, currently, the requirements are strictly the same.

NU

UCN

ERU

Percentage of works, on the heat loss surface, influencing the EPB

100%

≥ 75%

≥50%

Works on technical installations

New technical installations.

Works on the heat loss surface and replacement of all technical installations.

SRU

Works on the heat loss surface (and on technical Works on the installations) heat loss surface and on not covered at least one or by the other definitions. two technical installations depending on the occupancy.

Table 1 Summary of nature of works. The EPB requirements for high energy efficiency inspired by the passive standard only apply to new units and units considered as new, and only for three types of occupancy: housing, offices and schools (source: BE).

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THE EPB REQUIREMENTS FOR INSULATION AND VENTILATION

1.1 W/m2K for the glass. This is what is traditionally available on the market.

For all EPB units that are extensively or simply renovated, only two requirements have to be satisfied: insulation and ventilation. The insulation requirement solely concerns the modified walls of the envelope, namely (where appropriate) the walls, floor, roof or windows. Where a window is added or replaced there is also a ventilation requirement for the premises in question. In fact, the EPB is not only connected with energy consumption; it is also aimed at improving the quality of the internal air. These two requirements, insulation and ventilation, exist in an identical form in the three Regions of the country. As regards the insulation requirement, the Regions have (with the support of the Belgian Building Research Institute (BBRI)) set the heat transmission values that every project, including any modification of walls, must satisfy when applying for planning permission as of 1st January 2014. For walls and roofs, the maximum U-value is 0.24 W/m2K. This value gives the following indicative thicknesses (tables 2 and 3), which vary depending on the type of insulation. In this way, the thickness of the insulation for a wall will vary from 9 to 17 cm. While these thicknesses seem significant, the requirements are cost optimal, as required by the European Directive. When carrying out works it is important to keep in mind that they are generally not repeated for at least thirty years and it is therefore important to have a long term vision and reflect on the irreversibility of the changes made and what impacts they will have on energy over time. For windows, the maximum U-values are 1.8 W/m2K (including frame) and

The ventilation required when a window is replaced or added ensures a healthy climate by removing waste air (humidity, domestic pollutants, etc.) There are four systems of ventilation:

natural ventilation; mechanical ventilation; and hybrid versions of the two systems. The EPB does not require a particular system but simply sets down the rates of ventilation which, for housing, are well known by the sector (those of the NBN50001 standard, in force since 1991). Added to this requirement for healthy ventilation is (in the

Structural element

Umax (W/m2K)

Rmin (m2K/W)

1. WALL DELINEATING THE PROTECTED VOLUME excluding walls forming the separation with an adjacent protected volume 1.1. TRANSPARENT/TRANSLUCENT WALLS excluding doors and garage doors (see 1.3), curtain walls (see 1.4) and glass bricks (see 1.5)

Uw max = 1.8 and Ug max = 1.1

1.2. OPAQUE WALLS excluding doors and garage doors (see 1.3) and curtain walls (see 1.4) 1.2.1 Roofs and ceilings

Umax = 0.24

1.2.2. Walls not in contact with the ground excluding walls referred to in 1.2.4

Umax = 0.24

1.2.3. Walls in contact with the ground

Rmin = 1.5

1.2.4. Vertical and sloping walls in contact with crawl spaces or with a cellar outside the protected volume

Rmin = 1.4

1.2.5. Floors in contact with the outside environment

Umax = 0.3

1.2.6. Other floors

Umax = 0.3 or

1.3. DOORS AND GARAGE DOORS (including frame)

Ud max = 2.0

1.4. CURTAIN WALLS (according to prEN 13947)

Ucw max = 2.0 and Ug max = 1.1

1.5. GLASS BRICK WALLS

Rmin = 1.75

Umax = 2.0

2. Walls between two protected volumes situated on adjacent plots

Umax = 1.0

4. Opaque walls inside the protected volume or adjacent to a protected volume on the same plot excluding doors and garage doors

Umax = 1.0

Table 2 Insulation requirements. U/R-values (since 1st January 2014) (source: BE). Type of wall

Umax since 01/01/2014 (W/m2.K)

Lambda value of the insulation

Thickness in cm of mineral wool type insulation (λ = 0.045 W/mK)

Thickness in cm of plant wool type insulation (λ = 0.04 W/mK)

Thickness in cm of synthetic foam type insulation (λ = 0.035 W/mK) (3)

Thickness in cm of PIR foam type insulation (λ = 0.023 W/mK)

0.045

0.04

0.035

0.023

Sloping (or flat) roof, 80%/20% insulation between rafters

0.24

26

25

24

20

Flat (or sloping) roof, continuous insulation on wooden structure

0.24

16

15

13

9

Flat (or sloping) roof, continuous insulation on concrete structure

0.24

17

15

13

9

Exterior wall (29 cm bricks), external insulation

0.24

17

15

13

9

Exterior wall (14 cm blocks), external insulation

0.24

17

15

13

9

Exterior wall wooden framework

0.24

20

19

17

14

Heavy floor in contact with exterior

12

11

10

7

Heavy floor on ground

9

8

7

5

Heavy floor over cellar with door and window

9

8

7

5

Table 3 Insulation requirements. U/R-values (since 1st January 2014). Example of indicative insulation thicknesses that comply with the EPB regulation (source: BE).



case of housing) intensive ventilation, which enables a rapid solution to be provided for problems of overheating or excess pollution. In this case, the requirement is a simple obligation to have a minimum opening.

POSSIBLE EXEMPTIONS It is sometimes impossible to comply with the requirements. For this reason the Brussels Government has provided the option of applying for exemptions, both for renovations and new builds. The client submits the application before the project begins, either to Brussels Environment, or (if it concerns a simple renovation) to the issuing authority, which assesses the application and then grants or refuses the exemption. The client may submit an appeal to the Government if not happy with the decision. There are two types of exemptions. The first is called a “heritage” exemption as it concerns listed buildings or buildings that are included on the list of protected structures. This type of exemption applies where full, or even partial, compliance with the requirements would affect conservation of the architectural heritage. It is granted directly by Brussels Urban Development. The second case concerns non-listed new buildings, buildings considered as new and/ or renovated buildings. The exemption is possible where full or partial compliance with the requirements is technically, functionally or economically impracticable. An exemption will be granted: 1° For technical reasons, where the works pose problems for the stability, fire resistance, air or water tightness of the wall or

building, or if there is no material or product available that enables compliance with the requirements. 2° For functional reasons, where the insulation and ventilation works or additional works subsequent to such works endanger the use of the building, disproportionately harm the architecture or result in non-compliance with planning constraints. 3° For economic reasons, where the cost of the insulation and ventilation works, including any additional works subsequent to the insulation and ventilation works, is three times greater than the cost of works of the same type in another building. Between 2008 and 2014, only 37 applications for exemptions were submitted to Brussels Environment and more than two thirds were granted. Those based on the requirements drawn from municipal regulations were systematically approved. From 1st January 2015 exemptions for simple renovations are no longer processed by Brussels Environment but instead are handled directly by the authorities that grant planning permission. Finally, it is worth reiterating that there is no obligation to comply with these requirements. Where a project does not comply with them, the client will be required to pay a fine but planning permission will not be refused and they will not be required to make it compliant.

lation. We are also supported by a scientific consortium composed of the BBRI, consultancy firms and universities. We invite you to participate in this continuous improvement loop. Respecting heritage and improving energy efficiency can be mutually beneficial, particularly through regular consultation between the actors concerned. Brussels Environment is about more than just a regulation; it’s also a financial support that can be activated via the “energy bonuses” and the “Brussels green loan”. It also comprises technical support, assistance with applying the regulation and assistance with technical design. There are many information tools available on the Brussels Environment website (the “EPB Works” pages, the Sustainable Buildings guide, etc.) Finally, we organise an entire range of training courses and seminars on sustainable construction aimed at training for excellence. We have outsourced a support service for professionals called the “Sustainable Buildings Facilitator” service. As regards assistance for private individuals, every municipality has an EPB official who assists people in understanding the legislation. We also support the “regional information desks” that provide citizens with personalised support for their energy problems. Translated from French.

CONCLUSION The EPB regulation is evolving. In order to do so it relies on feedback from professionals, architects and contractors as well as the administrations and municipalities who are helping us to apply the regu13

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EXEMPLARY BUILDINGS

The experience gleaned from exemplary buildings (Batex) constitutes a source of highly interesting information. These projects went further than the EPB Energy Regulation recommended at the time. They were followed up by experts and are currently monitored, which enables us to inform future discussions with concrete facts. Each Batex is presented in detail on the Brussels Environment website.

Fig. 3 Avenue Ducpétiaux 47 in Saint-Gilles. Low-energy renovated standalone house. The façade was retained. It is internally insulated on the non-listed internal sections which concern three of the four floors. The owners opted for the installation of a second window set back from the first in order to preserve the original aspect (A. de Ville de Goyet, 2015 © SPRB).

Fig. 1 Rue Rubens 92 in Schaerbeek. Low energy, single-family dwelling house, 39 kWh/m2/year. The front façade was retained and the joinery, although triple-glazed, was reproduced to exactly match the original setup. The front façade was internally insulated and, in order to respect the heritage, certain bands were left without any insulation (A. de Ville de Goyet, 2015 © SPRB).

Fig. 2 Avenue Besme 107-109 in Forest. Apartments and offices. Art Deco style low energy building. The window frames on the front façade were retained and renovated with the single-glazing being replaced with double-glazing 1.1 (A. de Ville de Goyet, 2015 © SPRB).

Fig. 4 Rue du Comte de Flandre 45-51 in Molenbeek-Saint-Jean. Mommaerts workshops, the front façade of which is listed. It was not insulated internally but a low energy solution was, nevertheless, achieved. (A. de Ville de Goyet, 2015 © SPRB).

Fig. 5 Rue Royale-Sainte-Marie 237 in Schaerbeek. Apartment building. Almost passive example of a building included on the list of protected structures, the façade of which was retained (A. de Ville de Goyet, 2015 © SPRB).



WEBSITE • All information about the EPB, training courses and seminars is available on the website: www.environnement.brussels

SUPPORT SERVICES Professionals • Sustainable building facilitator: [email protected] Private individuals: • Municipal EPB officers • Maison de l’énergie/Energiehuis: www.maisonenergiehuis.be

Quelles exigences PEB en rénovation ?

Welke EPB-eisen bij renovatie?

Depuis le 2 juillet 2008, les projets de rénovation soumis à un permis d’urbanisme en Région de Bruxelles-Capitale sont concernés par la réglementation Travaux PEB qui impose différentes exigences de performance énergétique. Dans la plupart des cas, il s’agira d’exigences d’isolation des parois et de ventilation. Pour les rénovations de plus grande envergure (plus de 75 % de la surface du mur), dont l’ampleur des travaux est à comparer à une construction neuve, le projet devra également répondre à de nouvelles exigences inspirées de l’expérience des Bâtiments exemplaires et du standard passif.

Voor renovatieprojecten die onderworpen zijn aan een stedenbouwkundige vergunning in het Brussels Hoofdstedelijk Gewest. In de meeste gevallen gaat het om eisen inzake isolatie van muren en ventilatie. Voor grootschalige renovaties (meer dan 75% van de uitgevoerde werkzaamheden aan de oppervlakten met warmteverliezen), waarbij de omvang van de werken vergelijkbaar is met nieuwbouw, zal het project eveneens moeten voldoen aan nieuwe eisen geïnspireerd op de ervaring met de voorbeeldgebouwen en de passieve standaard.

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ARCHITECTURAL HERITAGE AND ENERGY PERFORMANCE: COMPATIBILITY CHALLENGES? MANJA VANHAELEN

MONUMENTS AND SITES DEPARTMENT

THIS ARTICLE COMPRISES AN OVERVIEW OF THE ISSUES WITH WHICH THE MONUMENTS AND SITES DEPARTMENT IN PARTICULAR, AND THE HERITAGE SECTOR IN GENERAL, ARE CURRENTLY CONFRONTED WHEN APPLYING LEGISLATION REGARDING THE IMPROVEMENT OF THE ENERGY PERFORMANCE OF BUILDINGS. With recent advances in the battle to reduce CO2 emissions and improve the energy efficiency of buildings, the heritage sector has been looking for a new way to deal with architectural heritage within that context. The assumption that heritage and energy performance are placed in direct opposition may seem like something of a caricature; in many building dossiers, the applications we are confronted with in reality sadly do resemble this harsh depiction of two sides performing contradictory actions on each other’s terrain.

THE TASK OF THE HERITAGE CONSERVATOR Let us first take a closer look at the role of the heritage conservationist. Essentially, the heritage conservationist is charged with preserving heritage; he or she ensures that buildings, as expressions of an architectural past, of culture and of savoir faire, are preserved. This includes preservation

of materials from the past, monuments and their valuable aspects and facets such as decorations, details, materials, techniques, architecture from the various construction periods (from Gothic to Renaissance and Eclecticism to the late Modernism of the 1950s and 1960s), and the preservation of expression, concept and urban design context. In this way, monuments are passed on to future generations as witnesses of history, culture, science and knowledge. Heritage conservationists guide monuments towards their future while battling against natural erosion and the ageing of buildings, damage caused by natural disasters, wars or even previous restoration attempts. They also strive to guide the monuments through the heritage renewal, through renovations, new allocations, adaptations to styles, flavours, comfort requirements and of course the energy performance improvement requirements. Exactly what is deemed valuable depends on

16 | Architectural heritage and energy performance

the monument. Sometimes it is a unique expression, sometimes it is the old material with a unique historical testimony, sometimes it is the concept or idea behind the building rather than the materials. The heritage conservationist’s task is supported by a theoretical framework based on the 1964 Venice Charter. The legislation in use and under development today also stems from this charter. The two cornerstones of this restoration philosophy are as follows. Firstly a good knowledge of the monument is imperative; this highlights the importance of thorough research prior to any intervention, both historical and technical as well as any other research. This allows us to recognise what is truly valuable and make a decision on how to intervene or not. The second cornerstone is respecting a hierarchy in the intervention. Maintenance must always be the top priority. If maintenance alone does not prove sufficient, restoration and repairs are embarked


Fig. 1 and 2 Typical Brussels buildings. Left: Brussels residences around the turn of the last century (Ch. Bastin & J. Evrard © GOB); right: Neoclassical façade facing the Pachecogodshuis, Fermerijstraat, arch. H. Partoes, ca. 1830 (© GOB). None of these buildings can be insulated on the exterior without impacting their heritage value.

upon. An element is replaced only as a last resort and when absolutely necessary. Reconstruction of an identical model is the exception rather than the rule. This approach is highly sustainable in and of itself. I will summarise, based on this intervention philosophy and starting from the essence of the heritage conservationist’s role, why in reality the heritage sector almost always locks horns with the energy sector, despite the energy performance exemption regulation applicable to listed monuments. This regulation is clearly necessary, but simultaneously illustrates the unresolved discrepancies. Furthermore, whether or not a project has permission to deviate from the standard, the applicant’s starting point justly remains the improvement of the situation and/ or an increase in comfort. The requirements of the Energy Performance of Buildings (EPB) energy performance legislation for building and renovating only

apply when works are being carried out and a building permit is also required. However, in reality the opposite happens: an application for a building permit tends to be submitted in order to be able to carry out works with the intention of meeting the EPB standard. The following section details the entire envelope of the building, the skin which forms the transition between a listed and unlisted environment, and the intervention plan for improving energy performance.

INSULATION OF THE FAÇADE Historical façades come in many forms: these might be brickwork façades, austere or polychrome, with decorative masonry, interspersed with limestone or façades made solely of limestone, with sculptural elements or a rather plain Neoclassical façade in white lime plaster with simple mouldings (fig. 1 and 2). These examples are very typical of the Brussels development.

None of these can be insulated on the exterior without losing their heritage value. Exterior insulation may be possible on very simple façades, though a great deal of detailed work remains with such an intervention. What about cohesion with the existing windows? These will be partially covered due to the thickness of the insulation, will appear to be embedded deeper into the façade than they originally were, and the sills will need to be adapted in order to disperse water. What about the eaves and cohesion with receding and protruding features? This type of intervention often leads to visually awkward or technically half-hearted solutions. The ultimate solution for a newbuild project often proves to be a cumbersome operation and never-ending story for a renovation - if I renovate the façade, then I should also do the windows, the roof, the gutters, the extension, the neighbour, etc. If exterior insulation is not possible, then we must use interior 17

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Fig. 3 Dining room in the residence of architect Jamaer, 1876, Stalingradlaan 62, 1000 Brussels (© KIK-IRPA). The rich décors that decorate not only grand Brussels residences, but more modest homes too, make interior insulation impossible without removing the heritage elements.

Fig. 4 The windows and doors are an integral part of the façade architecture. Brugmannlaan 30, arch. Lesec et Quoilin, 1937 (© GOB).

Fig. 5 Diongre garden city, arch. J. Diongre, 1925, Sint-Jans-Molenbeek, (Ph. de Gobert© KCML). The replacement of the historical woodwork has radically altered the character of the façade.

insulation. Unfortunately, this is also often impossible from a heritage point of view because of historical buildings’ décors. Figure 3 we see elegant mouldings, colours and panelling. It is obvious that you cannot just glue insulation board onto this. Nor is this type of décor reserved solely for so-called “top-class” heritage. The interior of many Brussels middle-class homes are quite similar to this. This contributes to the richness of the Brussels heritage. Modern

buildings and concrete structures do not suffer as much from the new, smooth look, but in these cases the technical challenge of solving cold bridges is often a difficult problem.

HISTORICAL WOODWORK Let us now concentrate on the façade and the historical woodwork, the windows and doors. Each period, typology and architec-


tural style is characterised by a different type of woodwork, bringing great diversity to the architectural heritage of Brussels. The windows and doors contribute as no other to the coherent image of the façade and the architecture and are in some cases even small works of art themselves (fig. 4 and 5). They bear witness to the technique and the craftsmanship of yesteryear. But they could also be considered elements of valuable and precious materials: 150 year old oak, for


example, is particularly sustainable. Thanks to its assembly, historical woodwork also allows for easy local repairs. Consequently these elements can attain a considerable life span (fig. 6 and 7).

Fig. 6 and 7 Restoration of doors, Vanderschrickstraat, 1060 Brussels (© GOB).

Some of this historical woodwork can be perfectly equipped with double glazing, subject to adaptation of the groove to accommodate the thicker, double-glass sheet. In most cases however, the necessary fitting of a thicker glass sheet means that the woodwork must also be replaced. Not only can a groove often not be made large enough, but the original woodwork is often not strong enough to carry the extra weight of the glass sheets. Furthermore, extra airtightness is also often a requirement. In this circumstance the choice is often made to use a remake of a quasi-identical model. Depending on the quality of the original woodwork, this may or may not be tolerated. Even if the remake is a solution for woodwork of low value, it is not a solution from a heritage point of view if the original woodwork is still in good condition or has a design of exceptional quality.

Fig. 8

Fig. 9 Fig. 8 and 9 The quality of the glass also influences the choice of intervention. Decorative glazing and remnants of glass production from the past, such as pulled and blown glass or crystal, require a different approach (© GOB).

Fig. 10 In many cases, double glazing or secondary glazing can be an effective and technically feasible solution. It has been used as a solution for a long time now. Knuyt de Vosmaer House, Rue du Congrès/Congresstraat in Brussels (© GOB).

Another aspect is the quality of the glazing itself, because even if the window frame is strong enough for an insulating glass sheet, decorative glazing and examples of remnants of glass production from the past (such as pulled and blown glass, crystal, etc.) still require a different approach (fig. 8 and 9). In many cases, a double window or secondary glazing can be a good and technically feasible solution, yet this is only used sporadically (fig. 10). Even when replacing a window by a higher performance one, this too can become an ongoing saga. 19

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An assessment must be made as to how this new level of performance relates to the original environment, which is of course lower in performance. Installing high-performance glass in a non-insulated wall must be done with care to ensure that a healthy interior climate is maintained. It is also usually necessary to insulate the walls (at least partially) or to install a well-functioning ventilation system. In many cases, adapting the level of insulation can provide a solution. Fig. 11

INSULATION OF THE ROOF As long as an insulation mat is placed between the rafters - i.e. within the material contours there is usually no problem with the roof. However, the standard for each building element requires more; extra insulation on the exterior is often a solution, but it is a very awkward measure in larger wholes, such as the Le Logis-Floréal garden cities (fig. 11). In that case, raising the roof (a necessary step to accommodate the extra exterior insulation) must be carried out in consultation with the neighbours so that the entire row can be renovated, thus avoiding unevenness and awkward-looking connections in the roof surfaces. Even then, cohesion with the façade is not easily solved. The austerity and simplicity of these houses means that few new elements and details suit them. It becomes even more difficult with a roof with dormer windows (fig. 12 and 13); the architectural relationships become distorted and the ornaments lose their elegance due to a somewhat inflated effect. Self-supporting systems are often opted for in order to lessen the 20 | Architectural heritage and energy performance

Fig. 12

Fig. 13

Fig. 11, 12 and 13 Insulation of the roof is indisputably an energy efficient solution. Nevertheless, the problems of installing it around a dormer or on a raised roof over terraced houses must be thoroughly assessed before installation takes place.


formance manifests as a conflict between two sides: restoration-intervention. For instance, a thorough investigation of the monuments’ building elements might be conducted, but the evaluation of their value is threatened by performance requirements which are inflexible and have top priority. There is consequently no more room for the study.

Fig. 14 Hôtel Dewez. Lakensestraat 73, Brussels. Loft, view of the roof trusses and beams (© KIK- IRPA).

Fig. 15 Roof support with visible panels, municipality school indoor play area no. 6, Bordeauxstraat 14-16, Sint-Gillis, 1891, municipality arch. Ed. Quétin (© GOB).

load on the original structure and to apply good, complete insulation. Because these leave the physical space within the original structure of the roof untouched, the extra height becomes even more noticeable (easily 15 cm). Interior insulation is also an option, though of course not if the roof’s interior surface has an aesthetic finish as shown in the example in figure 14. Skylights made of classical T, L and I moulding which form complex, refined structures cannot (in most cases) bear the weight of insulated double-glazing or safety glass (fig. 15 and 16). In many

cases they are rebuilt with sturdy, modern mouldings. The extra load of the added insulation often causes structural problems, thus making the original roofing beams structurally unsuitable. They must therefore be supported or replaced, sometimes with the replacement of the entire roof as a consequence.

HERITAGE CONSERVATION VERSUS ENERGY PERFORMANCE The contradiction between heritage preservation and energy per-

Not only is research into the value of the existing elements lacking, but the evaluation of the effects and side-effects of the mandatory improvements are seldom really thoroughly examined. Nor is the actual performance of old buildings carefully examined; real knowledge of the buildings and all their characteristics has not yet been acquired. The limited research we do have already shows, for example, that the values for actual energy consumption deviate greatly and are mostly much lower than the theoretical values. We seldom see evaluations for the prioritised improvements to be carried out or a thorough investigation to determine what the most gainful intervention actually is. The intervention occurs before knowledge has been acquired and research carried out. In a second example, the measures proposed or taken might be in complete contrast to the sustainable intervention hierarchy. These examples clearly illustrate that in the approach to improve the energy consumption of the elements in existing buildings, replacement and reconstruction often take precedence and have become more the rule than the exception. This is not at all the objective of heritage preservation and actually completely misses the point. 21

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in which energy is generated and how people use and maintain their buildings; then the same questions can be asked on both of the opposing sides - heritage and energy and common answers formulated.

Fig. 16 Preschool, indoor play area after being restored to its original condition, Sint-Gisleinsstraat, arch. V. Horta, 1895 (Ch. Bastin & J. Evrard, 2000 © KCML).

The various examples cited above also illustrate how an intervention to one element often means that a much larger intervention subsequently becomes necessary: insulating the roof quickly becomes replacing the entire roof; insulating windows becomes replacing windows; insulting the façade becomes replacing the façade. In principle, rebuilding monuments with respect for the original appearance but resulting in a high energy performance version is not part of the heritage conservationist’s task. Reconstructing the image, and nothing more - and many interventions intended to improve energy performance have this result - goes hand in hand with the loss of genuineness, authenticity. It’s a new façadism. Such restorations are no longer a sustainable intervention either, and not in the spirit of the task of heritage preservation: that is, to preserve, repair and reuse as much as possible, taking the value

of the elements and the maximum possible life span of the materials into account. The extent to which interventions require radically altering the contours of existing buildings makes it an expensive undertaking. The costs are not always in balance with the benefits. Indeed, quite the contrary can be true: making buildings energy efficient while preserving the heritage appearance comes with a very high price tag. This can mean interventions which are out of proportion on several levels. However, improving the energy performance of buildings also plays a role in sustainability. If we take a step back and shift our focus from the performance requirements for each individual building component to take a more global view, envisioning a long-term future; if not every element must meet maximum performance criteria; if we also consider the way


The improvement of the energy performance of existing buildings also raises questions regarding the life span of the materials; whether replacement is necessary; and whether replacement is dealt with in a responsible manner, such as taking into account the energy needed for waste disposal and production of new materials, or whether we can reuse materials. In this common field, it must be possible to examine the elements’ specific values (material, cultural, financial, historical, etc.). it must also be possible to examine the intrinsic qualities of the existing buildings and to evaluate whether or not we can operate them or use them in a more energy-efficient way. Consider, for example, inertia, density, ventilation options, etc. It must be possible to search for a healthy balance between the extent of the operations and the potential benefits (financial, energy-related, material, etc.). Is there a good return on investment time? It must be possible to evaluate the real impact of the interventions by measuring the results in order to adjust calculations and models. Finally, it must also be possible to carry out a thorough analysis of the possible risks and the side-effects (condensation, frost, moisture, etc.). This way of thinking will lead to a global approach and higher global-efficient performance; an upgrade at building, block and city level; and to high energy performance historical cities. Translated from Dutch.


Patrimoine architectural et énergie : des enjeux conciliables ?

Bouwkundig erfgoed en energie: verzoenbare uitdagingen?

Il existe un paradoxe dans la manière d’aborder la conservation du patrimoine architectural et l’économie d’énergie. Actuellement, les rénovations pour raisons d’économie d’énergie sont de plus en plus nombreuses et touchent un grand nombre de bâtiments historiques, classés ou non. S’il apparaît évident qu’un bien à caractère patrimonial doit participer à l’effort de réduction des gaz à effet de serre, il apparaît tout aussi évident que les interventions menées doivent prendre en compte les caractéristiques architecturales et constructives de ce bâti, pour que la démarche ne soit pas contreproductive.

Er bestaat een tegenstelling tussen de aanpak voor het behoud van het architecturaal erfgoed en de maatregelen voor energiebesparing. Het aantal renovaties met het oog op energiebesparingen neemt tegenwoordig alsmaar toe en betreft een groot aantal historische gebouwen, al dan niet beschermd. Het lijkt evident dat een pand met erfgoedwaarde moet deelnemen aan de inspanning om de broeikasgassenuitstoot te verminderen, maar het lijkt evenzeer vanzelfsprekend dat de ingrepen rekening moeten houden met de architecturale en bouwkundige kenmerken van het gebouw, opdat de aanpak niet contraproductief zou zijn.

À travers des cas concrets d’intervention sur du bâti classé et non classé, cette contribution brossera le cadre de la problématique de ce paradoxe et introduira les pistes pour promouvoir une application de la PEB compatible avec le patrimoine architectural.

Aan de hand van concrete gevallen van ingrepen aan beschermde en niet-beschermde gebouwen schetst deze bijdrage het kader van de problematiek van deze paradox en reikt ze pistes aan om een toepassing van de EPB aan te moedigen die verenigbaar zijn met het architecturaal erfgoed.

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URBAN FORMS, TYPOLOGY AND IMPROVING THE ENERGY EFFICIENCY OF OLD BRUSSELS BUILDINGS JULIEN BIGORGNE

ENGINEER, PARIS URBAN PLANNING AGENCY

THIS STUDY, COMMISSIONED BY THE BRUSSELS-CAPITAL REGION, STEPS OUTSIDE THE WELL-TRODDEN SCOPE OF BUILDING-CENTRIC ENERGY STUDIES AND INSTEAD TAKES A SYSTEMS-WIDE APPROACH. IT INCLUDES PARAMETERS USUALLY IGNORED BY THIS TYPE OF WORK AND QUESTIONS PRACTICES CENTRED ON THE APPLICATION OF STANDARDS. This study, carried out at the request of the Brussels Region, was finalised in 2012. We were asked to apply a method that we had previously trialled in Paris to evaluate the thermal capacities of old buildings and to incorporate it into the research currently underway regarding improvement of the energy efficiency of Brussels’ architectural heritage. The full report is available on the website of the Monuments and Sites Department. This presentation is a summary of our work. I will firstly return to the working methodology, as well as the three scales of assessment of the problem that we took into account: region; city; and building. I will not spend a lot of time on the first as it was covered in the presentation on the EPB (see pp. 10-15).

I will then focus on issues related to urban forms before coming to those relating to buildings.

THE BROAD OUTLINE OF THE METHODOLOGY We are, in the medium term, facing a dual challenge: supplies of energy for urban systems, dependence on which will have to be reduced, and climate change, which means reducing greenhouse gas emissions and adapting the territory to this change. In order to respond to these issues, Europe is proposing a regulatory mechanism (“3x20”) up to 2020. Application of this mechanism generally passes from the European Union to the country or region that then applies it directly

24 | Urban forms, typology and improving the energy efficiency of old Brussels buildings

to the building. This means that the energy question is rarely considered at district level. However, before working on a building, it is important to consider its direct environment, to think about the role it plays in relation to its neighbours. It is therefore this method that we favoured in our approach. There are two characteristics of our work: it is exploratory and illustrative. Exploratory, as it opens up avenues that include energy-related elements but which are absent from the regulations. In this way, we are trying to apply a method that goes beyond simply taking the regulatory standards into account and enables us to expand the research. It is also illustrative as the purpose of this


Location of sites Housing blocks used for the calculation phases Housing blocks that were the subject of field visits and thermal analysis (1A) MUNICIPALITY OF SCHAERBEEK and St JOSSE-TEN-NOODE “Housing block 18” Rue GUSTAVE FUSS

Housing blocks preselected by the Monuments and Sites Directorate Building audited using the Energy Audit Procedure method and the subject of field visits

MUNICIPALITY OF WOLUWE St PIERRE Town Hall quarter “Housing block 4A and 4B” Rue MARTIN LINDEKENS

MUNICIPALITY OF ANDERLECHT JARDIN: LA ROUE quarter Plaine des Loisirs MUNICIPALITY OF IXELLES TENBOSCH quarter “Housing block 2A” Rue Américaine

MUNICIPALITY OF IXELLES BERKENDAEL quarter “Housing block 1A” Rue de la Réforme

Fig. 1 Location of the sites studied (Produced with Brussels Urbis © CIRB).

mission is to present a method that enables more extensive work to be started on changes to the energy performance of Brussels’ built heritage. A six-month long project does not permit a large quantity of work to be carried out. Nevertheless, in order to have a representative panel, we have chosen ordinary architecture, i.e. buildings that have been replicated citywide over fairly large territories. These structures are not always the work of architects. They involve property development, housing estates, average houses, etc. from which we have attempted to identify the problems associated with renovations. The raw material for our work was made up of 21 “typical” blocks

pre-selected in agreement with the Monuments and Sites Department; 11 buildings audited using the Energy Audit Procedure method by Centre Urbain; “infrared” thermal analysis carried out on the selected sites; and research in the archives of the municipalities concerned (fig. 1).

