Embodied Energy for Energy Efficiency Measures - CiteSeerX

Embodied Energy for Energy Efﬁciency Measures An Assessment of Embodied Energy‘s Relevance for Energy Saving in the Swiss Residential Building Sector

Diploma Thesis Department of Environmental Science ETH Zurich Simone Hegner September 2007 Supervisors Prof. Dr. Dieter Imboden Dr. Michael Kost

Summary The Swiss residential building sector plays a key role for the Swiss energy system and thus, for the reduction of total energy consumption and the achievement of the climate protection demands in Switzerland. The key role of the Swiss residential building sector can be explained by the fact that the energy consumption for heating and hot water generation in residential buildings applies for a quarter of the total energy consumption. An option to reduce the energy consumption is the implementation of energy-efficient renovation measures and energy-efficient construction alternatives for new buildings. These energy efficiency measures result not only in a reduced heating energy consumption, but also in an increased embodied energy affordance compared to common renovation measures and common construction alternatives for new buildings. In this conntext, the objection that the embodied energy affordance may overcompensate the reduced heating energy consumption has been expressed several times. The present diploma thesis assesses the relation between the embodied energy afforded for energy efficiency measures and the reduced heating energy consumption achieved by implementing these measures. The juxtaposition is conducted on a model building level and on a country level for the time period 2000 to 2050. The assessment on the country level is conducted using a simulation model of the Swiss residential building sector. In addition, different renovation material compositions and various wall construction options for new buildings with a low heat demand are compared concerning their embodied energy content. The results calculated on the model building level show that the embodied energy affordance caused by energy efficiency measures accounts for on average 5 % of the reduced heating energy consumption and for 3 % of the total primary energy demand (sum of embodied energy affordance and heating energy consumption), if the embodied energy affordance is allocated to an operating time of 50 years. The relation between embodied energy demand and reduced heating energy consumption depends basically on the construction period of the considered building. The relation is more beneficial for older buildings. This is because of the considerable heat demand of older buildings, which can be reduced drastically by investing only a small amount of embodied energy. The results of the embodied energy calculations for different renovation material compositions show that the embodied energy content of a certain renovation material composition is often determined by a certain embodied energy-intensive or embodied energy-extensive renovation material. Concerning the wall construction options for new buildings with a low heat demand, various wall construction alternatives with a low embodied energy content can be recommended depending on the customers' preferences. The results of the simulation procedure on the Swiss residential building sector level show that the cumulative embodied energy afforded for energy efficiency measures for the time period from 2007 to 2050 accounts for 5 to 10 % of the corresponding cumulative reduced heating energy, whereas the cumulative embodied energy affordance increases with the decreasing heating energy consumption. The bandwith of the embodied energy affordance that has to be invested in order to reduce the heating energy consumption to different levels appears marginal, if this bandwith is compared to the bandwith of the heating energy consumption. Thus, the development of the total energy consumption (sum of embodied energy demand and heating energy consumption) seems to be determined basically by the development of the heating energy consumption. It can be concluded that the beneficiation of the total energy consumption in the Swiss residential building sector can only be achieved, if the heating energy consumption is reduced, although a certain embodied energy affordance has to be invested to achieve this beneficiation.

Table of contents

1 Introduction........................................................................................................... 1 1.1 Background.............................................................................................................................. 1 1.2 Embodied energy..................................................................................................................... 3 1.3 Questions dealt within the diploma thesis............................................................................. 3

2 Methods and data..................................................................................................5 2.1 Embodied energy calculation methodology for model buildings ........................................ 6 2.1.1 The model buildings................................................................................................................ 6 2.1.1.1 Reference renovation and reference construction alternative .............................................. 6 2.1.1.2 Renovation packages and construction alternatives ............................................................ 7 2.1.2 Definition of the reference material composition...................................................................... 9 2.1.3 Embodied energy calculation for the model buildings.............................................................. 9 2.1.4 Comparison of alternative renovation material compositions and wall construction options for new buildings ...................................................................................... 9 2.1.4.1 Alternative renovation material compositions........................................................................ 9 2.1.4.2 Wall construction options for new buildings........................................................................ 11 2.2 Data for embodied energy analysis...................................................................................... 11 2.2.1 The concept for embodied energy used in the diploma thesis............................................... 11 2.2.2 Embodied energy data for construction materials.................................................................. 12 2.3 Embodied energy calculation for the Swiss residential building sector for the time period 2000 to 2050.................................................................................................. 16 2.3.1 The Swiss residential building stock model........................................................................... 16 2.3.2 Integration of embodied energy in the building stock model.................................................. 17

3 Results and Discussion......................................................................................19 3.1 The relevance of embodied energy for the model buildings............................................... 19 3.1.1 The relation between embodied energy demand and reduced heating energy consumption 19 3.1.2 Differences between model buildings of different construction periods.................................. 24 3.1.3 Comparison of alternative renovation material compositions and wall construction options for new buildings..................................................................................... 25 3.1.3.1 Comparison of alternative renovation material compositions.............................................. 25 3.1.3.2 Survey of different wall construction options for new buildings with a low heat demand..... 28

3.2 The relevance of embodied energy considering the Swiss residential building sector... 32 3.2.1 Future development of ERA and heating system distribution................................................ 32 3.2.2 Future development of heating energy consumption and embodied energy demand............ 34

4 Conclusions.........................................................................................................38 4.1 The development of energy consumption and total embodied energy demand in the Swiss residential building sector................................................................................................ 38 4.2 The relevance of embodied energy for energy efficiency measures................................. 38 4.3 How to reduce the total energy consumption in the Swiss residential building sector... 39

5 Bibliography........................................................................................................ 41

Acknowledgement Writing my diploma thesis had a lot in common with a challenging climbing tour: Having to accept setbacks, searching for new ways to reach the summit and asking oneself several times, if the summit can be reached. However, the present diploma thesis has been finished, and I feel like being on the coveted summit, when all the overborn troubles are forgotten. On climbing tours, it is often impossible to reach the summit by oneself. In fact, several people encourage and support you on your way to the top. Similarly, there are a lot of people who supported me during the last six months of my diploma thesis. On this note, I thank Professor Dieter Imboden for supervising my thesis and giving me constructive feedback. I would like to thank my advisor Michael Kost for attending me on my challenging tour and for preventing me from losing my way. I am grateful that the success of my diploma thesis was in his interest as well. Furthermore, my thanks go to Rolf Frischknecht and to Hans-Jörg Althaus of the EMPA in Dübendorf for their helpful additional information concerning the ecoinvent database. Sincere thanks go to the further members of the “Efficiency Office” Ana Sesartic and Matthias Stucki, who were also on the way to the summit during the last six months. I cherished Ana and Matthias as my office and break colleague and enjoyed especially our discussions. Additionally, I would like to thank the Environmental Physics team for their efforts to integrate us diploma students in the working team, for their interest in our diploma studies and for the enjoyable coffee breaks. Last but not least, my sincere thanks go to my family for their support and their patience concerning my changing humours during my ETH studies. A heartfelt gratitude goes to Lydia Ziltener and Patrick Egli for their encouraging company during the last five years.

1 Introduction 1.1 Background At present, the reduction of global greenhouse gas emissions in order to prevent negative impact of climate change is one of the main topics on political agendas all over the world. The publication of the fourth IPCC climate report in spring 2007 has amplified the perception that global climate change is a problem with high political relevance. Among other things, the report indicates a significant increase of the global CO2 emissions over the last decades. The fact that global warming is strongly related to the increasing CO2 emissions is currently accepted in the international research community. Furthermore, the various consequences of global warming are a main topic in the international research community, and they are also discussed in the fourth IPCC climate report. The scientists of the IPCC board consider a global warming of two degrees Celsius as a critical boundary for the regulation abilities of the global ecosystems (IPCC, 2007). The limitation of global warming on a level of two degrees Celsius requires a reduction of global CO 2 emissions by 50 to 80 % until the year 2050 (IPCC, 2007). Such a drastic beneficiation can only be obtained, if the global CO2 emissions decrease as of 2015 (IPCC, 2007). Since a reduction to this extent diminishes the global gross domestic product by only 3 % at the most, it can be realised with marginal economical loss (IPCC, 2007). The discussion about how to achieve the emission target values for CO 2 is strongly connected with the discussion about the essential elements of a sustainable energy system. Since a sustainable energy system can contribute a remarkable part to the reduction of global CO2 emissions, such a system has to be an integral component of a global reduction strategy. The need for a sustainable energy system to reduce CO2 emissions applies especially to industrialised countries, because the main part of their CO2 emissions results from energy supply (Imboden, 2000; Imboden & Jaeger, 1999; Steger et al., 2002). A sustainable energy system is not only characterised by an abdication of non-renewable energy sources. In fact, it has additionally to include a strategy to reduce the total energy consumption (Imboden, 2000; Imboden & Jaeger, 1999; Steger et al., 2002). The “2000 Watt society” is one example for a concept of a sustainable energy system. The “2000 Watt society” is a national strategy to reduce the energy consumption and the associated CO2 emissions. The idea of the “2000 Watt society” was launched by the Board of the Swiss Federal Institutes of Technology in 1998 and serves as a strategic goal for energy and climate policy in Switzerland (CORE, 2004). The basic assumption for the concept of the “2000 Watt society” is that an industrialised country like Switzerland could meet its needs with a primary energy consumption of 2000 Watt per capita instead of the present 6000 W/cap 1 (Imboden & Jaeger, 1999). This drastic reduction of the energy consumption could be achieved without any loss in living standard (Imboden & Jaeger, 1999). The main conclusion of the “2000 Watt society” can be considered as an advice for a respectable potential concerning the augmentation of energy efficiency in Switzerland. Since the operation of buildings (heating, cooling, hot water generation, lightening) consumes about half of the Swiss energy supply (BFS, 2000b), the building sector plays a key role in the context of an increase in energy efficiency. Because the re-investment cycles of 1

This number includes the net import of embodied energy of imported or exported goods; embodied energy is the cumulative energy needed to produce a good.

1 Introduction 1/41

buildings are quite long, it will need decades to make use of this efficiency potential (Steger et al., 2002; Jochem, 2004). The present diploma thesis is restricted to the Swiss residential building sector that accounts for about half of the energy demand of the overall building stock (which represents roughly a quarter of the total Swiss energy demand) (BFS, 2000b). In Switzerland, it is common to conduct major renovations every fifty years. Therefore, the time period of fifty years can be considered as a typical cycle for major renovations (Wüest & Partner, 1994; Christen & Meyer-Meierling, 1999). These major renovations represent an occasion to reduce heat demand by implementing additional energy efficiency measures. High insulating windows, controlled air exchange systems or insulation of the façade are examples for such measures. Additionally, the implementation of special technologies allows to keep the heat demand of new buildings below average. The appliance of energy efficiency measures within the usual renovation cycles can be regarded as a high technical potential for energy saving in the Swiss residential building sector. Siller et al. (2007) conclude that it is possible to reduce the final energy consumption for heating and hot water generation in the Swiss residential building sector to a third and associated CO2 emissions to a fifth by 2050. Furthermore, the potential of increased energy efficiency in the residential building sector of other countries is affirmed by variorious studies. For instance, the results of a Danish study show that heating energy can be reduced economically profitable by 80 % in the Danish building stock (Tommerup & Svendsen, 2006). The argument that the implementation of additional energy efficiency measures within the usual renovation cycles offers an economical profit is more and more accepted. Amstalden et al. (2007) conclude that the degree of this economical benefit depends on various factors. Energy price expectations, policy instruments such as subsidies, a possible carbon tax or the potential future cost degression of energy efficiency measures (which depends itself on the considered operating time of the building) are examples of such decisive factors (Amstalden et al., 2007). Another critical objection, which is expressed very often in the discussion concerning the potential of energy efficiency measures, is the argument that the embodied energy afforded for energy efficiency measures exceeds the reduced heating energy consumption. A considerable embodied energy affordance can result for example from an energy-intensive manufacturing of insulating materials or the essential use of additional building material (Thormark, 2006). Especially in case of buildings with a low heat demand, the relation between embodied energy afforded for energy efficiency measures and heating energy consumption is different from the relation in the event of conventional buildings (Thormark, 2006). Therefore, as the heat demand decreases, the more important it is to pay attention to the embodied energy affordance (Thormark, 2006). Sartori et al. (2007) show that there is a linear relationship between heating and total energy demand. The linear relationship is valid through all the cases despite climate and other contextual differences. Sartori et al. (2007) conclude that buildings with a low heat demand result in being more energyefficient than conventional ones, even though their embodied energy is somewhat higher. The decision for a building with a low heat demand induces both, a net benefit in total life cycle energy demand and an increase in embodied energy affordance (Sartori et al., 2007). Thus, the most urgent measure to reduce the total energy demand of buildings is the reduction of the heating energy consumption.

