Daylighting and Visual Comfort in Buildings ... - Science Direct

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ScienceDirect Procedia Environmental Sciences 38 (2017) 522 – 529

International Conference on Sustainable Synergies from Buildings to the Urban Scale, SBE16

Daylighting and Visual Comfort in Buildings’ Environmental Performance Assessment Tools: a Critical Review Christina Giarmaa,* , Katerina Tsikaloudakia, Dimitris Aravantinosa a

Laboratory of Building Construction and Building Physics, Department of Civil Engineering, Aristotle University of Thessaloniki, P.O. Box: 429, Gr-54124 Thessaloniki, Greece

Abstract In this paper, some well-known buildings’ environmental performance assessment tools and methods are reviewed with regard to the consideration of visual comfort in their structure and assessment process. Specifically, the parameters used for visual comfort’s assessment in widely used tools (BREEAM, LEED, SBTool and CASBEE - versions for office buildings) are examined; the type and the kind of criteria used for the assessment, the weightings applied and references to relative standards are reviewed and comparatively assessed. Although the presented results cover the issue of visual comfort as a whole, emphasis is given on daylighting–related factors. © 2017 2017The TheAuthors. Authors. Published by Elsevier © Published by Elsevier B.V. B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of SBE16. Peer-review under responsibility of the organizing committee of SBE16. Keywords: daylighting; visual comfort; illumination; glare; buildings environmental performance assessment tools

1. Introduction The provision of a safe and comfortable indoor environment is one of the principal demands that have to be met by buildings; indeed, the quality of the indoor environment, defined by its main axes, i.e. thermal, acoustic and visual comfort, as well as the quality of indoor air, is a critical factor for reasons related not only to health issues but also to the well-being and the productivity of building occupants1. As such, the quality of indoor environment is taken into consideration in the context of all widely used methods and tools for the assessment of buildings environmental performance. The study presented in this paper focuses on the way visual comfort is dealt within the

* Corresponding author. Tel.: +302310995412; fax: +302310995603. E-mail address: [email protected]

1878-0296 © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of SBE16. doi:10.1016/j.proenv.2017.03.116

Christina Giarma et al. / Procedia Environmental Sciences 38 (2017) 522 – 529

context and the process of the assessment conducted by well-known methods and systems rating the environmental performance of buildings. Emphasis is put on daylight-related parameters. Specifically, in this paper the parameters used for visual comfort’s assessment in four widely used tools (BREEAM, LEED, SBTool, CASBEE) are examined; the analysis is based on the versions of the methods dealing with buildings of the tertiary sector, and specifically with office buildings. This choice was based on the hypothesis that office buildings are characterized by certain features, which are common or similar around the world (this is not the case e.g. for residential occupancies, in the design, construction and operation of which regional conditions, tradition and local mentality are much more pronounced); as a result, the comparative review and assessment attempted in this paper would have a sound basis. In the context of the analysis presented in this paper, the type and the kind of criteria used for the assessment of visual comfort-related parametres, the weightings applied and references to relative standards are reviewed and comparatively assessed. 2. Visual comfort parameters in buildings’ environmental performance assessment tools 2.1. Background The tools examined in this paper (BREEAM, LEED, CASBEE and SBTool) vary in their philosophy, approach and structure. Therefore, the presentation of their main features is an inseparable part of the analysis regarding the consideration of visual comfort related parameters in the assessments they conduct. These features are presented in the following subsections. 2.1.1. BREEAM BREEAM (Building Research Establishment Environmental Assessment Methodology), the oldest method for the assessment of buildings’ environmental performance, was initially published in 1990 by Building Research Establishment, UK. Currently BREEAM can be used for the assessment of buildings of various uses (residential, office buildings, hospitals, schools, etc.) at various stages of their lifecycles. In fact, there are available several schemes, each one of which can be used for different cases. Also, a scheme has been developed for the assessment of projects of bigger scales (BREEAM Communities). With regard to the method’s applicability in different regions, BREEAM International, which includes a set of assessment methods for all the stages of the building’s lifecycle, can be employed in any part of the world, with its adjustment to the local conditions and standards being feasible. Furthermore, versions of BREEAM for application in specific countries (e.g. Germany, The Netherlands, Norway, etc.) have been developed. In BREEAM, the performance of a building is quantified with the consideration of several criteria extending across a range of environmental issues, which, in the scheme under consideration in this paper (BREEAM UK New Construction - Non Domestic Buildings UK2), are organized into the following sections: “Management”, “Health and Wellbeing”, “Energy”, “Transport”, “Water”, “Materials”, “Pollution”, “Waste”, “Land Use and Ecology” (an additional section, “Innovation”, is introduced to provide additional credits). Depending on whether the assessed building meets the performance levels set for each criterion, it is awarded or not the credits assigned to it, with the achievement of minimum accepted levels in some key areas being prescribed as compulsory for the achievement of various BREEAM ratings. The aggregated sum of the ratio of the number of the awarded credits and the number of the available credits corresponding to each one of the first 9 environmental sections and the addition of the contribution of the credits awarded for the issues covered by Innovation section are resulting to the final rating of the building. The categories, under which the buildings assessed with the use of BREEAM method are classified according to the achieved score, are: Unclassified, Pass, Good, Very Good, Excellent, Outstanding. 2.1.2. LEED LEED (Leadership in Energy and Environmental Design) has been developed in U.S.A. by U.S. Green Building Council (USGBC). It is a very widely used system for the rating of buildings environmental performance. The different LEED schemes can be used for the assessment of buildings of various uses at all phases of development. Furthermore, a LEED rating system (LEED Neighborhood development) has been developed for the assessment at a larger scale (neighborhood level, land development projects, etc.). LEED can be applied, with the appropriate adjustments, in various regions of the world. It is noted that in the previous years there have been developed some