METHODOLOGICAL CONSIDERATIONS AT A REGIONAL SCALE The energy issue must be thought of as a series of “tiles”, or systems, involving multiple parameters. The occupant of a building doesn’t only use energy for heating. He or she also moves around: this is a question of transport. He or she has

a high or low income: these are socio-economic questions. When energy costs rise, certain items are squeezed and others not. There are therefore territorial inequalities in terms of energy. Considering energy dependence as a factor of vulnerability means territorialising energy consumption and, therefore, revealing the region’s already existing or future inequalities. However, this is not incorporated within the regulations as, in short, they assume that all buildings are to be viewed in the same way and that the same method and objective should therefore be applied to them without distinction. However, it appears that it’s not so simple. The people in charge of planning, and particularly energy planning, must carry out the relatively complex 25

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process of overlapping the different territorial “tiles”.

URBAN FORM: REDUCING ENERGY CONSUMPTION IS PRIMARILY A TERRITORIAL CONCERN, NOT A BUILDING-RELATED ONE A building never exists as a separate entity. It is always one element in a larger-scale composition. As soon as it is designed, it is envisaged within and in relation to its environment (e.g. logic of sub-division, rationale behind the “greening” of urban spaces, etc.). The urban form enables us to easily document these elements relative to energy consumption and to draw out elements for analysis. An examination of building contiguity is interesting in this regard. Historically, in order to compensate for the absence of efficient heating systems, buildings were constructed adjoining each other. By grouping houses together in this way, heat loss surfaces were

reduced, thereby also proportionally reducing energy consumption. In new, fully insulated buildings, this fact is less important. However, in old, non-insulated buildings, contiguity was already being used as an energy strategy. Any evaluation of the intrinsic qualities of a building, prior to any work, must take this essential fact into account. Figure 2 illustrates the density of buildings over time in a series of seven housing blocks. A move away from contiguity and greater consumption of space can be seen. One of the historical reasons for this phenomenon is linked to the definition of a town as a place of exchanges, where the distances needed to be short to facilitate travel by foot or by horse. There was a historical benefit in the town being compact. This design is also valid for buildings. The more compact they are, the more “liveable” they become. Over time, with better heating systems and other modes of transport, towns began

to spread out, consuming more territory. In the diagram, this is illustrated by a reversal of the ratio of open to built-up areas. The consequences of these changes were significant. In the 19th and 20th centuries there was a reversal in the amount of green spaces. This fact must be taken into account because when talking about urban heat islands, urban microclimates and summer comfort, we are dealing with an old and dense city. This means that in winter the energy consumption of a building is, theoretically, less significant than in peri-urban areas. However, when a thermal audit is carried out, the data used often to come from peri-urban weather stations, which can skew the initial calculations. For example, if the same weather file is used for calculations in a zone in Woluwe-SaintPierre and for another area in the old city centre, the errors will be more pronounced in the calculations concerning the area within the Pentagon (inner ring road) due

EXAMPLES OF BLOCK-LEVEL BUILDING DENSITIES

Grand Place (Brussels)

Béguinage (Brussels)

Pre Industrial Revolution

Tenbosch (Ixelles)

Consolation (Schaerbeek)

Berkendael (Ixelles)

Late 19th century

Logis (Woluwe-Saint-Pierre)

Bémel (Woluwe-Saint-Pierre)

Interwar period

Post-war boom years

Fig. 2 Diagram of the historical evolution of building density. Over time, there has been a reversal of the ratio between built up and open spaces. A rapid increase in the consumption of regional space can be seen (© Apur). 26 | Urban forms, typology and improving the energy efficiency of old Brussels buildings


to the greater density. The differences can be as much as 10%. An analysis of green spaces reveals microclimate disparities, another form of territorial inequality. Each neighbourhood has a unique climate. The enclosed blocks from the late 19th century, for example, are urban creations where nighttime ventilation occurs naturally during the summer. Figure 3 shows a housing block the layout of which produces a significant thermal contrast between the green interior and the surfaced public space. This has the advantage of creating a stack effect, which is an excellent alternative to air conditioning. The natural ventilation inherent in the building is assisted by the presence of landings and the resulting offsetting of levels (fig. 4). The cellars also play a role in this phenomenon, as do the chimney flues. These are often blocked off during renovations to install controlled mechanical ventilation (CMV), which results in a loss of the ver-

Fig. 3 Top view of natural stack effect at block scale. The difference between how the ground is treated in the central courtyard (entirely covered in plants) and the public space (fully surfaced) is likely to create a pronounced thermal contrast which initiates effective natural ventilation (between the street and the yard). The green areas have the capacity to retain water, which evaporates during heat waves (Produced with Brussels Urbis © CIRB).

tical stack effect from the chimney and its air vents. This can eventually make things unpleasant as if the building is insulated, airtight and a CMV system replaces the chimney, this can create the ideal conditions for problems to arise during the summer months. The design of the various types of single-family dwellings is flexible. It can be seen that pressure on land caused these spaces to gradually shift and single-family houses to transform into standard apartments. The adaptability of the design is interesting because, in reality, it enables each resident’s energy consumption to be reduced. Indeed, if it is possible to move from a single-family house, housing three or four people, to three apartments; if there is a financial advantage to this division and, moreover, energy savings are achieved, then the entire inner ring becomes a focal point; this therefore results in a high demand for housing. These are natural phe-

nomena and occur as a result of a favourable market. The increased density is based on a relatively simple adaption of the design. The stairwell, for example, can easily incorporate the communal areas as this space was, from the outset, conceived in this way. However, this transformation also produces problems: three apartments potentially presenting damp rooms on all floors. Yet, when renovating, dampness is a basic fact. Any audit starts with the bathrooms as hydrometry plays a central role.

MODIFICATION OF SEQUENCES Our work has led us to address architectural heritage at an urban scale, focusing on high-density developments, the quality of spaces, etc. We are working on the principle that, where renovation implies the partial or total revision of building complexes, an urban analysis provides elements

Fig. 4 Cross-sectional view of natural stack effect at the building scale depicted between the yard and street. The landing adds a vertical component to the stack effect (© Municipality of Ixelles). 27

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that can be used to determine the extent of work possible. We have compared sectors and sequences of buildings. A perusal of the archives and planning permission records has enabled several facts to be identified concerning these sequences. I am going to focus on three such sequences. The first is located in Ixelles, in the Berkendael quarter (fig. 5). Ordered and symmetrical, it concerns a housing development. The developer presumably used a catalogue from which his customers selected what they wanted. He arranged it so that two similar buildings would not appear side by side and designed his sequence. He played around somewhat with the symmetry, striving for consistency, in the end creating an urban streetscape. However, an exception can always be seen at each end, where the buildings stand out in some way so as to constitute urban landmarks. Here, if we take one of the buildings and insulate it externally, the streetscape will suffer. In this case, the heritage issue is not at the building scale but at street scale. Our second example of a sequence is situated on Rue Eeckelaers, in Saint-Josse-ten-Noode (fig. 6). Composed of mixed stock, it is most likely the result of successive modifications. It is difficult to give an opinion without seeing the buildings up close. However, it can be said that insulating one of these buildings would not fundamentally alter the appearance of the street. These are typical examples from the 19th century and are undoubtedly the subject of less attention from a heritage point of view. The third sequence concerns housing types from the 1950s, which, in my opinion, offer some fairly interesting elements. Their construction

is still quite traditional while also incorporating pre-fabricated components, such as the window frames. In Woluwe-Saint-Pierre, these types of houses offer a coherent sequence with regard to the Town Hall, which is part of a vista. While the buildings, taken separately, do not arouse much sympathy from a heritage point of view, there is nevertheless a coherent sequence. Modifying any one of these buildings would affect this coherence even though the Town Hall is behind them. In fact, its construction marks the completion of the quarter and the streetscape sequence in which it is perfectly integrated. Conversely, the sequence on Rue François Gay, composed of older housing types that feature heritage elements, is mixed. Modification of an individual building would not pose any particular problem here (fig. 7). Urban form therefore enables heritage to be viewed from the perspective of sequences without focusing on the building and its details. Working at this scale also involves examining the relationship between the buildings and their immediate environment, and considering their sustainability, their vulnerability, and their ability to cope with climate change. The increase in energy prices and the population explosion will tend to bolster the process of densification of the existing city, particularly for the inner ring with its consistent land use availability. To what extent, therefore, are the public authorities likely to act? To what extent must densification be managed? Urban planning must facilitate this phenomenon while at the same time protecting the intrinsic qualities of existing fabrics, which means giving special attention to existing green spaces (conservation, removal of barriers, enhancement,


etc.), anticipating the emergence of urban heat islands, identifying the landscape qualities of architectural and urban compositions, etc.

THE IMPLEMENTATION OF ENERGY EFFICIENCY MEASURES IN OLD BUILDINGS The selection offers a range of housing types covering a period of one hundred years, from the first half of the 19th century up to the post-war period. It involves ordinary architecture, the most common stock type, as well as a garden city. Here, I will address some of the types, the use of materials and their thermal conductivity. We were surprised by the systematic use of brick and its persistence over time along with the late presence of wooden floors, which certainly raise questions during renovations. As regards the thermal conductivity of the walls, the target - perhaps not overly ambitious was set at 0.4 (the bar is currently 0.2). In general, the buildings studied are not insulated and place us within a classical analysis scheme.

The evolution of buildings The first change to be noted is the materials used. Throughout the 19th century, construction methods remained traditional but the range of materials, which were increasingly mass-produced, expanded and enabled the style of architecture to become more diversified. In this respect, the difference between Neoclassicism (where the bricks are rendered) and Eclecticism (where the materials are exposed) is striking (see pp. 17). The limited use of dense, and therefore conductive, materials in eclectic architecture resulted in a decline in the energy efficiency of buildings (fig. 8)


Fig. 5 Berkendael quarter: Rue de la Réforme and Rue Van Driessche in Ixelles. The sequence is made up of pre-defined building types “from a catalogue”. The use of symmetry creates an impression of diversity. A limited modification to the appearance of a building impacts the streetscape (© Apur).

Mixed sequence

Fig. 6 Rue Eeckelaers in Saint-Josseten-Noode. This is a mixed sequence with no particular logic to the arrangement at street scale. A limited modification to the appearance of one building would not impact the streetscape (© Apur).

TOWN HALL QUARTER IN THE MUNICIPALITY OF WOLUWE-SAINT-PIERRE 1920-1935 1950-1960 1960-1965 1971 - Town Hall Mixed sequence

ce sequen Mixed

ce sequen enous Homog

Hall Town

Mixed sequence

• Absence of unity; • The façades do not have a uniform appearance; • No particular care required for urban renovation.

Homogenous sequence

• The buildings are part of a coherent sequence; • Renovation of this complex precludes any modification of the façades.

Town Hall, urban landmark

Fig. 7 More recent streetscapes, such as those from the 1950s or 1960s, often form successful streetscape compositions (Diagram produced with Brussels Urbis © CIRB. Photos by the author). 29

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The same process can be seen after the 1950s: improvements in heating systems resulted in a greater number of openings in façades, in a search for ever more light. In Neoclassical buildings, the proportion of openings to solid wall is 1/3 to 2/3. In the first quarter of the 20th century, it reached 50/50. With technical advances, everything then became possible: strip windows, glass walls, etc. An examination of the evolution of construction techniques and their impact on energy consumption shows a widespread falling off in the postwar period (fig. 9). There are numerous difficulties involved when renovating an old building, depending on the construction techniques used. Modifying spaces is a complex operation that can produce problems, most notably an increase in thermal bridges. This risk arises when working on reinforced concrete, beams, windowsills, lintels, etc. Partial insulation of an area can be dangerous; problems can arise in places where the thermal conductivity is greater. The less standard the façade - for example, when there is a double wall the more serious are the thermal bridge-related issues. Specific solutions to address the problems inherent in these types of buildings will have to be used for renovations. In this regard, backyard annexes constitute a specific problem. These outgrowths, made from lightweight materials, pose real problems in relation to density. Erected with no consistency between them, these small structures generate thermal bridges in all directions. They are generally less dense than the main building. Carrying out work on annexes has a high potential for energy savings.

THERMAL CONDUCTIVITY OF OPAQUE STREET-FACING WALLS (W/M2.K)

Fig. 8 The thermal conductivity of opaque walls is a reflection of the construction techniques used. These techniques are based on a constant: a solid load-bearing wall, which explains the relative uniformity of the results and why they fall so considerably short of the performance target formulated by the EPB (fixed at 0.4) (© Apur). RATE OF HEAT LOSS OF STREET-FACING FAÇADE Neo-classical (33% openings) Art nouveau (50% openings)

Walls (U = 1.8)

Bay windows (U = 4.65) Entrance (U = 3.06)

PERCENTAGE OF OPENINGS ON THE STREET-FACING FAÇADE

Increase in openings

Neo-classical: 1/3 openings

Art nouveau: 40% to 50% openings

Atypical

No particular logic

“Bel-étage” house

Fig. 9 Over time, the thermal properties of the buildings deteriorate (© Apur).



DEFINITION OF A RENOVATION PROJECT OR FINDING A BETTER BALANCE

Heritage requirements Winter comfort (1) (thermal resistance, efficiency of heating and ventilation systems, etc.)

Winter comfort is often the sine qua non of renovation. This is the criterion that takes precedence in the standard calculations. However, the measures taken for winter comfort must not counter summer comfort. For example, interior insulation of solid walls may compromise the benefits that they provide in the summer. In the same vein, it is necessary to anticipate the problems that may be created by the renovation work. Furthermore, there is also one essential element missing in the reasoning applied to renovations: the behaviour of users. This means

The audit techniques The audit of the eleven buildings was carried out by Centre Urbain using PAE (Energy Audit Procedure) software, currently used by auditing firms. It is interesting to be able to analyse and critique this PAE method and the results that it provides. The main point is the difference between the reality of the building’s occupation and what the calculation takes into considera-

Summer comfort (2) (creation of masks, boosting of inertia) Change in climate (climate change modifies the relationship between heating and cooling needs)

Double-glazing (U = 1.63)

135

200

Behaviour of users and occupation strategies (set-point temp., buffer spaces)

Renovation project

Urban heat island Putting the cost of the operation into perspective with regard to the expected gains in energy savings

Legend Criterion systematically absent Criterion not properly taken into account Criterion taken into account in renovation operations

(1) The sole criterion actually addressed by the EPB regulation (2) Not sufficiently taken into account by the EPB regulation

understanding that people’s behaviour is unpredictable and does not follow a pattern. The sociology of the building must be taken into account when dealing with a renova-

tion. Without the residents’ support, the energy saving objectives being sought will remain out of reach.

tion. A factor of 2, or indeed often far higher, is often diagnosed for a single-family house. The occupancy scenario - how the rooms are actually used - is a decisive factor, even more so if the renovation is intended to be cost effective. By over-estimating the costs of renovation, the payback periods calculated become too long. In most of the cases examined, the PAE software calculates a payback

period that exceeds the lifespan of the renovation solutions, and this is in the best-case scenarios. These findings can be interpreted in a number of ways: - The required level (U value) is too high; - The solutions envisaged are not suited to the consumption profiles of old buildings; or - The software is not appropriate for energy audits of old buildings.

Unit cost (€/m2) Insulation (U = 0.49)

Existing problems and anticipation of future problems

Price of gas (€/kWh)

0.065

Price of gas (€/kWh)

0.013

Interest rate

3%

Interest rate

3%

Inflation

2%

Inflation

2%

Surface area (m2)

Investment (€)

Lifetime of investment (years)

Payback period (years)

Updated payback period (years)

Payback period (years)

Updated payback period (years)

Front façade

34.93

92.66

30

39

46

20

23

Rear façade

29.43

92.66

30

39

46

20

23

Annex

19.75

61.32

30

19

22

9

11

Single-glazed window

7.09

29.26

20

35

38

14

15

Fig. 10 Example of a PAE audit, carried out on a neoclassical building. The payback periods calculated are long. If the economic actors do not see any financial benefit in undertaking energy efficiency works, the overall objective of a 20% reduction does not seem to be achievable. There is a high chance of the grants being misappropriated and fuelling a windfall effect (© Centre Urbain). 31

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Many materials currently used in renovations are not long-lasting and have to be replaced after ten or fifteen years. Unless the systems are used correctly and continuously - which is rare, as doing so restricts how the building in used - 50 kWh will not be achieved in old buildings. There are many examples of landlords who are paying building management fees for 50 kWh, which ultimately reaches 150 kWh. Was the money invested in the right place? Nothing is less certain. If the meter is showing 150 kWh instead of 50, it means there is a problem. Perfect examples can always be found. However, the question relates to the most frequently encountered situations and what happens in ordinary buildings.

Fig. 11 External insulation in rear courtyards does not, in principle, cause problems (photo by author). LA ROUE GARDEN CITY: VARIED BUILDING TYPES REQUIRING DIFFERENT RENOVATION SOLUTIONS Municipality of Anderlecht “La Roue” Garden City Network of public spaces: hierarchy and composition Neighbourhood perimeter Network hierarchy Transit route Link road between quarters Local access road Private alley Urban composition Local square Square within a housing block Public green space

EXTERNAL INSULATION: USE WITH CARE External thermal insulation means revising existing façades. It is possible, indeed even recommended, for annexes and the rear façades of buildings, where it does not, in principle, pose any problem (fig. 11). It can be applied to street-facing façades under certain conditions: buildings with significant damage or with façades that were redesigned during unscrupulous restorations. Buildings that are part of a mixed streetscape must be considered on a case-by-case basis. It may be possible to insulate some of them externally but not others. Buildings that are part of heritage streetscape sequences require a more subtle approach, again on a case-by-case basis. The highly complex example of La Roue is interesting in more ways than one (fig. 12): it is an estate that has changed a lot. We have had the opportunity of looking at some

width of roadway (parcel to parcel) width of roadway (building to building)

Plaine des loisirs” (1921): typical building façades in La Roue Garden City.

Rue des Citoyens (1907): a homogenous sequence that should be preserved.

Drawing of “Plaine des Loisirs” at the La Roue metro station.

Experimental project (1921): a zone that could be returned to its vocation using energy saving techniques.

Fig. 12 La Roue in Anderlecht. The oldest historical sequences (1907) still standing necessitate preservation of the façades as they currently stand. There is a particular symbolic dimension to “Plaine des loisirs”, which has undergone vernacular modifications (polychrome render, etc.). Any future renovation solutions will have to take heritage like this into account. Studies need to be carried out to determine possible changes (diagram produced with Brussels Urbis © CIRB. Photos by the author).



sequences from this development: some of them are of historical importance and external insulation must be prohibited. However, certain types are suitable, as they have changed a great deal. It would be necessary to study the details of these changes; to see how people have adapted the spaces, which is acceptable with such changes; as well as how they should be managed, etc. Insulating renders could offer a solution. Nevertheless, there is no universal technical solution applicable everywhere at all times. Certain zones such as the “experimental project” in La Roue, a former technology showcase, could be returned to its original vocation through the use of innovative renovation solutions. Clearly, such an approach requires moving away from the regulatory mindset.

INTERIOR INSULATION: A SOLUTION THAT CAN CREATE PROBLEMS Interior insulation does not require planning permission. The absence of any requirement for permission gives the impression that the technique belongs to the realm of basic DIY. In reality, it is the most complex types of insulation as it can create a lot of problems, especially in old buildings. This doesn’t mean that it shouldn’t be used, only that great care should be taken when it is. We have gained substantial experience in Paris with the use of brick, both in terms of insulating it and learning about its inherent problems. We have noticed the harmful effects of interior insulation on numerous timber frames. When the structure is affected and the building becomes unhealthy, the only solution is demolition/recon-

struction. The advantage and disadvantage of using brick is that it retains dampness well. It may take five or ten years, or even longer, for problems to appear. Interior insulation often prevents the dampness stored by the bricks from drying out. This is what we often encounter in west/south-west facing walls, pounded by rain, or in walls covered with glazed bricks, which are highly permeable to damp.

CONCLUSION

If we want to achieve the standard of U= 0.4 or 0.2, highly insulating materials such as polystyrene or rockwool will have to be used. However, solutions such as these can be counter-productive over the long term. By conceding that no attempt will be made to achieve the standard, we open up the possibility of using materials that are compatible with old structures (such as hemp concrete, cellular concrete, lime renders, cork, etc.) whose thermal properties are, today, almost on a par with polystyrene.

Another area worthy of investment is planning regulations, which have a role to play in guiding the phenomenon of densification. This involves, among other things, the preservation of certain interior green spaces to prevent the emergence of urban heat islands.

We have tried, on certain projects, to aim for a performance of 0.8 and not 0.4. Meter readings indicate a building now using 80 kWh. The cold wall effect has been eliminated and the residents no longer suffer from a lack of comfort. They are therefore using less heating. Once again, it involves considering the actual situation and actual behaviour of the residents. Nowadays, there are other materials besides polystyrene which, admittedly, are less efficient in theory, but with which interesting things are being done in practice.

To conclude, I want to return to some key points from the study. Firstly, it would be interesting to territorialise energy dependence so as to be able to prioritise energy ambitions at a regional scale. It is not possible to be efficient everywhere; choices must therefore be made, especially since budgets are, in general, limited.

As regards buildings in the strict sense, improving knowledge about the existing stock and their specific features requires the collection of a large amount of statistical data on energy consumption. This initial step will also help to refocus the level of public subsidies for the performance required in old buildings and validate the effectiveness of work by means of “before and after” comparisons. Finally, the question of capitalising on feedback arises: knowing what has been done, what works, what doesn’t work, etc. over the long term is essential in order to assess the actions taken and decisions made. The dogma that states “a good building is one that is airtight and thermally insulated” is not a valid one. Greater subtlety is required. There must be room for observation and experimentation. Help must be provided to improve the qualifications of project managers and promote the smart approach to buildings and renovations. Translated from French. 33

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Formes urbaines, typologie et amélioration des performances énergétiques du bâti ancien bruxellois

Stadsvormen, typologie en verbetering van de energieprestaties van oude Brusselse gebouwen

The complete study is available on the websites of the Direction des Monuments et des Sites and APUR:

À la demande de la Région de Bruxelles-Capitale, l’Apur a réalisé une étude sur la performance énergétique des bâtiments de logements anciens. Cette étude aborde les perspectives d’économies d’énergie dans le bâti ancien bruxellois sur la base d’un échantillon de bâtiments audités. Au-delà du commentaire portant sur les bâtiments, la démarche propose également de considérer la question de la forme urbaine et de regarder en quoi cette dernière impacte, elle aussi, les consommations d’énergie du bâti. Enfin la question de la vulnérabilité énergétique du territoire régional est abordée, ainsi qu’un questionnement sur la nécessaire cohérence entre les leviers qui relèvent d’une part du territoire régional, d’autre part des quartiers et, enfin, du bâtiment.

Op verzoek van het Brussels Hoofdstedelijk Gewest realiseerde APUR een studie over de energieprestatie van oude woningen. Deze studie buigt zich over de energiebesparingsvooruitzichten voor oude Brusselse gebouwen op basis van een audit van een staal van de gebouwen. Naast opmerkingen over de gebouwen stelt de studie voor om de vorm van het stadsweefsel in aanmerking te nemen en na te gaan hoe die ook een impact heeft op het energieverbruik van de gebouwen. Tot slot wordt aandacht besteed aan de energiekwetsbaarheid van het gewestelijk grondgebied en worden vragen gesteld over de noodzakelijke coherentie tussen de hefbomen die enerzijds afhankelijk zijn van het gewestelijk grondgebied en anderzijds van de wijken en ten slotte van het gebouw zelf.

http://bit.ly/1CMqiqM


http://bit.ly/1UDw6Am


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THE LISTED HOUSES OF THE LE LOGIS AND FLORÉAL GARDEN CITIES ADAPTATIONS TO CURRENT ENERGY AND COMFORT NEEDS GUIDO STEGEN

ARCHITECT, ARCHITECTURAL FIRM ARSIS BVBA

LE LOGIS AND FLORÉAL IS A GARDEN CITY THAT SHOWS US AN INTERESTING INSTRUMENT FOR COMBINING CULTURAL VALUES AND ENERGY NEEDS. TWO ASPECTS WILL BE ADDRESSED HERE: THE MANAGEMENT PLAN AND THE FINANCIAL ASPECT OF THE ENERGY SAVING MEASURES EMPLOYED. OPTIMISING THE ENERGY PERFORMANCE OF LISTED HERITAGE: AN EXERCISE WITH IMPACT The title of this contribution is: “Adaptations to current energy and comfort needs”. The word “needs” instead of “standards” has been chosen deliberately. Through energy measures that conform with heritage, the Beheersplan voor Erfgoed (Heritage Management Plan) of the Le Logis and Floréal garden city is striving to fulfil the need for efficient energy consumption in the most optimal manner. “Optimising” is the key word here: it is an exercise in balancing the potentially conflicting interests of the heritage, cost price and performance. The investment to

energy performance ratio is key to ensuring maximum energy savings within a limited time frame (20 to 25 years). Within a limited amount of time, the financial means must be found and invested in order to improve the energy performance in the majority of houses. Only then can the largest global energy savings be realised within this time frame. The Le Logis and Floréal garden city is large. It is a complex of two garden cities, situated in section of the Brussels periphery built up in the 20th century, approximately six to seven kilometres from the city centre. There are currently approximately 540,000 residences in the Brussels-Capital Region, of which (only) ± 8% are social housing

36 | The listed houses of the Le Logis and Floréal garden cities

residences (fig. 1). Between 1920 and 1940, approximately 125,000 houses were built in the Brussels municipalities, 9,000 of which were social housing residences. 4,000 of these have fewer than three floors, including the Le Logis and Floréal listed houses. With these figures, I am trying to give an idea of the impact the conclusions of the management plan can have. About 4,000 social housing residences in the Brussels-Capital Region are structurally and technically comparable to the Le Logis and Floréal listed houses, not to mention the non-social housing residences of the same type (approximately 40,000). Figure 2 shows the houses that, in the government decisions of


Residences in the Brussels-Capital Region As of January 2013 540,000 residences of which 39,400 social housing residences (= 7.3%) 3,500 social housing residences managed by a social rental office 42,900 total, i.e. 7.94%

‹ 3 lev.

3 to 6 lev.

› 3 lev.

Total

LE LOGIS AND FLORÉAL: A MATTER OF COHERENCE

Residences in the Brussels-Capital Region As of January 2013 125,000 residences (estimated) of which 9,000 social housing residences (1921-1937) of which 4,000 with fewer than 3 floors of which 25% in the garden city Le Logis & Floréal

Evolution of the construction of social housing residences in the Brussels-Capital Region

Fig. 1 Houses in the Brussels-Capital Region. (Guido Stegen, based on the “Inventaris van de Volkswoningen te Brussel” (Inventory of Public Housing in Brussels), Sint-Lukaswerkgemeenschap, Lagrou E., Sept 1985).

1,000 single-family residences

30 duplex houses (60 residences)

2 apartment buildings

- on a site of 57.32 ha - 1,060 sheltered housing units - dating from before 1940 - 1/4 private - 3/4 statutory social housing residences

The whole garden city complex consists of two cooperatives, Le Logis and Floréal. Each has a centre characterised by high-rise buildings and central functions: offices, shops and even a theatre in Le Logis. The whole encompasses four entities characterised by the colour of the exterior woodwork. This is yellow for Floréal. Three entities are present in Le Logis: green/white, off-white and green/black. The garden cities were built according to designs by four individuals. These were Louis Van der Swaelmen who designed the spatial structure of the neighbourhoods, and the design plan; and three architects: Jean-Jules Eggericx, Raymond Moenaert and Lucien François. More than 90% of the houses were built according to Eggericx’s designs; Moenaert and François designed approximately one hundred houses, all in Floréal.

Within the site (which is marked with a black line) many other buildings can be found, including two high-rise apartment buildings which are listed as monuments but are not part of the management plan.

The 1,060 dwellings were constructed across six sites and in 16 design phases (or dossiers). The varying procurements, prices and contractors resulted in diversity in techniques and details to the on-site phases. When drawing up the management plan, we are confronted with this diversity; we must ascertain whether this is a coincidental diversity with no importance for further conservation or a conceptual diversity which must be studied and maintained.

Although built in the same way, not all listed houses are managed

The garden cities comprise a large, cohesive whole. For decades people

Source: in situ registrations by Arsis, original plans, old postcards Graphic support: Urbis top

Fig. 2 The garden cities are listed as an entirety by the Government decision of the Brussels-Capital Region Government of 15 February 2001 and 6 December 2007 (© ARSIS).

15/02/2001 and 06/12/20071, are listed as part of the garden cities “as a whole”. Only the so-called outer shell of these houses is listed: façades, roofs, exterior woodwork, etc.; in short, everything that is visible from the outside. In figure 2, the singlefamily dwellings are marked in red, duplexes in orange and low apartment buildings in blue.

as social housing residences2; one quarter is managed privately and three quarters are managed by social housing companies.