1 Introduction 2/43

1.2 Embodied energy The appliance of embodied energy as an ecological evaluation parameter in the building sector has been established over the last twenty years. In the eighties, the building material ecology focused its research work on the avoidance of known hazardous substances with negative ecological impact (Kasser & Pöll, 1998). The world climate conventions and the discussion concerning the sustainability pointed out the importance of an integral approach also in the building sector (Kasser & Pöll, 1998). The embodied energy is an evaluation parameter, which allows for such an integral approach, because it takes into account comparatively many environmental impacts (Kasser & Pöll, 1998). The kind and number of environmental impacts, which are taken in consideration, depend on the definition for embodied energy. At the present time, almost every study bases on its own definition, although most of these definitions are very similar to each other. The potential of embodied energy as an evaluation parameter for environmental sustainability of different materials is accepted nowadays (Kasser & Pöll, 1998). The acceptance applies especially to the building sector, where today embodied energy is today an established parameter for the environmental evaluation of building materials (KBOB, 2006). In the present diploma thesis, embodied energy is defined based on a study of Kasser & Pöll (1998) concerning the embodied energy content of building materials. According to this definition, the embodied energy assesses all fuel resources and the primary energy resources (used for example for electricity production), which are available in a limited amount. Thus, the embodied energy of a certain system can be defined as the sum of all kinds of energy, which are only available in a limited amount. In other words, the embodied energy represents a parameter that allows for an ascertainment of the environmental impacts occurring due to greenhouse gases and air pollution in connection with the energy usage. The risks of nuclear power plants and the environmental impacts of the water power usage are assessed in a certain degree as well.

1.3 Questions dealt within the diploma thesis The present diploma intends to answer the following two questions: Does the embodied energy demand afforded for energy efficiency measures overcompensate the achieved reduction in heating energy consumption? Are there considerable differences between the embodied energy content of different renoavation materials and wall construction options for new buildings? The diploma thesis considers the situation of the Swiss residential building sector, which implies that the embodied energy data, the data for model buildings and renovation measures as well as the model used for the simulation procedure are restricted to Swiss conditions. The main question of the present diploma thesis is discussed on two levels for the time period 2000 to 2050: Firstly, embodied energy data are calculated for described model buildings as well as the corresponding renovation packages and construction alternatives. Secondly, the embodied energy data calculated on the model building level are integrated in the model of the Swiss residential building sector. The embodied energy calculation on the model building level allows to assess the relation between embodied energy affordance and heating energy reduction for model buildings of different construction periods. Secondly, the calculated embodied energy data can be integrated in the model of the Swiss residential building sector. Concrete calculations are made for the comparison between alternative renovation material compositions to implement renovation packages using the 1 Introduction 3/43

same data for model buildings and renovation packages. The recommendations for wall construction options for new buildings are given on the basis a literature study. To consider the relation between embodied energy affordance and heating energy reduction on a country level, simulations are performed using the model of the Swiss residential building stock of Kost (2006) and Siller et al. (2007). The model allows to simulate the future development of energetic meaningful characteristics of the Swiss residential building sector for the time period 2000 to 2050. Examples for such characteristics that are of high interest for the present diploma thesis are the renovated and newly constructed energy reference area (ERA), the primary energy consumption for heating or the embodied energy affordance for energy efficiency measures.

1 Introduction 4/43

2 Methods and data To evaluate the relevance of embodied energy affordance for energy-efficient renovation measures and energy-efficient construction alternatives for new buildings, embodied energy calculations are made on two levels: Firstly on a model building level and secondly on a country level for the Swiss residential building sector considering the time period 2000 to 2050. In addition, a comparison of different renovation material compositions and of various wall construction options for new buildings with a low heat demand concerning their embodied content is made. To assess the relevance of embodied energy on the model building level, embodied energy calculations for eight model buildings are conducted. These calculated embodied energy values can additionally be used as input data for the Swiss residential building stock model to evaluate the relevance of embodied energy on a country level for the time period 2000 to 2050. The model buildings are differentiated according to their building type (single- or multi-family house) and their construction period (up to 1947, from 1947 to 1975, from 1976 to 2000 and as of 2000, i. e. newly constructed buildings). The model building definitions are adopted from Kost (2006). They include information on the building components area, the energy reference area (ERA) and energy relevant properties of the construction materials such as heat transfer coefficients. Additionally, Kost (2006) defined several renovation packages and construction alternatives for the eight model buildings including the calculation of the required heat demand and the additional costs caused by investments in energy efficiency measures. Within this diploma thesis, the embodied energy demand for all the renovation packages and construction alternatives is calculated. To assign embodied energy values to each implemented construction material, four databases are used as data source, where the widely-used ecoinvent database contributes the most. To assess the bandwith of the embodied energy content of the different renovation packages, alternative construction material compositions are considered for one specific model building (single-family house of the construction period from 1947 to 1975). To compare the embodied energy content of wall constructions for new buildings with a low heat demand, alternative wall construction options are compared based on a literature study. The embodied energy demand for energy-efficient renovation measures and energy-efficient construction alternatives for new buildings on the level of the Swiss residential building sector is calculated using the building stock model described by Kost (2006) and Siller et al. (2007). Simulations are performed for a reference and four reduction scenarios considering the time period 2000 to 2050 and starting the measures of the reduction scenarios in 2007. The model simulates the development of the building stock including renovation, demolition and construction. Energy relevant building parameters are represented, allowing energy consumption for space heating and associated CO2 emissions to be quantified. Additionally, costs for energy and investments can be calculated. To be used in the present diploma thesis, this model is extended to account also for the embodied energy that is afforded for the energy efficiency measures of the reduction scenarios. For the integration of basic embodied energy values, the embodied energy data calculated for the eight model buildings are applied. In the following Section, the definitions of the eight model buildings are presented including the assumption on the construction material compositions. Section 2.2 deals with the applied concept of embodied energy, the used databases and the derived embodied energy values for the 2 Methods and data 5/43

construction materials that are used to implement the renovation packages and construction alternatives. In Section 2.3 the building stock model and the examined scenarios are described including the scenario assumptions concerning embodied energy.

2.1 Embodied energy calculation methodology for model buildings 2.1.1 The model buildings To allow for a representative acquisition of the Swiss residential building stock, eight model buildings are defined; four for the building type single-family house (SFH) and four for the building type multi-family house (MFH). The four model buildings, which represent the two building types (SFH or MFH), differ concerning their construction period (up to 1947, from 1947 to 1975, from 1976 to 2000 and as of 2000, i. e. newly constructed buildings). Key figures of the eight model buildings are summarized in Table 1 and more detailed information can be found in Annex I. The detailed definitions of the eight model buildings including energy relevant characteristics have been adopted from Kost (2006). The classification of the model buildings is based on Wüest & Partner (2004), where information on typical areas of building components (energy reference area, floor, ceiling, roof, façade, window) are given. Furthermore, the energy relevant properties are assigned to the building components according to evaluations of Jakob et al. (2002). The physical building stock model provided by the Swiss Society of Engineers and Architects (SIA, 2001) is used to calculate the specific heat demand of the model buildings. To allow for a comparison between the specific heat demand and the embodied energy afforded for the energy efficiency measures, the primary heating energy consumption to meet the specific heat demand is calculated. This calculation is performed assuming an oil heating system, because oil heating systems are still widespread in the Swiss residential building sector. Information on the calculation procedure and the efficiency factors of different heating systems can be found in Annex VII. 2.1.1.1 Reference renovation and reference construction alternative As a reference, against which the alternative renovation packages are compared, a “reference renovation” for each of the six existing model buildings is defined. The “reference renovation” includes the reparation of the roof, a visual renovation of the façade and the replacement of old windows. The new windows cause a reduction of the heat demand compared to the initial, prerenovated state. (Kost, 2006) In the case of the two categories for newly constructed model buildings (construction period as of 2000), a reference construction alternative is defined, against which the defined construction alternatives can be compared. The reference construction alternative is characterised by a certain insulating degree of the different building components areas and by the use of a certain window system. (Kost, 2006)

2 Methods and data 6/43

2.1.1.2 Renovation packages and construction alternatives For each of the existing model buildings, up to nine alternative renovation packages are described in Kost (2006). Each renovation package includes several renovation measures and results in a decrease of heat demand. The spectrum of the renovation measures ranges from thin insulation of certain components to extensive insulation of the entire building envelope or the appliance of high insulating windows. The detailed description of the renovation packages including the implemented renovation materials and the essential material input is adopted from Kost (2006). For the newly constructed model buildings, up to nine construction alternatives are described analogous to the renovation packages. These construction alternatives include similar energy relevant measures as the renovation packages do and differ in the assigned heat demand. In addition to the renovation measures that are defined for the renovation packages, one construction alternative of the two new model buildings includes the installation of a controlled air exchange system.


Table 1: Energy reference areas (ERA), heat demand values, values for the reduced heat demand and values for the reduced primary heating energy consumption of the model buildings of the Swiss residential building stock 2000. Abbreviations: SFH: single-family house; MFH: multi-family houses; CP 1: construction period < 1947; CP 2: construction period 1947 - 1975; CP 3: construction period 1976 - 2000; new: construction period > 2000. (Kost & Imboden, 2007; own calculations, 2007) Initial state before renovation or reference construction alternative Energy reference area ERA [m

2 ERA

]

SFH CP 1

MFH CP 2

CP 3

new

CP 1

CP 2

CP 3

new

180

184

190

195

357

669

896

805

Floor

area [m2]

72

112

89

82

135

167

221

271

Façade

area [m2]

195

131

136

208

336

482

631

437

Roof

area [m2]

72

114

120

113

165

167

313

317

Windows

area [m2]

34

47

55

53

65

162

233

236

Specific heat demand [MJ m-2ERA yr-1]

509

580

338

242

494

430

330

209

Ratio of building shell area to ERA [-]

1.95

2.18

2.01

1.95

1.86

1.39

1.51

1.50

459

523

301

457

387

292

Reference renovation Specific heat demand [MJ m-2ERAyr-1]

Renovation packages resp. construction alternatives: heat demand reduction compared to the initial state resp. compared to the reference construction alternative Reference renovation: heat demand reduction [MJ m-2ERAyr-1]

50

57

37

-1

37

43

38

90

127

56

-1

21

64

76

57

19

yr ]

127

144

3 heat demand reduction [MJ m-2ERAyr-1]

134

260

61

39

202

103

84

30

108

55

232

130

119

-1

52

255

333

-1

128

74

240

199

129

56

yr ]

266


277

336

170

85

259

216

154

64

352

179

91

269

217

164

-1

68

-1

278

362

189

100

270

227

168

74

yr ]

296

370

195

112

285

230

116


306

375

146

288

233

121

-2 ERA

1 heat demand reduction [MJ m

-2 ERA


-2 ERA


-2 ERA


-2 ERA


-2 ERA



-2

yr ]

yr ]

yr ]

ERA

-1

yr ]

156

123

Renovation packages resp. construction alternatives: reduced heating energy consumption, expressed in primary energy units assuming an oil heating system, compared to the initial state resp. compared to the reference construction alternative Reference renovation: reduced heating energy consumption [MJ m-2ERAyr-1]

142

162

105

105

122

108

1 reduced heating energy consumption [MJ m-2ERAyr-1]

256

361

159


361

409

173

60

182

216

162

541

111

574

293

239

-1

852

381

738

307

-1

156

659

369

338

148

yr ]

724

946


755

954

364

210

682

565

366

159

483

241

736

613

437

-1

182

787

-1

1000

508

258

764

616

466

193

-1

190

1028

537

284

767

645

477

210

yr ]

841

1051

554

318

809

653

329


869

1065

415

818

662

344

-2 ERA

3 reduced heating energy consumption [MJ m

-2 ERA


-2 ERA


-2 ERA


-2 ERA



-2

yr ]

yr ] yr ]

ERA

-1

yr ]

443

349


2.1.2 Definition of the reference material composition To calculate the embodied energy afforded for the renovation packages and construction alternatives, a reference material composition is defined. The reference material composition should consist of materials, which are commonly used to renovate buildings at the present time. Thus, the reference material composition should not be composed of superannuated or extremly innovative and rarely used renovation materials. Kost (2006) suggests a certain material composition in connection with the definition of the renovation packages and the construction alternatives. The suggested composition consists of polystyrene (EPS) for the insulation of the façade and the embrasures, the interior walls, ceilings and floors and of glass wool mats for the insulation of the steep roof. The study of literature and the consultation of the product segment of different insulating material producers show that this suggested material composition is often implemented at the present time and can be therefore used as reference material composition (Sto, 2006; Sager, 2007).