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“national” LEED schemes that are adjusted to the local conditions (e.g. LEED Canada). As also in BREEAM, the assessment performed by LEED is based on credits awarded to the object of assessment, depending on whether or not it meets well defined requirements and performance levels. Of course, the examined criteria, on the basis of which the credits are awarded, are organized in different categories in LEED (in comparison to BREEAM); in the examined version in this paper (LEED v4 for BUILDING DESIGN AND CONSTRUCTION, 2015 3), these categories are: “Location and Transportation”, “Sustainable Sites”, “Water Efficiency”, “Energy and Atmosphere”, “Materials and Resources”, “Indoor Environmental Quality”, “Innovation”, “Regional Priority”. The rating of the building in the LEED system is based on the arithmetic sum of credits awarded to it and, based on this sum, the buildings under study are classified into the following categories: certified, silver, gold, platinum. 2.1.3. CASBEE CASBEE (Comprehensive Assessment System for Built Environment Efficiency) has been developed in Japan. It can be used for new buildings, existing buildings and buildings under refurbishment (different versions of the tool-in this paper the examined version is CASBE for New Construction4 (the data for offices are taken into consideration)). It covers several building uses; also, a CASBEE tool has been developed for the assessment of urban districts (CASBEE for Urban Development) and another one for cities (CASBEE for cities). Furthermore, CASBEE tools for specific purposes have been developed (e.g. for heat island effect, for temporary construction, etc.). CASBEE is used mainly in Japan and takes into consideration, among others, issues that are peculiar for Japan and Asia. The assessment fields covered by CASBEE in its general context are energy performance, resource efficiency, local environment and indoor environment. It is in the context of these 4 fields that the around 90 sub-issues examined by CASBEE are included. The philosophy of assessment in CASBEE is different than in most environmental performance assessment methods. In CASBEE there are two spaces defined, internal and external; these spaces are separated by a hypothetical boundary. Two factors correspond to these spaces: Q: (built environment quality), which “evaluates "improvement in living amenity for the building users, within the hypothetical enclosed space (the private property) "”, and L: (environmental load of building), which “evaluates "negative aspects of environmental impact which go beyond the hypothetical enclosed space to the outside (the public property). "” and is derived from LR (environmental load reduction of building). These factors are further divided into three items each (Q1: “Indoor Environment”, Q2: “Quality of Service”, Q3: “Outdoor Environment on site” and LR1: “Energy”, LR2: “Resources & Materials”, LR3: “Off-site Environment”); these items comprise sub-categories, which consist of criteria. The score of the largest entities is calculated via the aggregated summation of the directly smaller ones. The rating of the building is based on the ratio BEE={a function of score of Q}/{a function of score of LR}. The building is classified under the following categories: class C (poor performance), class B-, class B+, class A and class S. 2.1.4. SBTool SBTool5 (Sustainable Building Tool), which is the evolvement of GBTool (Green Building Tool), has been developed by iiSBE (international initiative for a Sustainable Built Environment). It is the computational tool of the Sustainable Building method, which is constantly developing with the contribution of several organisations, institutions and researchers around the world. SBTool is a generic framework that can be used for the assessment of buildings of various uses at various phases of their lifecycles (design, construction, operation). There have been developed some versions of SBTool adjusted to national conditions and priorities in some countries (e.g. SBTool CZ, SBToolPT, etc.). A major characteristic of SBTool is that it is fully adjustable to local conditions and priorities as well as to the needs of the assessment performed (e.g. type of building, extent of assessment scope, life cycle stage, etc.); this adjustment can be made through the modification of several factors, e.g. relative weightings of criteria, throughout the tool. The topics assessed by SBTool are organized in 7 large sections (Performance Issues): “Site Regeneration and Development”, “Urban Design and Infrastructure”, “Energy and Resource Consumption”, “Environmental Loadings”, “Indoor Environmental Quality”, “Service Quality”, “Social, Cultural and Perceptual Aspects”, “Cost and Economic Aspects”. It is noted that when the pre-design phase is under consideration, the issues examined are relative to only one Issue: “Site Location, Available Services and Site Characteristics”. Every Performance Issue consists of Performance Categories, each one of which includes several Performance Criteria. The determination of the relative weights takes place at the lower level of the tool’s structure (Criteria-Subcriteria); specifically, for the active in each study (depending on the use of the building and the stage of its life, for which the