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Spatial coherence (neighbourhoods), by acquiring a spatial continuity arranged in a hierarchy (avenues, streets, paths, squares, etc.) and through colour themes.

The colours of the exterior joinery are linked to the neighbourhoods.

Front door types and the way the houses are arranged in rows are linked to the open space.

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Groups of houses, composed through connection, mirroring, rotation, etc., of the offer of house types, and through adjustment of the site relief.

66 house types as originally designed, with a varying programme, and compiled using the elements of local heritage.

Elements of local heritage, compiled starting with standardised type details, and with continuous windows with a ratio of √2.

Standardised type details

Fig. 3 The composition of a large whole (© ARSIS).

have been trying to determine just exactly what the cement is that makes a cohesive whole. The usual way of obtaining large wholes is “bottom up”. This means that construction is executed from one level to the next using standard details (doors, windows, roof shapes, etc.). These are then brought together in larger scale design decisions, such as façades, houses, etc. These are grouped together in combinations of houses or groups of houses. The effect of pure bottom-up grouping is that many houses are identical and there is a lack of diversity and recognisability. In the case of Le Logis - Floréal, various pioneering ideas have resulted in: • diversity which is neither arbitrary nor chaotic;

• unity without similarity or boredom. Coherence comes from complexity, which essentially boils down to “making connections”. The garden city features not only connections between successive scale levels (detail > elements > type of house > group of houses > neighbourhood level) but also between non-successive scale levels (for example: elements > groups of houses, or type of house > neighbourhood level (fig. 3)). Since the designers did not simply link elements to types of houses, the management plan provides a distinction in the description of the composition logic between: 1) elements inherent to the type of house; and 2) elements which are not inherent to the type of house. All of this is explained in one of the volumes of the management plan,


namely “T04. Unity in diversity”. The fact that some elements could not simply (1/1) be linked to a type of house is the reason why the tables of houses (T01), the thematic maps (P03), and the global construction plans (P11, P12, P13 and P21) have been included in the management plan. These documents localise elements not inherent to the type of house. The tight, complex coherence leads to the feeling that the garden city is the result of one large, unique design, notwithstanding the building of 1,000 houses over a period of 15 years. Standardisation in the production and design process was absolutely essential. Only a limited number of basic elements were used to create one large, coherent, organic whole while avoiding repetition, boredom and a lack of


wholes of connected open spaces rows of houses house types

local heritage construction details

Fig. 4 The coherence in the larger whole of the garden city originates from the complexity of the composition, more specifically the arrangement of the elements and houses on different scale levels

personality. The modernists called this quality: “unité dans la diversité, diversité dans l’unité”- unity in diversity, diversity in unity.

THE MANAGEMENT PLAN Recently, the Brussels legislation regarding urban development has begun to allow large groupings of buildings belonging to different owners to be managed by heritage management plans. Thanks to the management plan, most buildings are exempt from building permits and subsidies are easier to obtain. The management plan for Le Logis and Floréal was the first in the new legal urban development framework in Brussels; the plan was approved by the Brussels Government on 23/05/2014 and published in the Belgian Official Gazette on 01/09/2014. The first steps towards the management plan were taken back in 1999, i.e. before the heritage protection act. The composition principles (“unity in diversity, diversity in unity”) had to be unravelled, technical details measured and the diversity of the local heritage mapped out. Also the form and content of a management

plan as an instrument still had to be first invented and then refined. In 2000, an inventory was made of the 1,060 listed houses. In an inventory, the condition of the houses is assessed and documented with the intention of applying the heritage protection act. The inventory allows the nature of the works and subsidies to be determined as well as any violations of the heritage protection act. In 2001, the houses and the design of their surroundings as a whole were both listed. In the period 2006-2008, the first-generation documents from 2000-2002 were complemented with new themes and detail relating to built-up elements in the surroundings. Finally, in May 2014 the official management plan became a reality. The management plan describes the permitted works both in text and with drawings: • to the outer shell of the dwellings: the façades, exterior woodwork, roofs and garages; • in the surroundings: the garden sheds, parapets and banisters, retaining walls and technical installations (energy, water, telephone, etc.).

The objectives of the management plan are: • to preserve the principle of “unity in diversity, diversity in unity”; • to cater to contemporary needs (thermal, acoustic, hygiene) without damaging the heritage value of the buildings; • to avoid the usual permission procedures for the above-mentioned works. Two exceptions remain subject to permission: insulating the façades and treating damp in walls and façades. An audit demonstrating that the intended works are effective, of priority and without any adverse side effects for the building and its inhabitants must be carried out prior to these works being undertaken. The previous intervention (pp. 24-34), by Julien Bigorgne, clearly demonstrated that damp problems only become worse if treated incorrectly. The authorities act as coaches for the management plan. Specifically, this means: • informing, documenting and raising awareness regarding the heritage; • providing well-researched solutions; • granting subsidies. The management plan functions in relation to two other concepts, and distinguishes itself from these: • The reference situation describes the technical, historical and artistic individuality and the coherence of the heritage, including the adaptations to current needs. • The management plan for heritage describes all of the possibilities permitted to realise the reference situation. • The projects are the descriptions of the specific works owners are carrying out on their property.

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The management plan, drawn up for the Le Logis and Floréal garden cities and approved by the Brussels Government, contains 13 volumes: seven textbooks (T00 to T06); six books containing drawings (P01 to P20); and four large overview plans of the neighbourhoods. T00: Management plan manual T01: Table of the listed houses T02: Technical provisions T03: Research reports T04: Unity in diversity T05: Adaptations to the current needs T06: Inventory - instructions P01: Catalogue of local heritage P02: Construction details P03: Theme maps PO4: A4 documents from plans P11, P12, P13, P21 P10: House types, Le Logis P20: House types, Floréal P11, P12, P13, P21: Built-up areas of the houses in the neighbourhoods These documents form one whole, as do the garden cities themselves. They refer to each other and thus themselves describe the principle of “unity in diversity, diversity in unity”. The volumes detailing types of houses (P10 and P20), for example, show which windows are present in a certain type of house. The catalogue for local heritage (P01) shows these windows and refers to the details from which the windows have been constructed. The construction details (P02) show these details, etc. The texts and drawings describe both the original and present condition as well as which adaptations are permitted. This is how the management plan works: it is based on an interaction between the various volumes, so readers will know (starting from the specifications and detailed plans) which specific works are permitted in any specific place, and at whichever scale: house, element, detail, etc.

ADAPTATIONS TO THE CURRENT NEEDS WITH REGARD TO INTERIOR CLIMATE AND ENERGY

The origin of the energy section of the management plan

21/02/2013: Amendment by the Brussels-Capital Region regarding EPB • Centre d’Étude et de Recherche et d’Action en Architecture (CERAA) 2009-2011: Audit énergétique des maisons classées des cités jardins Le Logis et Floréal • Atelier parisien d’urbanisme (APUR) 2013: Amélioration des performances énergétiques du bâti ancien de la Région Bruxelles Capitale. Study requested by the Brussels-Capital Region • CENERGIE April-May 2014: Energy audit of two Le Logis houses (as described in the management plan) in compliance with the energy and comfort measures provided in the Heritage Management Plan The energy study and audit performed by CERAA in 2009-2011 used the Energy Performance of Buildings (EPB) standard as a starting point to examine whether or not it could be reconciled with the heritage and global3 budget planning. This was not the case, and it remained difficult to decide which measures should take precedence in a joint heritage and energy policy, and which would be both technically and financially (in terms of both financing and subsidies) sustainable for the entire neighbourhood.

The measures in the management plan regarding comfort in interior climate and energy performance cannot be separated from a development in legislation and studies which preceded the final approval of the management plan. • Energy Performance and Indoor climate (EPB) 12/12/2002: European Directive 21/12/2007: Government decision of the Brussels-Capital Region regarding EPB 19/05/2010: Adaptation European Directive

Dealing with the aspect of energy savings in a purely performance-based manner or using standard solutions for energy savings is not feasible: the design of the garden city, its occupancy, its history and its fame are aspects of sustainability. For the energy transition in Le Logis-Floréal, the proposed solutions must take all criteria relating to the conservation of the heritage into account. These residences were originally fitted with numerous devices and

Volume T05 highlights how the permitted works seek meet the current needs regarding energy, comfort, acoustics and safety. It forms connections between those themes and also points out certain contradictions between the objectives of these various themes to the owners. In volume T05, the relevant application of certain works is explained. The management plan expects and requires: • priorities to be determined according to the funds available; • the works to be executed in the correct order; • a realisation that gains in a certain area can mean losses in another area; • choices to be made which are adapted to the specific house a person is living in and envisaging the house after the works have been completed; • that the potential energy savings resulting from simple and small habits and improvements compared to those requiring large investments should not be underestimated.



innovations which offered a certain level of comfort against the cold (e.g. locks and lay-out of the rooms), overheating (e.g. shutters, thermal inertia), etc. However, due to a rise in energy costs there is a risk of the residences being heated, used and modified incorrectly. The problems which may arise can be detrimental to both the conservation of the heritage and the health and comfort of the residents. Cenergie’s energy study and audit was performed in compliance with the management plan in order to be eligible for regional subsidies. The starting point of this approach was the improvements regarding energy and interior climate provided for in the management plan. It then examined the energy performance of each specific case4; based on this, the most efficient measures are suggested. Jonathan Fronhoffs from Cenergie tells us more about this study in his contribution (pp. 48-53).

Limitation of energy needs with an emphasis on improving comfort In the Trias Energetica, it is assumed that a sustainable building first limits its energy needs and, secondly, makes use of renewable energy sources instead of wasting fossil fuels. The first measure is usually realised by insulating the outer shell. Not all types of insulation used on the outer shell are equally efficient; the management plan requests that this efficiency - with regard to finances and energy - be taken into account in order for a project to be granted a subsidy. However, limiting energy needs can also be achieved in ways other than insulating the outer shell, namely by creating a feeling of comfort for the residents at

a lower room temperature. It is, after all, widely known that feeling comfortable is influenced not only by the temperature in the room but also by drafts, humidity and air quality. This is called the interior climate. By avoiding drafts, humidity and cold surfaces, a feeling of comfort can be created at a lower room temperature. In this way, less energy is lost through the outer shell through conduction, convection and air leaks. In the audit style developed by Cenergie it is assumed that the average (day and night) room temperature can drop by 1°C after comfort has been restored. This alone produces a considerable saving, without loss of comfort. We are all familiar with the examples of convection heaters and the cosy heat they emit when it is cold, or the pleasant feeling of a cold, sunny day. Measures which benefit comfort and health are also beneficial to energy savings, but saving energy is not necessarily beneficial to comfort and health. Insulating the outer shell produces generally acceptable, calculable energy savings. Solving comfort deficiencies influences the energy bill indirectly; the energy loss decreases because the difference between the inside and outside temperature is decreased. Air temperature is a decisive factor in the influence of the thermal resistance of the outer shell on the energy bill. If the room air temperature can be lowered, the efficiency of insulating the outer shell decreases. Insulating the outer shell and interior climate comfort are very closely connected, but nonetheless clearly distinguishable. They influence one another, but require different actions. The

former mesures are often less heritage-friendly than the latter; therefore the management plan characterises the measures according to this distinction. In short, the management plan provides the following measures to limit the energy need, in descending order of priority, by: • improving comfort (interior micro climates, humidity, etc.); • improving the airtightness of the shell; • insulating the shell (roofs, floors above non-heated spaces, façades); • improving the performance of equipment (lighting, heating, sanitary fittings, hot water). These measures have been refined into a dozen specific measures, listed in the figures 5a and 5b: • from 1.1 to 1.5: comfort and hygiene • from 2.1 to 2.6: insulating the shell • 5: energy-efficiency of the techniques This appendix also summarises all the works from the technical provisions (T02) which contribute to one or more of the aforementioned measures, and demonstrates the connections between them. Lastly, figure 6 shows the location of the various measures using the façades and design plans of one type of house (LLw_D).

The energy results of the heritage-conformance measures Both as an example and for research purposes, two specific houses were examined in the energy audit to ascertain the exact energy performance of specific measures (see pp. 48-53). Clearly, two houses is a very small sample to draw conclusions from, but for the time being this small study gives us an 41


B1.1

Restoring crumbling decorative plaster Herstellen van afgebrokkelde sierpleister

B1.2

Herstellen van barsten in decorative de sierpleister Restoring cracks in the plaster

B1.3

Aanbrengen van een nieuwe speciale eindlaag van Applying a special new end layer of dedecorative sierpleister plaster isolatie van de plastered bepleisterde gevels Thermische Thermal insulation of the façades

B1.4 B1.5 B2 B4

Herstellen vanexisting een bestaande schouw type B Repair of an type B hearth

B5.5.1

Repair of an type E hearth Herstellen vanexisting een bestaande schouw type E

B6.1

Herstelling van deurdorpels Repair of door thresholds

B6.2

Herstellen van vensterbanken Repair of window sills

B7.1.3

Thermal insulation at the of van de Thermische isolatie aan de interior binnenkant the cold bridgeaan by betonnen concrete canopies koudebruggen luifels.

C2.2

Zinken dakbedekking - Alle dichtingswerken Zinc roof cladding - All sealing works

C2.3

Bituminous sealing op on beton concrete Bitumineuseroof dakdichting - Alle -dichtingswerken. All sealing works

C2.4

Kroonlijsten engutters dakgoten - alle dichtingswerken Cornices and - All sealing works

C1.4.1

Insulation works slopingdaken, roofs,ter gelegenheid Isolatiewerken vanon hellende for purpose works around the exterior vanthe werken langsofde buitenkant.

C3.2.4 C4.6 D1.2.2 D1.2.3 D1.2.4 D1.2.5 D1.3.3 D1.3.4

2.6 Saneren van vochtige Decontamination muren enwalls vloeren of damp

2.5 Isolatie vanofde Insulation voordeuren the front doors

2.4 De beglazing de Glazing of thevan exterior buitenschrijnwerkerij woodwork

2.3 De daken Roofs

2.2 Vloeren boven niet Floors above verwarmde non-heatedruimtes spaces

2.1 De gevelmuren Façade walls

Thermische isolatie van de cold koudebruggen Thermal insulation of the bridges aan de at the interior bow windows (loggias) binnenkant vanof dethe bow-windows (loggia's).

C2.1

C1.4.2

1.5 Sanering van vochtige Decontamination of muren en vloeren damp walls and floors

Thermal insulation at the of van de Thermische isolatie aan de interior binnenkant the cold bridgeaan by betonnen concrete cornices koudebruggen kroonlijsten.

Thermal insulation of the of van de bowThermische isolatie van de exterior buitenzijde the bow windows windows (loggia's).(loggias) Thermal insulation of the of the Thermische isolatie van de interior binnenzijde vanwalls de under windows of thevan bow dewindows bow-windows. muren the onder de vensters Pannenbedekking - Alle dichtingswerken Tile roof cladding van - Alldaken sealing works

B7.3.4

1.4 Zomerconfort Summer comfort

Drip moulding on plasteredgevels - Restitutie & Druiplijsten op bepleisterde façades - Restitution & Restoration Restauratie

B5.2.1

B7.3.3

1.3 Wegwerken Eliminating van cold koudebruggen bridges

Black layeraan at the base van of de gevels Zwarteprotective beschermlaag de basis the façades&- herstelling Maintenance and repair Onderhoud

Herstellen vanexisting een bestaande schouw type A Repair of an type A hearth

B7.3.2

5. 5. Other Andere

Thermal insulation at the Thermische isolatie aan de interior binnenzijde van de of the reveal the façade openings dagkanten vanofde gevelopeningen

B5.1.1

B7.2.3

1.2 Luchtdichtheid Air-tightness ofvan de buitenschrijnwerkerij the exterior woodwork

Articles provided for in the technical specifications Artikels voorzien in(book de technische voorschriften T02) (boek T02)

1.1 Compartimentering van Compartmentalisation de ruimtes of the spaces

Huidige behoeften Current needs Hygrothermal measures for 2. Energy savingdoor by working 1.1.Hygrothermische maatregelen 2. Energiebesparing werken aan comfort and health onde the outer shell voor comfort en gezondheid buitenschil

5.1 Performantie Performancevan of de infrastructuur infrastructureen and equipment uitrusting

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Insulation works slopingdaken, roofs,ter gelegenheid Isolatiewerken vanon hellende for purpose works around the interior vanthe werken langsofde binnenkant. Placing roof window Plaatseninsulated van een geïsoleerd dakvlakvenster - met -zonnewering with sunblind Insulation sides and thedaken roofsvan de Isolatie vanofdethe zijkanten en de of the dormers dakkapellen Placement or replacement of Plaatsen of vervangen van beglazing door gelaagde glazing by layered glazing beglazing. Placement or replacement of glazing bygelaagd layered Plaatsen of vervangen van beglazing met insulated glazing, A (U=+/-3.4) isolerend glas, typetype A (U=+/-3,4) Plaatsen of vervangen van de met Placement or replacement of beglazing the glazing bydun thin double glazing, B (U=+/-1.9) dubbel glas, typetype B (U=+/1,9) Adding safety to originalaan glass Toevoegen vanlayer veiligheidslaag oorspronkelijk glas. Sealing thedeexterior between Opkittenat aan buitenzijde tussenthe deexterior woodwork and the carcass buitenschrijnwerkerij en de ruwbouw. Sealing thedeinterior between thede exterior binnenzijde tussen Opkittenat aan woodwork and the interior finishing buitenschrijnwerkerij en de binnenafwerking

Fig. 5a 42 | The listed houses of the Le Logis and Floréal garden cities

Fig. 5b


D1.4.1 D1.4.2 D1.4.3 D1.4.4

Guillotineramen - toevoegen tegengewicht Guillotine windows - addingvan counterweight

D3.1-5

Front doors--driepuntsluiting three-point locks Voordeuren

D3.1-6

Front doors--Tochtwering Draught excluders in the lower Voordeuren in de onderlijst van het strip of the door leaf deurblad Voordeuren Front doors--Inbraakwerend burglar-proofglas glass

D3.1-8 D3.1-9 D4.1

D4.2.23 D4.2.24

Energy saving measures for thevoor rolling shutters Energiebesparende maatregelen de rolluiken.

D7.1.2

Aanpassingswerken oorspronkelijke houten Adaptation works onaan thedeoriginal wooden garage gates garagepoorten. Aanpassingswerken oorspronkelijke metalen Adaptation works onaan thedeoriginal metal garage gates (burglar-proof glass) glas) garagepoorten (inbraakwerend Portaal, type 11 -- Adaptations Wijzigingen en werken aan de Portal, type and working on the classed existing toestand. condition geklasseerde bestaande Portal, type and working Portaal, type 22 -- Adaptations Wijzigingen en werken aan de on the classed existing toestand. condition geklasseerde bestaande Portaal, type 33 -- Adaptations Wijzigingen en werken aan de Portal, type and working on the classed existing toestand. condition geklasseerde bestaande Portaal, type - Wijzigingenand en werken aan de ortal, type 44 - Adaptations working on the classed existing toestand. condition geklasseerde bestaande Portaal, type 55 -- Adaptations Wijzigingen en werken aan de Portal, type and working on the classed existing toestand. condition geklasseerde bestaande Non-original parapets and handrails en handgrepen. Niet oorspronkelijke borstweringen

D7.2.3 D8.1 D8.2 D8.3 D8.4 D8.5 E4.1.3 G1.11 G1.12 G1.21 G1.22 G1.31.1 G1.31.2 G2.10 G2.20

5.1 Performantie Performancevan of de infrastructuur infrastructureenand equipment uitrusting

2.6 Saneren van vochtige Decontamination of muren en vloeren damp walls and floors

2.5 Isolatie vanofde Insulation Roofs voordeuren the front doors

2.4 De beglazing Glazing of thevan de buitenschrijnwerkerij exterior woodwork

2.3 De daken Roofs

2.2 Vloeren boven niet Floors above verwarmde non-heatedruimtes

2.1 De gevelmuren Façade walls

1.5 Sanering van vochtige Decontamination of muren en vloeren damp walls and floors

1.4 Zomerconfort Summer comfort

1.3 Wegwerken Eliminating van cold koudebruggen bridges

Voordeuren isolatie van Front doors--Thermische Thermal insulation of deuren met doors with thin filling panels dunne vulpanelen Front doors--luchtair and proof profiles Voordeuren en sound geluidsdichte profielen between framesenand wings tussen kozijnen vleugels Restitution ofklapluiken folding shutters Restitutie van Restauratie van rolluiken, met betere aansluiting Restoring rolling shutters, withde better connection of the parts van onderdelen. Restitutie van Restitution ofrolluiken rolling shutters

D4.2.21

5. 5. Other Andere

Air-tightness of opening wingsvleugels – Luchtdichtheid van opengaande - restoration works restauratiewerken Air-tightness of opening wingsvleugels – Luchtdichtheid van opengaande - restitution works restitutiewerken Thermische isolatie van buitenschrijnwerkerij Thermal insulation of exterior woodwork – - restoration works restauratiewerken Thermal insulation of exterior woodwork – Thermische isolatie van buitenschrijnwerkerij - restitution works restitutiewerken

D2.3.2-2

D3.1-7

1.2 Luchtdichtheid Air-tightness ofvan thede buitenschrijnwerkerij exterior woodwork

Articles provided for in the technical specifications T02) Artikels voorzien in(book de technische voorschriften (boek T02)

1.1 Compartimentering van Compartmentalisation de ruimtes of the spaces

Huidige behoeften Current needs 1. Hygrothermal measures 2. Energy savingdoor by working 1. Hygrothermische maatregelen 2. Energiebesparing werken aan forcomfort comfortenand health onde the outer shell voor gezondheid buitenschil

Thermische isolatie van houten dragende vloeren Thermal insulation of wooden load-bearing floor above accessible spaces boven toegankelijke ruimtes Isolatie vanof dragende vloerenfloors uit beton of holle or Insulation load-bearing of concrete hollow slabs accessible spaces welfsels bovenabove toegankelijke ruimtes

Thermische isolatie van dragende vloeren boven Thermal insulation of load-bearing floors above dry, inaccessible spaces droge ontoegankelijke ruimtes Thermal insulation of load-bearing floors above Thermische isolatie van dragende vloeren boven humid, inaccessible spaces vochtige ontoegankelijke ruimtes Verwijdering van de bestaande vloer voor de Removal of existing floor for treatment of damp non-load-bearing floors behandeling van vochtige niet-dragende vloeren Aanleg van een ondervloer onder Construction ofdrainerende draining blind floor for damp non-load-bearing floors vochtige niet-dragende vloeren Behandeling tegen opstijgend vocht van muren van Treatment against rising damp in walls of spaces above floors ruimtes boven self-supporting zelfdragende vloeren Behandeling tegen opstijgend vocht van muren van Treatment against rising damp in walls of spaces above the ground ruimtes boven floors vloerendirectly op volleon grond

Fig. 5a and 5b Technical specifications extracted from The Le Logis and Floréal heritage management plan (© ARSIS).

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Comfort & hygiene Art.1.1. Compartmentalisation of the space Art.1.2. Airtightness of the opening panes Art.1.3. Airtightness of the connection of the exterior joinery Art.1.4. Removal of thermal bridges Insulation of the shell Art.2.1. Insulation of the façade Art.2.2. Insulation of the floor Art.2.3. Insulation of the roof Art.2.4. Insulating glazing

Drawn up by private limited

(House type LLw_D)

for the Brussels-Capital Region

Fig. 6 Various measures are presented on the plans for a specific type of house.

idea of the scale we can expect regarding energy-efficiency and costs. Additional audits will provide more information and provide a clearer picture of the qualities of the houses and the financial means needed to realise the energy policy of these social housing residences. The return on investment time (ROI) plays a crucial role in decisions, both short-term and medium-term. “Medium-term” means a term which is reconcilable with the 2040-2050 energy goals. On the one hand, the estimated costs of the works (as described in detail in the management plan) are taken into account when calculating the ROI. On the other hand, the obtained energy saving

also plays a role in both the ROI and the energy costs. The energy saving is the difference between the current consumption and the estimated future consumption. Over the years, it has become ever clearer that energy use models can divert greatly from actual consumption. Old, non-insulated buildings appear to draw their energy performance from other, undocumented qualities. They consume much less (up to 3 or 4 times less) than what can be expected based on the calculations. In the past, this has also been found to apply to the houses of the Le Logis and Floréal garden cities. In the energy audit of the two aforementioned houses,


it was therefore conservatively assumed that the houses consume 2.5 times less than indicated by the calculations5. This difference between actual and calculated consumption also leads to a difference between the ROI based on the actual consumption and that based on the theoretical, calculated consumption. With the goals for 2040-2050 in mind, the following conclusion can be made based on a preliminary evaluation of the energy efficiency of the measures provided in the management plan: • A 50% reduction in energy consumption with a selection of measures a) with an ROI of less than 50 years,


calculated based on the actual, measured consumption of the houses; b) with an ROI of less than 20 years, calculated based on the theoretical, calculated consumption of the houses. The measures considered feasible are those with the shortest return on investment time, namely: 1. insulating the roof and roof windows; 2. making the shell airtight; 3. installing more efficient lighting; 4. installing more efficient heating; The total costs for these measures can be estimated at EUR 75 to 150/m² of heated floor space. • A 75% reduction in energy consumption is feasible by applying all of the measures provided in the management plan. The total costs for these measures can be estimated at EUR 400 to 700/m² of heated floor space. This includes the measures with a ROI of 100 to 150 years, such as insulating the façades. This very long ROI is, in combination with the large impact on the heritage, the reason why such works are subject to a mandatory audit before the Brussels-Capital Region can grant subsidies for them. For clarification and rectification purposes, it must be noted that: • these calculations are valid assuming a steady energy price; in the case of increasing prices, the return on investment time will decrease; • these calculations do not take future maintenance costs into consideration, costs which are certain to arise as the return on investment times are quite long. The maintenance costs will increase the return on investment times.

CONCLUSION The Heritage Management Plan for the Le Logis and Floréal garden cities became operational in 2014 in the legal framework for urban development which recently came into effect in the Brussels-Capital Region. The instrument was realised over a period of 15 years and in several phases and versions; the energy section is fully integrated in the most recent version. Thanks to an in-depth study of the original condition of the houses, the composition principles and the strengths and weaknesses of the 1,060 residences, heritage-friendly measures were provided to save energy and to keep energy bills as low as possible for the residents. The position taken here is to prioritise measures which will result in a maximum reduction to energy bills with a minimum investment. Thanks to a preliminary, calculated evaluation (audit) the conclusion can be made that it is possible to reduce the energy bill of a residence by 50% with affordable, energy-saving and heritage-friendly measures with am ROI of less than 20 or 50 years, depending on whether the calculations are based on the calculated consumption or the actual consumption. This big difference shows, once again, that: • considerable, affordable energy savings are possible and are also feasible for large scale implementation; • a deeper knowledge of the hygrothermal behaviour of historical heritage is needed in order to explain why current calculation methods for energy consumption deviate considerably from reality, and to understand that standard solutions for energy saving applied to newbuilds do not deliver the expected results or can even cause problems.

The complete Le Logis and Floréal management plan can be found on the website of the Direction des Monuments et des Sites: http://bit.ly/1iMnupW Translated from Dutch.

NOTE 1. In 2007, two houses from Floréal were added to the listing when it became apparent that they too were built before 1940. 2. Houses were sold to private owners from the outset. 3. For a possible energy upgrade of all the Le Logis and Floréal houses. 4. The audit takes into account the specific qualities of each house in its current condition in relation to renovations, energy measures, technical installations, etc. 5. The actual consumption figures for the two houses were incomplete, but based on the figures available it is safe to assume that they consumed more than 2.5 times less energy than calculated.

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Les maisons classées des cités-jardins Le Logis et Floréal : adaptations aux besoins actuels en énergie et en confort Les cités-jardins Le Logis et Floréal forment un ensemble cohérent de rues, de places, de chemins et de bâtiments. L’équilibre général s’appuie sur le leitmotiv «l’unité dans la diversité, la diversité dans l’unité», qui préside par ailleurs à toute composition. Mais les besoins et les attentes changent; la performance énergétique et le confort n’y échappent pas. Au stade actuel, le plan de gestion – adopté après quinze ans d’évolution et premier de ce type en Région bruxelloise – concerne seulement l’enveloppe extérieure des maisons et vise prioritairement le maintien de la cohérence de l’ensemble, tout en permettant une réduction effective des besoins en énergie. Il permet de faire évoluer la situation d’origine, de différentes manières, en fonction de la performance recherchée et de manière compatible avec d’autres mesures. Les solutions doivent également rester équilibrées tant sur le plan technique que financier. Le plan de gestion s’est notamment attaché à cela en opérant une distinction entre les mesures de confort, pour l’augmenter tout en

diminuant la demande en énergie, et d’isolation. En effet, beaucoup d’interventions liées au confort et au climat intérieur des bâtiments visent à réparer des dégradations constructives. Dans ce cas, les qualités patrimoniales du bâti sont peu, voire pas, concernées. En revanche, les mesures d’isolation, qui doivent freiner la conduction de l’énergie à travers l’enveloppe extérieure, sont plus intrusives et ont un impact sur la valeur patrimoniale du bâtiment. Ces mesures doivent donc être subordonnées à des critères d’efficacité, à évaluer précisément. De beschermde huizen van de tuinwijk Le Logis en Floréal. Aanpassingen aan de huidige energie- en comfortbehoeften De tuinwijken Le Logis en Floréal (1922-1940) vormen een samenhangend geheel van straten, pleinen, paden en constructies. De evenwichtige samenhang volgt het leidmotief ‘eenheid in verscheidenheid, verscheidenheid in eenheid’, in wezen de eigenschap van elke geslaagde compositie. De noden en verwachtingen veranderen; en dat geldt ook voor energieprestatie en comfort. Het goedgekeurde beheersplan viseert voorlopig slechts de buitenschil van de huizen en


enkele ondergeschikte elementen in de omgevingsaanleg. Het plan is tot stand gekomen na een evolutie van bijna 15 jaar en beoogt in de eerste plaats het behoud van de samenhang; het laat tegelijk ruimte voor een toepasbare en effectieve vermindering van de energiebehoefte. De oorspronkelijke toestand mag op verschillende manieren worden aangepast, in functie van de beoogde performantie en van de compatibiliteit met andere maatregelen. De oplossingen moeten technisch en financieel evenwichtig zijn. Er wordt een onderscheid gemaakt tussen comfortgerichte en isolatiegerichte maatregelen. De comfortgerichte maatregelen beogen tegelijk het verlagen van de energievraag en het verhogen van het comfort. De meeste van deze maatregelen staan in verband met de sanering van scheefgegroeide bouwfysische omstandigheden, en nopen tot weinig of geen veranderingen aan het erfgoed. Deze maatregelen verminderen de energievraag in het binnenklimaat. De isolatiegerichte maatregelen beogen het verminderen van energiegeleiding door de buitenschil. Deze maatregelen zijn meer ingrijpend ten aanzien van de oorspronkelijke erfgoedtoestand en zijn dan ook aan criteria van efficiëntie gebonden.