2.1.3 Embodied energy calculation for the model buildings The embodied energy that has to be afforded for the renovation packages and for the construction alternatives is calculated for each model building. The descriptions of Kost (2006) concerning the different renovation packages and the different construction alternatives for new buildings include information on the renovated and newly constructed building areas, on the used renovation materials and on the implemented material mass. Based on this information, the essential renovation material mass used to implement one certain renovation package or one certain construction alternative can be calculated. The specific embodied energy values for the different construction materials are offered by the considered databases. Thus, the embodied energy demand for the implementation of one certain renovation package or one certain construction alternative for a new building can be calculated. To allow for a direct comparison of the embodied energy demand to the annual primary heating energy consumption, the embodied energy afforded for a renovation package or for a construction alternative is calculated per year using the time period of 50 years as a divisor. The time period of 50 years does not comply with the durability of all considered materials, but it is identical with the assumed renovation frequency in the building stock model. In addition, the calculation per year allocates the embodied energy afforded for energy efficiency measures to the time period between two renovations or between a new construction and a renovation. A complete compilation of the calculated embodied energy values for the different renovation packages and construction alternatives can be found in Annex I.

2.1.4 Comparison of alternative renovation material compositions and wall construction options for new buildings 2.1.4.1 Alternative renovation material compositions The calculation of the embodied energy content of different renovation material compositions allows to assess the bandwidth of the embodied demand for the renovation packages and construction alternatives. Furthermore, it can be reassessed that the reference material composition does not feature a very high or a very low embodied energy content. The comparison of different material compositions is only performed for the renovation package number nine of the single-family house, construction period from 1947 to 1975. 2 Methods and data 9/43

In addition to the reference material composition, 15 alternative material compositions are compiled based on a study of the product segments and the product recommendations of different production companies (Sager, 2007; Sto, 2006). It is evident that the considered 16 material compositions do not represent a complete collection of all possible renovation material compositions that are commonly implemented nowadays. Furthermore, the production companies point out in their product recommendations that not every insulating material can be used to insulate every building component. In fact, certain insulating materials have typical physical and chemical characteristics and are therefore adequate for the insulation of certain building components. The application areas of the considered renovation materials are indicated in Table 2. Table 2: Application area of the different renovation materials, which are considered for the comparison between different renovation material compositions. The application area of a certain insulating material is marked grey in the corresponding column. The insulating material combination EPS/ XPS is used for the insulation of the façade, whereas XPS is used for the insulation of the basical parts of the façade, which contact the ground (Sto, 2006). Insulating material

Interior insulation of the cellar ceiling

Interior insulation of the garage wall

Insulation of the façade

Insulation of the embrasures

Insulation of the steep roof

Polystyrene (EPS) Glass wool mat Glass wool slab Extruded polystyrene solid foam, foamed with CO2 (XPS) Foam glass Cork slab Isofloc Combination EPS/ XPS

The embodied energy content of the alternative renovation material compositions is not calculated for a certain insulating material thickness, but for a reference insulating capacity that is obtained by the reference material composition. The essential insulating material input to obtain the reference insulating capacity can be calculated for each of the considered material compositions. Based on the data for the material input and on the embodied energy values of the corresponding insulating materials, the embodied energy content of the alternative material compositions can be calculated. The embodied energy data that are used for the calculation can be found in Table 3 of Section 2.2.2.


2.1.4.2 Wall construction options for new buildings In addition to the comparison between the embodied energy content of different renovation material compositions, the embodied energy content of wall construction options for new buildings with a low heat demand is compared. Two reference wall construction options and six further construction alternatives are chosen for the comparison, whereas certain options are available in two different versions. The comparison is made independent of the model buildings on the basis of a literature study. Unlike the comparison of different renovation materials, complete wall construction alternatives are compared in case of new buildings. The comparison between complete wall construction options can be explained by the fact that at the present time, complete wall systems and not single renovation materials are implemented to obtain a certain insulation capacity for new buildings (Enz & Hastings, 2006). This is true especially in case of buildings with a low heat demand (Enz & Hastings, 2006). Furthermore, a few of the innovative insulating materials that are used for the insulation of buildings with a low heat demand can only be implemented in the form of complete wall constructions and not in the combination with any common wall construction anymore.

2.2 Data for embodied energy analysis 2.2.1 The concept for embodied energy used in the diploma thesis The ecoinvent database2 is used as a main database to provide embodied energy data for the different construction materials. This can be explained by the fact that this database is broadly accepted and implemented for life cycle assessment in Switzerland. Particularly in the Swiss building sector, the ecoinvent database is commonly used as a data source for life cycle data. To complete the embodied energy data offered by the ecoinvent datbase, the KBOB database 3, the IBO database4 and the BauBioDataBank5 are chosen as additional data sources. The ecoinvent, IBO and KBOB database base on the same concept for embodied energy. Therefore, the life cycle data offered by these three databases can be used to perform one certain calculation. The concept determines that the embodied energy demand of a certain system consists of the non-renewable primary energy resources, the energetic usable fossil raw materials and the hydropower used in this system (ecoinvent, 2006). Thus, the criteria to decide, whether a form of energy contributes to the embodied energy demand or not, are regenerability, availability and environmental impacts due to the gain of raw materials and due to the energetic use (ecoinvent, 2006). The embodied energy concept of the BauBioDataBank is identical with the concept of the other three databases, but does not include the hydropower (gibbeco, 2006). The BauBioDataBank is used as a data source for embodied energy data of wall construction options for new buildings. Concerning spatial boundaries, the data of the four used databases are mainly investigated for Swiss and European conditions (ecoinvent, 2006). In the Tables 3 to 5 that include the embodied energy values, it is indicated, whether the embodied energy data are calculated for Swiss or for European production conditions. 2 3 4 5

More information on the ecoinvent database: www.ecoinvent.ch More information on the KBOB database: www.kbob.ch More information on the IBO database: IBO – Österreichisches Institut für Baubiologie und -ökologie, DonauUniversität Krems, Zentrum für Bauen und Umwelt More information on the BauBioDataBank: www.gibbeco.org


In conjunction with life cycle assessment, the functional boundaries have to be taken in consideration, because different functional boundaries result in different life cycle data. Functional boundaries define the processes, which are included to calculate life cycle results for certain products and services (Kasser & Pöll, 1998). In case of the four databases that are used in the present diploma thesis, the embodied energy values are calculated for the production “at plant” (ecoinvent, 2006). The calculation method for the production “at plant” includes all processes that are necessary to produce a certain good, but not the transport (for example to the building site in case of building materials), the implementation and the disposal of the products or the infrastructure (ecoinvent, 2006). Construction and operating of the plant in case of the production of building materials and construction of streets, tunnels, bridges and fabrication of cars in the event of transport services are examples for processes that belong to the infrastructure.

2.2.2 Embodied energy data for construction materials The Tables 3 to 5 include embodied energy data for the construction materials, which are applied for the renovation packages and the construction alternatives and for the insulating materials that are used for the renovation material comparison. In addition, explications concerning the different embodied energy contents of the insulating materials are given.


Table 3: Compilation of the insulating materials that are considered in the context of the renovation material comparison. Application area, heat conductivity, density, regional validity of the embodied energy values, functional unit, embodied energy content per kilogramme, embodied energy content per functional unit and data source for the embodied energy values are indicated. The embodied energy content per functional unit allows for a comparison of different insulating materials on the base of the same insulating capacity. The code for the regional validity indicates the geographical validity of the embodied energy data. Abbreviations: CH: embodied energy values are valid under Swiss production conditions (ecoinvent, 2006); RER: embodied energy values are valid under European production conditions (ecoinvent, 2006). The abbreviation RER refers to all European countries and not only to the countries of the European Community (ecoinvent, 2006). Insulating material

Application area

Heat Density conductivity λ ρ [W m-1 K-1] [kg m-3]

Regional validity

Functional Embodied unit (FU) energy content [MJ kg-1]

Embodied energy content [MJ FU-1]

Data source

Polystyrene (EPS)

Interior insulation of floors, ceilings and walls, insulation of the embrasures, exterior insulation of the façacde, insulation of the steep roof

0.035

30

RER

1.05

100.2

105.2 ecoinvent (2006)

Glass wool mat


0.032

40

CH

1.28

48.1

61.6 ecoinvent (2006), Sager (2007)

Glass wool slab

Interior insulation of ceilings, floors and walls, insulation of the embrasures, exterior insulation of the façacde

0.036

70

RER

2.52

39.4

99.3 IBO (2000), Sager (2007)

Extruded polystyrene solid foam, foamed with CO2 (XPS)

Interior insulation of ceilings, floors and walls, exterior insulation of the façacde (in the base region of the façade)

0.035

30

CH

1.05

67.2

70.6 ecoinvent (2006), Sto (2007)

Cork slab

Interior insulation of ceilings, floors and walls

0.045

120

RER

5.40

26.3

142.0 ecoinvent (2006), KBOB (2006), IBO (2000)

Foam glass


0.045

110

CH

4.95

27.1

134.1 IBO (2000), KBOB (2006)

Isofloc


0.039

60

CH

2.34

7.8

18.3 ecoinvent (2006), KBOB (2006)


The insulating material cork slab is characterised by a low embodied energy content per kilogramme, but a high embodied energy content per insulating capacity. The high density and the high heat conductivity of cork result in a huge mass demand to obtain a certain insulating capacity and thus in the considerable embodied energy content per insulating capacity. The low embodied energy content per kilogramme can be explained by the fact that fossil fuels account for a very small share of the energy needed for the cork production. The consideration of the substantial lorry transport distances necessary for the transport of the cork from southern European countries would enhance the low embodied energy content per kilogramme. The embodied energy values offered by the used databases include the transport distances only in the form of rail transports, which is not very realistic. Furthermore, the low embodied energy content per kilogramme belies the non-sustainable exploitation of the cork woods. It can be concluded that the low embodied energy content per kilogramme of the cork slab has to be interpreted carefully. (ecoinvent, 2006; IBO, 2000; KBOB, 2006) The abbreviation isofloc refers to an insulating material, which is made of pressed cellulose fibres. Isofloc features a low embodied energy content per kilogramme and per insulating capacity. The low embodied energy content per kilogramme can be attributed to the low energy demand for transport and production: The cellulose fibres are gained from local recovered paper, which results in short transport distances. The production process is characterised by a low energy demand, because the compression of cellulose fibres gained from recovered paper does not consume huge amounts of energy. Therefore, isofloc can be recommended as an insulating material with a low embodied energy demand. (IBO, 2000) The synthetic insulating materials polystyrene (EPS) and XPS (extruded polystyrene solid foam) can be arranged in the middle range concerning their embodied energy content. In addition, the embodied energy content of these insulating materials depends on the density and the heat conductivity. Synthetic insulating materials possess an “unrenewable feedstock” that results in a considerable embodied energy content. This “unrenewable feedstock” occurs due to the extraction of crude oil and the following production processes, which consume remarkable amounts of energy. The differences in embodied energy content between XPS and EPS can be explained by the discriminative production processes as from the production of styrol. Recapitulatory, EPS and XPS can be characterised as common and frequently implemented insulating materials with a medium embodied energy content per insulating capacity. (IBO, 2000; Sto, 2006) Foam glass is characterised by a relatively low embodied energy content per kilogramme, but by a quite high embodied energy content per insulating capacity due to a high density and a considerable heat conductivity. The embodied energy demand affordance has been diminished drastically during the last ten years because of new production methods, the increasing use of recovered glass and because of the consumption of electricity derived from renewable energy sources. The decreased production energy, which results in a better ecological reputation and in lower prices contributes to an increasing popularity of foam glass. Additionally, foam glass offers various advantageous characteristics compared to other insulating materials: It is water-, fire- and dampproof, resistant against humidity, acidity and vermins. Additionally, foam glass is characterised by longevity and compression strength (IBO, 2000; Pittsburgh, 2007).