assessment is conducted) Performance Criteria predefined relative weights are available (defined on the basis of a systematic procedure); they can nevertheless be altered according to the priorities/conditions of every region. The building finally receives a score between -1 and +5. 2.2. General considerations The criteria used to assess visual comfort in each one of the afore presented tools are organized in a different way, depending on the general assessment context, structure and system of each tool. In BREEAM, the assessed parameters related to visual comfort (Table 1) are organised under the issue of “Visual Comfort”, which belongs to the environmental section “Health and Wellbeing”. In LEED, the respective credits (Table 1) belong to the category of “Indoor Environmental Quality”, while in CASBEE most of these parametres (Table 1) are listed under the subitem “Lighting and Illumination”, which is a part of the item “Indoor Environment”. In SBTool, the first 3 parameters belong to the Performance Issue of “Indoor Environmental Quality” and the Performance Category of “Daylighting and Illumination”, the 4th one is listed under the Performance Issue “Service Quality”, and the 5 th one is classified under the Performance Issue “Social, Cultural and Perceptual Aspects”. It should also be mentioned that some parameters might be examined under different categories in these tools; for example, as described in the following sections, glare related considerations in LEED are examined in the context of “Daylight”. Table 1. Parameters related to visual comfort in the examined methods. BREEAM

LEED

CASBEE

SBTool

1. Glare Control

1. Interior lighting

1. Daylight

1. Appropriate daylighting in primary occupancy areas

2. Anti-glare measures

2. Control of glare from daylighting.

3. Illuminance level

3. Appropriate illumination levels and quality of lighting in non-residential occupancies.

2. Daylighting 3. View out 4. Internal and external lighting levels, zoning and control

2. Daylight 3. Quality views

4. Lighting controllability 5. Perceived spaciousness and access to view (in sub-item “Amenity”, of the item “Service Ability”)

4. Controllability (including several criteria with regard to the degree of control for lighting systems) 5. Access to exterior views from interior