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FINANCIAL IMPACT OF ENERGY EFFICIENCY MEASURES IN LE LOGIS AND FLORÉAL JONATHAN FRONHOFFS BUREAU CENERGIE CVBA

TWO HOUSES IN THE GARDEN CITY LE LOGIS AND FLORÉAL WERE EXAMINED. THE GATHERED DATA WERE EXTRAPOLATED AND A MODEL CREATED WHICH CAN BE APPLIED TO OTHER BUILDINGS IN THE GARDEN CITY. A HIERARCHY OF INTERVENTIONS WAS DRAWN UP IN RELATION TO THEIR IMPACT ON ENERGY CONSUMPTION AND RETURN ON INVESTMENT TIME. In the course of this study two buildings were audited: a threefaçade building on Kruisbooglaan and a two-façade building on Ibissenstraat. They were examined in order to extrapolate energy saving measures for the entire garden city at a later time. The measures of course fit into the management plan; a link is made between the audit and the management plan. For example, the course of the ventilation tube is clearly marked, through the roof or through the side façades, in particular colours. Firstly, all losses through the building shell and the characteristics of each building were analysed (fig. 1 and 2). The roof of the Ibissenstraat building was not insulated and 75% of the energy loss was found to take place through the roof. The opposite is true for the Kruisbooglaan: the roof was insulated and we ascertained that a large portion of the losses occurred through the façades. This is a three-façade building so it is logical that a higher

Fig. 1 Ibissenstraat 5 in WatermaalBosvoorde (A. de Ville de Goyet, 2015 © GOB).

Fig. 2 Kruisbooglaan 34 in WatermaalBosvoorde (A. de Ville de Goyet, 2015 © GOB).

Ibissenstraat 5

Kruisbooglaan 34

Heated

190 m²

137 m²

Volume

338 m³

475 m³

approx. 1930

approx. 1930

/

/

Built Most recent major renovation Fig. 3 Buildings studied (© Cenergie).

48 | Financial impact of energy efficiency measures in Le Logis and Floréal


Sloped roof 57%

Floorboard 5%

Sloped roof 13%

Floorboard 3%

Façades 14%

Cellar steps 1%

Façades 40%

Cellar steps 1%

Cellar walls 2%

Wood 100SV 11%

Cellar walls 1%

Wood 100SV 19%

Front façade dormer 1%

Back door 6%

Front façade dormer 1%

Back door 1%

Board above attic 1%

Cellar door 1%

Board above attic 10%

Cellar door 1%

Fig. 4 Ibissenstraat 5: division of losses through transmission per type of wall (© Cenergie).

proportion of losses occur through the façades (fig. 3, 4 and 5). Before measures are taken, the building’s current energy use is always examined first. This is true of all cases, whether the building in question is listed or not. Based on the invoices examined, there was a factor of 3.4 to 3.8 between the actual value and normal consumption figures for this type of building. A large discrepancy was thus immediately evident. A large difference between theoretical and actual levels, for example with a factor of 3.5 to 4 above, means that the theoretical values are not actually realistic. For this reason we delved into the literature in order to find a more realistic figure and ended up with a factor of approximately 2.5 with regard to the actual consumption measured in these two houses. The consumption based on the gas invoice was low, though electric heating may be used by the residents for additional heating, which cannot be measured. This is probably the reason for the large difference (fig. 6).

Fig. 5 Kruisbooglaan 34: division of losses through transmission per type of wall (© Cenergie).

Ibissenstraat 5

Kruisbooglaan 34

Consumption from additional devices

Losses from the residential hot water systems Losses from the heating systems

Net energy needed for residential hot water

Supply through sunlight/internal supply Loss due to ventilation

Loss due to air leaks

Loss due to transmission

Fig. 6 Final energy consumption of the two houses (© Cenergie).

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If the global consumption - i.e. including heating - between the two houses is compared, we can conclude that the Ibissenstraat house had a greater loss through the façades and the Kruisbooglaan through the roof. These differences are compensated for because one home contained an old atmospheric boiler and the other a more recent boiler. This more or less creates a balance, which can be seen in the difference between the blue zone on the Ibissenstraat house and the orange zone on the Kruisbooglaan. Research was carried out to determine all of the possible energy saving measures which could be applied to the building. The following is a complete list detailing the situation before and after improvement works. When energy saving measures are applied, one measure will have an effect on the following measure with regard to the return on investment time and savings. For example, by insulating the façade first and then replacing the boiler, the boiler will consume less due to the façade insulation and thus the boiler’s return on investment time will improve. Below are detailed the results if the complete package of measures is applied. Tables 1 and 2 show the situation before and after applying the measures. We can see that the situation in both homes is more or less the same. There are of course a variety of priorities which could be chosen to assess the efficacy of various measures taken;. in our case the return on investment time has been used as the primary assessment measure.

Area to be improved

Performance before improvements [W/m².K]

Improvement

Performance after improvements [W/m².K]

Sloped roof

5.00

Interior insulation

0.33

Façades

1.60

Exterior insulation

0.58

Dormer front

5.62

Exterior insulation

0.31

Board above cellar

1.36

Insulation under

0.54

Wooden window, single glazing

5.24

Version A: replaced with laminated glass (Ug=3.4 W/m².K) / panel

3.16

Version B: replaced with double glazing (Ug=1.9 W/m².K) / panel

1.99


2.81


2.05


2.77


2.06

Bad v50 = 12m³/h.m²

Improve airtightness

Good5 v50 = 3m³/h.m²

Heating

Efficiency: 80%

No improvement realised

Efficiency: 80%

Lighting

Several incandescent light bulbs

Replace incandescent light bulbs with LEDs

Only low-energy light bulbs

Ventilation

No ventilation system

Natural air supply and extraction via the wet areas

+/- System C

Back door

4.80

Front door

Airtightness

4.46

Table 1 Measures Ibissenstraat 5 (© Cenergie).



Area to be improved

Performance before improvements [W/m².K]

Improvement

Performance after improvements [W/m².K]

Sloped roof

1.03

Interior insulation

0.33

Façades

1.60

Exterior insulation

0.58

Dormer front

2.45

Exterior insulation

0.78

Board above cellar

1.97

Insulation under

0.40

Wood, single glazing

5.24


3.16


1.99


2.81


2.38

Back door

4.23

Veranda roof

2.26

Heated roof system

0.58

Attic roof

1.92

Insulation of the wooden floor in the attic

0.81

Veranda façades

2.84

Exterior insulation

0.70

Bad v50 = 12m³/h.m²

Improve airtightness

Good5 v50 = 3m³/h.m²

Heating

Efficiency: 65.40%

No improvement realised

Efficiency: 83.02%

Lighting

Several incandescent light bulbs

Replace incandescent light bulbs with LEDs

Only low-energy light bulbs

Ventilation

No ventilation system

Natural air supply and extraction via the wet areas

+/- System C

Airtightness

Table 2 Measures Kruisbooglaan 34 (© Cenergie).

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Significantly, interventions in an old building can be more expensive than in a “regular” building. For example: in one of the two homes the façade insulation costs between EUR 400-500 /m2, while in a classic building the cost ranges from about EUR 100-150. Different improvement priorities were applied for each building as well as for each scenario: scenario 1 was the purely theoretical value; scenario 2 was the revised theoretical value, which is closer to the actual value for energy consumption. The heating in the Ibissenstraat home was the last priority because it had a good boiler but the roof was not insulated. The priorities were thus firstly insulating the roof, then the building shell and, somewhere in the middle, the windows. The return on investment times in scenario 1 is three years for the roof and 90 years for the façades. But scenario 2 gives 300 years for the façades’ return on investment time; for this reason this measure was not applied. Conversely, in the Kruisbooglaan home heating was the priority – the house had an old boiler situated outside the protected volume in the cellar. Replacing this was prioritised. A similar list then follows, with the façades again at the very end. Scenario 1 gives us 60 years if we take the longest return on investment time; that becomes 166 years when a more realistic existing energy consumption is applied.

Final energy use - Ibissenstraat 5 Before improvement

After improvement

Energy use for lighting Additional energy consumption Loss through SWW system Loss through heating system Net energy required for SWW Net energy required for heating

Fig. 7 Savings Ibissenstraat 5. Primary energy consumption (© Cenergie).

Final energy use - Kruisbooglaan 34 Before improvement

After improvement

Energy use for lighting Additional energy consumption Loss through SWW system Loss through heating system Net energy required for SWW Net energy required for heating

Fig. 8 Savings Kruisbooglaan 34. Primary energy consumption (© Cenergie).

The full audit is available on the website of the Direction des Monuments et des Sites: http://bit.ly/1GPWL0X Translated from Dutch.



IBISSENSTRAAT 5: RETURN ON INVESTMENT TIME - SCENARIO I

IBISSENSTRAAT 5: TERUGVERDIENTIJD - SCENARIO II

Priority in relation to the return on investment time Improvements


Priority

Sloped roof

ROI (years)

1

Sloped roof

3

2

Front façade dormer

3 4 5

Priority

Sloped roof

ROI (years)

1

Heating

5

3

2

6

Airtightness

13

3

Board above cellar Front façade dormer

Board above cellar Wood, single glazing

15

4

Airtightness

7

Version A: 38 Version B: 42

5

Attic roofing

8

6

6

Sloped roof

18

6

Back door


7

Veranda façades

20

7

Front door


8

8

Façades

91

Wood, single glazing


9

Back door

9

Heating

0


10

Façades

60

KRUISBOOGLAAN 34: RETURN ON INVESTMENT TIME - SCENARIO I

KRUISBOOGLAAN 34: RETURN ON INVESTMENT TIME - SCENARIO II



Priority

Sloped roof

ROI (years)

1

Heating

5

2

Board above cellar

3

Priority

Sloped roof

ROI (years)

1

Lighting

6

6

2

Heating

13


6

3


17

4

Airtightness

7

4

Board above cellar

18

5

Attic roofing

8

5

Airtightness

20

6

Sloped roof

18

6

Attic roofing

21

7

Veranda façades

20

8

Wood 100SV


7

Veranda roofing

28

8

Sloped roof

50

9

Back door


9

Veranda façades

56

10

Façades

60

10

Wood 100SV


11

Back door


12

Façades

166

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Impact financier des mesures d’économie d’énergie dans Le Logis-Floréal

Financiële impact van energiebesparende maatregelen in Le Logis-Floréal

Afin d’élaborer des mesures prioritaires, deux audits énergétiques détaillés ont été réalisés. Les deux immeubles ont tout d’abord été analysés sous l’angle de leurs installations (le chauffage, la ventilation, l’éclairage…) et de leurs consommations d’énergie. L’analyse de ces dernières a montré qu’elles étaient particulièrement basses par rapport aux valeurs de consommation théoriques. Ces données de consommation réelles ont donc été extrapolées et modélisées pour pouvoir travailler sur d’autres bâtiments du Logis-Floréal. Les mesures d’intervention établies sur la base de l’audit de ces deux immeubles ont été classées selon quatre niveaux de priorité en fonction de l’impact sur la consommation d’énergie et du délai de retour sur investissement. Elles ont ensuite été confrontées au plan de gestion patrimonial du Logis-Floréal, pour y être intégrées.

Om prioritaire maatregelen uit te werken, werden twee gedetailleerde energie-audits uitgevoerd. Eerst werden de twee gebouwen geanalyseerd op het vlak van hun installaties (verwarming, ventilatie, verlichting...) en energieverbruik. Uit de analyse van de energieverbruiken bleek dat er bijzonder lage verbruiken geregistreerd waren ten opzichte van de theoretische verbruikswaarden. Deze werkelijke verbruiksgegevens werden vervolgens geëxtrapoleerd en gemodelleerd om bruikbaar te zijn voor andere gebouwen van LogisFloréal. De interventiemaatregelen die op basis van de audit van deze twee gebouwen werden uitgewerkt,werden volgens 4 prioriteitsniveaus gerangschikt naargelang hun impact op het energieverbruik en de terugverdientijd. Daarna werden ze getoetst aan en verwerkt in het beheersplan van Logis-Floréal.



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ANALYSIS OF UNCERTAINTIES IN DYNAMIC THERMAL SIMULATIONS FOR OLD HOUSING: A CASE STUDY OF ONE APPARTMENT AND ONE HOUSE IN THE PARIS REGION JULIEN BORDERON

CENTER FOR EXPERTISE AND ENGINEERING ON RISKS, URBAN AND COUNTRY PLANNING, ENVIRONMENT AND MOBILITY (CEREMA) - REGIONAL LABORATORY OF STRASBOURG (FRANCE)

THE EXISTING TOOLS FOR EVALUATING BUILDINGS AND THE UNCERTAINTIES ASSOCIATED WITH THE INPUTS FOR DYNAMIC THERMAL SIMULATIONS ARE PRESENTED, ALONG WITH A WAY OF EXAMINING THE LIMITATIONS OF MODELS WHEN APPLIED TO EXISTING BUILDINGS. This presentation centres on the method that we have applied to a certain number of buildings and that we continue to use. In fact, our approach has been deemed sufficiently beneficial by the French Ministry of Ecology, Sustainable Development and Energy that we have been asked to go even further. I will illustrate my talk with studies carried out on an apartment located in a building in the 16th arrondissement of Paris and a house in the inner suburbs of Paris (figs. 1 and 2).

THERMAL SIMULATION APPLIED TO OLD BUILDINGS Dynamic thermal simulation is one of the common auditing tools for buildings and therefore also for old housing. In fact, to perform a general audit, a number of aspects are worked on: the health of the building; its functional state; its suita-

bility for purpose; the comfort of occupants; its strengths and weaknesses; its heritage status and elements that need to be preserved are evaluated. The energy status of the building is also addressed through consumption, thermal efficiency, performance of systems and management and use. It is then possible to use simulation tools, if there is sufficient concern, to compare or test different packages of solutions. An attempt is made, via this energy audit, to determine typical consumption and how it is broken down by type of use in order to obtain itemised distribution graphs of heat loss. The ultimate objective is to establish priorities. This also enables the building’s behaviour when used in another way and/or independently from the occupant’s habits to be simulated. To explain this further: the energy bills of a person heating an apartment to 26°C are higher than those of a person heating

56 | Analysis of uncertainties in dynamic thermal simulations for old housing

the same place to 20°C. Thermal simulation of a building allows the consumption specific to an apartment in a classic usage scenario to be determined. In France, we refer to the conventional usage scenarios of the thermal regulations. A reference condition can therefore be obtained prior to works being carried out and used to model different simulations of packages of work. In order for our simulations to be reliable and be able to forecast the investment payback period, precise and realistic data are required. If our target is, for example, 80 kWh/m²/year and our initial situation indicates 200 kWh/m²/year, even though in reality our building is at 150, the general saving produced by the works will be a lot less than expected. It will therefore be harder to pay off the investment and could even result in a situation whereby it is not economically viable. Simulation also facilitates


Fig. 1 Two-family house in Noisiel (France). Early 20th century. The street-side façade is west facing (© Cerema).

an understanding of the building’s behaviour in a summer comfort configuration, especially in a scenario of global warming and more frequent summer heat waves. In order to use this thermal simulation tool for old or existing buildings, it is necessary to know what input data are available. Are they sufficiently reliable? Are significant errors produced when using the default values? The first stage in the technique involved collecting information on the two dwellings presented below. Certain information is obtained more easily than others. We realise that in the current case, where the modellers are neither a specialised consultancy firm nor an architectural firm specializing in the area, accessing data soon becomes complicated. Our work involved preparing models with the necessary input data and

Fig. 2 Parisian apartment. Late 19th/early 20th century (© Cerema).

Sources of uncertainty design assumptions U values opaque walls U values glass walls Solar factors glass wall Nearby masks Distant masks Linear thermal bridges (psi value) B values, wall in contact with unheated space Mechanical ventilation flow rate bathroom/kitchen Natural ventilation flow rate by opening windows Opening window scenario Closing sunscreens scenario Presence in apartment scenario Solar processor for radiators on vertical surfaces Internal contribution from electricity Internal contribution from cooking Internal contribution from domestic hot water Average set-point temperature of temperatures measured in the house Inertia class Building orientation

From measurement or expert appraisal E E E M M E E E, CF CF E, M E, M E, M M, calculation M, calculation E M, E

Typical uncertainty 15 % 10 % 20 % 5 % 30 % 30-50 % 15 % 100 % 100 % 100 % Extreme: all open all closed 30 % see report % 10 % 50 % 50 %

M, calculation

0,7 k

E, CF M, E

1 class 0%, verif.

%

E, M M E, M calculation

20/50 5 7 5

% % %

M M,E

7 20

% %

Sources of uncertainty measurement assumptions Breakdown of energy domestic hot water/cooking/heating Accuracy of energy sensors Accuracy of temperature measurement Boiler output Accuracy of weather data Accuracy of I4 air tightness measurement Distribution of electricity consumption over the year

KEY Transmission via the walls Solar contribution Internal contributions Renewal of air Other Fig. 3 Typical input uncertainties (source: Cerema).

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estimating the associated uncertainties, whether these are due to the reliability of the information collected or the confidence interval of the typical values used. A certain number of simulations of local and global sensitivity analyses were then carried out to assess the impact of these uncertainties on the result in terms of the energy audit. We used a research version of a software tool similar to that used by the French thermal regulation on existing buildings. That is to say, we were not bound by the calculation conventions imposed by the reference scenarios. We used a weather file measured locally on an hourly basis¹, presence scenarios, internal contributions on an hourly basis and ventilation by opening windows on an hourly basis (with a fixed flow rate) to establish a working hypothesis. Air permeability was in this case measured using a blower door. Around thirty inputs are listed (fig. 3). We have detailed knowledge of some of these inputs, and less about others. For example, it is estimated that there is a margin of error of only 10% for the U values of glass walls. However, we had difficulty in estimating the distant masks, i.e. shade on the building. Internal contributions are also not very well known (evaluated at around 50%), because use of household appliances varies. There are therefore uncertainties around this input data, the propagation of which are assessed until output.

CASE STUDY 1: THE WORKER’S HOUSE IN NOISIEL This is a traditional, brick, two-family, worker’s house in the Paris suburbs (fig. 1). It is a typical

building of this geographical sector. The building is symmetrical, has two storeys and an occupied attic space. The bricks, arranged in two thicknesses, are externally rendered. There is also an interior plaster render. Certain windows were replaced by double-glazing around 1985-1990. Other windows are single-glazed. Natural ventilation is used with the exception of mechanical ventilation that was recently added in a laundry. It is a building in the somewhat heavy thermal inertia class, with significant slabs particularly the one over the brick cellar with jack arches and double brick walls. The house is occupied by a total of three adults who all work. My department monitored annual consumption with electronic meters so as to compare readings and calculations. All the data are summarised in a graph (fig. 4). Total consumption for this house of 106 m² amounts to 241 kWh/m²/year, which is around the French average. Gas is responsible for 194 kWh/m²/year, mainly for heating (domestic hot water is also provided by the boiler). I will comment on this item in particular. The first step involved propagating the basic uncertainties. To do this, we took the uncertainty about each item of input data, separately from the others: 29 of them are fixed and one moves. We then examined the impact on the results by setting that item at both maximum and minimum limits. The results of this exercise are illustrated in the graph of propagation of basic uncertainties (fig. 5). Let’s take a look at some of the results. If we take the U values of opaque walls (i.e. the brick walls and the roof) we see that by increasing the values deter-


mined after our on-site visit by 15%, the heating requirements of this house increase by 14%. We are therefore almost at 1 to 1. The inverse is also true: if the values are reduced by 15%, the heating requirements are reduced by just under 14%. Temperature is also an important variable, therefore air temperatures in the house were measured. An average was then calculated for the house based on these measurements in the rooms. A variation of 0.7°C of the set-point temperatures in the modelling, corresponding to the upper range of uncertainty regarding the actual interior temperatures measured, implies a 10% shortfall in heating requirement. Site measuring is also important and is often under-estimated. In effect, if we are 7% out in the estimate of heat loss surfaces, a shortfall of 7, 8 or 9% in heating requirements in a winter scenario is easily possible (the study was not concerned with what happens in summer). However, it is known that the margin of error with laser measurements is 3% to 4% and not all auditors carry out site measuring; some instead work using the construction plans. Input inaccuracies in our simulation model therefore have an immediate impact on the results and it is important to be aware of them in order to focus on input data with a significant impact. The second step involved a global analysis of all of the propagated uncertainties using a statistical method, namely the Monte-Carlo method. 1,000 simulations with drawings from all of the input data were run. The resulting curves (fig. 6) represent the 95% confidence interval of the heating energy consumption of the house. The initial finding was that the curves do not perfectly overlap. This is due to the

Day of the year Gas cooker

Domestic hot water

Heating

Lighting

Electricity other than lighting

Fig. 4 Annual monitoring of consumption of the house in Noisiel (source Cerema).

(Input difference A, Input difference B)

difference between the measurement and the calculation, which means that my simulation is not necessarily close to the reality. There are multiple explanations for this: certain physical phenomena are not modelled by the calculation engine, such as hygroscopic inertia, for example. Our behaviour scenarios are less complex than actual family life. Nevertheless, we find that the dotted curves on either side of the bold curves form a significant range that represents the uncertainties about the model’s input data. This illustrates well the importance of paying attention to these uncertainties when running simulations. In fact, it is necessary to be aware of the differences and the range of responses that can be obtained.

kWh/day


Solar factor opaque wall (+50%, -50%) Linear length (+15%, -15%) A Opaque walls + bay windows (+5%, -5%) A Opaque wall only (+7%, -7%) A bay windows (+5%, -5%) Accuracy weather data air temp. (-2K, +2K) Accuracy weather data wind speed (+10%, -10%) Accuracy weather data exterior temp. (-0.5K, +0.5K) Accuracy weather data solar radiation (-5%, +5%) Accuracy measurement of I4 air permeability (+7%, -7%) Building orientation (-, -) Inertia class (-1 class, +1 class) Average temperature measured in the house (+0.7K, -0.7K) Internal contribution from domestic hot water (-50%, +50%) Internal contribution from cooking (-50%, +50%) Internal contributions from electricity (-10%, +10%) Contributions due to occupation in the house (-30%, +30%) Closing sunscreens scenario (all open, all closed) Opening windows scenario (x2, =0) Natural ventilation air flow by opening window (x2, /2) Mechanical ventilation air flow bathroom/kitchen (x2, =0) b values, walls in contact with unheated space (+15%, -15%) Linear thermal bridges (psi value) (+50%, -50%) Distant masks (+30%, -30%) Nearby masks (+5%, -) Solar factors glass walls (-20%, +20%) U values glass walls (+10%, -10%) U values opaque walls (+15%, -15%)

Relative differences B

Relative differences A

Fig. 5 House in Noisiel. Step 2, static. Propagation of basic uncertainties (source: Cerema).

Fig. 6 House in Noisiel. Step 3, week by week. Annual curves on the confidence interval in kWh/week/m². The measurement, in blue, also includes an uncertainty, as our sensors are not 100% reliable. Furthermore, the breakdown between hot water and heating is not clear (source: Cerema).

Pivotal calculation

Pivotal measurement -2K measurement

-2K calculation +2K measurement

+2K calculation

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We’ll now focus on one particular week in winter to take a detailed look at what is happening (fig. 7). The temperature of the house is stable, with a low inertia effect. The external temperature is cool and variable. We can see that the curve corresponding to the measurement displays more significant variations than the simulation curve, even though the set-point temperatures of the simulation are those that were measured (fig. 8). From a consumption point of view, this means that the boiler, in reality, is continually stopping and starting, a phenomenon that is not taken into account by the simulation. This typically illustrates a difference arising from the way in which the calculation engine takes the reality into account. In practical terms, the calculation somewhat smooths out the heating system even though, in reality, an old boiler operates a lot less smoothly. Inversely, when the heating flow is imposed on the model and changes in temperature are observed, we notice that changes are much more marked in the calculation. In this case, the inertia of the heating system is not taken into account in the calculation, which constitutes yet another bias of my mathematical tool. This phenomenon is not very significant over an average. However, it becomes very significant when we look at exactly what happens on an hourly basis.

CASE STUDY 2: THE PARISIAN APARTMENT The apartment dates from the late 19th/early 20th century (fig. 2). With a surface area of 108 m², comprising three bedrooms, it is located on the 5th floor of a handsome apartment building. The façades are made from hard limestone

Temperatures over 3 weeks on either side of the period studied

Interior temperature

External temperature

Fig. 7 Dynamic analysis over one week (source: Cerema).

Measurements

Temp. calculation imposed

Fig. 8 Changes in heating output measured and calculated. The interior temperature is imposed (source: Cerema).

(called Paris stone) with beautiful dressed stone on the external street-facing side and plaster render on the interior walls. Thinner, less elaborate breezeblocks covered in render are found in the courtyard-facing side. Paris stone, which is very hard, offers very poor thermal conductivity for a limestone. All of the windows are single-glazed and original. They are thermally inefficient. A family of two adults and two teenagers occupies the apartment. All family members are occupied during the day. There is no mechanical ventilation apart from a basic extractor in the bathroom, added retrospectively. The family opens the windows every day.


The same method as previously was applied. This gives a graph of annual consumption (fig. 9). Energy consumption is a bit lower than the house in Noisiel: 165 kWh/m²/year, the correct figure for a building with single glazing. The extreme contiguity plays a positive role here. The occupants, who are quite well off, have no hesitation in turning on the heating; we are not dealing with a scenario of energy insecurity here that would require the setpoint temperatures to be lowered. On the contrary, the apartment is comfortable but, nevertheless, does not consume a particularly high amount of energy. This example illustrates how certain


The propagation of basic uncertainties is relatively similar to those from the first case study. Nevertheless, it should be noted that in this case there are a greater number of glass walls, meaning that there is greater uncertainty in relation to this item. The opaque walls also play an important role here (though less than in the previous example) with a 15% input difference implying a 10% output difference for the heating. One reason for this could be the solar factor of the opaque walls, which we do not completely understand. This can produce a difference of up to 1.5% in consumption. All of these small errors, when put together, ultimately produce significant output errors. The annual curves representing the overall uncertainties again evidence in the same difficulties outlined above in relation to matching the calculations with the measurements in the field. For this building, the bias arises from our lack of information about the adjoining apartments, which is limited to temperature measurements. I would like to mention an interesting bias relating to the calculation engine. The apartment is southeast facing. The first version of the calculation engine that we used took the general orientation into account as either due north, due south, due east or due west. However, by using a second, improved version of the calculation engine which enabled the exact orientation to be taken into account, divergences emerged in the results. When it was due south, consumption fell by 8%; when due east, it increased by 5%. This showed once again the importance

kWh/day

old buildings can consume less energy than buildings from the 1960s or 1970s.

Day of the year Gas cooker

Domestic hot water

Heating

Lighting

Electricity other than lighting

Fig. 9 Annual monitoring of apartment’s consumption (source: Cerema).

of inputting precise data in the calculation engine, including orientation.

CONCLUSION In conclusion, for our two buildings, the input parameters with the biggest impact on the results of these dynamic simulations were the U value of opaque walls, the average temperature measured in the apartment (a deviation of less than one degree from the set-point temperature has a significant impact on consumption) and site measuring. This fact is often forgotten, especially with these buildings. However, not having the architect’s blueprints, drawing them up in situ, or making estimates based on inaccurate documents can have major effects on the calculations. Finally, the closing of sunscreens scenario also plays its role, in particular in the extreme cases of where they are closed during the day or not used at all. The annual heating projection graphs (fig. 10 and 11) were produced

with very poor simulation data because the extremes of the input uncertainties had been used, which, statistically, have a very low chance of occurring. The blue bell curves, which are the outputs obtained with the simulations, are very wide. This means that the average measurement, which according to my simulations should be 125 kWh/m²/year for the Parisian apartment with regards to heating, may increase to a maximum of 175 kWh/m²/year and decrease to a minimum of 75 kWh/ m²/year. Once again, it is very difficult to “tune” the measurement to the calculation. Clearly, the data used could be refined. However, we deliberately put ourselves in a situation which consultancy firms frequently encounter, namely a lack of time and difficulty in collecting information. A consultancy firm working on dynamic thermal simulations is not going to spend three weeks collecting input data; there will therefore be a lack of precision in its results. We therefore worked within this realistic constraint. 61

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This doesn’t mean that such tools should not be used, simply that one must keep in mind that there are uncertainties and that those uncertainties propagate. These calculation engines are powerful tools for comparing different solutions. However, to achieve the most optimal results, it is necessary to work with a range of values of a realistic span (and not a value of 2 kWh/ m²/year). After carrying out work, the more in-depth knowledge of the package of works applied may enable future consumption to be correctly simulated, but any saving (which is the difference between consumption before and after the works) will always be inaccurate for all the reasons stated above, most notably that relating to the initial condition of the building.

Parisian apartment.

Translated from French.

House in Noisiel. KEY The measurement (with the uncertainties linked to the sensors and the breakdown of consumption by item) Model Fig. 10 and 11 Probability curves of heating requirements in kWh/m²/year. If care isn’t taken, the heating requirements can vary significantly with major uncertainties in relation to the input data (source: Cerema).



NOTE 1. Field of variables calculated on an hourly basis (depending on the weather station and simulations).