The mineral insulating materials glass wool mat and glass wool slab are characterised by a medium embodied energy content depending on their density and their heat conductivity. The larger embodied energy content of the glass wool slab can be explained by the higher density and heat conductivity compared to the density and to the heat conductivity of the glass wool mat. The embodied energy content of mineral insulating materials can also be reduced by increasing the recovered glass' share in the basic material. (IBO, 2000)

Table 4: Description of the window components, which are used for the embodied energy calculation on the model building level. The heat transition coefficient (U-value), the embodied energy content per square metre and the data source are indicated. Embodied energy data in case of sheet glasses and window frames are commonly indicated per square metre. The embodied energy data are valid under Swiss production conditions. Description of the window component

Heat transition coefficient, U-value

Embodied energy content

[W m-2 K-1]

[GJ m-2]

Regional validity

Data source

Wooden window frame

1.5

2.67

CH KBOB (2006)

Sheet glass, dual vitrification

1.1

0.65

CH KBOB (2006)

Sheet glass, triple vitrification

0.7

1.00

CH KBOB (2006)


0.5

1.12

CH KBOB (2006)

Table 5: Embodied energy content of the controlled air exchange system that is implemented in the context of one construction alternative for the two new model buildings. A short description of the system, the data source and the regional and the plane validity for the embodied energy values are indicated. The data offered from a study of Hässig & Primas (2007) refer to a controlled single room air exchange system for a multi-family house with an energy reference area (ERA) of 780 m2. Furthermore, the embodied energy content for the same air exchange system is given per square metre. The extrapolation from the embodied energy content per square metre to the content valid for the air exchange system of the multi-family house with ERA 780 m2 results in an identical value. Therefore, the embodied energy content per square metre is extrapolated to the two new model buildings with an ERA of 195 m 2 for the single-family house and 805 m2 for the multi-family house. Description of the controlled single room air exchange system

ERA

Embodied Regional energy demand validity

[m2]

Data source

[GJ]

Controlled single room air exchange system, peripheral 6 x 120 m3 h-1, steel tubes, with earth register

780

146.3

CH Hässig & Primas (2007)


805

151.9



195

36.6



2.3 Embodied energy calculation for the Swiss residential building sector for the time period 2000 to 2050 2.3.1 The Swiss residential building stock model The embodied energy affordance for energy efficiency measures in the Swiss residential building sector is calculated based on a model that has been described by Kost (2006) and Siller et al. (2007). This model allows for the simulation of the chronological development of the residential building stock in Switzerland by accounting for renovation, demolition and construction. As an example, the model releases annual values for the total heating energy consumption for the renovated and newly constructed ERA (energy reference area). For the present diploma thesis, the dynamics of the energy relevant properties of the Swiss residential building stock (for example the total heating energy consumption) are of high interest. To assess the future development of the embodied energy affordance and the total heating energy consumption, simulations can be conducted for one reference scenario and four alternative reduction scenarios. The alternative reduction scenarios differ in the defined boundary values for the heat demand of renovated and newly constructed buildings. The defined heat demand boundary values determine the renovation package or the construction alternative that is implemented for a certain model building to achieve the defined boundary value. The reference scenario that has been simulated by Kost (2006) and continues today's trends for the development of the model parameters to the future. Thus, the reference scenario “BAU” can be labelled as “business-as-usual-scenario”. The four alternative reduction scenarios S1 to S4 are characterised by lower boundary values for the heat demand than the reference scenario is. The development of the heat demand boundary values is affected by various parameters as for example energy price expectations or policy instruments as subsidies, income tax deductions or a future carbon tax (Amstalden et al., 2007). Thus, these boundary values are not randomly determined parameters, but depend on various influencing factors. Table 6: Definition and labelling of the four alternative reduction scenarios S1 to S4. Scenario labelling

Required specific heat demand (MJ m-2ERAyr-1) new building

renovation

S1

200

300

S2

150

250

S3

100

200

S4

50

150


To obtain a starting position for the simulations, the building stock of the year 2000 had to be acquired. For these purposes, the data of the Swiss census 2000 were analysed (BFS, 2000a). Based on the census data, the existing residential buildings were organised into the three categories depending on their construction period (up to 1947, from 1947 to 1975, from 1976 to 2000). The residential buildings that have been constructed after 2000 belong to the two model building categories of the construction period as of 2000. For the present diploma thesis, the simulations start in 2000, beginning with the energy efficiency measures determined by the scenarios in the year 2007. Further information about the modelling procedure, the initial building stock and the selected model parameters for the simulation period 2000 to 2050 can be found in Kost (2006) and Siller et al. (2007).

2.3.2 Integration of embodied energy in the building stock model The embodied energy demand for renovation and new construction is calculated as a product of the change in energy reference area (ERA) and of the specific embodied energy demand EmbE. The EmbE describes the embodied energy demand per new constructed or per renovated area differentiated according to the model building. Furthermore, for one certain model building several EmbE values can be assigned to corresponding heat demand values. Thus, the reduction scenarios that differ in the heat demand boundary values define the renovation packages and construction alternatives and the corresponding EmbE values that are implemented for one model building. The EmbE values, which are calculated in the first part of the diploma thesis to assess the relevance of the embodied energy on the model building level, are used as input data for the building stock model. As mentioned in Section 2.3.1, the changes in energy reference area (ERA) due to renovation, demolition and construction of new buildings are delivered from the building stock model for every year and for each of the eight model buildings. The model calculates annual values for the total heating energy consumption of the Swiss residential building sector in final energy units. Thus, these values have to be converted from final energy units into primary energy units to allow for a comparison between embodied energy demand and heating energy consumption. On the country level, this conversion is performed for the heating system distribution as it is assumed in the model (the development of the heating system distribution can be seen in figure 4c of Section 3.2.1). For the graphical representations generated by the model on the model building level, the heat demand values offered by Kost's model building descriptions are converted into primary energy units assuming an oil heating system. The oil heating system has been selected, because it is still widespread in the Swiss building sector. Additional information on the conversion factors of different heating systems can be found in Annex VII. The embodied energy afforded for renovation or new construction accumulates completely in the year of renovation or construction, respectively. The savings in heating energy consumption caused by renovation or by new construction are achieved during the years after renovation and construction until the next renovation will be implemented. Thus, the embodied energy that accumulates during one certain year can not be directly compared with the reduction in heating energy consumption that is achieved during the same year. On one hand, a considerable part of the reduced heating energy consumption is obtained by an embodied energy amount that has been invested before the considered year. On the other hand, the afforded embodied energy results in a reduction in heating energy over the next fifty years and not only in a reduction during 2 Methods and data 17/43

the considered year. Therefore, cumulative values of the reduced heating energy and the embodied energy demand for a certain time period will be compared in the present diploma thesis. If conclusions are made on the base of such comparisons, one has to keep in mind that the heating energy consumption reduced during a certain time period can not be attributed directly to the embodied energy afforded during the same time period. Nevertheless, the comparison of cumulative values allows for a general assessment of the relation between reduced heating energy consumption and embodied energy affordance for energy efficiency measures.


3 Results and Discussion 3.1 The relevance of embodied energy for the model buildings 3.1.1 The relation between embodied energy demand and reduced heating energy consumption Figure 1 allows for a first impression of the relation between the embodied energy affordance for energy efficiency measures and the achieved reduced primary heating energy consumption for the eight model buildings. The values for the embodied energy affordance are calculated and represented in megajoule per square metre and per year. As mentioned in Section 2.1.3, the embodied energy affordance for one certain energy efficiency measure is allocated to an assumed operating time of 50 year. The time period of 50 years does not comply with the durability of all considered materials, but it is identical with the assumed renovation frequency in the building stock model. More detailed and model building specific data concerning the relation between the embodied energy affordance and the reduced heating energy consumption can be found in Annex I. Figure 1 illustrates that in case of every renovation package or construction alternative a certain amount of heating energy consumption can be reduced by investing a lower amount of embodied energy. Apparently, the embodied energy afforded for the renovation packages or the construction alternatives seems not to overcompensate the reduced heating energy consumption. Furthermore, Figure 1 illustrates that the curves for the four model buildings of the construction periods up to 1947 and from 1947 to 1975 run flater than the curves for the four newer model buildings of the construction periods from 1976 to 2000 and as of 2000. Thus, the heating energy consumption can be reduced more drastically by investing a lower amount of embodied energy in case of buildings that have been constructed before 1975. This finding can be explained by the higher specific heat demand and the associated higher heating energy consumption of the four older model buildings, which is a typical characteristic of buildings that have been constructed during the construction period up to 1975. The considerable heating energy consumption of these older buildings can be reduced drastically by investing a low embodied energy affordance for energy-efficient renovation measures. The differences between model buildings of different construction periods are explained more detailed in Section 3.1.2.

3 Results and Discussion 19/43

Figure 1: The relation between the embodied energy affordance for energy-efficient renovation measures or for energy-efficient construction alternatives for new buildings and the reduced heating energy consumption. The embodied energy affordance and the reduced heating energy consumption are compared to the reference renovation or to the reference construction alternative, respectively (the reference renovation and the reference construction alternative are represented by the point 0/0). Each curve shows the situation for one model building, whereas the data points on the curves represent the different renovation packages or the construction alternatives. Abbreviations: SFH: single-family house; MFH: multi-family house; CP < 1947: construction period up to 1947; CP 1947 – 1975: construction period from 1947 to 1975; CP 1976 – 2000: construction period from 1976 to 2000; CP > 2000: construction period as of 2000.

The values, which represent the embodied energy demand's percental share of the reduced primary heating energy consumption, in Table 7 confirm the conclusions that have been made considering the curves in Figure 1: The embodied energy affordance for renovation packages or construction alternatives does not overcompensate the reduced heating energy consumption. The values for the embodied energy demand and the reduced heating energy consumption are calculated per year for an assumed operating time of 50 years. The embodied energy affordance accounts for at most 10 % of the reduced heating energy consumption, if a model building of the two construction periods from 1976 to 2000 and as of 2000 is considered. In the case of the model buildings of the construction periods up to 1947 and from 1947 to 1975, the embodied energy demand accounts for at most 5 % of the reduced heating energy consumption.