Of course, the relative weighting of the various issues varies among the examined tools. Differentiations can be observed in not only the contribution of visual comfort as a whole to the directly larger entity in the tool, e.g. “Indoor Environmental Quality” in LEED, but also in the relative importance of the latter in final rating/grade of the assessed building. For example, in BREEAM (scheme for fully fitted out offices), the environmental section “Health and Wellbeing” has a relative weight of 15% within the final score of the building, while “Visual comfort” can contribute 4 out of the total achievable 17 credits in “Health and Wellbeing” section (Fig. 1(a)). In LEED (scheme for offices new construction and major renovation), “Indoor Environmental Quality” can contribute up to 16 credits to the total of 110 possible points for the assessed building, while visual comfort related parameters represent 6 out of the 16 available credits of “Indoor Environmental Quality” category (Fig. 1(b)). In CASBEE, the assessment approach and process is different in comparison to LEED and BREEAM; as a result, the relative weightings of parameters related to visual comfort are not directly comparable to the ones presented for LEED and BREEAM. For reasons of completeness in the presentation of results it is mentioned that “Lighting and Illumination” sub-item has a relative weight of 25% within the item “Indoor Environment” (Q1), which has a contribution of 40% to the score of factor Q (built environment quality). Finally, the relative weightings in SBTool are, as mentioned before, highly adjustable. Indicatively, it is mentioned here that in the generic version of the tool, in which only office use is considered, the maximum range of criteria is taken into consideration and the design phase is examined5, “Indoor Environmental Quality” Performance Issue’s score has a relative weight of 3,6% for the calculation of the final score of the building. 2.2.1. BREEAM As mentioned before, the scheme of BREEAM examined in the current study is BREEAM UK New Construction Non Domestic Buildings UK. In Table 2, the main issues, on the basis of which visual comfort related parametres

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are assessed in this scheme are listed; specifically, for each issue, the main context of the relative criteria is referred to (“main axes of compliance criteria”), and the type of each criterion is mentioned. Moreover, in the last column of

Fig. 1. (a) contribution of section “Health and Wellbeing” to the final score of the building, and of “Visual comfort” to “Health and Wellbeing” section in BREEAM2; (b) contribution of category “Indoor Environmental Quality” to the final score of the building, and of visual comfort related parameters to “Indoor Environmental Quality” section in LEED3.

Table 2, the standards, guidelines, reports, studies or specific methods related to all the examined criteria (as referred to in the tool’s manual) are listed. It has to be noted that daylight-related criteria are not included in Table 1 and are separately analysed, since, as mentioned previously, daylighting is one of the focal points of this paper. Table 2. Criteria for the assessment of visual comfort in BREEAM. Issue examined

Glare Control

View out

Internal and external lighting levels, zoning and control

Main axes of the compliance criteria

Type of criteria

Avoidance of glare through either the building form and layout and/or building design measures

Descriptive (e.g. use of compliant shading measures)

Avoidance of the increase of energy consumption for lighting

Descriptive (requirements related to the glare control system)

Ensuring that occupants of the relevant areas of the building have adequate view out.

Quantitative (window opening area, room depth, etc.)

Requirements for fluorescent lamps (internal lighting)

Descriptive (high frequency ballasts)

Provision of adequate illuminance level (internal lighting)

Quantitative (accordance to relative standard)

Special provisions for rooms where computers are frequently used

Quantitative and descriptive (accordance to relative standard)

Provision of adequate illuminance level by external lighting located within the construction zone *1

Quantitative and descriptive (accordance to relative standard)

Allowance of occupant control by interior lighting zoning

Mostly descriptive (criteria for each type of use, e.g.”in office areas, zones of no more than four workplaces”)

Ref. to standard/ method/ guide

BS 8206, SLL Code for -Lighting 2012, CIBSE Lighting Guide 7, BS 5489-1: 2013, BS EN 12464-2: 2014, CIBSE Lighting Guide LG10

*1: it is mentioned here only because it is a part of the examined issue

Daylighting is assessed both on a quantitative and a qualitative basis. The adequacy of daylighting is addressed via the use of daylight factor and illuminance levels on the working plane, while the quality of daylight is interrelated mostly with its uniform distribution across the indoor area. More specifically, an office building can get up to 1 credit for daylighting if one of two alternatives is satisfied. For the first alternative, the adequacy of daylight

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is assessed through the daylight factor; an average value of 2% is required for more than 80% of the floor area. The quality of daylight distribution is fulfilled either when x the uniformity ratio (i.e. the ration between the minimum and the average value of daylight factor) is equal/greater than 0.3 or the minimum value of daylight factor exceeds 0.6% or when x at least 80% of the examined area has a view of sky from desk (i.e. on the level of 0.7m from the floor) and the room depth criterion is satisfied:d/w+d/HW