Analyse des incertitudes sur des simulations thermiques dynamiques de logements anciens : cas d’un immeuble et d’une maison en région parisienne Les simulations thermiques dynamiques (STD) de logements sont de plus en plus répandues dans le cadre de projet de réhabilitation. Les difficultés d’obtention de certaines données d’entrées, la difficulté d’être précis dans l’utilisation de scénarios stochastiques, pour certains paramètres liés à l’occupation ou l’usage du bâtiment, mènent à de larges incertitudes sur les entrées des modèles de simulation. Pour pointer le « coût » en précision lié à toutes ces incertitudes, deux cas de logements anciens ont été étudiés : un appartement dans un immeuble post-haussmannien et une maison ouvrière du début du XXe siècle. Pour ces logements, un monitoring des consommations et des ambiances est disponible dans le cadre d’un projet de recherche plus vaste. Des simulations avec un outil de STD avec des propagations d’incertitudes sont réalisées. Les comparaisons mesures/calculs avec des bandes d’incertitudes permettent de montrer les limites de l’outil par rapport à la connaissance des entrées des modèles. Les incertitudes sur certaines entrées sont particulièrement importantes sur des bâtiments anciens.

Analyse van de onzekerheden over de dynamische thermische simulaties van oude woningen: geval van een gebouw en een huis in de Parijse regio Er worden steeds meer dynamische thermische simulaties (DTS) van woningen uitgevoerd in het kader van herwaarderingsprojecten. De moeilijkheid om bepaalde inputgegevens te verkrijgen en om nauwkeurig te zijn in het gebruik van stochastische scenario’s voor parameters gelinkt aan de bezetting of het gebruik van het gebouw leidt tot grote onzekerheid over de inputgegevens van de simulatiemodellen. De impact van al deze variabele gegevens wordt geïllustreerd aan de hand van twee cases van oude woningen: een appartement in een gebouw in post-Haussmanstijl en een arbeiderswoning van het begin van de 20ste eeuw. Voor deze woningen werden het verbruik en het effect van de omgevingsfactoren gemonitord in het kader van een ruimer onderzoekproject. Er worden simulaties met de DTS-tool uitgevoerd waarin gekeken wordt naar het effect van deze variabele gegevens om aan de hand van vergelijkingen (metingen/berekeningen) met onzekerheidsmarges de beperkingen van deze tool aan te tonen. In oude gebouwen spelen deze variabelen in de inputgegevens immers een bijzonder belangrijke rol.

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RISK ANALYSIS FOR APPLYING INTERIOR INSULATION IN HISTORICAL BUILDINGS: A CASE STUDY OF THE FORMER VETERINARY SCHOOL IN ANDERLECHT ROALD HAYEN

ROYAL INSTITUTE FOR CULTURAL HERITAGE (KIK-IRPA).

THE RENOVATION OF HISTORIC BUILDINGS OFTEN REQUIRES THE OUTER SHELL TO BE INSULATED. HOWEVER, SUCH TASKS ARE NOT ALWAYS COMPATIBLE WITH THE HISTORICAL CHARACTERISTICS OF THE BUILDING. A STUDIES CARRIED OUT ON INTERIOR INSULATION AT THE OLD VETERINARY SCHOOL HAVE BROUGHT THE RISKS INHERENT TO SUCH WORKS TO LIGHT, AS WELL AS THEIR POTENTIAL IMPACT ON THE PROTECTION OF THE BUILDING’S MONUMENTAL FAÇADES IN BRICK, EUVILLE LIMESTONE AND BLUESTONE. HISTORY OF THE VETERINARY SCHOOL IN ANDERLECHT In around 1761, the very first veterinary school was established in Lyon by Claude Bourgelat, a veterinary surgeon who was searching for a remedy for the ruminant infectious disease rinderpest, which plagued France at the time (Wikipedia, 2015). This initiative was being repeated throughout the whole of Europe by the late 18th and early 19th century. Initially, the first veterinary surgeons focused primarily on (army) horses. A veterinary school was also established in the United Netherlands in this period, in Utrecht (1821). Several years later, when Belgium seceded from the Netherlands, it quickly became clear that the gap

which had been created had to be filled. There was an acute need for veterinary education, both to serve the army and to improve the indigenous cattle and horse breeds. Above all, the authorities’ costs for the mandatory slaughter and monetary compensation of sick cattle were much too high and they therefore wished to focus on healing the animals instead. Two private initiatives were started as early as 1832: a limited education in veterinary medicine in Liège by Pierre-Antoine Pétry; and the École d’Économie Rurale et Vétérinaire, initiated by André-Joseph Brogniez in Binche (Bogaerts, 2015). Shortly after, Brogniez relocated his school to an old riding school in the centre of Brussels, where the Museum for Fine Arts is now located. In

May 1836, this Brussels school was taken over by the authorities and reformed into the École de Médecine Vétérinaire et d’Agriculture de l’état. The original school moved to the territory belonging to Kuregem, near a rural area and the slaughterhouse in Anderlecht yet still not too far from Brussels. Brussels’ urban development in the first half of the 19th century was indeed limited to the zone within the second medieval city wall. The current inner ringroad, also known as the Small Ring, follows the path of this wall. Originally, the school was nestled along what is now the Poincarélaan, on both sides of the Lesser Senne river. Regular flooding of the Senne caused a great

64 | Risk analysis for applying interior insulation in historical buildings: a case study of the former veterinary school in Anderlecht


the entirety formed by these buildings and the park in which they are located was listed as a protected landscape. However, this protection did nothing to hinder the decades-long neglect that was to follow.

Fig. 1 View of the main administrative building, according to a postcard dating from the early 20th century (verzameling Belfius Bank-Académie royale de Belgique© ARB-GOB).

Fig. 2 View of the rear façade after more than 20 years of neglect (photo by author).

number of problems. After some time, the school also stood in the way of Brussels’ urban development, so at the end of the 19th century the decision was made to move the school to the site which is now the Veeartsenstraat. The current building was realised, under architect Seroen’s supervision, in the 1903-1909 period and was officially inaugurated on 14 August 1910 on the occasion of the Brussels World Expo (ARTER, 2012).

In 1969, the veterinary school became part of the University of Liège. Throughout the years, various parts of the school gradually moved to the campus in Liège and in 1991 the site was left completely desolate. In 1999, Anderlecht Municipality became the owner of the administrative building on the street side. In the meantime, on 22 February 1990, the façades and roofing of the original buildings were declared monuments and

The veterinary school forms an extensive pavilion complex with a total of 19 buildings in Flemish neo-Renaissance style and large green spaces in between. The veterinary school of Hanover was the inspiration for architect Seroen when designing the pavilion complex (ARTER, 2012). At the start of this study, various pavilions had already been restored. The study was therefore limited to the former main administrative building, located on the Veeartsenstraat (fig. 1). The monumental front and side façades are made predominantly of Euville limestone with parts in bluestone. The south west facing rear façade is for the most part brick. The results of the more than 20 years of deterioration are clearly visible (fig. 2): the jointing has all but disappeared in various places; the limestone elements often show considerable loss of material and crack forming; and biological corrosion runs rampant, from lichens and moss to small trees sprouting from brickwork at the top of the façade.

PLANS FOR THE FUTURE If a monument cannot be reinstated to its original function, then an appropriate new use is essential for sustainable conservation. It was decided to turn the main building into a centre for young businesses. The architectural project, which was entrusted to ARTER (a different architect is being used for the interior: HASA Architecten bvba), is endeavouring 65

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to combine old and new: new floor levels were added to increase the amount of usable floorspace while at the same time maintaining the existing interior elements (oak floors, marble mosaics, historical carpentry, etc.) to the maximum extent possible. This is all being done with the intention of turning the building into a low-energy office building after its transformation. According to a study of the energy consumption carried out by the design and construction consultancy bureau Daidalos Peutz, the primary energy consumption was initially (i.e. before works) estimated at 400 kW/m²a - which delivers an E-level of 180 and a K level of 110 for the building shell (Daidalos, 2011). To calculate this estimate, the existing building shell as well as a new technical installation for heating, cooling, lighting and sanitary fittings were taken into account. As the original installations are missing - and most likely cannot be adequately simulated in accordance with existing calculation modules - this estimate delivers a lower limit with regard to the original consumption. However, this result does reflect the consumption to be expected if no architectural adaptations were made to the construction. Since this energy consumption does not meet the current energy standard for new-built office buildings in the Brussels metropolitan area, a decrease in the energy consumption was desirable, although such monuments are in principle not subject to this regulation. As heating was estimated to make up approximately three-quarters of the total energy consumption in the building’s initial state, an improvement to the insulation value of the building shell would immediately lead to a considerable

Buildings

Current value (W/m²K)

Solution A Solution B (W/m²K)

(W/m²K)

Maximum U value (W/m²K)

Roof

3.8

0.26

0.26

0.30

Façade

1.0

0.27

0.62

0.40

Floor (in contact with complete ground or cellar)

0.7

0.32

0.32

0.40

-

-

-

0.60

5.1

1.8

1.8

2.50

-

-

-

1.60

Floor (in contact with the exterior environment) Window Glass

Table 1 Overview of the transmission loss for the various sections of the building shell in their initialcondition and the proposals drawn up for improving the insulation. The maximum U values permitted for individual building sections according to the current standards are also included in the table (© KIK-IRPA).

decrease in primary consumption. The uninsulated roof in particular was a major source of heat loss: 44% of the total heat is lost through the roof. But the façades (20%) and windows (28%) were also areas of large losses. The transmission loss (U values) for the various sections of the building shell were far above the maximum standard values for new builds (Table 1). Using these data, a proposal was drawn up to improve the insulation values of the various building sections by: i) insulating the façades on the inside; ii) insulating the roof and floors; and iii) placing secondary glazing with mobile awnings in the space between the protected and the new windows. Initially a proposal was drawn up (Solution A) in which the exterior walls would be insulated on the inside with a 12 cm thick calcium silicate board with a plasterwork finish. This would provide a U value of 0.26 W/m²K. In this way, the various building sections would meet the current standard values (Table 1) after adaptation. In a second phase (Solution B) an alternative

solution for the inside insulation was put forward using 3 cm thick insulating plasterwork, which could provide a U value of 0.62 W/m²K. Insulation on the inside provides a gain in comparison to the original situation, although this does not meet the current requirements according to the energy performance regulations. This would decrease the primary annual energy consumption from 400 kW/m² to 188 kW/m². The new K and E levels would become 27 and 81 respectively: a substantial improvement. However, for the E level, the energy consumption is still too high to be able to call it a nearly energy-neutral office building (i.e. K level lower than or equal to K40 and E level lower than or equal to E40).

POTENTIAL BENEFITS AND RISKS OF IMPROVING THE INSULATION OF MONUMENT FAÇADES In principle, there are three possible scenarios for improving the façades’ thermal insulation:



floor 6%

cellar wall 4%

cellar wall 2%

windows 28%

roof windows 3%

cellar wall

roof 12%

floor 10%

roof 44%

façade 22% windows 40%

façade 28%

floor

cold bridges 9%

roof

façade

windows

roof windows

cold bridges

Fig. 3 Distribution of heat losses to building section according to the initial situation (left) and the situation after improvement of the insulation according to Solution A (right). (Daidalos, 2011).

exterior insulation, cavity wall insulation and interior insulation. Regarding quality and performance, exterior insulation is without a doubt the best option; cold bridges are avoided and the supporting structure is protected against changes in temperature and moisture content. However, because the original façade is lost, this is often not an option for listed monuments. If such an alteration were permitted, this solution would provide better protection for valuable interior elements because the interior volume is better protected. Buildings with an uninsulated cavity wall can be insulated retrospectively. But as cavity walls have only been used since WWII, this approach is also often not applicable to monuments. The most common practice for improvement of the insulation value of monument façades is therefore the placement of interior insulation. Interior insulation strengthens the impact of cold bridges and as a consequence is less efficient and of course leads

to the loss of the original interior decoration. Furthermore, this solution too is not always applicable to historical heritage. Applying interior insulation to monument façades also carries with it risks in terms of keeping the exterior façade intact. Interior insulation does, after all, have an impact on temperature division and moisture balance in the cross-section of the façade, particularly when no cavity wall is present and the façade forms the direct separation between the interior and exterior environments. The temperature in simple brickwork tends to vary gradually between the interior and exterior surface (fig. 4a). However, after applying the interior insulation a large temperature difference will occur across the insulation layer, making the interior surface of the façade warmer and the parts of the walls on the exterior of the insulation layer considerably colder (fig. 4b and 4c). As a consequence, the depth of influence of frost on the exterior surface of the façade increases.

Moisture balance is determined by the balance between the precipitation on the façade, possible condensation in the wall and the evaporation from both the interior and exterior surface. Drying is influenced by the temperature division in the cross-section of the façade. A higher temperature in the façade without thermal insulation will promote drying. Conversely, after the application of interior insulation the moisture content in the wall will increase, thus increasing the risks of frost damage (increased by the decreased temperature near the exterior surface) and biological attacks to the exterior surface. There are two ways to insulate the interior: methods that form a water- and condensation-tight layer on the interior surface to keep out the moisture; and methods that make use of capillary active materials. Methods that form a water- and condensation-tight layer make use of watertight and water resistant insulation materials such as rock wool, polyurethane, etc. in addition to applying a 67

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Fig. 4a

Fig. 4b

Fig. 4c

Fig. 4a, 4b and 4c Overview of the temperature transition (red curve) and the possibility of moisture exchange between the interior and exterior environment (blue arrow) for non-insulated mass brickwork (a) and an interior insulated construction with water and damp proof insulation material (b) and capillary-active insulation material (c) (© KIK-IRPA).

condensation-tight film to the interior surface in order to prevent condensation problems. Such a solution rules out moisture transfer between the wall and the interior (fig. 4b). Drying of the brickwork is thus only possible from interior to exterior, which results in an increase in the average moisture content. However, the insulation materials always remain dry, thus retaining their insulating qualities. Therefore such a solution is of better quality from a tech-

nical point of view. The increasing moisture content near the exterior surface does however increase the risk of frost damage and biological attacks. On the other hand, if capillary active insulation materials are used (such as calcium silicate boards or insulating plasterwork) the moisture transfer through the construction, from the interior to exterior, is retained (fig. 4c). On average, this leads to a decrease in moisture content in the brickwork, thus also decreasing the risk of damage to the historical façade elements. This solution is thus the preferable option for maintaining heritage property. However, the fact that the insulation materials can (temporarily) absorb moisture and therefore (temporarily) lose a portion of their insulation value must be taken into account. Applying interior insulation to historical buildings with brickwork façades is thus not without risk. By insulating the inside walls, heat loss decreases, causing an average increase in the moisture content in the brickwork of the façade and simultaneously making it colder. The combination of these two elements increases the risks of both frost damage and biological attack to the façades. Particuarly when materials are present in the historical façades which create a risk of frost damage, taking a good look at the pros and cons is very important.

RISK-EVALUATION OF FROST DAMAGE WHEN APPLYING INTERIOR INSULATION TO THE FAÇADE OF THE VETERINARY SCHOOL In order to be able to evaluate the risk of frost damage, the evolution of the temperature and the moisture content in the veterinary

school’s façades were examined based on the interior insulation choice. This approach was based on the heat and moisture transport in the façade brickwork as a function of the interior and exterior climate and the material characteristics of the cross-section of the façade. Material characteristics such as density Ð, accessible porosity Ð0, pore division, capillary water absorption coefficient Acap and degree of capillary saturation wsat were experimentally determined on illuminated samples (table 2). Absent material characteristics, such as thermal conductivity Ð and moisture permeability µ, were estimated in a rational way based on known correlations to the other experimentally determined, material characteristics. A model of the combination of heat, moisture and mass transport was created in the Delphin 5.6 program, developed by the T.U. Dresden. This study on the influence of the interior insulation on the temperature division and the moisture balance in the façade brickwork concentrated, firstly on the rear façade and secondly on the façade brickwork masonry of the front façade, where the ashlar is made of Euville (table 3). The core of the brickwork, just behind the ashlar, is also made of brickwork masonry on the front façade. The initial situation of each façade was then compared with the condition in which interior insulation based on a 12 cm thick calcium silicate board, and a 3 cm layer of insulated plasterwork, was used. The results show the evolution of the temperature and moisture content in the cross-section of the wall over time. The evolution of the moisture content is shown in figures 5 and 6, for the rear and front façade respectively, at each



Euville

Brick

Bricklaying mortar

Euville grout

Brick grout

Porosity (vol%)

11

31

24

22

28

Average pore diameter (µm)

6.1

0.56

0.069

0.67

0.60

Density (kg/m³)

2310

1624

1789

1886

1676

Water absorption coefficient (kg/m²s0.5)

0.03

0.16

0.03

0.08

0.11

Degree of capillary saturation (kg/m³)

91

219

103

242

248

Thermal conductivity (W/mK)

0.7

0.6

0.7

0.7

0.7

Moisture permeability (-)

56

20

15

5

10

Material characteristic

Table 2 Overzicht van de experimenteel bepaalde materiaaleigenschappen (© KIK-IRPA).

Condition

Front and side façades

Rear façade

Initial condition Solution A interior insulation with 12 cm thick calcium silicate board Solution B interior insulation with 3 cm thick insulated plasterwork Brick Euville limestone Multipor insulation panel

bricklaying mortar current plasterwork Multipor adhesive mortar Volcalite insulated plasterwork New plasterwork

Table 3 Overview of the different calculation models for analysing the temperature division and moisture balance in the façade brickwork based on the interior insulation. The exterior wall of the façade is always on the left of the façade cross-section in the diagram (© KIK-IRPA).

time interval for each of the possible situations. Figure 7 shows the evolution of the temperature in the front façade. The simulation was always performed over a reference period of several years in order to obtain a balance of the moisture content in the wall. The graphs show only the evolution of the temperature and the moisture content during the last year of this reference period. A total reference period of three years was sufficient for the façade brickwork at the rear (the brickwork masonry

only). A reference period of five years was needed to reach a balance for the brickwork on the front façade, with the ashlar in Euville limestone. The evolution of the moisture content in the façade brickwork shows considerable differences between the front and rear façade, and also between the initial condition and both interior insulation options. Periods of heavy rainfall, mainly in the spring and autumn, can be

easily recognised in the division of moisture content in the brickwork. The water is absorbed by the façade via the exterior surface, which is always shown at the bottom of the graphs. This evolution is easy to recognise via the change of colour, from red (dry, 1-2 vol. % moisture content) to green (wet, > 10 vol. % moisture content). Subsequent drying of the brickwork follows the same pattern, but in the other direction. The analysis shows that the façade is saturated 69

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Fig. 5 Evolution of the moisture content in the brickwork of the rear façade according to their initial condition (a), after applying interior insulation based on 12 cm thick calcium silicate board (b), and after applying 3 cm thick insulating plasterwork layer (c). The scale shows the moisture content (vol. %) of the total pore volume. The exterior surface is always shown at the bottom of the graph and the interior surface at the top. The diagram of the wall cross-section is shown to the left of the graph (© KIK-IRPA).

Fig. 6 Evolution of the moisture content in the brickwork of the front façade according to the initial condition (a), after applying interior insulation based on 12 cm thick calcium silicate board (b), and after applying 3 cm thick insulating plasterwork layer (c). The scale shows the moisture content (vol. %) of the total pore volume. The exterior surface is always shown at the bottom of the graph and the interior surface at the top. The diagram of the wall cross-section is shown to the left of the graph (© KIK-IRPA).

Fig. 7 Evolution of the temperature in the brickwork of the front façade according to the initial condition (a), after applying interior insulation based on 12 cm thick calcium silicate board (b), and after applying 3 cm thick insulating plasterwork layer (c). The scale shows the temperature(°C). The exterior surface is always shown at the bottom of the graph and the interior surface at the top. The diagram of the wall cross-section is shown to the left of the graph (© KIK-IRPA).



quite quickly, as the set mortar behind it greedily draws out water from the bricks. From there, the moisture slowly penetrates deeper into the brickwork. The comparison of the brickwork on the front and rear façades clearly shows that the front façade is much more susceptible to absorbing moisture; the rain water penetrates deeper into the façade and the moisture content reached is also much higher. On the front façade the moisture almost reaches the interior surface, while on the rear façade only the first two layers of the brickwork become damp. When comparing the initial condition with the available options for interior insulation, the 12 cm thick calcium silicate board receives considerably lower marks. The core of the brickwork behind the Euville ashlar is completely saturated all year round. Even the insulation board itself is almost completely saturated, with the exception of the last few cm of the interior surface, which can dry inside during winter. The dampness of the insulation board is accompanied by a significant loss in the insulating value of the façade’s cross-section. This condition deteriorates even more when the influence of an edge joint from the exterior surface to the insulation board is considered. The moisture quickly penetrates deep into the façade and dampens the insulation board locally to the extent that the joint will inevitably become clearly visible on the interior surface of the façade. Therefore, such a solution would be unacceptable without additional measures. On the other hand, the moisture balance in the brickwork of the rear and front façades after application of insulating plasterwork with a 3 cm layer is not significantly different to the initial condition.

The evolution of the moisture content in the façade’s cross-section must also be assessed in combination with the temperature division. The front façade is shown in figure 7. At first glance, the temperature division according to the three available alternatives (i.e. the initial condition and both options for improvement of the insulation) appear quite similar. Only the depth to which cold temperatures penetrate the façade increases visibly with an increasing insulating value. This can be recognised by the increasing amount of green and blue colours in the temperature division after application of interior insulation. The increasing temperature drop throughout the entire cross-section of the façade is particularly recognisable when opting for a 12 cm thick calcium silicate board. Based on these results, the number of frost-thaw cycles to the exterior façade were compared to the number of times the moisture content in this zone was higher than 30%, 50% and 70% respectively of the saturation degree of the Euville limestone (table 4) to evaluate the risk of frost

Condition

damage to the front façade. The critical moisture content causing frost damage to the Euville limestone is however unknown, therefore these moisture contents are purely arbitrary. The results clearly demonstrate the influence of the application of an insulating calcium silicate board to the interior surface: the number of cycles in which frost occurs while the Euville limestone is wet increases significantly (+230% at w > 30% wkr). The situation is less dramatic when applying a thin layer of insulating plasterwork. A slight increase (+50% at w > 30% wkr) in critical frost-thaw cycles can be observed. Exposure of facing brick to frostthaw cycles does not necessarily lead to damage. The degree of sensitivity or resistance to frost of the facing brick in question is the determining factor here. The previous Belgian standard, NBN B27-010, used the Gc criterion for this. Although the applicability of this criterion has been questioned and certainly cannot be applied to all materials, it can still serve as a first indication when assessing the

Number of Number of frost-thaw cycles at which frost-thaw cycles the moisture content is higher than 30% of 50% of 70% of wsat wsat wsat

Initial condition

61

13

4

2

Solution A interior insulation with 12 cm thick calcium silicate board

67

30

9

6

Solution B interior insulation with 3 cm thick insulated plasterwork

65

19

5

3

Table 4 Overview of the number of frost-thaw cycles and the number of critical frost-thaw cycles at which the moisture content in the brickwork of the front façade is higher than the set limits (© KIK-IRPA). 71

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risk for frost damage. The Gc factor is calculated using the following formula: Gc = -14.53 - 0.309 α + 0.203 S Where α is the water absorption coefficient of the material, expressed as saturation percentage per time unit in s0.5, and S the water accessible porosity, expressed as a percentage of the total volume. The experimentally determined Gc values based on the illuminated samples are recorded in Table 5. The standard dictates that the Gc value for vertical façade elements in solid brickwork must be less than -1 and less than -2.5 for horizontal façade elements. Therefore, depending on the exact value, both the joint mortars and the façade parts in Euville display a possible risk of frost damage according to the aforementioned criterion. Take note that Euville limestone is generally considered to be frost resistant and that the WTCB is more likely to list guideline values between -4.4 and -5.5 for the Gc factor. The Euville limestone results are more varied, which may indicate the use of lesser-quality materials , leading to a risk of local frost damage. It is important to note that for the evaluation of the materials’ sensitivity to frost, only possible frost damage to the materials is taken into account. Damage resulting from the combination of materials in the masonry, such as a joint being pushed outwards for example, is not taken into account in this criterion.

CONCLUSION The evaluation of the available options to improve the insulating quality of the exterior façades of

Material Euville limestone

Gc factor -3.42 to 0.28

Brick

-1.66

Bricklaying mortar

-6.96

Grout Euville limestone

-0.33

Grout brick

-0.64

Table 5 Overview of the experimentally determined Gc factor for the various façade materials (© KIK-IRPA).

the former veterinary school in Anderlecht shows that the risks of possible frost damage to the façade’s brickwork increase significantly, particularly to the front and side façades, which have an ashlar in Euville limestone, and to a lesser extent to the rear façade, which is mainly brickwork. Therefore, the construction of the historical brickwork has an important influence on temperature division, moisture content and the accompanying risk of frost damage to the ashlar, regardless of the type of interior insulation. The initial decision to reduce the primary energy consumption of the building from approx. 400 kW/m² to 188 kW/m² by improving the insulation to the shell of the building entailed the application of a 12 cm thick insulation board based on calcium silicate to the interior surface of the exterior walls. The study shows that this type of approach leads to a marked increase in the risk of frost damage to the ashlar, particularly to the façade sections in Euville limestone, which are already sensitive to moisture. Moreover, there is a risk of edge joints becoming clearly visible on the interior surface, caused by

water transfer through the joint and the insulation board. A 3 cm thick layer of insulating plasterwork, resulting in a somewhat higher energy loss through the exterior walls, allows for a substantial gain – in terms of possible frost damage – in comparison to the original proposal for improvement of the insulation. An increase in the risk of frost damage in comparison to the current situation remains, though it is less significant. To assess the actual risks of frost damage, the Gc criterion for the materials according to an old Belgian standard was compared to on-site observations of the damage. An evaluation of the sections of the front and side façades showed considerable damage to the limestone (fig. 8). However, the primary cause of the observed damage to the Euville limestone has more to do with the formation of gypsum as a result of air pollution than with frost damage. This in and of itself confirms the general assessment of Euville as a frost-resistant limestone. The formation of the gypsum crust does however influence the pore structure close to the stone’s surface, thus increasing the risk of frost damage over time. Therefore, totally eliminating the risk of frost damage is impossible. The possible risks are, however, connected to the amount of rain which penetrates the wall. It is above all the uppermost sections of the walls (which are more exposed to rain) that are particularly susceptible to this. Based on the study, the decision was made to diversify the application of interior insulation: on the ground floor and first floor it was opted to follow the original proposal and apply insulation, namely 12 cm thick calcium silicate boards. On the top



floors, 8 cm thick calcium silicate boards would be used, thus countering the increased risk of frost damage. The permeation of moisture through the horizontal joints was countered by using suitable interior finishings. Visual inspection of the rear façade shows that, in spite of the limited risk of frost damage according to the results of the modelling and the general assessment of the materials as being not or only slightly sensitive to frost, frost damage appears frequently (fig. 9).

Fig. 8 Overview of the damage to the Euville limestone front façade of the main administrative building of the veterinary school (photo by author).

The brickwork’s sensitivity to frost as a whole is therefore substantially more important than might be expected based on the Gc criterion, which only allows for an assessment of the individual materials. The jointing in particular can be described as highly sensitive to frost. Appropriate selection of new grout and minimum interior insulation using insulating plasterwork are therefore recommended for obtaining an acceptable level for the risks of frost damage. Translated from Dutch.

Fig. 9 Overview of the damage to the brickwork rear façade of the main administrative building of the veterinary school (photo by author).

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REFERENCES ARTER, École vétérinaire d’Anderlecht, Phase 3: Restauration extérieure des façades et toitures, Notes historiques, December 2012, p. 12 Bogaerts Philippe, La médecine vétérinaire en Belgique, http://www.ping.be/~ping0522/ Histoire.html, consulted on 6 February 2015 Daidalos-Peutz, Renovatie van de oude veeartsenarijschool te Anderlecht in een laag energie kantoor, Energetische haalbaarheidsstudie VETO, 1 March 2011, p. 6 Wikipedia, Claude Bourgelat, http://fr.wikipedia.org/wiki/ Claude_Bourgelat, consulted on 6 February 2015

Analyse des risques de l’application de l’isolation intérieure dans des bâtiments historiques : l’étude de cas de l’ancienne école vétérinaire à Anderlecht La revalorisation des bâtiments historiques génère souvent une demande d’isolation plus efficace de leur enveloppe, surtout en cette époque où l’énergie coûte cher et où les valeurs écologiques s’imposent. Cela dit, il n’est pas facile de renforcer l’isolation d’un bâtiment historique sans toucher à ses qualités patrimoniales. Les façades monumentales, en effet, limitent généralement la possibilité d’améliorer leur isolation par l’extérieur. L’isolation intérieure constitue souvent la seule possibilité. Mais les interventions de ce type influencent aussi la gestion de l’humidité dans toute la coupe de la façade, en augmentant parfois substantiellement les risques de dégâts du gel dans les matériaux de façade. Les restrictions et les risques inhérents à ce genre de travaux sont exposés dans le contexte de l’ancienne école vétérinaire d’Anderlecht : l’application de l’isolant intérieur est évaluée du point de vue de la protection des façades monumentales en brique, pierre d’Euville et pierre bleue.

Risico-analyse van de toepassing van binnenisolatie in historische gebouwen : case study, de voormalige veeartsenijschool te Anderlecht De herwaardering van historische gebouwen leidt vaak tot een vraag naar een betere isolatie van de gebouwschil, zeker in tijden van hoge energieprijzen en verhoogd besef van ecologische waarden. Echter, een verbetering van de isolatie van een historisch gebouw is zelden evident, zeker zonder daarbij afbreuk te doen aan zijn erfgoedwaarden. De gevelpartijen van monumenten beperken immers vaak de mogelijkheid om de isolatiewaarde van een gevel langs de buitenzijde te verhogen. Het aanbrengen van binnenisolatie is vaak de enige mogelijkheid. Een dergelijke ingreep beïnvloedt evenwel de vochthuishouding van de gehele geveldoorsnede, met soms een substantiële verhoging van het risico op onder meer vorstschade aan de gevelmaterialen. De beperkingen en risico’s inherent aan een dergelijke ingreep worden toegelicht aan de hand van de voormalige veeartsenijschool te Anderlecht, waarbij de toepassing van binnenisolatie wordt geëvalueerd ten overstaan van de bescherming van de monumentgevels in baksteen, Euville en blauwe hardsteen.