Table 7: Maximum, minimum and mean values for the embodied energy demand's percental share of the reduced primary heating energy consumption. To calculate the mean values and to determine the minimum and maximum values, the values of all renovation packages or construction alternatives, respectively, have been considered as the basic set. For each model building, two values are indicated; the first one valid for an oil heating system, the second one valid for a wood heating system. Abbreviations: SFH: single-family house; MFH: multi-family house; CP 1: construction period up to 1947; CP 2: construction period from 1947 to 1975; CP 3: construction period from 1976 to 2000; CP 4: construction period as of 2000. Building type

SFH, CP 1

SFH, CP 2

SFH, CP 3

SFH, CP 4

MFH, CP 1

MFH, CP 2

MFH, CP 3

MFH, CP 4

Minimum value oil heating [%]

2.8

2.2

5.6

3.4

2.4

2.8

4.6

6.3

Minimum value wood heating [%]

3.1

2.5

6.3

3.8

2.7

3.1

5.2

7.1

Mean value oil heating [%]

3.9

2.9

6.1

8.5

3.0

3.4

5.3

7.8

Mean value wood heating [%]

3.9

3.2

6.8

9.6

3.4

3.9

6.0

8.8

Maximum value oil heating [%]

4.9

5.6

7.6

11.5

4.8

5.7

6.5

9.4

Maximum value wood heating [%]

5.5

6.3

8.6

13.0

5.4

6.4

7.3

10.6

In addition, Table 7 shows that the percental values calculated assuming a wood heating system are continuously higher than the percental values that are valid for an oil heating system. This is because the total primary energy demand (which is the sum of the embodied energy demand and the primary energy demand to produce 1 MJ useful heat) afforded to produce 1 MJ useful heat is higher in case of the oil heating system than in case of the wood heating system. The higher total primary energy demand of useful heat produced by an oil system can be attributed to the higher embodied energy content of the useful heat that is produced by an oil heating system. Unlike the embodied energy demand, the primary energy demand per 1 MJ useful heat is lower in case of the oil heating system than in case of the wood heating system because of the high efficiency factor that characterises the oil heating system. Detailed information about the total primary energy calculation for different heating systems can be found in Annex VII.


Table 8: Compilation of the embodied energy content per heat demand and per final energy demand for the heating systems that are taken in consideration in the model. In addition, the efficiency factors are indicated. Finally, the primary energy demand values per final energy demand and per heat demand are indicated. The data are restricted to Swiss conditions. Heating system

Embodied energy demand per heat demand [MJ/MJ]

Embodied Efficiency Primary energy factor energy demand per demand per final energy final energy demand demand [MJ/MJ] [MJ/MJ]

Primary energy demand per heat demand

Data source

[MJ/MJ]

Oil heating, oil superlight, 10 kW

1.420

1.29

0.91

1.29

1.42 KBOB (2007), Koschenz & Pfeiffer (2005), Kost (2006)

Gas heating, condensend, < 100 kW

1.280

1.25

0.98

1.24


Electric heating, Swiss strom mix

3.041

2.89

0.95

2.91


Wood heating, pellets, 50 kW

0.357

0.21

0.58

1.26


District heating

0.582

0.45

0.77

1.52

1.97 Frischknecht (2007), Koschenz & Pfeiffer (2005)

Solar heating

0.061

0.06

1.0

6.69


The considerable bandwith between the minimum and the maximum values is an indication of differences between the renovation packages and construction alternatives concerning their efficiency. Firstly, the relation between embodied energy demand and reduced heating energy consumption depends on the implemented renovation package or the implemented construction alternative. Secondly, the relation depends also on the considered model building with its characteristic building components areas. As an example, a considerable embodied energy amount has to be afforded for the replacement of old windows by windows with a higher insulating capacity because of the embodied energy-intensive fabrication of high-insulating window glass. For the improved insulation of the façade the same embodied energy amount has to be afforded as for the replacement of old windows. But the improved insulation of the façade reduces the heating energy consumption more drastically (in case of some model buildings twice this amount that the replacement of the windows does). Table 9 gives a survey of the relation between embodied energy demand and total primary energy consumption. The total primary energy consumption for one renovation package or construction alternative, respectively, is the sum of the embodied energy affordance for the considered renovation package or construction alternative, respectively, and of the primary energy demand for heating. The values for the embodied energy demand and the total primary energy consumption are also calculated per year assuming an operating time of 50 years. 3 Results and Discussion 22/43

The maximum values show that the embodied energy demand accounts for 10 to 15 % at most of the total primary energy consumption in case of the model buildings of the construction periods from 1976 to 2000 and as of 2000. The observable model building specific differences comply with the conclusions made considering Figure 1 and Table 8. In case of some model buildings (as for example in the event of the SFH of the construction period as of 2000) the maximum values for the embodied energy demand's percental share of the total energy consumption are higher than the maximum values concerning the embodied energy demand's percental share of the reduced heating energy consumption. At first glance, this finding may be confusing. It can be explained by the fact that in case of these model buildings, the reduced heating energy consumption is higher than the total primary energy demand that is assigned to the concerning renovation package or construction alternative. This applies especially to renovation packages, which include renovation measures that reduce the heating energy consumption drastically. Table 9: Maximum, minimum and mean values of the embodied energy demand's percental share of the total primary energy consumption (sum of embodied energy demand and primary heating energy consumption for one certain renovation package or construction alternative, respectively). To calculate the mean values and to determine the minimum and maximum values, the values of all renovation packages or construction alternatives, respectively, have been considered as the basic set. For each model building, two values are indicated; the first one valid for an oil heating system, the second one valid for a wood heating system. The minimum values are valid for the first renovation package or construction alternative (which includes only one renovation measure). The maximum values are valid for the last renovation package or construction alternative (which includes all renovation measures that are defined for one model building). Abbreviations: SFH: single-family house; MFH: multi-family house; CP 1: construction period up to 1947; CP 2: construction period from 1947 to 1975; CP 3: construction period from 1976 to 2000; CP 4: construction period as of 2000. Building type

SFH, CP 1

SFH, CP 2

SFH, CP 3

SFH, CP 4

MFH, CP 1

MFH, CP 2

MFH, CP 3

MFH, CP 4


0.5

0.6

0.9

0.3

0.4

0.6

0.8

0.9


0.6

0.7

1.0

0.4

0.4

0.7

1.0

1.0


2.7

2.7

3.9

5.6

2.4

2.2

3.0

4.5


3.0

3.1

4.4

6.3

2.7

2.5

3.3

5.1


5.7

5.2

7.7

14.1

4.1

4.1

5.0

10.0


6.4

5.8

8.6

15.5

4.6

4.6

5.5

11.0

Looking at the values in Table 9 in a more detailed way, an irregularity can be observed in case of the two model buildings MFH of CP 1 and MFH of CP 2: The mean values of the MFH CP 2 are lower than the mean values of the MFH CP 1. In the event of the remaining model buildings, the mean values always increase with the decreasing age of the buildings. The decrease of the mean values from the MFH of CP 1 to the MFH of CP 2 can be explained by the high ratio of the building shell area to the ERA of the MFH of CP1 (the values for this ratio can be found in Table 1). Thus, some percental fractions of the MFH CP 1 are higher than the percental fractions of the MFH CP2, which results in the higher mean value of the MFH CP 1. The ratio of building shell area to the ERA 3 Results and Discussion 23/43

for the MFH of CP 1 appears very high, if it is compared to the ratios valid for the three further MFHs. This finding illustrates that the ratio of the MFH of CP 1 corresponds rather to the ratio of the building type single-family house than to the ratio of the building type multi-family house. Thus, the MFH of CP1 is assumed to be rather similar to single-family houses than to multi-family houses in Kost's (2006) descriptions of the model buildings, The tables including the complete compilation of the percental shares for all eight model buildings in case of every renovation package or construction alternative, respectively, can be found in Annex II (concerning the embodied energy demand's share of the reduced heating energy consumption) and Annex III (concerning the embodied energy demand's share of the total energy consumption).

3.1.2 Differences between model buildings of different construction periods Figure 1 and the Tables 8 and 9 show that the relation between the embodied energy demand to the reduced heating energy consumption is more beneficial in case of older buildings: For model buildings of the two construction periods up to 1947 and from 1947 to 1975, a significant reduction in heating energy consumption can be obtained by investing a low embodied energy demand. In the event of the model buildings of the construction periods from 1975 to 2000 and as of 2000, the embodied energy affordance has to be higher to reduce the heating energy consumption considerably. This finding can be explained by the fact that newly constructed and quite new buildings are usually characterised by a lower specific heat demand and by a higher average insulation of all building components than buildings, which have been constructed in the fifties and sixties. Thus, the heating energy consumption of older buildings can be reduced drastically by improving the insufficient insulation of these buildings. Whereas the heating energy consumption of newer buildings can only be reduced, if the already existing high insulation degree of the buildings is enhanced considerably. The conclusion that the embodied energy affordance for energy efficiency measures is more relevant in case of highly insulated buildings with a low heat demand has been asserted by previous studies. For instance, Nässén et al. (2006) conclude that the relative importance of the production phase and of the associated embodied energy demand in the building sector may increase in the future, since the heat demand can be reduced substantially. In addition, the production and maintenance of the technical equipment for low-energy houses results in a higher embodied energy consumption compared to the embodied energy consumption for a conventional construction method (Thormark, 2006). But one has to keep in mind that this high relevance of the production phase applies only to buildings with an extremly low heat demand and not to the majority of common buildings. At this point, it has to be mentioned that the model buildings are described to represent the common residential building stock. Thus, the increasing relevance of the embodied energy demand in case of the model buildings of the construction periods from 1976 to 2000 and as of 2000 can not be explained by the additional use of technical equipment. In fact, the additional relevance of embodied energy for the four newer model buildings can be explained by the increasing renovation material input that is described for the renovation packages and construction alternatives for the newer model buildings. Only in case of the two model buildings of the construction period as of 2000, one construction alternative includes the installation of a controlled air exchange system, which can be considered as an additional technical equipment that contributes to the increasing embodied energy demand.


Thormark (2006) shows that energy-efficient renovation measures can change the ratio of embodied energy demand to heating energy consumption. According to this study, embodied energy can account for as much as 40 to 60 % of the total energy demand (which is calculated in primary energy units) consumed by a low-energy building. The percental fractions calculated for the model buildings are about 10 to 15 % for the model buildings of the construction periods from 1976 to 2000 and as of 2000. This can be explained by the fact that the model buildings are characterised by an average heat demand and don't belong to the category of low-energy houses. Finally, Thormark (2006) suggests to reduce first of all the heat demand, because heating energy consumption accounts in case of common buildings for about 85 – 95 % of the total energy consumption of the building. These percental values that indicate the high relevance of the heating energy consumption comply with them assessed in this diploma thesis.