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IEDER ZIJN HUIS: THE RENOVATION OF A MODERNIST SOCIAL HOUSING TOWER BLOCK CHARLOTTE NYS

ORIGIN ARCHITECTURE & ENGINEERING

THE RENOVATION PROJECT OF THE IEDER ZIJN HUIS SOCIAL TOWER BLOCK COMPLIES WITH CURRENT REQUIREMENTS REGARDING INSULATION, COMFORT, FIRE SAFETY, ACOUSTICS AND SAFETY, WHILE AT THE SAME TIME TAKING INTO ACCOUNT THE CHARACTERISTICS OF THE BUILDING, ITS LAYOUT AND ORGANISATION, DESIGN AND ARCHITECTURAL LOGIC. THE RESOURCES USED AND THE RESULTS OF THIS AMBITIOUS OPERATION, WHICH INCLUDED PROBLEMS REGARDING HOUSING, ECONOMICS, ENERGY AND HERITAGE, ARE PRESENTED HERE. The following contribution is a presentation of the renovation project of the Ieder Zijn Huis modernist tower block in Evere. Through Beliris, the federal government has undertaken to renovate this building. Beliris determined the general building programme, including the important principle that the homes must comply with current regulations, in particular the Energy Performance of Buildings (EBP) regulations. This had to be done with the necessary respect for and/or conservation of this heritage’s characteristics. For this project the building history research was carried out by Ghent University, the building physics and acoustics were studied by Daidalos Peutz, the techniques were studied by Marcq en Roba and the stability and architecture by Origin. Belgium has an exceptionally rich and extensive heritage when it comes to social (i.e. govern-

ment-assisted) housing. The construction of social housing has played an active role in the history of our Belgian architecture. Pictured are two garden city buildings (fig. 1 and 2) and two tower blocks (fig. 3 and 4). This recent heritage was built between the 1920s and the 1970s. The difficulty with these homes is that they often do not achieve current comfort requirements or comply with EPB regulations. Heritage buildings are all too often in a terribly dilapidated state. They are mostly unlisted, which means that this valuable heritage is in danger of being lost. Ieder Zijn Huis is located in Evere. A defining feature of this building is that the tower is long, narrow and high: 9 m wide, 90 m long and 50 m high. In 1954, Willy Van Der Meeren received the design commission from mayor

76 | Ieder Zijn Huis: the renovation of a modernist social housing tower block

Franz Guillaume, a socialist who was very interested in this type of residence. Initially, Le Corbusier had been asked to build this tower block. When he declined, Franz Guillaume turned to Willy Van Der Meeren. There were two calls for tenders because the initial price was too high. Construction began in 1959 and the building was delivered in 1961.

WILLY VAN DER MEEREN AND HIS CONSTRUCTION PRINCIPLES Willy Van Der Meeren was born in 1923 and died in 2002. He trained as an architect at the La Cambre modernist school of architecture. Van Der Meeren is best known for the CECA house, which he designed together with Leon Palm as a solution to the acute housing shortage at that time. It was an inexpensive labourer’s cottage that


Fig. 1 Le Logis and Foréal, Watermaal-Bosvoorde (A. de Ville de Goyet © GOB).

Fig. 2 De Moderne Wijk, Samenwerkersplein, Sint-Agatha-Berchem (© Origin).

Fig. 3 Modelwijk, Laken (A. de Ville de Goyet © GOB).

Fig. 4 Ieder Zijn Huis, Evere. The east façade, almost completely renovated (© G. De Kinder).

made extensive use of modulation and standardisation. Furthermore, Van Der Meeren should be viewed as a total-concept designer. Before discussing the renovation, it is important to identify and acknowledge the characteristics of this building. The characteristics have been grouped into eight themes: The first characteristic is that the building very clearly illustrates “new communal living principles”. It is a high-rise building. Willy Van Der Meeren described his building as “streets in the sky”, as can be seen in figure 5 as well as in the cross-section (fig. 6). He designed wide circulation corridors which

can be found on every third floor. This gave people the chance to meet one another, thus emphasising the “streets in the sky” concept. The advantage here is that the apartments span from façade to façade, which allows natural light to saturate the homes. The roof terrace is typical of that period, along with a large variety of public functions and collective facilities, such as a mortuary, a relaxation room and a laundry room.

as the predecessor to open-plan living. He also wanted to integrate an open kitchen, but the time was not yet ripe.

A second characteristic: “the ideas about modern living”. The building is built on stilts. All of the homes receive a great deal of natural light, which Van Der Meeren achieved by bringing in diagonal light. The homes could be seen

The following characteristic is “the hierarchical construction of plan and façade”. In other words, the façade is a translation of the plan behind it. For example, the bedrooms have three windows at the top of the wall, the kitchens have

Another characteristic: “simple and affordable”. Van Der Meeren created a type of Meccano system with doorways of reinforced concrete supporting the arches. The entirety was sealed using façade panels and all that was left to do was to add a layer of paint.

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Fig. 5 Stairwell (© G. De Kinder).

Fig. 6 Cross-section illustrating the division principle of the apartments (© Willy Van Der Meeren Archives).

Fig. 7 Entrance door to apartments (© G. De Kinder).

Fig. 8 Entrance hall with mailboxes and fresco by Jo Delahaut (© Willy Van Der Meeren Archives).

Fig. 9 Staircase with access to the apartments. The colour was retained. (© G. De Kinder).

Fig. 10 Here, a typical Willy Van Der Meeren touch: the tap can be used for both the bathtub and the sink (© K. Verswijver).

Fig. 11 Living room. The height from the finished floor to the lower side of the arches is exactly 2.5 m. The measured height between the bottom of the doorways and the finished floor is 2 m (© Origin).



a terrace, the living rooms have windows both at the top and at the bottom of the wall. Van Der Meeren uses functional architecture which he brings to life with the use of art and colour (fig. 7, 8 and 9). The final three characteristics typical of Van Der Meeren are “modulation”, “prefabrication” and “standardisation”. These relate to the intensive use of modulation in order to make prefabrication and standardisation possible. For this he used the Modulor. Even the arches are custom made with a width of 57.5 cm, or half a module.

CONDITION OF THE BUILDING UPON START OF WORKS The first problem, and one of the most significant, was linked to the building physics. According to information received from the Housing Association, for the majority of the residents energy costs were higher than rental costs. The façade was built using sandwich panels - 5 cm concrete on the exterior and 5 cm concrete on the interior with a thin 2 cm insulation layer in between - and thus had very limited thermal resistance. The façade panels were hung up in the structure; as a result the structure runs from the interior to the exterior in the façade and large thermal cold bridges are created via the structure. A second difficulty in the building was fire safety. According to the letter of the law there are too few emergency staircases because they are placed 57 m from each other (it should be 60 m). There was also no compartmenting between the emergency staircases and the lifts, thus (as a high-rise building) both had to be equipped with an airlock. Some apartments had direct access to the stairwells.

The apartments are not compartmented in regard to circulation and the structure does not have a fire resistance of two hours, which in this case applies to the arches above all. The final important point is that the fire spread criterion in the façade is insufficient. Normally, there must be a zone with a development of one metre in length and a fire resistance of one hour, both between two floors and between two apartments (i.e. both horizontally and vertically). In addition, the technical installations were antiquated. There was no ventilation system installed into the building. The acoustic problems are obvious when considering the construction method: problems with noise transfer via the communal technical shafts; problems with contact noise throughout the entire structure; far too few absorbent surfaces; and too little mass between adjoining apartments. A final problem was the very limited height of the apartments. In figure 11 you can see that the height from the finished floor to the bottom of the arches is exactly 2.5 m. The measured height between the bottom of the doorways and the finished floor is 2 m. There is therefore very little room for providing technical or other equipment as the screed is only 7 cm thick and is located on the arches. The screeds and the arches do not work together, making the screed extra weigh on the arches. In order to gain a more in-depth knowledge of the construction and condition of the tower block, a series of probes, prototypes and mockups were carried out. These included dismantling a façade panel to see just how that panel was installed, whether it was easy to dismantle and to better understand

the panel’s composition. Research into the condition of the concrete was carried out (there is quite a lot of visible concrete present). The composition of the roof, the floors and the existing brickwork were examined. Additional research was carried out regarding the fire safety of the stairs and additional measurements taken relating to the structure of the entire building to determine the correct dimensions of the façade panelling. Many acoustic measurements were taken as this was an important factor in living comfort. Research into the building’s lateral stability was also needed. The most important themes for the renovation philosophy of the project were as follows: to design a comfortable layout for the apartments with a particular focus on the communal spaces and a façade that meets the EPB requirements, all achieved with respect for the characteristics summarised above.

THE PROGRAMME The building originally consisted of 105 homes. They have since been turned into 103 apartments, and to optimise living comfort all of the three-bedroom apartments were converted into two-bedroom apartments. Regarding energy performance, the result is a global K level of K30 and an E level of E80 per home. To improve acoustics and fire safety, all floors and ceilings were fitted with insulating acoustic materials. This caused the loss of the building’s internal thermal inertia. Despite the brand new façade, overheating in the summer period remained a problem. Due to this, a number of windows had to be sacrificed, mainly in the bedrooms. Exterior sun protection was also placed on every top window. 79

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For the façades an extensive range of solutions was examined. Firstly, the possibility of keeping the existing façade was explored, but this was very difficult to justify in terms of energy performance. Installing a new skin in front of the old skin could not be justified in terms of heritage, particularly as the building is built on stilts. Another idea was a metal structure with integrated windows as a new type of prefab system, finished with insulation and a type of plaster. This solution deviated too greatly from the project and gave nearly no thermal inertia to the building. Finally, the architects went back to the idea of using concrete prefab elements again, but this time with a new prefab element that completely covered the structure, thus avoiding cold bridge problems - either at floor level or around the columns - and with the following element: 12 cm concrete on the interior, 15 cm polyurethane insulation and then 7 cm concrete on the exterior. Regarding the design for the façade, Willy Van Der Meeren’s concept was used again, including the same design parameters. Two additional parameters were added in order to determine the design: on the one hand fire safety and on the other energy performance (fig. 13 and 14). In this concept, the outermost arch was first dismantled and a new beam installed on which the new façade could be hung. In order to solve the fire safety problem of the new façade, a type of nosing was integrated into the façade. The developing length measured at one metre. This solves the fire spread problems and means that it is still possible to integrate a fair number of windows.

Fig. 12a

Fig. 12b

Fig. 12c

Fig. 12a, 12b and 12c 12a: original building by Willy Van Der Meeren (© Willy van der Meeren Archives). 12b: the building before renovation; showing the brick stair shafts covered due to water infiltration. They were equipped with a metal cover long ago (© G. De Kinder). 12c: a drawing of the final project (© Origin).



Fig. 13 Sandwich panel principle (© Origin).

Fig. 14 Assembly sketch (© Origin).

Fig. 15 Current situation (© Origin).

Fig. 16 Detail of a concrete panel (© Origin).

To meet the fire spread criteria horizontally as well as vertically, one fewer window was placed between every two apartments. A few photos of the façade panel are included for illustrative purposes: figure 15 shows the original situation and figure 16 shows the new façade panel installed in front of the structure. In addition to the façade, all of the terraces were replaced. For each terrace, an arch was dismantled and replaced with a new prefab element through which the concrete nosing runs. That prefab element was then connected to the structure with a thermal breaker so that no cold bridges were created along the terraces.

The manner in which the façade insulation was integrated is interesting. The building is, after all, built on stilts and the floor above the stilts has a brick façade with storage rooms and a large shaft for technical pipes and cables behind it. It was decided during the design process not to insulate this brick façade. The insulated volume includes the roof and the façade elements and runs along the top of the storage area and around the technical shaft. The internal geometry was hardly altered. The arches were retained, except for the first arch along the façade, which was necessary for placing the façade panel. The screed was completely dismantled in order

to make room for a new, independent floor complex so that no contact noise can be transferred via the structure. For reasons of fire safety, a lowered ceiling was placed in direct contact with the arches; this also proved beneficial to the acoustics. As mentioned earlier, the layout has a diagonal working to bring in light. The new layout is very similar to the original concept. The bathrooms and kitchens were changed slightly, but the interior stairs were kept. The compartmenting was improved as the lift airlocks and stairwells were separated by automatic fire doors. All of the railings have been adapted in some way. In the new façade, windows have disappeared in some places in order to solve the problems of overheating and fire spread. 81

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IZH TOWER BLOCK RENOVATION COSTS Surface, gross 12,150 m2 ESTIMATE

PROCUREMENT excl. VAT

FINAL COST excl. VAT

excl. VAT

SITE INSTALLATION

EUR 1,039,725

EUR 86/m²

7%

EUR 1,245,251

EUR 102/m²

10%

EUR 1,230,932

EUR 101/m²

9%

DEMOLITION

EUR 1,147,472

EUR 94/m²

8%

EUR 442,531

EUR 36/m²

4%

EUR 501,592

EUR 41/m²

4%

ROOFING

EUR 170,529

EUR 14/m²

1%

EUR 139,956

EUR 12/m²

1%

EUR 139,011

EUR 11/m²

1%

FAÇADES

EUR 4,367,039

EUR 359/m²

29%

EUR 4,095,999

EUR 337/m²

34%

EUR 4,379,440

EUR 360/m²

34%

EUR 894,380

EUR 74/m²

6%

EUR 930,894

EUR 77/m²

8%

EUR 1,223,677

EUR 101/m²

9%

INTERIOR FIXTURES

EUR 4,243,412

EUR 349/m²

28%

EUR 2,945,457

EUR 242/m²

24%

EUR 3,036,695

EUR 250/m²

23%

TECHNICAL EQUIPMENT

EUR 3,327,623

EUR 274/m²

22%

EUR 2,405,123

EUR 198/m²

20%

EUR 2,496,867

EUR 206/m²

19%

SHELL COSTS

TOTAL

EUR 15,190,180 EUR 1,250/m² 100%

EUR 12,205,212 EUR 1,005/m² 100%

A FEW FIGURES

CONCLUSION

During the study we estimated the costs for works at EUR 1,250 m² (gross surface area excluding VAT). At the time of the procurement the price came in at approximately EUR 1,000/m², and the final price including all additional works was EUR 1,100/m². The largest portion went on the façade (35% of the total cost price), while the technical costs amounted to just 20% of the total cost price. These figures are not yet definitive as delivery is not until January (2015).

The character of the renovation interventions is largely determined by the manner and strictness in which heritage is viewed. An important question in this regard is what takes priority: the original concept; the original material; or both? In this project, we primarily prioritised the original concept and then “irreparably improved it”, as the Dutch architect Maarten Fritz puts it; an apparent paradox that is arguably most applicable to this type of building. Translated from Dutch.


EUR 13,008,215 EUR 1,071/m² 100%


Fig. 17 and 18 Original construction of the building and the current site. In this case a level with apartments from façade to façade. These floors were completely dismantled. At the “streets in the sky” levels, the complete finish of the circulation corridors was retained (right: © Willy Van Der Meeren Archives; left: © G. de Kinder).

Fig. 19 Making the prefab elements with the window panes immediately integrated into the elements. During assembly, projecting reinforcements were provided so that, after pouring the concrete floor, they could be placed as a whole (© Origin).

Fig. 20 Assembly of the new terraces in prefab concrete. The exterior of the stairwells was insulated with a system of prefab elements with insulation and brick panels fixed onto large elements of the bearing structure of the original well (© Origin).

Fig. 21 Many samples were taken and tests carried out to ensure the airtightness of the various walls (© Origin).

Fig. 22 The stairs, not yet finished. During the works, it was decided to treat them with a fire retardant paint for fire stability. These stairs turned out to have a thin, wooden stringer (© Origin).

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Ieder Zijn Huis: la rénovation d’une tour d’habitations sociale

Ieder Zijn Huis: renovatie van een modernistische woontoren

Le projet de rénovation de la tour Ieder zijn Huis a eu pour ambition de répondre aux normes actuelles d’isolation, de confort, de protection incendie, d’acoustique et de sécurité dans le périmètre des qualités de l’immeuble, de son plan, de sa distribution, de sa forme et logique architecturale. L’élément le plus symbolique de la tour, mais aussi le plus problématique, fut la façade, avec ses panneaux sandwichs en béton préfabriqué. Ces panneaux résument à eux seuls la logique du projet et du concepteur : la standardisation à outrance, dans des dimensions et une composition inspirés des principes du modulor, la préfabrication en série d’une manière quasi industrielle, le gros oeuvre qui coïncide avec la situation achevée, l’implantation ludique et abstraite des fenêtres, offrant une lumière et une vue optimales, tant pour les enfants que pour les adultes. Le projet de rénovation prévoyait de reconstituer la façade selon sa logique, sa forme et sa matérialité à l’aide d’un nouveau panneau sandwich en béton, préfabriqué selon la technologie actuelle et dans le respect des normes en vigueur aujourd’hui. Les moyens mis en œuvre pour réaliser ce projet ainsi que les résultats de cette opération de grande ampleur, croisant des problématiques de logement, d’économie, d’énergie et d’architecture, seront présentés ici.

De ambitie van het renovatieproject ‘Ieder zijn Huis’ bestaat erin om de huidige normen inzake isolatie, comfort, brandveiligheid, akoestiek en veiligheid te realiseren binnen de krijtlijnen van de kwaliteiten van het gebouw, de planopbouw en organisatie, vormgeving en constructieve logica. Het meest exemplarische maar ook problematische element van de toren is de gevelopbouw met geprefabriceerde betonnen sandwichpanelen. In deze panelen wordt de logica van het project en de ontwerper samengevat in één element: de doorgedreven standaardisering met maatgeving en compositie volgens de principes van de modulor, prefabricatie in serie op quasi industriële wijze, de ruwbouw die samenvalt met de afgewerkte situatie, de speelse en abstracte inplanting van de ramen met maximale lichtinval en een optimaal zicht, zowel voor de kinderen als de volwassenen. In het renovatieproject wordt ervoor gekozen om de gevel in zijn logica, vormgeving en materialiteit te reconstrueren in een nieuw betonnen sandwichpaneel, geprefabriceerd volgens de huidige technologie en de thans geldende normen. De middelen die voor de realisatie van dit project werden ingezet en de resultaten van deze grootschalige ingreep, die rekening moest houden met problematieken van huisvesting, besparingen, energie en architectuur, worden hier gepresenteerd.



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THE BRUNFAUT TOWER PRESENTATION OF THE CONCEPTUAL DESIGN CHALLENGES OF A RENOVATION VINCENT DEGRUNE

ARCHITECT/ENGINEER, MUNICIPALITY OF MOLENBEEK-SAINT-JEAN

THIS CASE STUDY RAISES THE QUESTION OF THE FUTURE OF TOWER BLOCKS, THE HERITAGE VALUE OF WHICH IS, AT FIRST GLANCE, NOT IMMEDIATELY EVIDENT. MANY EXAMPLES OF SUCH CURRENTLY UNFASHIONABLE BUILDINGS ARE TODAY THREATENED WITH DEMOLITION, AND NOT JUST IN BRUSSELS. FACED WITH THIS POSSIBILITY, THE MUNICIPALITY OF MOLENBEEK-SAINT-JEAN COMMISSIONED THE PARISIAN ARCHITECTURAL FIRM LACATON-VASSAL & DRUOT TO CONDUCT A CONCEPTUAL DESIGN STUDY TO ASSESS THE IMPACT AND FEASIBILITY OF VARIOUS RENOVATION OPTIONS. I have been fascinated by this project to renovate the Brunfaut tower (fig. 1) and the issues raised by the project for more than four years. However, the work has yielded more questions than answers, which is probably a very good thing. My presentation is not overly technical but rather aims to extend the notion of heritage to culture, and that of energy performance to sustainability. The Brunfaut tower was not lucky enough to have been designed by a famous architect; it was little known architect, J. Roggen and his consulting engineer, M. Van Wetter, who designed the building. The absence of such renown has probably contributed to the critical, even malicious, way in which the structure is viewed today. It is referred to as the kartonenblok or “cardboard box” in the neighbourhood. The building is thus perceived as a symbol of an era when people were punished by

being piled on top of each other in office buildings. We have tried to immerse ourselves in the context in which it was built, which is important when talking about heritage. The Brunfaut tower was built in 1966. At that time, the ideal of modernity had to some degree arrived in Belgium (and in Brussels in particular), but some twenty or thirty years behind the United States and France. These countries had been building based on the Corbusian model since the end of the war, with the strong, simple idea that high-rise construction would provide a solution both to urban sprawl and the preservation of ground space. Today, the issue of tower blocks has arisen again, but it seems that we are no longer concerned about the second notion, even though the two are inextricably linked. The 1960s were also a period of great enthusiasm with regard to mobility. For example, the Leopold II

86 | The Brunfaut tower. Presentation of the conceptual design challenges of a renovation.

viaduct was built to link the Expo ’58 site to the city centre (fig. 2). This structure was subsequently dismantled and rebuilt in Bangkok, where it has recently been renovated. This pretty amazing example of reuse took a completely ground-breaking approach to recycling. A newspaper article from 9th October 1966 was very useful in helping us to understand the extremely innovative and ambitious nature of the tower, not only from a technical but also a social perspective, as its construction was aimed at effectively addressing problems with hygiene in this “inner suburb” of Brussels. The construction process was also described in the article. It can be seen that the building was completed in less than eight months, with an extraordinarily sparing use of resources and materials. Today, a culture of performance predominates, whereas fifty years ago it was a culture of efficiency that


took precedence: intervention was minor, fast and economical. The difference in approach changes a lot of things.

BACKGROUND TO THE TOWER’S RENOVATION In 2009, the municipality of Molenbeek-Saint-Jean enjoyed the benefit of a new neighbourhood contract. The programme provides for the construction of around twenty passive homes in accordance with the decision taken by the municipality in 2007 to apply the passive standard to all its new buildings (fig. 3). These buildings were to be at the base of the tower which could not itself be renovated as part of the neighbourhood contract

because such programmes are not generally intended for buildings owned by social housing companies. We could not, therefore, in principle, take action. However, we noted that the Molenbeek Social Housing Company had been concerned about what to do with the tower for several years. The standard two options presented themselves: renovation or demolition/ reconstruction, with the second option being strongly favoured. At our request, the Brussels-Capital Region agreed to a feasibility study being carried out, as part of the neighbourhood contract, to answer the simple question of whether or not to keep the tower. This study was to be carried out in four phases, namely: a technical

assessment; an analysis of options for restoration (renovation or demolition/reconstruction); the restoration programme itself; and a final report which could be added to the specifications for the architectural competition. After receiving tenders from three teams, the study was eventually awarded to the Paris-based architectural firm Lacaton-Vassal & Druot. A few years before, the same firm had authored a work entitled Plus¹ which examined the merits of demolishing social housing tower blocks in the Paris suburbs. The firm had been shocked by the media coverage of the dynamiting of the towers which dramatically collapsed in front of a clapping audience which was most likely

Fig. 2 Léopold II viaduct. Constructed in 1957, it was dismantled in 1984 and rebuilt in Bangkok in 1988 (Thai-Belgian-Bridge) (old postcard).

Fig. 1 The Brunfaut tower (© K. Deruyter).

Fig. 3 Belle-Vue cinema neighbourhood contract (© municipality of Molenbeek-Saint-Jean) 87

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2 STAIRWAYS

2 LIFTS

Fig. 4 and 5 Plans of the Brunfaut tower. A simple efficient layout combined with optimal use of materials (© Lacaton & Vassal).

not made up of residents of the apartments. The underlying theme of this work is “that one must never demolish, take away or replace, but protect, add, transform and use”. It is therefore heritage writ large, consisting of working on what’s already there, adding value to it and developing its qualities. The architectural firm led us to look at the tower in a different way, appreciating that while it was relatively unremarkable architecturally, it possessed a great number of qualities and its faults could be significantly reduced by carrying out work on the envelope. Their work drew our attention to the fact that even though the appearance of the building fell out of favour over time, it nevertheless possessed values worth conserving.

THE COURSE OF THE FEASIBILITY STUDY The first phase of the study therefore involved listing the qualities of the building. Anne Lacaton firstly showed us that the tower was similar to many others visible in Chicago, Detroit, Copenhagen and other cities, built by renowned architects such as Mies Van der Rohe or Arne Jacobsen, and that those towers were clearly not lacking in elegance. She next drew our attention to questions of common sense and to the incredible efficiency evident in the Brunfaut tower, such as, for example: the layouts reduced to their most basic form; a central concrete core with a spiral staircase at each end; incredibly sparing use of materi-


als and a lot of subtlety (fig. 4 and 5). Efficiency is in evidence again with regard to the building’s footprint: 380 m² for 242 inhabitants. This building therefore provided great service to numerous families over fifty years. Actual energy consumption figures (provided by the Foyer Molenbeekois) are quite surprising: 179 kWh/m²/year, which corresponds to around 38 euros/month/apartment of heating costs for rent that varies between 175 and 324 euros/month. These figures are very reasonable when compared with other buildings of the same period, due, in particular, to the extreme compactness of the building. However, there must certainly be a lack of comfort linked to the total absence of any insulation in the external walls. The same efficiency can be found in the design which displays obvious architectural qualities: the apartments are bright, with a window in each room (including the kitchen and bathroom) and wide views over the city (fig. 6 to 12). At the same time, the municipality of Molenbeek -Saint-Jean was faced with the problem of a rapidly growing population which had to be urgently tackled. The conclusion was as follows: a lot of new residents were going to have to find housing within the municipality’s territory and the public housing waiting lists were already swamped (this is still the case today). Anne Lacaton asked us how we planned to manage the situation with the residents if the demolition/reconstruction option was chosen. The solution envisaged at the time by the public authorities was the usual “temporary relocation” operation which consists of housing people elsewhere and bringing them back once the building has been renovated. She queried this practice since the residents of the tower were going to take the place of


other tenants on the housing waiting list, forcing them to have to wait even longer. She felt that the building ought to be renovated while the site was still occupied. This initial phase of the study therefore enabled the Molenbeek Housing Company as well as the Municipal Council to adopt a position definitively in favour of renovation rather than demolition. The second phase consisted of using common sense to examine what could be optimised in the existing structure. The underlying logic was that of improvement and not compliance with standards. This approach was not favoured by the Brussels Region Housing Company (SLRB), which had no choice but to comply with standards - no exceptions. However, Anne Lacaton didn’t give up: it was first necessary to determine how the existing structure could be improved, otherwise any renovation operation would have been pointless. Her firm also worked on the human element: the teams visited the families in each apartment in order to study situations of overcrowding or under-occupation. This enabled them to discover, for instance, that a bedroom intended for one child was actually used for three even though, in other apartments, certain rooms were unoccupied as the children had grown up and no longer lived there. This method showed that by simply optimising the distribution of residents within the tower, via internal movements, much could already be achieved.

SOME FIGURES: Footprint

381 m²

Total surface area

6482 m²

Number of apartments

97

Number of residents

242

Consumption

179 kWh/m²/year

Average heating cost

456 euros/year; 38 euros/month

Base rents

From 175 to 324 euros/month

Actual rents

122 to 227 euros/month

Fig. 6 to 12 The apartments are bright with a window in each room. The flat roof offers a panoramic view over the city (© Lacaton & Vassal).

Significant technical considerations were also involved. The firm proposed fireproofing and protecting the structure, making the cores fireproof, adding sprinklers to areas where fire resistance 89

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standards could not be met and installing double door systems to ensure the safety and evacuation of people. The questions posed were always extremely relevant. For example, Anne Lacaton wondered about the need to make a stairway fireproof given that the compartments already were, and as the stairways were split into two and stairs are clearly not to be used when a fire breaks out. The conclusion from this second phase was that it was necessary to add one room per floor to maintain 97 apartments and satisfy the needs of the residents even in spite of the internal movements of tenants and optimisations. However, this work was never put into practice as, simultaneously, the Molenbeek Housing Company, understandably not very enamoured with the idea of an occupied renovation, decided not to rent out the apartments that were being vacated. The tower was therefore progressively emptied of its population, but the firm continued its work into finding ways to optimise the existing situation, believing that bringing the building into compliance did not make sense without this. As regards compliance with regional planning regulations, for example, following these to the letter would mean adding a small floor area to each room. However, this type of extension can only be carried out if the walls are destroyed, which is not in keeping with the spirit of the renovation, and only if the existing stairways are demolished and replaced by other, fire service compliant, versions. Of course, Lacaton-Vassal’s approach is all the more credible given that they have already worked on other towers in this way, most notably the Bois-le-Prêtre tower in Paris

Energy

Biotopes Water

Materials Waste

ECOLOGY

Shared space

Diversity

History

Partnerships

Adaptability

Heritage

Resources

Quality of life

Context

ECONOMY

SOCIAL

CULTURE

Density

Fig. 13 The four pillars of sustainable development.

which is almost the twin sister of the Brunfaut tower. In 2000, the firm undertook the renovation of this building with the simple idea of increasing the thickness of the walls based on a bioclimatic winter garden concept. The principle involves removing the existing façade and replacing it with a double façade (a double skin) with a three metre space between the two sections. This new space has to be managed by each resident as a small winter garden. Inside, the work carried out was very understated and extremely low tech, with a partition being adjusted here and there. One element that should be mentioned is that no double flow technology was used. The existing radiators were retained but the boiler was replaced. These minor renovations enabled energy performance of 78 kWh/m²/year to be achieved. This figure is far removed from the


low energy standard required for the Brunfaut tower, i.e. 60 kWh/ m²/year, but hasn’t this gap been largely offset by the savings made in terms of special technologies (including the embodied energy used to manufacture, transport, maintain and replace this technology)? This study raises, in a somewhat obvious manner, the question of taking embodied energy into account when evaluating the sustainable nature of a project. Today, all possible on-board technical means are used: since 2007, only passive buildings with rainwater harvesting systems for bathrooms (systems which initially posed severe problems when they were combined with green roofs), thermal solar panels, photovoltaic solar panels, double flow systems, etc. are built in Molenbeek-


Saint-Jean. The question of obsolescence also arises: we’re living in an age where toasters are no longer repaired! Let’s face it, people no longer want to repair things. It’s our culture. It’s not an inevitability, of course, it’s simply a way of boosting the economy and creating growth, but look at what is thrown out! Why not include the costs of embodied energy in the overall calculation of energy balances and returns on investment? Where is the credibility in a study that says a double flow system, after twenty years, pays for itself if we’re following the toaster model, i.e. if it’s been replaced three times over the same period of time? I am not saying that it should not be done. We have a collective responsibility with regard to global warming and therefore have an obligation to research and innovate. However, I think that the issues of embodied energy and obsolescence urgently need to be considered and seriously included in the calculations. It is also important to consider the question of balance between the three pillars of sustainable development and to include a fourth: culture, as proposed by the French urban planner, Philippe Madec (among others). Culture doesn’t belong to the social, the economy or to ecology. There can be no social project without culture. Culture is the basis of every society. As part of this seminar, I believe that considering this fourth pillar as being completely inseparable from the three others would help to address these issues of history, heritage and context that are so important. I think that there is, currently, an overemphasis on the environmental pillar and, through it, even more so on the energy pillar and the striving for energy performance (fig. 13).

Fig. 14 and 15 Sketches of the winning project in the competition (© A229 architects/Dethier Architecture).

THE RESULT OF THE COMPETITION The architectural competition was finally held with the inclusion in the specifications - to the great displeasure of Anne Lacaton - of a requirement that the renovated building comply with low energy standards of 60 kWh/m²/year. The Molenbeek Housing Company received five proposals. To our great surprise, all proposed passive projects! However, all of the project authors confirmed to us that without double flow ventilation it would not be possible to get below the bar of 70 kWh/m²/year:

“If you require us to achieve 60, double flow has to be installed. If it is necessary to use a double flow system, the additional cost involved to achieve the passive standard is negligible. We are therefore proposing a passive project to have a greater chance of winning the competition!”. The five projects are therefore of the passive type, most of them based on increasing the thickness of the envelope, with the obligation of adding extra space in each apartment. The winner (the Dethier Architectures-Atelier 229 firm) was announced after 91

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three days of deliberations by a jury of 18 people, including Anne Lacaton. The firm’s project stood out from the others due to its close adherence to the idea of heritage identified in the study, including the symbolic value of the building which is part of the Brussels landscape (fig. 14 and 15). There was something odd about calling for its demolition while the Upside tower was rising from the ground on the other side of the canal. If high rise buildings were the way to go then either both or neither of the two should be retained. In addition, the project authors believed that to increase space, five floors needed to be added to preserve the proportions and elegance of the tower. Their project was just as radical in terms of the techniques to be used: although all of the other projects proposed very low ceiling heights, due to cladding of the structures, this project achieved a height of 2.6 m by proposing a system of solid wood flooring (requiring major work as well as negotiations with the fire service), combined with the use of visible engineering techniques to facilitate its replacement where necessary. There will be natural light in all of the hallways; seating areas on each floor; distri-

bution of boilers and double flow systems to save on stairwells.

CONCLUSION I wanted to share three short quotations with you. The first is from Anne Lacaton: “We have been too fast with the standards and are now paying the consequences: it’s necessary to struggle to bring about the sustainable!”. The second is from Pierre Blondel: “Are we not in the process of over-complicating the simple fact of housing at the cost of an excess of embodied energy and, ultimately, consuming ever more in order to supposedly consume less?”. The third comes from Lao-Tzu, so as to finish on a positive note: “Failure is the foundation of success.” I believe that, in this sense, we are definitely heading in the right direction.

NOTE 1. Druot, Fr., Lacaton, A., Vassal, J.-Ph., PLUS - Les grands ensembles de logements. Territoires d’exception. Ed. G. Gili SL, Barcelona, 2007.




La tour Brunfaut. Présentation de l’étude de définition des enjeux d’une réhabilitation

De Brunfauttoren. Presentatie van de studie over de definiëring van de uitdagingen van een renovatie

La tour Brunfaut est un immeuble emblématique du paysage bruxellois. Édifiée en 1966, elle incarne tout à la fois le rêve moderne de la construction en hauteur et l’ambition du logement pour tous. Mais 40 ans plus tard, la réalisation est jugée avec une telle sévérité que son avenir semble tout tracé : une lente agonie suivie d’une démolition/ reconstruction, dans des gabarits plus… acceptables. C’est dans ce contexte que la commune de Molenbeek-SaintJean décide en 2009 de mandater l’agence d’architecture LacatonVassal, associée à Frédéric Druot, afin de répondre à cette question simple : doit-on vraiment détruire la tour Brunfaut ? Leur étude, à travers les notions de patrimoine, d’identité, de confort..., questionne les fondements mêmes du concept de développement durable, bien au-delà de la notion de performance énergétique.

De Brunfauttoren is een emblematisch gebouw in het Brusselse landschap. De in 1966 opgetrokken toren belichaamt tegelijk de moderne droom van de hoogbouw en de ambitie van een woning voor iedereen. Veertig jaar later wordt de realisatie echter met zoveel gestrengheid beoordeeld dat haar toekomst al helemaal lijkt vast te staan: een langzaam verval gevolgd door een afbraak/wederopbouw met meer... aanvaardbare afmetingen. In die context besliste de gemeente Sint-Jans-Molenbeek in 2009 om het architectenbureau LacatonVassal, in samenwerking met Frédéric Druot, op te dragen om een antwoord te geven op deze eenvoudige vraag: moet de Brunfauttoren echt worden afgebroken? Aan de hand van begrippen als erfgoed, identiteit, comfort enz. stelt hun onderzoek de grondslagen in vraag van het concept duurzame ontwikkeling, dat veel verder reikt dan het begrip energieprestatie.

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PRESENTATION AND RESULTS OF THE “PLAGE” PROJECTS LOCAL ACTION PLANS FOR ENERGY MANAGEMENT EMMANUEL HECQUET

CICEDD, NAMUR. HE HAS BEEN WORKING IN PARTNERSHIP WITH BRUSSELS ENVIRONMENT ON THE IMPLEMENTATION OF THE “PLAGE” PROJECTS SINCE 2006

THE GOAL OF THE PLAGE PROJECTS IS TO IMPROVE ENERGY EFFICIENCY IN BUILDINGS IN THE BRUSSELS REGION IN ORDER TO ACHIVE ENVIRONMENTAL AND COST SAVING BENEFITS THROUGH THE IMPLEMENTATION OF PROACTIVE ENERGY CONSUMPTION. SIGNIFICANT RESULTS HAVE BEEN ACHIEVED SINCE THE LAUNCH OF PILOT TESTS IN 2006.

The regulatory background to the programme of Local Action Plans for Energy Management (PLAGE) is the European Directive 2012/27 on Energy Efficiency and the implementation of that directive throughout the Region, imposing a reduction of 30% in greenhouse gas emissions by 2025 compared to 1990 levels.

OBJECTIVES AND METHODS USED FOR THE PLAGE PROJECT The goal of the PLAGE project is to manage energy consumption with a view to reducing it. It targets managers or owners of large building stocks, as well as occupants, encouraging them to take actions that will produce rapid results. The programme includes pilot tests and will take place over three to four years. The project primarily focuses on rationalising energy use, application of regulations and insulation of

boiler installations than on making heavy investments. We therefore try to optimise consumption with a priority on heating and (to a lesser degree) on electricity. This programme applies to existing buildings, not to new buildings or buildings that have been the subject of extensive renovation works. We used a specific process quality method or ISO, namely the Deming Wheel (fig. 1). This is a continuous improvement process. PLAGE focuses first on energy accounting, or more precisely what we call the “energy register”, as well as an administrative and technical inventory of the building stock. This first stage may be laborious depending on the number of buildings. In the municipalities where the PLAGE project was launched in 2006, the mere creation of a register (involving up to 100 to 150 buildings) took some time. The objective is to identify “priority” buildings: those

94 | Presentation and results of the “plage” projects

that offer the greatest potential for energy savings for the lowest cost. This is followed by a three- to fouryear action plan involving the close monitoring of energy consumption. We analyse the initial results of this energy accounting process, evaluate them and then carry out corrective measures where necessary. The register and the action plan are then updated and a new cycle begins. The idea is to enter a virtuous circle for improving the energy consumption of the building stock. The preparation of the action plans allows us to draw up an outline of the technical and energy aspects of each building. The priorities are always low-cost measures (e.g. management of boiler installations, rationalising energy use (RUE), and generating awareness among the occupants or training technical services). We then analyse the results and energy consumption month by month, year by year, to see if


the measures used are effective. We use a series of reporting tools, including the energy signature, that allow us to compare monthly consumption with daily temperatures and thus weather conditions.

THE ROLE OF THE ENERGY MANAGERS The key person in the PLAGE projects is the Energy Manager, who works in an energy team within the institution or company. One key implement element in implementing the plan and the actions carried out by the Energy Manger is concerted decision-making. It is essential that the Energy Manager does not carry the whole energy burden and responsibility for reducing consumption himself or herself, but that everyone in the institution or company is involved. The Energy Manager is the conductor of operations. He or she coordinates

everyone who is involved - either directly or indirectly - with energy. He or she works with differently composed teams depending on the type of institution and the project duration: these include technicians, buildings departments and/ or communication departments of municipalities, players tasked with generating awareness, etc. In SISPs (public service real estate companies) for example, he or she works together with social assistants responsible for generating awareness among occupants, and also involves decision makers, managers, etc. in the process. In local councils this person will be the alderman; in an SISP, the director. The objective is to focus on transversal reports and to encourage everyone involved to be aware of the issues at stake. Subcontractors are also involved; for example, maintenance companies are encouraged to integrate the notion of energy performance into their contracts.

There is also a requirement for exigency regarding maintenance contracts so that companies offer the most effective services. At the end of the programme carried out by Brussels Environment, the participating communes have retained all the Energy Managers.

MUNICIPAL AND VOLUNTARY SISP PLAGE PROJECTS The municipal and voluntary PLAGE projects are interesting as they show the results obtained for buildings that have been identified as a priority among large groups of buildings (fig. 3). In these cases, the Energy Manager started off by targeting 10 - 12 priority buildings among all the municipal buildings, and these then underwent improvement plans for energy efficiency. The resulting reduction in consumption over the medium term spilled over to the whole of

Fig. 1 PLAGE projects are based on the continuous improvement process (© BE). ENERGY ACCOUNTING

ANALYSIS OF RESULTS

2006 Municipalities 1

ACTION PLAN

MONITORING OF CONSUMPTION

2007 Hospitals

2008 Municipalities 2

VOLUNTARY PLAGE PROJECTS

Fig. 2 The origins of the PLAGE projects date back to 2005, and are an initiative of Brussels Environment. The first pilot experiments with the municipalities were carried out in 2006. In all, 15 of the 19 municipalities took part in the experiment. The pilot projects were then rolled out in hospitals and more recently with the SISPs. After ten years of conclusive pilot tests, the programme will be made mandatory for private sector groups of buildings of more than 100,000m² and public sector groups of buildings of more than 50,000m² (© BE).

2009 Schools

2011 SISP

2015

MANDATORY PLAGE PROJECTS

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the building stock as the practices applied to the first buildings were then applied to the others. Over time, therefore, the energy performance of the whole group of buildings improved.

Voluntary PLAGE - PLAGE - MUNICIPALITIES PARC

Specific consumption (kWh/m²)

These encouraging results were also recorded in the SISPs that participated in the programme (fig. 4).

Voluntary Schools PLAGE projects The Schools PLAGE project started up in 2009 and also produced impressive results. This PLAGE project was organised by a variety of networks. The results show reductions in fuel consumption as high as 22%, but electricity consumption in certain instances continued to increase. The reasons for this are relatively simple: we see an annual trend of a 2 - 3% increase over the whole of the tertiary buildings sector, mainly due to the increase in the amount of machinery used. PLAGE projects focus primarily on reducing fuel consumption, and address electricity consumption to a far lesser degree. Working on a boiler installation or optimising centralised hot water production are campaigns that can be carried out within a short space of time, while electricity consumption is much more widely dispersed throughout the building stock. Moreover, reducing electricity consumption requires changes in change consumer habits (e.g. photocopier usage, computer usage, etc.) which means that the effort required is much more disparate. In addition, in terms of cost, fuel consumption is much more onerous than electricity consumption. This article concludes by presenting two local schools where interventions took place. The first is the

Woluwé

Uccle

Jette

Koekelberg Etterbeek

PLAGE

Woluwé

Legends year 1

Forest

Auderghem

Brussels

Specific consumption (kWh/m²)

Uccle

Jette

Koekelberg Etterbeek

Forest

Auderghem

Brussels

year 4

Fig. 3 It is interesting to note that situations within the municipalities were very different at the start in 2008. We note that it is easier to make far-reaching improvements with regard to energy to a group of buildings in very poor condition than to a group of buildings that is already quite efficient (© BE).

municipal primary school, (preschool and primary school) in Forest (fig. 5). The establishment currently has 400 pupils with a heated surface area of almost 5,000 m². It was built in the 1930s and the energy efficiency is very low compared to the number of pupils. The pre-PLAGE energy cost per pupil/year was 206 euros. At the end of the programme, it was 142 euros per pupil/


year. Consumption dropped from 300 kWh/m²/year to 182 kWh/m²/year thanks to classic PLAGE actions: adapting the heating schedule to fit in with occupancy of the buildings. We tried to answer the following questions: Can heating start up later? How low can we set the heating? Can we lower the heating curves? Modify the boilers? Some boilers ran at one speed when they could run at two.


Voluntary PLAGE - SISP PLAGE PLAGE sites : changes in average, normalised specific consumption

Legends average 2009-2011 (kWh/m²)

average 2012 (kWh/m²)

average 2013 (kWh/m²)

Fig. 4 The SISPs involved currently in the PLAGE project account for almost 1,200,000 m² heated surface area. The priority for intervention is placed on collective heating installations. Although this PLAGE project is not yet finalised – this is planned during 2016 - we can already see major improvements of up to 20% reduction for the most advanced companies (© BE).

We corrected all of this. We insulated the heating pipes, particularly in the basement as it serves no purpose to heat the boiler installation or the corridors in the cellars. These are low-cost actions that do not involve façade insulation, replacing frames, etc., which are not PLAGE actions. Our actions involve working towards a rationalised use with lower costs. The result for this school was a reduction of 42% consumption in heating over four years which led to a 2% increase in electricity, although this element was not taken into account at all. The financial savings was almost 27,000 euros. The second example is the “Athénée Robert Catteau” (fig. 6). Built in 1925, this large school has a heated surface area of 14,000 m². It is a more

imposing site than that of Forest, with a multitude of buildings, a big centralised boiler installation and underground pipes, which suggests high energy loss in transporting heat to each of the units. The situation at the beginning of the project was worse than that of the previous example, but the gains were nevertheless substantial after four years as we dropped from 162 euros per pupil/year to 135 euros and from a consumption of 156 kWh/m²/year to 118 kWh/m²/year. We changed the heating timetable. This may seem like pure common sense, but in reality it is not always that easy. When the heating system is centralised one has to ascertain if there are separate circuits for the different parts of the school

Fig. 5 Municipal primary school n° 9, rue du Monténégro in Forest. At the start of the PLAGE project, energy costs amounted to 206 euros/pupil/year. At the end of the project this had fallen to 142 euros/pupil/ year (A. de Ville de Goyet, 2015 © SPRB). 97

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(some buildings are used for music classes or sports activities during the evening or at weekends). It is just common sense, however, that the temperatures should be lowered considerably during school holidays; however, in reality even this is far from evident because the cleaning team are present at times and various activities take place in the school holidays. Reorganising everything may take time and may present numerous obstacles for the Energy Manager. These changes cannot be carried out from one day to the next. In this school we lowered the temperatures during the night, replaced the outer doors, regulated the thermostat valves and trained occupants to use them effectively. In the end fuel consumption fell by 24%, but at the same time electricity consumption rose sharply for the same reasons mentioned above. We did not tackle this problem, and there is a lot of work for the Energy Managers to take up here. However, we noticed that in spite of this increase, we still achieved an energy saving of 22,000 euros over all the energy vectors.

CONCLUSION These examples show that the public sector can set a strong example for other sectors. The goal of Brussels Environment is to encourage demand and improve services via a number of specific actions such as training programmes, seminars and pilot projects like PLAGE, in order to improve energy efficiency in the building stock. In view of the results already obtained in previous and current PLAGE projects, thanks to an efficient methodology that requires minimal financial input, the programme has been made mandatory for building stock in the private sector with a surface area of more than 100,000m² and more than 50,000 m² in the public sector, as part of the Brussels Air, Climate and Energy Code (COBRACE). This next compulsory action for major blocks of building stock is an important stage in reaching our objectives to reducing consumption. Translated from French


Fig. 6 Athénée Robert Catteau, rue Ernest Allard in Brussels. Here again considerable savings were made; at the start of the PLAGE project energy costs amounted to 162 euros/pupil/year and at the end this had fallen to 135 euros/pupil/year (A. de Ville de Goyet, 2015 © SPRB).


WEBSITE : http://www.environnement.brussels/ thematiques/energie/economiservotre-energie/plan-local-dactionpour-la-gestion-energetique

Présentation et résultats des projets PLAGE – plan local d’actions pour la gestion énergétique.

Presentatie en resultaten van de PLAGE projecten: Plan voor Lokale Actie voor het Gebruik van Energie.

Depuis 2006, Bruxelles Environnement a lancé plusieurs appels à projets dans le cadre du Plan local d’Action pour la Gestion énergétique (PLAGE). Leur but est d’améliorer l’efficacité énergétique du parc de bâtiments de la Région au bénéfice de l’environnement et des finances des institutions en instaurant une gestion proactive des consommations d’énergie. Des résultats importants ont été engrangés, mettant en avant des réductions de consommations d’énergie de l’ordre de 15 à 20% sans perte de confort sur une période de trois quatre ans. Après des programmes menés dans des bâtiments scolaires, des hôpitaux et divers bâtiments communaux, un nouveau programme PLAGE a été lancé dédié, cette fois, aux logements sociaux étant donné l’importance du logement dans les consommations énergétiques. La méthodologie et les résultats de ces programmes sont présentés, à travers des exemples précis, à l’occasion de cette journée.

Sinds 2006 lanceerde Leefmilieu Brussel meerdere PLAGEprojectoproepen (Plan voor Actie voor het Gebruik van Energie). Het doel van deze oproepen is de energie-efficiëntie van het gebouwenpark van het Gewest op te krikken ten voordele van het leefmilieu en de financiën van de instellingen door de invoering van een proactief beheer van het energieverbruik. In enkele jaren tijd werden uitstekende resultaten behaald, met verminderingen van het energieverbruik van 15 tot 20% zonder comfortverlies over een periode van 3 à 4 jaar. Na de projecten in schoolgebouwen, ziekenhuizen en diverse gemeentelijke gebouwen werd een nieuw PLAGEprogramma voor sociale woningen gelanceerd, aangezien woningen een aanzienlijk deel van het energieverbruik voor hun rekening nemen. Ter gelegenheid van deze dag zullen de methodologie en de resultaten van deze programma’s worden voorgesteld aan de hand van specifieke voorbeelden.

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THE BELGIAN BUILDING RESEARCH INSTITUTE: A CONTRIBUTION TO HERITAGE MAINTENANCE EXPLORING THE TRAINING OF HERITAGE ADVISORS SPECIALISING IN ENERGY MICHAEL DE BOUW AND SANDRINE HERINCKX BELGIAN BUILDING RESEARCH INSTITUTE (BBRI)

IMPROVING THE ENERGY EFFICIENCY OF LISTED BUILDINGS IS A PRACTICE NOT YET COMMONPLACE IN BELGIUM. NEVERTHELESS, OPTIMISING THE ENERGY EFFICIENCY OF BUILT HERITAGE, WHETHER LISTED OR NOT, COMBINED WITH RENEWABLE ENERGY, OPENS UP NUMEROUS OPPORTUNITIES. THE BELGIAN BUILDING RESEARCH INSTITUTE (BBRI) IS SPONSORING A SEVEN-YEAR PROJECT WHOSE PURPOSE IS TO GIVE PRACTICAL EFFECT TO THE “ARCHITECTURAL HERITAGE ADVISORS SPECIALISING IN ENERGY” MEASURE INCLUDED IN THE NEW CLIMATE PLAN DEVELOPED BY THE FLEMISH GOVERNMENT. This article first presents the Renovation Laboratory, which is one of the laboratories of the Belgian Building Research Institute (BBRI), before addressing an energy training project for heritage advisors that has recently started in Flanders.

WHAT IS THE BBRI? The BBRI works on new and existing buildings undergoing renovation, including heritage buildings.

It is a research centre for the construction sector. It represents contractors in Belgium and currently has 90,000 members. We provide scientific and technical research and support and technical assistance advice to our members and, more generally, to professionals in the construction sector. We also conduct more specific research, under contract, for manufacturers, companies and public authorities. We produce technical publications and

participate in scientific research projects as well as specific development projects for companies. We work towards the establishment of standards (through participation in standards committees), and also support innovation, which brings us outside the standards context. Our administrative offices are located in Woluwe-Saint-Étienne and our research centre, along with all the laboratories, is in Limelette.

100 | The scientific and technical centre for construction renovation laboratory: a contribution to heritage maintenance


We also have a site in Brussels, with a conference centre close to the Gare du Midi/Zuidstation train station. We will soon be moving to a new a site close to Tour & Taxis, in the canal zone. The Renovation Laboratory, among others, will be situated there.

THE MISSION OF THE RENOVATION LABORATORY This laboratory specialises in damp problems in buildings and how to treat them. It also deals with work on building façades: cleaning, restoration, water-repellent protections, etc. It develops new activities relating to energy renovation which, in the current climate, are becoming essential. Two presentations (pp. 76-83 and pp. 86-93), relating to the housing blocks are relevant to this article. We are currently running a project that involves the collection of all European experience regarding energy renovation of façades carried out with pre-fabricated panels. These panels have the advantage of being usable while the buildings are occupied. Standardised, they enable economies of scale to be achieved. Adaptations are of course possible, but the buildings involved in this project are not listed. Nevertheless, this type of solution could be envisaged for garden cities or buildings that are duplicated. Ultimately, we are increasingly moving towards energy efficiency, even in heritage buildings. The programme presented below stems from this observation.

THE TEAM The BBRI has a reputation for being particularly interested

in new buildings. However, the Renovation Laboratory team is made up of people who are trained in heritage conservation. Two of us have studied at the Centre Raymond Lemaire. My colleague Michael de Bouw completed a doctoral thesis on the “Model Schools (1860-1920)” in Brussels. He is also a member of the Vlaamse Commissie Onroerend Erfgoed. Samuel Dubois, who joined the team recently, deals with energy simulation. We therefore endeavour to have a team that enables all aspects of heritage and energy to be reconciled. We are also building partnerships: we give classes in various institutes and universities; and cooperate with most of the large universities and research centres in Belgium (including the Royal Institute for Cultural Heritage), in Europe and further afield.

ENERGY ADVISORS SPECIALISING IN HERITAGE OR HERITAGE ADVISORS SPECIALISING IN ENERGY? This project is aimed at training energy advisors specialising in heritage or heritage advisors specialising in energy. The principle is that one individual should possess both sets of these skills. The current environment we are working in is well known: the regulations are becoming more complex and restrictive and efforts are increasing being expended in trying to achieve the required energy efficiency. In fact, the heritage value of buildings is often not taken into account, a value that cannot always be reconciled with the primary motivation of achieving energy efficiency. However, it should be noted that such buildings generally make up only a tiny por-

tion of the stock to be renovated. As a result, from the point of view of overall energy efficiency and savings in energy and greenhouse gas emissions, it would be possible to not take them into account. However, such an approach would not be satisfactory. What is important is how these buildings are used: if we do not intervene, they will become too expensive to be used, comfort standards will not be satisfied and we run the risk of having empty buildings which are not maintained. It is principally for this reason that we are trying to reconcile the two aspects of heritage and energy. Improving the energy efficiency of listed buildings or high heritage value buildings is not yet commonplace. There are several reasons for this: on the one hand, the fact that the Energy Performance of Buildings (EPB) regulation does not apply to such buildings and, on the other, the difficulties encountered in trying to reconcile the heritage and energy efficiency agendas. Finally, whether any unforeseen negative consequences might arise from such interventions is as yet unknown. Nevertheless, the EPB regulation may constitute an opportunity. It is important for consideration to be given to it in order to reduce greenhouse gases - even if the biggest savings will not be achieved on this type of construction - and, above all, to improve the comfort and interior climatic conditions of such buildings. One of the strengths of our project is its global approach to the building. The heritage value is the factor that will determine the limits of any intervention. It is inside such buildings that we will attempt to reduce energy consumption, while endeavouring to minimise the risks to the building itself. For 101

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this reason it is essential to work not only on the envelope, but also on the behaviour of the building’s users. The objective is to maintain a balance between the heritage value and maximising energy efficiency, with a focus on the overall balance of the building. The relationship between thermal efficiency, ventilation and damp is a delicate one. It is necessary to be aware of the possible consequences that may arise if one of these aspects is affected in order to avoid destabilising the operation of the building. We are often called upon to deal with issues occurring on worksites after work has been carried out where we diagnose problems with damp connected with the installation of new windows (double glazing) with frames that are far more airtight than those that were previously fitted. The natural ventilation of the building is often found to be reduced and problems with condensation and mould have appeared

(fig. 1 and 2). This is a classic example. The balance of the building is affected and unforeseen damage is caused. However, these problems could have been avoided with the use of a properly designed ventilation system. Another classic example concerns cellars. If one wants to make use of a cellar or make it less damp, the initial response is to increase the ventilation and heating. If the cellar in question suffers from dampness problems (perhaps less visibly so initially) and the dampness is able to migrate from the ground into the stonework, it will evaporate more quickly with the increase in heating and ventilation. The salts will then crystallise more rapidly leading to damage to materials, another unforeseen consequence. These two examples illustrate the importance of anticipating the possible consequences of any work. With regard to maximising energy savings, we prefer to use the term “optimise” - it’s sort of like

Fig. 1 Efflorescence from salts and damage to materials in a ventilated and heated cellar (© BBRI).

saying: “Well, we’re going to do what we can, but always in accordance with the heritage values to be conserved and the balance of the building, which must remain positive”. Where we want to satisfy the requirements of the EPB or any other regulation, we do everything possible to do so. However, in this programme, which is focused on heritage buildings, we want to approach things differently. We start with the building, determine the limits of any action and, through a series of minor or major interventions, aim to reduce energy consumption as much as possible without attempting to achieve an objective that is essentially theoretical. We adapt to the building itself. We don’t want to reinvent the wheel. We will of course use innovative solutions where necessary, as there are materials that have not yet been extensively used or which are still on the expensive side but which can be employed when carrying out work on heritage buildings. In order to apply this

Fig. 2 Development of mould in a renovated vicarage, following the installation of new frames and double glazing without any system of ventilation (© BBRI).



approach to renovation, it is necessary to surround oneself with people who are familiar with historical and heritage buildings. The first phase of the programme will be aimed at restoration architects who have previously worked on heritage buildings and who wish to improve their expertise in the energy area. During the pilot years we hope to be able to train around fifty architects. Since the project is being developed by the Flemish Government it primarily concerns architects active in Flanders, but this experience will clearly be able to be reproduced elsewhere.

PROJECT IMPLEMENTATION AND TIMING The project has just started. It will be rolled out over a period of seven years, from 2014 to 2021. It is based on five pillars (fig. 3). The first is an energy desk which we will use to collect questions and

experiences concerning projects in progress and which will help architects working on heritage buildings. The idea is to pool together all information in a single database, take advantage of both Belgian and foreign experience feedback and distribute this knowledge. We have already begun to collect data. The first project on which my colleagues have started work concerns the Klein Rusland social housing development (in Zelzate). Prior to carrying out the planned works, surveys will be conducted. We want to work on concrete projects in a multidisciplinary manner. For this reason not only the will the Renovation Laboratory be involved, but so too will other BBRI laboratories. This is one of the strengths of the approach, since we can call on all the expertise of our various teams. The energy desk will be maintained beyond the seven year period. At the same time, during a two year period, course modules will

be developed to train architects in these energy and heritage aspects. These courses will be given during the third year. They should, in principle, result in some type of certification, the details of which have still to be determined. We want to take inspiration from both foreign and Belgian examples to put all of this in place. Representatives of the sector will also be consulted. A monitoring phase will then follow, carried out over four years. We want to give a concrete dimension to the project which is why this phase is the longest. At this stage, while we already have information on the possibilities for intervention, we have few data on experience feedback. In fact, information has rarely been provided about interventions carried out to date. After the initial seven year period, we will evaluate the training and the possibility of integrating it into existing training for restoration architects. In conclusion, I would like to call for cooperation within the framework of this programme. It is important that the information is circulated and that we are able to cooperate with the sector. Working on energy and heritage is fairly new. We are increasingly engaging in such thinking, but it is also necessary for that thinking to be rooted, in concrete terms, in practices. This is why cooperation with all of the professionals, in both the public and private sector, is essential.

Fig. 3 Structure for the planned training of heritage advisors specialising in energy (© BBRI).

A final point: if you are a contractor and have practical questions about a project, or any of the themes addressed here, please don’t hesitate to contact us. We will respond by telephone or e-mail and are also willing to travel. In Brussels, we have technical guidance and 103

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are able to extend our activities to the entire construction sector. Architects, consultancy firms, manufacturers, managers, etc. can contact us. In October 2016, we will organise an international conference on the theme of energy and heritage. We are still looking for partners. If you are interested, please do get in touch. Once again, it is a project that we want to carry out in cooperation with the sector.

WEBSITES : http://www.bbri.be http://www.eechb.eu


La contribution du Laboratoire Rénovation du CSTC à l’entretien du patrimoine – Conseillers en patrimoine spécialisés en énergie

De bijdrage van het WTCB-labo Renovatie aan erfgoedzorg – Gespecialiseerde Erfgoedenergieconsulenten

Améliorer l’efficacité énergétique des bâtiments classés : voilà une pratique encore peu répandue en Belgique. Les raisons sont multiples. Citons en particulier le fait que ces édifices peuvent déroger à la législation belge sur la performance énergétique des bâtiments ou que les mesures d’économie d’énergie sont souvent difficiles à concilier avec les caractéristiques historiques des bâtiments concernés. Pourtant, l’optimisation énergétique du patrimoine bâti, classé ou non, alliée aux énergies renouvelables, ouvre de nombreuses opportunités (réduction substantielle des émissions de gaz à effet de serre, utilisation et occupation plus attrayantes des bâtiments grâce à des factures plus basses et à un meilleur confort...). Cependant, il faut une approche soigneusement réfléchie et cohérente pour réaliser ces objectifs sans nuire au patrimoine, en minimisant/éliminant les risques pour les bâtiments. Ces préoccupations sont à la base d’un projet de sept ans dont le but est de concrétiser la mesure « Conseillers en patrimoine architectural spécialisés en énergie » inscrite dans le nouveau Plan climatique du gouvernement flamand. Un des volets importants du projet est une formation qui s’adressera aux architectes-restaurateurs (expérimentés) qui souhaitent améliorer leurs compétences en matière d’optimisation de l’efficacité énergétique du patrimoine bâti. La présentation se focalise sur la conception du projet ainsi que sur ses différentes étapes.