3.1.3 Comparison of alternative renovation material compositions and wall construction options for new buildings 3.1.3.1 Comparison of alternative renovation material compositions To get an idea about the bandwith concerning the embodied energy content of different renovation material compositions, the embodied energy content of 16 different composition is calculated for one model building. For these purposes, the model building single-family house of the construction period from 1947 to 1975 has been chosen and the embodied energy demand to implement the renovation measures one to nine is calculated. The calculation bases on the embodied energy values introduced in Table 3 of Section 2.2.2 and on the definitions for the model buildings of Kost (2006). The calculated embodied energy values are compiled in Table 10 that includes also a description of the renovation material compositions. In addition, Figure 2 offers a graphical survey of the results. On the face of it, the differences between the embodied energy content of different renovation material compositions appear quite notable. However, the considerable differences have to be interpreted against the background of that the embodied energy affordance is calculated to implement the renovation measures one to nine. The implementation of all these measures results in a considerable material input that enhances the differences between the embodied energy content of the different renovation materials. Recommendations for renovation material compositions with a low embodied energy content can not be given, because the use of one embodied energy-extensive or embodied energyintensive renovation material often determines the embodied energy content of the corresponding material composition. As an example, the use of isofloc (which is characterised by a low embodied energy demand per functional unit) reduces the embodied energy content of the corresponding composition, whereas the use of foam glass (which features a high embodied energy demand per functional unit) seems to enhance it. Furthermore, the commonly used EPS causes a low embodied energy content of the concerning material composition. The results show that the reference material composition is characterised by a medium embodied energy content. Therefore, the reference material composition is adequate for the general assessment of the relation between embodied energy demand and reduced heating energy consumption on the model building level. Additionally, the reference material composition includes materials that are commonly used at the present time. The use of commonly implemented 3 Results and Discussion 25/43

materials and the medium embodied energy demand are characteristics that allow the reference construction to be used for the general assessment on the model building level. It has to be pointed out that the reduction of heating energy consumption contributes by far the biggest part to a low total energy demand of a building. Thus, the consideration of the embodied energy content of different renovation materials and the decision for materials with a low embodied energy content only make sense for buildings with a very low heat demand. In this case, the embodied energy applies for a considerable part of the building's total energy consumption and the reduction of embodied energy demand contributes to a low total energy demand (Sartori et al., 2007).


Table 10: Embodied energy content of different renovation material compositions to implement the renovation measures one to nine for the single-family house, construction period from 1947 to 1975. The material compositions are grouped into the four categories: “high embodied energy demand”, “low embodied energy demand”, “often implemented” and “innovative, rarely implemented”. Composition Composition number category

Insulating material used for the interior insulation of the cellar ceiling and the garage wall

Insulating material Insulating material used for the exterior used for the insulation insulation of the façade of the steep roof and the insulation of the embrasures

Embodied energy affordance for the renovation measures one to nine [GJ]

1

reference

polystyrene (EPS)

polystyrene (EPS)

glass wool mat

304

2

low embodied energy demand

XPS

XPS/ polystyrene (EPS)

isofloc

253

3


XPS

polystyrene (EPS)

isofloc

260

4


XPS

glass wool slab

isofloc

254

5


cork slab


isofloc

233

6


cork slab

polystyrene (EPS)

isofloc

241

7


cork slab

glass wool slab

isofloc

234

8

high embodied energy demand

foam glass

foam glass

polystyrene (EPS)

372

9


foam glass

foam glass

glass wool mat

348

10


polystyrene (EPS)

foam glass

polystyrene (EPS)

362

11


polystyrene (EPS)

foam glass

glass wool mat

337

12

often implemented

polystyrene (EPS)


glass wool mat

296

13

often implemented

polystyrene (EPS)


isofloc

265

14

innovative, rarely implemented

cork slab

glass wool slab

isofloc

234

15


cork slab

glass wool slab

glass wool mat

265

16


cork slab

glass wool slab

polystyrene (EPS)

300


Embodied energy content [GJ]

400 350 300 250 200 150 100 50 0 1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16

Figure 2: Embodied energy content of the considered renovationmaterial compositions. The embodied energy content is calculated to implement the renovation measures one to nine for the single-family house of the construction period from 1947 to 1975. The renovation material compositions are described in Table 9.

Num ber of the renovation m aterial com pos ition

3.1.3.2 Survey of different wall construction options for new buildings with a low heat demand In this section, two reference wall constructions and six alternative wall construction options are briefly described and compared concerning their embodied energy content. The six alternative wall constructions were chosen for the comparison in the present diploma thesis, because they differ considerably concerning their wall assembly, their wall thickness or concerning the implemented materials. Therefore, the chosen wall construction options allow a survey of possible wall solutions for new buildings with a low heat demand. The considered wall construction options are described in Table 10. In case of the construction options that can be implemented in two versions, both versions are described. The descriptions and the comparison base on a literature study. More detailed information can be found in Enz & Hasting (2006). The two reference construction options are described to illustrate how a high insulating capacity can be achieved by using conventional building materials and a common wall assembling. The first reference construction option consists of a brick wall with an exterior insulation of polystyrene (EPS). The second conventional construction alternative is a wooden pedestal construction that is insulated with a glass wool mat. The two reference wall construction options are characterised by a medium wall thickness and by a moderate price. (Enz & Hastings, 2006) The solar buffer wall construction option is not developped to achieve a very low heat transition coefficient (U-value), but to allow for an equalized energy balance. In doing so, this construction option contributes to the heating energy generation with the passive utilisation of solar energy. The most important component of this wall construction is a wooden absorber element with an angleselective ripping. The flat solar radiation enters deeply into the wooden absorber element and is transferred by the glass wool mat to the interior wall construction (for instance a brick wall). The interior wall construction serves as heat accumulator and transfers the heat time-delayed to the interior rooms. In summer, the absorber element is shaded by the ripping and thus, an overheating can be avoided. Because this construction option was brought to the market two years ago, it is quite expensive. (Enz & Hastings, 2006)


The transparent insulation wall construction option belongs also to the group of wall constructions, which are developped for the passive utilisation of solar energy. This construction option consists of a massive wall construction, of an air gap filled with the special TWD-material (TWD = transparent insulation; in German: transparente Wärmedämmung) and of a glass panel. The solar radiation penetrates the glass panel and the light-transmissive TWD-body to strike the dark painted surface of the massive wall construction that converts the solar radiation into heat. The TWD-body inhibits the heat transfer outwards and thus, the heat can be absorbed and saved in the massive wall construction. The transparent wall construction option is characterised by a high price, by a considerable wall thickness and restrictions concerning the building position to obtain a high efficiency. (Enz & Hastings, 2006) The VIP (vacuum insulation panel) module component construction alternative offers an insulating capacity that is five to ten times higher than the insulating capacity of common insulating materials. The vacuum insulation panel (VIP) is mainly responsible for the high insulating capacity and consists of microporous silicia. Furthermore, it is enclosed by two layers of wood and concrete to prevent the panel from damages. At the present time, this construction alternative is implemented as a premium product or in case of certain problem areas (it allows for example for a very high insulating capacity by causing a minor wall thickness) and is therefore characterised by a considerable price. (Enz & Hastings, 2006) The solid foam boarding wall construction alternative consists of two exterior insulation layers and of an interior concrete layer in the middle. The insulation layers serve as boarding and insulation elements and consist of neopor that is a further development of EPS (polystyrene). To obtain an optimal functionality, the solid foam boarding wall construction alternative demands for a remarkable wall thickness. The costs to implement the solid foam boarding wall construction are relatively low and even decrease, if the long durability of this alternative is taken into account. (Enz & Hastings, 2006) For the solid wood wall construction option, two different versions are in use at the present time. Both versions include a triple-layered slab of massive wood, whereas the middle layer is characterised by slots. The first version is used more commonly and it is implemented in combination with a rear ventilated exterior wall cladding. The second version is a compact façade that consists of the massive wood slab and of a glass wool slab. In case of both versions, a high insulating capacity can be obtained with a minor wall thickness. The labour costs are quite high due to the local planning and prefabrication. (Enz & Hastings, 2006) The wall construction option that consists of bales of straw should be used preferentially in rural regions, where straw is harvested in huge amounts and thus, essential transport distances can be kept short. In addition, this wall construction alternative requires a considerable supply of living space, because it results in a wall thickness of 0.5 metre. At the present time, there are two construction versions on the market: The first version uses the straw as insulating and supporting element, the second version is a pedestal construction, whereas the bales of straw don't have a statical function. The costs depend on the chosen construction method, but they are generally low. In most of the countries, a lawful basis and practical experience are missing and thus, a certain scepticism predominates. (Enz & Hastings, 2006)


Table 11: Survey of the wall construction options for new buildings with a low heat demand that are described and compared in the present diploma thesis. To obtain the MINERGIE-P-standard, an approximate U-value of 0.15 W m-2 K-1 for the walls is necessary. The static U-values comply with the Uvalue of the material, whereas the effective U-value takes in consideration the potential buffer effect of certain wall constructions (utilisation, storage and allocation of solar energy). The embodied energy content is calculated per square metre and per year durability, whereas the wall option specific durability values are taken in consideration. The costs are indicated per square metre and include, planning, prefabrication and implementation of the wall construction options. The introduced abbreviations are used in Figure 3. (Enz & Hastings, 2006) Abbreviation

Thickness

[cm]

Heat transition coefficient U-value (static) [W m-2 K-1]

Heat transition coefficient U-value (effective) [W m-2 K-1]

Embodied energy demand

Costs

[MJ m-2 a-1]

[CHF m-2]

Reference construction alternative, compact façade

Ref., cf

43.0

0.15

0.15

18.9

344

Reference construction alternative, wooden pedestal construction

Ref., pc

34.3

0.15

0.15

8.9

377

Solar buffer wall construction, massive

Spwc

34.6

0.04 – 0.12

0.04 – 0.11

43.8

409 - 655

Transparent insulation wall construction

Tiwc

43.5

0.60

442

VIP module component construction, concrete

VIP, c

32.0

0.15

0.15

39.0

> 442

Solid foam boarding wall construction

Sfbwc

36.5

0.15

0.15

20.3

303

Solid wood wall construction, rear ventilated

Swwc, rv

35.5

0.15

0.15

9.9

344 - 393

Solid wood wall construction, compact

Swwc, c

31.0

0.15

0.15

13.3

344 - 393

Wall construction of bales of straw, supporting structure

Bos, ss

54.5

0.09

0.09

9.1

164 - 213

Wall construction of bales of straw, pedestal construction

Bos, pc

42.8

0.15

0.15

3.7

246


Figure 3: Embodied energy content of chosen wall construction options for new buildings with a low heat demand. The embodied energy content is calculated per square metre and per year durability. The wall option specific values for the durability are used for the calculation. Abbreviations are explained in Table 10.

Embodied energy demand -2 -1 [MJ m a ]

100 80 60 40 20

c Ti w

c VI P,

R ef .,

cf R ef ., pc B os ,s s B os ,p c Sb w , Sw m w c, r Sw v w c, c Sf bw c VI P, w

0

Figure 3 illustrates that there are considerable differences between the embodied energy content of the considered wall construction options. At first glance, the wall construction options can be divided into two groups: The first group includes wall options that are characterised by an embodied energy content, which is lower than 20 MJ m-2 a-1. The two reference construction alternatives, the option using the bales of straw, the solid foam boarding wall construction option and the solid wood wall construction belong to this group. The remaining three construction alternatives (solar buffer wall, VIP module component construction alternative and transparent insulation wall) feature an embodied energy demand that exceeds 20 MJ m-2 a-1. A final recommendation for a certain wall construction option with a low embodied energy demand can not be given in a definite way. In fact, different construction alternatives have to be recommended depending on the preferences (low costs or minor wall thickness for example) of customers. In addition, the options differ in their constraints concerning their application and thus, not every option can be implemented for every new building. A sufficient supply of living space or the southern orientation of the façade are examples for such constraints, which have to be taken in consideration as well, if recommendations for construction options with a low embodied energy are given. Table 12 offers an overview about the characteristics and constraints of the eight considered wall construction options. If a low price is of high interest, the solid wood wall construction alternative can be recommended, because this option is characterised by a low embodied energy, by a minor wall thickness and by comparatively low costs. Furthermore, the two reference construction alternatives and the solid foam boarding wall construction are three further options that are characterised by a low price, a high insulating capacity and a low embodied energy content. If the chosen wall construction alternative shall contribute to a low heat demand of the building, the solar buffer wall option can be recommended. In the event of a limited supply of living space, the solid wood wall construction offers an adequate solution, because it obtains a high insulating capacity with a minor wall thickness and a low embodied energy demand.


Table 12: Survey of the characteristics of the six innovative wall construction options and the two reference wall constructions for new buildings with a low heat demand. The marking of a certain characteristic with dark grey for one wall construction alternative means that the marked characteristic applies clearly to the construction alternative. The marking with light grey colour implies that a certain attribute characterises the marked construction alternative, but weakly distinctive. Fields that are empty show that the characteristic does not apply to a certain construction option. The indicated characteristics apply to both versions of a certain wall construction option, if two versions exist. The abbreviations are explained in Table 10. Ref.

Bos

Swwc

Sfbwc

Spw

VIP

Tiwc

Low embodied energy demand Low costs Generation of heating energy Small wall thickness Possibilities for multifarious scopes for design Possibilites for an ecological removal and disposal Constraints for the application Applicable for renovations

3.2 The relevance of embodied energy considering the Swiss residential building sector 3.2.1 Future development of ERA and heating system distribution Figure (4a) shows that in the considered time period from 2000 to 2050 the model calculates an increasing ERA of renovated buildings and a decreasing ERA of not renovated buildings. This finding can be explained by the model assumption that 70 % of the buildings of the existing building stock (construction period up to 2000) are renovated after a time period of 50 years. Because of these model assumptions, 70 % of the existing buildings are renovated once in the time period from 2000 to 2050. The ERA that is not renovated in the year 2050 is caused by the assumed 30 % of the building stock that are not renovated after a renovation cycle and by the ERA of buildings that are constructed in the time period from 2000 to 2007. The ERA of buildings that are constructed after the year 2007 is represented by the category “constructed” in figure 4a. Figure (4b) indicates that the construction activity for new buildings seems to decrease distinctly over the time period from 2000 to 2050. The general range of the renovation activity seems to remain constant and depends on the number of buildings that are renovated during a certain year. On this note, the model assumptions result in a high renovation activity fifty years after a high construction activity. Thus, the peak of the renovation activity that occurs around the year 2010 can be attributed to the high construction activity around 1960.


Figure (4c) shows that on the base of the model assumptions, the oil heating system seems to remain one of the most widespread heating systems that are in use in the Swiss residential building sector, even though the ERA that is heated with oil may decrease during the time period from 2000 to 2050. Because the share of ERA that is heated with oil heating systems seems to be still high, the primary heating energy consumption to meet a certain heat demand is calculated assuming an oil heating system. The calculation of the heating energy consumption that is necessary to meet a certain heat demand is conducted to allow for a comparison of the embodied energy demand to the heat demand (see chapter 2.1.1). Additionally, Figure (4c) shows that the model assumptions result in an increasing ERA that is heated with gas heating systems and heat pumps.

Figure 4: Figure 4a illustrates the development of the energy reference area (ERA) for not renovated, renovated and newly constructed builidings since 2000. Figure 4b shows the development of renovated and constructed ERA per year as 5-year means for the time period from 2007 to 2050. Figure 4c illustrates the share of different heating systems in the Swiss residential building stock (heat pumps are assumed to be operated with electricity). (Kost & Imboden, 2007)


3.2.2 Future development of heating energy consumption and embodied energy demand

Figure 5: Development of the primary energy consumption for heating for the reference scenario “BAU” and the four alternative reduction scenarios S1 to S4. The alternative reduction scenarios S1 to S4 are characterised by different boundary values for the heat demand of newly constructed and renovated buildings, whereas the boundary values decrease from scenario S1 to the scenario S 4.

Figure 5 shows that the model calculated development of the heating energy consumption decreases for the reference scenario and for all alternative reduction scenarios. The heat demand boundary values are assumed to decrease from the alternative reduction scenarios S1 to S4 (see Table 6). The alternative reduction scenarios S3 and S4 allow for a reduction by 50 % and 55 %, respectively, whereas the reference scenario reduces the heating energy consumption by only 18 %. Thus, the heat demand boundary values for renovated and newly constructed buildings (S3 and S4 are characterised by low heat demand boundary values) have a very strong impact on the development of the future primary heating energy consumption.


Figure 6: The future development of the embodied energy affordance for energy-efficient renovation measures and energy-efficient construction alternatives (for new buildings) for the alternative reduction scenarios. The reduction scenarios S1 to S4 are characterised by different boundary values for the heat demand of renovated and newly constructed buildings, whereas the boundary values decrease from scenario S1 to scenario S 4.

In Figure 6, the values for the embodied energy affordance are represented in megajoule per square metre and per year. As mentioned in Section 2.1.3, the embodied energy affordance for one certain energy-efficient renovation package or construction alternative, respectively, is allocated to an assumed operating time of 50 year. The time period of 50 years does not comply with the durability of all considered materials, but it is identical with the assumed renovation frequency in the building stock model. The future development of the total embodied energy affordance for energy-efficient renovation measures and energy-efficient construction alternatives is mainly a function of the total amount of renovated and constructed ERA. This finding can be seen, if Figure 4b is compared with Figure 6. The absolute level of the embodied energy affordance is determined by the corresponding reduction scenario. Figure 6 shows that the differences between the embodied energy demand values of the four alternative reduction scenarios are remarkable, particularly, if only the plots of the embodied energy demand are considered. As an example, the embodied energy affordance for the reduction scenario S1 ranges about 5 PJ per year, whereas the embodied energy affordance for the reduction scenario S4 fluctuates between 7 and 16 PJ per year. However, if the general range of the embodied energy demand is compared to the general range of the heating energy consumption, these differences appear quite marginal: The heating energy consumption fluctuates between 250 and 550 PJ per year, the embodied energy affordance between 3 and 15 PJ per year. Thus, it is obvious that the embodied energy demand accounts for a marginal share of the total energy consumption (which is the sum of the primary heating energy consumption and the 3 Results and Discussion 35/43

embodied energy demand). It can be concluded that the reduction scenarios differ considerably in their potential to reduce the heating energy consumption. If only the values for the embodied energy affordance are considered, differences between the values of the different reduction scenarios can be found. Looking at the ratio of the reduced heating energy consumption to the embodied energy affordance, it can be concluded that this ratio decreases from S1 to S4. The ratio of reduced heating energy to embodied energy affordance for the four alternative reduction scenarios is illustrated in Figure 7. As an example, in case of the reduction scenario S1, the heating energy consumption can be reduced by 3820 PJ by investing 187 PJ of embodied energy (ratio 20: 1) during the time period 2007 to 2050. In the event of the reduction scenario S4, a reduction of 7400 PJ can be achieved by investing an embodied energy affordance of 558 PJ (ratio 13 : 1). Thus, the ratio of the the reduced heating energy consumption to the embodied energy demand more beneficial in case of the less ambitious reduction scenarios.

8000 7000 6000 Cumulative embodied energy demand

[ PJ]

5000 4000

Cumulative reduced heating energy consumption

3000 2000 1000

Figure 7: Cumulative embodied energy demand and cumulative reduced heating energy consumption for energy efficiency measures during the time period 2007 to 2050. The cumulative values are calculated by adding the annual values of the years 2007 to 2050. The numbers one to four refer to the alternative reduction scenarios S1 to S4.

0 1

2

3

4

Reduction scenario

Figure 8 shows the relation between embodied energy affordance for energy-efficient renovation packages or construction alternatives and the heating energy consumption and the the total primary energy consumption (sum of heating energy consumption and embodied energy demand for energy efficiency measures) for the time period 2007 to 2050. Figure 8 illustrates the marginal relevance of the embodied energy compared to the heating energy consumption and compared to the total primary energy demand. The marginal relevance of the embodied energy becomes also obvious, if the percental share of embodied energy affordance of the total primary energy consumption is considered: In case of the alternative reduction scenario S1, the embodied energy demand accounts for 0.8 % of the total primary energy consumption. In the event of the most ambitious alternative reduction scenario S4, the embodied energy demand's share of the total primary energy consumption is 2.6 %. Finally, it can be recorded that the embodied energy demand for energy efficiency measures accounts for a negligible share of the total primary energy consumption (sum of the primary heating energy consumption and of the embodied energy affordance for energy efficiency 3 Results and Discussion 36/43

Total primary energy demand [103 PJ]

measures) in the Swiss residential building sector. Because of the minor relevance of the embodied energy demand compared to the total primary energy consumption, it makes sense to reduce the heating energy consumption drastically by investing a higher amount of embodied energy. The relation between embodied energy affordance for energy efficiency measures and the corresponding heating energy reduction changes, if buildings with an extremly low heat demand are considered. In the event of these low-energy buildings the embodied energy accounts for a more relevant share of the reduced heating energy consumption and also of the total primary energy consumption of a building (Sartori et al., 2007).

25 20 15

Cumulative heating energy consumption

10

Cumulative embodied energy demand

5 0 1

2

3

4

Figure 8: Cumulative embodied energy demand for energy efficiency measures, cumulative primary heating energy consumption and total primary energy demand for the time period 2007 to 2050. The cumulative values are calculated by adding the annual values of the years 2007 to 2050. The numbers one to four refer to the alternative reduction scenarios S1 to S4.

Reduction Scenario


4 Conclusions 4.1 The development of energy consumption and total embodied energy demand in the Swiss residential building sector In order to assess the future development of the total energy consumption (sum of primary heating energy consumption and embodied energy demand for energy efficiency measures) and of the total embodied energy demand in the Swiss residential building sector, simulations were conducted for one reference and four alternative reduction scenarios. The alternative reduction scenarios differ in the defined boundary values for the heat demand of newly constructed and renovated buildings. The results show that the total heating energy consumption of the Swiss residential building sector decreases for all considered scenarios. This reduction of heating energy consumption can be explained by the fact that the average heat demand of newly constructed and renovated model buildings decreases in case of every scenario. Nevertheless, the scenarios differ considerably in their reduction potential: Whereas the two most ambitious scenarios S3 and S4 achieve a heating energy reduction by 50 and 55 %, respectively, the reference scenario results in a reduction by only 18 %. Therefore, the heat demand boundary values have a strong impact on the development of the future energy consumption in the Swiss residential building sector. At this point, it has to be mentioned that the heat demand boundary values are not randomly defined parameters. In fact, they are affected by various parameters as for example energy price expectations or policy instruments as subsidies, income tax deductions or a future carbon tax (Amstalden et al., 2007). The future development of the total embodied energy demand is mainly a function of the total amount of renovated and constructed ERA, whereas the absolute level is determined by the simulated reduction scenario.

4.2 The relevance of embodied energy for energy efficiency measures The relevance of embodied energy afforded for energy efficiency measures is marginal, if it is compared against the absolute heating energy consumption or against the reduced heating energy consumption. This conclusion applies to the model building level and to the level of the entire Swiss residential building sector. Embodied energy calculations have been made for the renovation packages and construction alternatives that are described for the eight model buildings. The results show that the embodied energy affordance for these energy efficiency measures accounts for on average 5 % of the reduced heating energy consumption. In case of energy-intensive measures for model buildings of the construction periods from 1976 to 2000 and as of 2000 the percental values can top 10 %. Considering the total energy consumption (sum of the heating energy consumption and the embodied energy demand for one certain renovation package or one certain construction alternative) as a basis for comparison, the embodied energy demand accounts for on average 3 %. Maximum values of about 15 % concern also embodied energy-intensive measures for model buildings of the construction periods from 1976 to 2000 and as of 2000. Thus, the embodied energy demand's relevance is lower in case of residential buildings that have been constructed in 4 Conclusions 38/43

the fifties, sixties and seventies. This finding can be explained by the fact that these buildings are often deficiently insulated and feature a correspondingly high heat demand. Therefore, a considerable reduction in heating energy consumption can be achieved by investing a low embodied energy amount for a better insulation or for the replacement of old windows, for example. The comparison between the embodied energy content of different renovation materials on the basis of an embodied energy calculation for one model building shows that there are differences between the renovation materials. The comparison of different renovation material compositions reveals furthermore that the use of one extremly embodied energy-intensive or extremly embodied energy-extensive material usually determines the embodied energy content of the entire composition. There are also differences concerning the embodied energy content of different wall construction options for new buildings with a low heat demand. Depending on the preferences of the customer (small wall thickness, low costs, aesthetical preferences, for example) and on constraints concerning the new buildings (exposition, available living space, for example), different options with a low embodied energy content can be recommended. Despite of these differences concerning the embodied energy content of renovation materials and wall construction options for new buildings, one should keep in mind that the embodied energy demand is much less crucial for the total energy demand (sum of heating energy consumption and embodied energy demand) of a certain building than the heating energy consumption. Thus, one has to give the reduction of the heating energy consumption top priority. If the cumulative embodied energy demand for the time period 2007 to 2050 is compared against the cumulative reduced heating energy consumption achieved in the same time period, the marginal relevance of the embodied energy demand compared to the reduced heating energy consumption becomes apparent. Because the cumulative embodied energy demand accounts for 5 to 10 % of the cumulative reduced heating energy consumption, the differences between the embodied energy that has to be afforded to achieve the considered scenarios appear inconsiderable. It can be concluded on the base of embodied energy demand's marginal relevance that it is profitable to aim at an ambitious reduction scenario, which results in a drastic reduction of heating energy consumption.