Beschermde gebouwen energieefficiënt maken is nog vrij ongebruikelijk in België. Daar zijn meerdere redenen voor, zoals het feit dat de Belgische energieprestatieregelgeving voor deze gebouwen een afwijkingsmogelijkheid voorziet en het feit dat mogelijke energiebesparingsmaatregelen dikwijls moeilijk te verzoenen zijn met de erfgoedwaarden van het gebouw. Toch biedt de energie-optimalisatie van zowel beschermde als nietbeschermde erfgoedgebouwen in combinatie met hernieuwbare energie veel mogelijkheden (beperking van de broeikasgassenuitstoot van een omvangrijk patrimonium, aantrekkelijker gebruik en bewoonbaarheid door lagere facturen en een verbeterd comfort, enz.). Om dit echter te bereiken zonder de erfgoedwaarden aan te tasten en alle risico’s voor het gebouw zelf te minimaliseren/ elimineren is een doordachte en coherente aanpak nodig. Deze bekommernissen liggen aan de basis van het lopende zevenjarenproject, dat de concrete toepassing beoogt van de maatregel ‘Gespecialiseerde energieconsulenten voor onroerend erfgoed’ van het nieuwe Vlaamse Klimaatplan. Één van de belangrijke delen van het project is het opleidingstraject ratiearchitecten die hun vaardigheden inzake de energie-efficiëntie van erfgoedgebouwen verder wensen uit te diepen.



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SUSTAINABLE RENOVATION OF A BRUSSELS HOUSE: A CHALLENGE FOR BUILDING TRADESMEN JÉRÔME BERTRAND CENTRE URBAIN ASBL

TRADITIONAL BRUSSELS HOUSES POSSESS NUMEROUS QUALITIES, IN TERMS OF SUSTAINABILITY, THAT CAN BE ENHANCED DURING A RENOVATION PROJECT. IN A CONTEXT WHERE THE MAJORITY OF WORKS ARE CARRIED OUT WITHOUT THE INVOLVEMENT OF ANY ARCHITECT, THE TRAINING OF COMPANIES AND THE EDUCATION OF CLIENTS PLAYS A DECISIVE ROLE. This contribution starts by considering the advantages and constraints of the traditional Brussels house (from the late 19th century and early 20th century) in terms of sustainability. This will therefore, initially, be a diagnostic type approach. It will then address energy renovation and heritage through a number of examples of works, focusing on a renovation carried out as part of the call for Batex projects by Brussels Environment (see p. 14), before illustrating some of the difficulties faced by craftspeople as a result of the application of new requirements in terms of energy. It concludes with the issue of training for these trades and the provision of information intended for the public.

THE BRUSSELS HOUSE: A SUSTAINABLE RESOURCE I really liked the suggestion by Vincent Degrune to add a fourth pillar to the three pillars that define sustainable development (the environmental, social and economic aspects) to include the cultural aspect (see p. 86-93). It is with this in mind that I will consider the heritage value of the Brussels house. Figures 1 and 2 show two familiar Brussels urban landscapes. Rue de Locht is lined with neoclassical-inspired façades rendered and painted in light tones. They represent the first major phase of urbanisation in the second half of the 19th century. The second row, on Rue des Pâquerettes, demonstrates the emergence, at the end of the

106 | Sustainable renovation of a Brussels house: a challenge for building tradesmen

century, of a new taste for exposed materials. The facings are composed of bricks of various colours which alternate with bands of blue or white stones. During this period, with the proliferation of balconies and bow windows, façades were increasingly coming alive in a threedimensional sense. Nevertheless, what characterised Brussels’ urban landscape at the time was the detail in the composition, which is reminiscent of the works of early Flemish painters. The detail was the starting point from which the whole was created (fig. 3 to 5). From the perspective of energy consumption, the contiguous nature of traditional Brussels houses is an asset since it reduces the surfaces from which heat is


Fig. 1 Rue de Locht in Schaerbeek (photo by author).

Fig. 2 Rue des Pâquerettes in Schaerbeek (photo by author).

Fig. 3, 4 and 5 Elements picked at random from different styles of façade. Fig. 3: neoclassical moulding created in the render (photo by author); Fig. 4: the stonework on a plinth. The way the light falls enables the craftsman’s handiwork and the tool used - toothed chisel finish, chiselling, etc. to be seen. (© G. De Keyser). Fig. 5: lovely stained-glass window with a dragonfly pattern in an Art Nouveau period intricately-shaped frame (photo by author).

fig. 5

fig. 3

fig. 4

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lost. However, there is significant potential for energy improvements in the rear façade, particularly when it comes to the annexes, as we saw in the presentation by Julien Bigorgne from Apur (see p. 24-34). Added to these qualities is the comfort of these old houses in summer, most notably because of the difference between the temperature in the back yard and that in the street, creating a cooling stack effect. The flexibility of the design is also an asset, as discussed in previous contributions. This design, which operates based on the “box” principle, enables each room to be turned into more or less airtight compartments in the building, heated in different ways depending on the season. The entrance hall, often sealed by an internal door positioned at the top of the stairs leading to the raised ground floor,

also serves as a buffer space in terms of heat. There are other mechanisms that also enable the occupant to control comfort, such as interior or exterior shutters. While Venetian blinds have today largely disappeared, they were highly popular at the end of the 19th and beginning of the 20th centuries. Old postcards show that most of the buildings on the city centre boulevards were fitted with such blinds. Venetian blinds filtered daylight, from which people protected themselves to a greater extent than today, and also helped to combat summer overheating. The majority of Brussels houses at the time had rainwater cisterns which could be used to supply wash boilers, toilets, etc., by means of a pump. Another advantage of these old buildings was the extremely long

Fig. 6 An owner with a love for heritage renovates his house. He removes, among other things, a suspended ceiling installed in the entrance hall in the 1970s-1980s. At the time, it was seen as essential to lower the height of ceilings in order to “heat less air”. However, heating air requires little energy compared to heating materials. Suspended ceilings like these which, moreover, are not airtight, are useless from an energy perspective (© P. Brusten).


lifespan of the components from which they were made, including second fix components such as exterior joinery. The tendency today is to systematically replace old window frames in the name of saving energy, even though they are often in reasonably good condition after a hundred years or more of use. Yet the design of this old exterior joinery enables localised repairs to be carried out, for instance replacing the window sash bottom rail or a supporting member (lower window sill). The blue stone slabs on the balconies can also be repaired. Traces of work are sometimes visible: insertion of stone plugs to fill a gap; metal staples which are reminiscent of stitches to strengthen a crack; etc. In an old building, almost everything can, in theory, be repaired. What defines the know-how of the craftsperson

Fig. 7 The observation that the single-glazed aluminium window frames of the same era were not energy efficient is identical. It was then considered essential to ensure air tightness. However, today, it turns out that these frames are significantly worse from a heat transmission point of view than the single-glazed wooden frames that they replaced. Now, these aluminium window frames are, in turn, also being replaced (photo by author).


is the unbroken continuity in the craft between manufacture, the construction of the component and its repair. Within the context of the diagnostic approach to Brussels houses that should precede any work on a building, it is interesting to examine the energy renovation campaigns carried out in the 1970s and 1980s (fig. 6 and 7). Today, exterior joinery installed thirty or forty years ago is being replaced, whereas if the maintenance cycles had been continued the original elements could have been preserved. The issue of construction waste is also important as it makes up a large part of the total volume of waste generated in the Brussels Region. Building tradesmen help to limit the volume they produce by mastering repair and maintenance techniques that enable the existing components in the building to be maintained.

ENERGY RENOVATION AND HERITAGE: SOME EXAMPLES OF WORK

way of the original building materials remaining and generates huge amounts of construction waste.

The example of the building located on Rue du Rouleau (in the Béguinage quarter, central Brussels) is interesting as it was the subject of a low energy renovation in the early 2000s (fig. 8 and 9). It was therefore, in defence of the person behind the project, one of the first energy renovations of this type in the city. The interior of the building was completely gutted leaving only the exterior walls remaining. This is therefore an example of façadism, justified by the energy renovation. In effect, the fact that only the exterior walls were retained ensured the continuity of the interior insulation without creating thermal bridges in front of the floors. An operation of this type does not leave much in the

The “menu” for a low energy renovation almost always includes two interventions that have a potentially significant technical and aesthetic impact. The first concerns the building envelope, which has to be heavily thermally insulated as well as airtight. The second involves installing double-flow ventilation with recovery of heat in interior spaces that were not designed for it. Figure 10 illustrates a low energy project in which the interior insulation of the façades faces a very practical problem: the join between the insulation and the ceiling. In this case, solutions must therefore be found in order to reproduce the mouldings. The same problem arises when integrating the double-flow ventilation.

Fig. 8 and 9 Low energy renovation, Rue du Rouleau, Brussels. Overview (left) and close-up of interior wall insulation (right) (photos by author).

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fig. 10

fig. 11

Fig. 10 and 11 Close-up of interior wall insulation where it meets the ceiling (left); perforated moulding concealing a ventilation duct (right) (photos by author).

When a building is sub-divided, the issue is more complicated than in the case of a single-family dwelling. In effect, each apartment is generally equipped with a separate ventilation system. This system takes up room as all the pipes have to be placed somewhere. The solution devised for the project illustrated in figure 11 was to fit a very large moulding, pierced by small circular openings, in front of one of the ventilation ducts in order to integrate it visually into the ceiling moulding. We’ll now focus on the renovation of a private home in Schaerbeek (fig. 12). It is a neoclassical building, of which there are thousands in Brussels. This project is especially interesting in that it succeeded in reconciling an ambitious approach to energy efficiency with a concern for preserving the heritage value of the building, even though compromises had to be made

(such as replacing all of the window frames). The low energy standard (under 60 kWh/m²/year), was easily achieved. By way of comparison, the usual consumption of a building of this type is somewhere around 150 kWh/m²/year. The energy accounting religiously maintained by the owners indicated, for the first year of occupation, energy use of 42 kWh/m²/year for heating, which is quite close to the consumption calculated when the project was being developed: 32 kWh/m²/year. The rear façade was of no particular architectural interest. It was therefore insulated externally and covered with new render. The blue stone window sills, which acted as thermal bridges, were replaced by aluminium sills. Similar work could not be envisaged for the street-side façade for heritage and urban planning reasons. Interior insulation was therefore chosen, even though this technique is more difficult to implement as it often


has the result of enhancing the thermal bridges (fig. 13). Contrary to usual practice only the lower part of the walls was insulated, which avoided having to encroach upon the ceiling mouldings with the overlapping insulation. Although only partial, this interior insulation provides significant comfort as it eliminates radiation of cold from the wall surfaces closest to the body. What’s more, there are a sufficient number of non-insulated surfaces remaining, avoiding the concentration of any dampness in a specific point on the wall. The risk of spot condensation at the point where the floors are anchored into the façade is therefore reduced. Another interesting aspect of the project is the housing of the ducts for the double-flow ventilation in the old chimney flues (fig. 14). This operation ties in with the original function of chimneys which also played a role in building ventilation. They were


fig. 12

fig. 13

fig. 14

Fig. 12, 13 and 14 Rue Rubens 92 in Schaerbeek. This renovation project received an award as part of the 2008 call for Batex projects (photo by author). Notable work carried out included: partial insulation of the street-side façade using wooden panels (fig. 13) and integration of the double-flow system in the old chimney flues (fig. 14) (© A. de Nys and S. Filleul).

originally fi tted with individual heating appliances and, with the draw from the fire, some of the rooms’ waste air was removed via the chimneys. Another advantage of installing the ventilation ducts in the chimney flues: it turns out that the system, according to the occupants, is particularly quiet.

Fig. 15 Rue des Archives 28 in WatermaelBoitsfort. The project received an award as part of the Brussels Environment 2009 Batex competition (© H. Nicodème and R. Tilman).

What is interesting about this project is that it could be used as inspiration for the renovation of numerous Brussels houses of the same type. However, it should be pointed out that it was carried out thanks to the owners’ involvement and that they carried out certain lengthy and difficult works (such as fi tting the ventilation ducts in the chimneys) themselves. This work, which was in keeping with the heritage value of the property, would most likely not have been financially possible if it had been carried out by a company.

The renovation of a bel-étage house in Watermael-Boitsfort (fig. 15) illustrates a more radical operation from an energy and architectural point of view. Since the objective was to achieve a passive standard (under 15 kWh/m²/year), this project required significant insulation of the envelope and, in this particular case, the street-facing façade was insulated externally. Not generally possible for urban planning and heritage reasons, this technique was accepted due to the presence of the set-back area and because it involved a building dating from the 1950s-1960s which did not present a significant heritage issue. However, this approach does raise questions: should this type of operation be applied generally given that, in certain cases, the interest of the architecture of this period is yet to be fully explored? To conclude this chapter, let us go back a little in time by examining a 111

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Fig. 16 Air vent incorporated into the decoration of a sgraffito (© M. Wal).

Fig. 17 and 18 Roofing poses various difficulties. On the left, the join between the roofing and cornice has been badly executed. On the right, the cladding has been installed correctly but a mistake has been made at the level of the zinc section intended to draw rainwater into the cornice. (photos by author). fig. 17

fig. 18

Fig. 19 Correct installation of cladding but an uncovered area remains between the structure and the masonry behind the chimney flues! (photo by author).



Fig. 20 and 21 Two examples of thermal insulation of bow windows: installation of internal doors fitted with low-emissivity glazing (left) and lining of the apron in order to install insulation (right) (photos by author).

fig. 20

detail of the façade of the private home of architect Henri Jacobs at Avenue Maréchal Foch 9 in Schaerbeek, dating from 1899. An intriguing element can be made out beneath the window sills on the ground floor (fig. 16). It is a lovely sgraffito that “clothes” part of a technical installation: an air vent, decorated with the monogram of the architect, connected with the ventilation and heating system. This image reminds us that the introduction of technical elements into traditional Brussels houses is not a recent phenomenon. In his book, Les dimensions de l’ordinaire, Vincent Heymans presents the history of the traditional Brussels house from a heritage point of view as well as retracing the progressive introduction of technology. He shows the reluctance with which each of these technologies was greeted: running water; gas; central heating; electricity; bathrooms; etc. For example, in the 19th century, taking a bath was seen as dangerous and required certain precautions to be taken... Every one of these steps required modifications to buildings. The architect’s

role was, and remains today, to give architectural form to these new technologies which are not, in themselves, problematic.

NEW CHALLENGES FOR BUILDING TRADESMEN The introduction of these new technologies meant that craftsmen were confronted with previously unseen issues. Roofers, for example, were faced with a complete transformation of the trade as a result of the changing requirements in terms of thermal insulation. In fact, the insulation in a roof is composed of different layers that it must be possible to manipulate and manage. Interior insulation of the existing roof space (i.e. between the rafters), which may be lined, does not pose too many problems for a roofer, as the technical details of the actual roof itself are not modified. However, in numerous cases – for instance where there insufficient under-roof height or existing finishes that need to be preserved it is not possible to apply interior insulation. The solution proposed

fig. 21

in this case is roof sarking, which consists of inserting the insulation on top of the rafters, requiring the roof to be raised. This technique involves redesigning all the details concerning water tightness and, in particular, the join between the roofing and the cornice gutter (fig. 17 to 19). Integration of thermal or photovoltaic solar panels, insulated cladding, etc.; all of these recent technologies are also a challenge for the trade. As regards exterior joinery, extreme care is always required. Should it be replaced? Should the existing joinery be improved? Various techniques enable the performance of exterior joinery to be improved while preserving it. The fitting of a double frame on the inside is an efficient solution from a thermal and acoustic point of view. It is also possible to insulate a bow window by installing internal doors to create a buffer space. This blocks cold in winter and prevents overheating in summer. Thermally insulating the apron is also a possibility (fig. 20 and 21). However, all of this requires learning and acquiring new skills since a joiner 113

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is not necessarily trained in thermal insulation techniques. Double-glazing can often be fitted into an existing window frame using a technique whereby the glazing rebate is widened. The width of the rebate, after milling, determines the performance of the glazing that will be fitted. In effect, the U-value, or heat transmission coefficient of the glass, is linked to the thickness of the air or gas space separating the two panes. By way of example, to obtain a U-value of 1.1 W/m².K, the thickness of the double-glazing interlayer should be 15 or 16 mm. Given the cross-sectional profiles of old wooden window frames, it is not always possible to fit glass of such thickness. Double-glazing with 12 mm or even 9 mm interlayers will therefore often be chosen. Another method is to fit single-glazing but with a low emissivity layer. This consists of laminated glass fitted with a low emissivity layer that reduces the heat transmission coefficient of the single-glazing to a U-value of around 3.2 W/m².K. As a reminder, normal single-glazing has a U-value of 5.8 W/m².K. This technique therefore offers a substantial improvement even if it is not comparable to the performance of contemporary double-glazing. In the case of heritage buildings this type of glazing is interesting, particularly when the glass in sash window frames is being replaced. This avoids having to install double-glazing with fake sash bars. This glazing is available in drawn and blown glass versions for the external face. The thermal efficiency of front doors can be enhanced by fitting seals. In the case of doors adhesive seals are generally used, while for window frames the best solution is fitting seals in a groove made using

a router. This is not recommended for doors as the door frame could be weakened. A brush seal can also be fitted to the bottom of the door to improve its performance. An old door cannot, of course, be brought up to level of performance of a new one, but a significant improvement can be made. Craftspeople face limits in terms of improving thermal efficiency and I think that these limits should be examined. A desire to ensure the continued existence of trades that enable existing elements to be maintained and preserved risks leading us into a dead end. Indeed, it should be borne in mind that, by dint of encouraging very high levels of efficiency, a point will be reached where the only choice possible will be to replace, especially in terms of exterior joinery. A quick examination of Batex projects shows, with some notable exceptions, that almost every one includes the replacement of window frames. Questions therefore need to be asked about the level that we want to achieve. As part of the reflections underway on reorienting the system of renovation and energy grants, it would perhaps be good to consider greater progressivity in the thresholds. If we take, for example, the fitting of double-glazing in an existing frame, the maximum U-value required for the energy grant is 1.2 W/m².K (this requirement is not appropriate for the renovation grant). In a sizeable number of cases, this level of efficiency will not be achieved and individuals could be discouraged. They will therefore opt for the “easy solution” and replace everything. As regards low emissivity single-glazing, it is automatically excluded as it has a U-value of 3.2 W/m².K. Double-glazing is subsidised for the purpose of the energy grant


but is not eligible for a renovation grant. Why not consider making it eligible? In the case of wall insulation, grants also encourage high levels of efficiency that rule out the insulating renders applied for the purpose of thermal correction referred to by Julien Bigorgne from Apur (see p. 24-34).

TRAINING PROFESSIONALS AND EDUCATING INDIVIDUALS For several years now, numerous courses on the theme of sustainable renovation have been offered to professionals by actors such as Brussels Environment, the Belgian Building Research Institute (BBRI) and the Construction Reference Centre (CDR). From these many initiatives, I want to highlight the “Interactive technical course on window frames” organised by the CDR and 21 Solutions. This is a course that focuses on both requirements in terms of energy performance and constraints in terms of heritage. It includes on-site visits, a diagnostic approach and encourages a very open-minded consideration of the range of technical solutions available, according to the energy renovation scenarios chosen. The role of the Centre Urbain’s information desk, situated at Halles Saint-Géry, is to inform individuals about all aspects of housing renovation. We don’t do this work alone, of course. There are also the associations that are part of the Habitat network, as well as other actors. We have been around for 25 years and our special feature is our cross-disciplinary approach. We approach housing from the perspective of different themes - energy, building pathology, heritage, acoustics, planning - by establishing bridges between all


Fig. 22 Practical workshop organised by the Centre Urbain on the theme of exterior joinery maintenance (photo by author).

of these (sometimes contradictory) constraints, around which private individuals often find it difficult to find their way. It should be pointed out that a large portion of renovation works, especially those aimed at improving energy efficiency, are carried out without an architect. In addition to training craftspeople, educating individuals is therefore essential to enable them to discuss things with their contractors. The client can be encouraged to hire an architect, which we do regularly, but it is still the case that a lot of works are carried out without them. This situation is problematic in the case of energy-related works as such renovations, which are carried out in phases depending on the resources available. However, there is often no long-term view taken of changes to the building. The classic problem, referred to earlier by Sandrine Herinckx from the BBRI (see p. 102-106), is

replacing window frames without considering the need for ventilation. Such works do not necessarily require planning permission and the EPB regulation - which contains obligations in terms of ventilation thus does not apply either. In this way, such works often escape any type of control. Education and awareness-raising work is therefore essential. We also make available to private individuals the Directory of Heritage Trades which directs them towards companies or craftspeople capable of carrying out work with a view to maintaining and repairing the existing structure. We also organise practical workshops for private individuals (fig. 22). These focus on maintenance techniques and, at the same time, also describe works that require the use of a professional. They are run by craftspeople. Translated from French. 115

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BIBLIOGRAPHY BERTRAND, J., Le Châssis de fenêtre en bois - Concilier Patrimoine et confort, Monuments and Sites Directorate of the Brussels-Capital Region, Brussels, 2008. BERTRAND, J., “Une maison bruxelloise au banc d’essai”, in Les Nouvelles du Patrimoine, Brussels, January, February, March 2013, pp. 30-31. HENNAUT, E., and DEMANET, M., Bois et métal dans les façades à Bruxelles, King Baudouin Foundation, Archives of Modern Architecture, Brussels, 1997. HEYMANS, V., Les dimensions de l’ordinaire: La maison particulière à Bruxelles, fin XIXe - début XXe siècle. L’Harmattan, Paris, 1998. SENNETT, R., Ce que sait la main. La culture de l’artisanat, translated from American English by P.-E. Dauzat, Albin Michel, Paris, 2010.

WEBSITE : Bâtiments exemplaires : http://www. environnement.brussels/thematiques/ batiment/sinspirer-des-batiments-exemplaires/vous-cherchez-un-projet-batex Bruxelles Environnement : Guide des déchets de construction et de démolition, 3e édition (IBGE, 2009) http:// documentation.bruxellesenvironnement. be/documents/Guide_Dechets_construction_FR.PDF Bruxelles Environnement : Guide pratique pour la construction et la rénovation durables de petits bâtiments : http://app.bruxellesenvironnement.be/ guide_batiment_durable Centre urbain : www.curbain.be ; www.patrimoine-metiers.be

Rénovation durable de la maison bruxelloise : un défi pour les artisans du bâtiment Le bâti résidentiel bruxellois du XIXe et du début du XXe siècle constitue un patrimoine de valeur tant par la cohérence des ensembles urbains qu’il forme que par la qualité exceptionnelle du détail architectural. Il est marqué par la présence des métiers artisanaux qui connaissent à cette époque une véritable renaissance malgré l’industrialisation. Au-delà du renforcement de la performance énergétique, un projet de rénovation de la maison bruxelloise aura pour objectif de valoriser ses atouts en terme de durabilité : flexibilité et évolutivité du plan, usage de matériaux traditionnels, principes constructifs qui privilégient l’entretien, la réparation, le réemploi... La majorité des rénovations de logements sont réalisées sans l’intervention d’un architecte ; la qualité de ces travaux repose donc avant tout sur la sensibilisation et l’information des maîtres d’ouvrage et sur la formation des artisans du bâtiment.

Direction des Monuments et des Sites de la Région de Bruxelles-Capitale : www.patrimoine.brussels


Duurzame renovatie van de Brusselse woningen: een uitdaging voor de bouwambachten Brusselse woningen uit de 19de eeuw en het begin van de 20ste eeuw vormen een waardevol erfgoed, zowel wegens de coherentie die ze verlenen aan het straatbeeld als omwille van de uitzonderlijke kwaliteit van de individuele gevel. Dit heeft veel te maken met de heropleving van de bouwambachten in die periode en dit ondanks de industrialisatie. Bij de renovatie van deze Brusselse woningen zouden naast het verbeteren van de energieprestaties hun eigen troeven op het vlak van duurzaamheid moeten aangewend worden: flexibiliteit en evolutiemogelijkheden van het plan, gebruik van traditionele materialen, bouwprincipes afgestemd op onderhoud, herstellingen, hergebruik... De meeste woningrenovaties worden uitgevoerd zonder de tussenkomst van een architect; de kwaliteit van deze werken hangt dus in de eerste plaats af van de sensibilisering en de voorlichting van de bouwheren en de opleiding van de ambachtslui uit de bouwsector.


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CONCLUSION

The seminar was most instructive and clearly showed the need, after a period of experimentation and innovation, to take time to evaluate and reflect with a view to a possible reorientation of priorities, such as those provided for in the Government agreement. The issue of standards being applied to existing buildings was extensively covered. One key observation is regarding the significant differences between the theoretical consumption resulting from models and the actual consumption of buildings. This observation is one we share with other European cities. It is therefore necessary to work on refining the models to take greater account of the diversity of structures and their environment on the one hand, and the methods of occupation of buildings, apartments, etc. on the other. This is an essential aspect of the sociology of buildings. Having a keen awareness of this data (with actual consumption often being less than half the theoretical results) will enable adjustments to be made to renovation works and the cost of investment. We must aim for a balance between the results sought and the resources required to achieve them in order to achieve a satisfactory pay-back period. The first step in this process is to implement monitoring of work on buildings in order to gather and evaluate the data. It is important that we move away from our somewhat entrenched opposing positions to be able to discuss the issues at hand on a real, sufficiently documented and informed basis. Such monitoring should include consumption before and after work and provide an opportunity to put in place a protocol for the collection of data. Since this work is not starting from scratch, this data collection must incorporate data from audits already carried out. These data currently remain in the records of public authorities who steer the audits or in the hands of private companies who carry them out, and even though they exist in large quantities such data are not necessarily known or compatible and therefore not capable of being compared. Pooling all of these elements in a common 118

database would facilitate access to them and enable comparative analyses to be carried out. The absolute priority is to generalise a base level of renovation and insulation for the building stock. Initial investments, as has already been shown in a number of cases, are the most cost-effective, while those necessary to achieve the final KhWs to comply with the normative requirements are the most costly. In short, the key is to work on a greater number of buildings with a view to regional economies of scale by intervening less intrusively on a systematic basis. The importance of a global approach is well established, both at city and neighbourhood level as well as in terms of preserving the urban planning and architectural qualities of old buildings. In this sense, we have arguably already made progress, particularly insofar as protecting rear courtyards is concerned, which has been a requirement since the introduction of the sectoral plan in 1979. The question of embodied energy was also raised in the course of the seminar: the overall assessment of any works must include embodied energy, i.e. the energy consumed when implementing the techniques and materials used in the renovations. Although this question is difficult to address in practical terms, it must not be ignored. All of this speaks in favour of enhanced cooperation between different institutional partners (foremost of which are Brussels Environment and Brussels Urban Development) and the construction sector, public or private actors in urban development, a range of scientific partners such as the Belgian Building Research Institute (BBRI) and the various universities running programmes addressing these issues of energy performance and modification of existing buildings. Enhanced cooperation in the near future between Brussels Environment and Brussels Urban Development is included in the Government agreement, particularly with regard to the management of


mixed permits, environmental permits and planning permission, simplification of the grants system with a mechanism integrating renovation grants with energy grants, and simplification of impact reports and studies. These comprise an entire set of topics that need to be re-evaluated to enable the Region to respond to today’s key issues: population growth; the need to provide sufficient quantities of housing; climate issues; and reducing greenhouse gas emissions. To conclude, thanks are due to the seminar’s organisers, especially the Monuments and Sites Department who undertook this project. Thanks also to the speakers for the quality and wealth of their contributions. This one-day seminar represented an important step towards the stated objective of reconciling energy performance and the preservation of not only exceptional heritage but also common heritage, made up of the old urban fabric.

Benoît Périlleux Director-Head of Department Brussels Urban Development

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COLOPHON

General organisation Anne-Sophie Walazyc Authors Jérôme Bertrand, Julien Bigorgne, Julien Borderon, Vincent Degrune, Jonathan Fronhoffs, Michael Govaert, Roald Hayen, Emmanuel Hecquet, Sandrine Heirinckx, Charlotte Nys, Guido Stegen, Manja Vanhaelen Prefaces and conclusion Benoît Périlleux, Arlette Verkruyssen, Bety Waknine Transcription of speeches FADE IN sprl English translation Data Translations International English editing Cate Chapman - Skylark Editing Graphics The Crew Communication

The texts were transcribed from the verbal presentations given by the speakers on 11 December 2014. The articles are published under the responsibility of their authors. All rights of reproduction, translation and adaptation reserved. Contact Direction des Monuments et des Sites CCN - Rue du Progrès/Vooruitgangsstraat 80, 1035 Brussels www.patrimoine.brussels Photo credits While every effort has been made to identify all copyright holders, any rights holders who could not be contacted are invited to make themselves known to the Monuments and Sites Directorate of the Brussels-Capital Region. Legal deposit D/2015/6860/025. First edition.

Digital version Newpress

Cover photo Ch. Bastin & J. Evrard, 2008 © SPRB Photo of Logis and Floréal in the contents A. de Ville de Goyet © SPRB

Publisher / Verantwoordelijke uitgever Arlette Verkruyssen, Director General of Brussels Urban Development/Regional Public Service of Brussels CCN - Rue du Progrès/Vooruitgangsstraat 80, 1035 Brussels

The proceedings of the seminar are available online in French and Dutch under the title: “L’avenir énergétique du bâti bruxellois existant: entre préservation et performance" and “De energietoekomst van de Brusselse gebouwen: tussen bewaren en presteren”.

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