4.3 How to reduce the total energy consumption in the Swiss residential building sector An effective reduction strategy to reduce the total energy consumption in the Swiss residential building sector has to include the beneficiation of the heating energy consumption. The argument that the embodied energy afforded for energy efficiency measures overcompensates the reduced heating energy can was proved wrong by the results of the present diploma thesis. The marginal relevance of the embodied energy demand compared to the reduced heating energy consumption has been demonstrated on the both model building and on the building stock level. The relation between reduced heating energy consumption and invested embodied energy affordance is particularly beneficial in case of residential buildings that have been constructed during the fifties, sixties and seventies. The energy-efficient renovation of these buildings offers a great potential to reduce the total heating energy consumption of the Swiss residential building stock. However, a reduction of the heating energy consumption makes also sense for common

4 Conclusions 39/43

new and common relatively new buildings: Although the embodied energy afforded for energy efficiency measures in case of these buildings appears quite high, it is overcompensated by the reduced heating energy consumption even during the year of construction or renovation. Finally, it has to be mentioned that in case of new buildings that are conceptually designed as low-energy houses, the relevance of embodied energy for energy efficiency measures increases. The increasing relevance has to be attributed to the very low heat demand and to the high embodied energy affordance for the implementation of special technique equipment (installation of a controlled air exchange system, for example). In the event of low-energy houses, the additional embodied energy demand can overcompensate the reduced heating energy consumption, if the embodied energy demand is not allocated to the operating time of the building. But if only a few years of operating time are considered, the afforded embodied energy is overcompensated by the reduced heating energy consumption. Thus, the reduction of the heating energy consumption is even profitable in case of low-energy new buildings.

4 Conclusions 40/43

5 Bibliography AMSTALDEN, R. W., KOST, M., NATHANI, C., IMBODEN, D. (2007). Economic potential of energy-efficient retrofitting in the Swiss residential building sector: The effects of policy instruments and energy price expectations. Energy Policy(35): 1819-1829. BFS (2000 a). Eigenössische Volkszählung 2000. Bundesamt für Statistik. Neuchâtel. BFS (2000 b). Umweltstatistik Schweiz Nr. 11. Bundesamt für Statistik. Neuchâtel. CHRISTEN, K., MEYER-MEIERLING, P. (1999). Optimierung von Instandsetzungszyklen und deren Finanzierung bei Wohnbauten. vdf. Zürich. CORE (2004). Konzept der Energieforschung des Bundes 2004 bis 2007. Bundesamt für Energiewirtschaft. Bern ECOINVENT CENTRE (2006). Ecoinvent database. Swiss Centre for Life Cycle Inventories. Dübendorf. www.ecoinvent.ch. ENZ, D., HASTINGS, R. (2006). Innovative Wandkonstruktionen. Für Minergie-P und Passivhäuser. C. F. Müller Verlag, Hüthig GmbH & Co. KG. Heidelberg. GIBBECO (2006). BauBioDataBank, gibbeco, Genossenschaft Information Baubiologie. Flawil. www.gibbeco.org. HÄSSIG, W., PRIMAS, A. (2007). Ökologische Aspekte der Komfortlüftungen im Wohnbereich. Empa Zen, Basler und Hofmann Ingenieur und Planer. Zürich. IBO (2000). Ökologie der Dämmstoffe. Österreichisches Institut für Baubiologie und -ökologie, Donau Universität Krems, Zentrum für Bauen und Umwelt (2000). Springer-Verlag. Wien, New York. IMBODEN, D., JAEGER, C. (1999). Towards a sustainable energy future. Energy: The next Fifty Years. OECD. Paris IMBODEN, D. (2000). Energy forecasting and atmospheric CO2 perspectives: two worlds ignore each other. Integrated Assessment 1: 321-330.

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IPCC (2007). The IPCC fourth Assessment Report. Cambridge University Press. Cambridge. JAKOB, M., JOCHEM, E., CHRISTEN, K. (2002). Grenzkosten bei forcierten EnergieEffizienzmassnahmen in Wohngebäuden. Bundesamt für Energie (BFE). Bern. JOCHEM, E. (2004). Steps towards a sustainable development. A white book for R&D of energyefficient technologies. CEPE/ETH Zurich and Novatlantis. Zurich. KASSER, U., PÖLL, M. (1998). Graue Energie von Baustoffen. Büro für Umweltchemie. Zürich. KBOB (2006). Empfehlung - Ökobilanzdaten im Baubereich. Bundesamt für Bauten und Logistik (BBL). Bern. KOSCHENZ, M., PFEIFFER, A. (2005). Potenzial Wohngebäude. Energie- und Gebäudetechnik für die 2000-Watt-Gesellschaft. Abteilung Energiesystem/ Haustechnik, Empa, Dübendorf. Faktor Verlag. Zürich. KOST, M. (2006). Langfristige Energieverbrauchs- und CO2-Reduktionspotenziale im Wohngebäudesektor der Schweiz. Dissertation Diss ETH Nr. 16421. ETH Zürich, Professur Umweltphysik. Zürich. KOST, M., IMBODEN, D. (2007). Costs of halving heating energy consumption in the Swiss residential sector by 2050. To be submitted. NÄSSEIN, J., HOLMBERG, J., WADESKOG, A., NYMAN, M. (2006). Direct and indirect energy use and carbon emissions in the production phase of buildings: An input-output analysis. Sciencedirect Energy(32): 1593-1602. PITTSBURGH (2007). Foamglas - Produkteprofile: Foamglas-Platten, Pittsburgh Corning AG (Schweiz). Rotkreuz. www.foamglas.ch.

Foamglas-Boards.

SAGER (2007). Technische Daten zu den Produkten. Sager AG, Dämmstoffe, Kunststoff-Profile. Dürrenäsch. www.sager.ch. SARTORI, I., HESTNES, A. G. (2007). Energy use in the cycle of convential and low-energy buildings: A review article Energy and Buildings(39): 249-257. SIA (2001). Empfehlung 380/1: Thermische Energie im Hochbau, Ausgabe 2001. Schweizerischer Ingenieur- und Architekten-Verein. Zürich. 5 Bibliography 42/43

SILLER, T., KOST, M., IMBODEN, D. (2007). Long-term energy savings and greenhouse gas emission reductions in the Swiss residential sector. Energy Policy 35: 529-539. SPÖRNDLI, C. (2005). Mehrkosten bei energetischen Erneuerungsmassnahmen am Beispiel des EFH der Bauperiode 1960-1975. Semesterarbeit. ETH Zürich, Professur Umweltphysik. Zürich. STEGER, U., ACHTENBERG, W., BLOK, K., BODE, H., FRENZ, W., GATHER, C., HANEKAMP, G., IMBODEN, D., JAHNKE, M., KOST, M., KURZ, R., NUTZINGER, H. G., ZIESEMER, T. (2002). Nachhaltige Entwicklung und Innovation im Energiebereich. Springer. Berlin Heidelberg. STO (2006). Technisches Merkblatt: Sto-Polystyrol-Hartschaumplatte EPS 15/20. Sto AG. Niederglatt. www.sto-ag.ch THORMARK, C. (2006). The effect of material choice on the total energy need and recycling potential of a building. Energy and Buildings(41): 1019 - 1026. TOMMERUP, H., SVEDENSEN S. (2006). Energy savings in Danish residential building stock. Energy and Buildings 38(12): 618-626. WÜEST & PARTNER (1994). Basisdaten und Perspektiven zur Entwicklung des Gebäudeparkes 1990-2030. Bundesamt für Energiewirtschaft. Bern. WÜEST & PARTNER (2004). Fortschreibung der Energiebezugsflächen: Modellrevision, Ergänzung um Bauteile, Perspektiven bis 2035; Schlussbericht. Bundesamt für Energiewirtschaft. Bern.

5 Bibliography 43/43

Annex I Detailed information about the eight model constructions

Content (can be found on the attached CD) Excel workbook concerning the SFH, construction period < 1947 Excel workbook concerning the SFH, construction period 1947 – 1975 Excel workbook concerning the SFH, construction period 1976 – 2000 Excel workbook concerning the SFH, construction period > 2000 Excel workbook concerning the MFH, construction period < 1947 Excel workbook concerning the MFH, construction period 1947 – 1975 Excel workbook concerning the MFH, construction period 1976 – 2000 Excel workbook concerning the MFH, construction period > 2000

Annex II Embodied energy demand's share of the reduced heating energy consumption Content Table 1: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the SFH, construction period < 1947 Table 2: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the SFH, construction period 1947 – 1975 Table 3: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the SFH, construction period 1976 – 2000 Table 4: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the SFH, construction period > 2000 Table 5: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the MFH, construction period < 1947 Table 6: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the MFH, construction period 1947 – 1975 Table 7: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the MFH, construction period 1976 – 2000 Table 8: The embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the MFH, construction period > 2000 Table 9: Maximum, minimum and mean values of the embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units)

Table 1: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the single-family house, construction period < 1947 Renovation package number

Ref.

1

2

3

4

5

6

7

8

9

Heat demand reduction [MJ m-2 a-1]

50

90

127

134

255

266

277

278

296

306

Primary heating energy reduction oil heating (oh) [MJ m-2 a-1]

142.0

255.6

360.7

380.6

724.2

755.4

786.7

789.5

840.6

869.0

Primary heating energy reduction wood heating (wh) [MJ m-2 a-1]

126.4

227.4

320.9

338.6

644.4

672.2

700.0

702.5

748.0

773.3

7

10

12

12

20

22

23

24

29

35

Embodied energy demand's share of the reduced primary heating energy (oh) [%]

4.93

3.91

3.33

3.15

2.76

2.91

2.92

3.04

3.45

4.03

Embodied energy demand's share of the reduced primary heating energy (wh) [%]

5.54

4.40

3.74

3.54

3.10

3.27

3.29

3.42

3.88

4.53

Embodied energy demand [MJ m-2 a-1]

Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period < 1947. The embodied energy demand and the reduction in heating energy are compared against the initial, prerenovated state.

Table 2: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the single-family house, construction period 1947 - 1975 Renovation package number

Ref.

1

2

3

4

5

6

7

8

9


57

127

144

260

333

336

352

362

370

375


161.9

360.7

409.0

738.4

945.7

954.2

999.7

1028.1

1050.8

1065.0


144.0

320.9

363.9

657.0

841.5

849.1

889.5

914.8

935.0

947.6

9

11

12

17

21

21

23

27

28

32


5.56

3.05

2.93

2.30

2.22

2.20

2.30

2.63

2.66

3.29


6.25

3.43

3.30

2.59

2.50

2.47

2.59

2.95

2.99

3.38


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1947 1975. The embodied energy demand and the reduction in heating energy are compared against the initial, pre-renovated state.

Table 3: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the single-family house, construction period 1976 – 2000 Renovation package number

Ref.

1

2

3

4

5

6

7

8


37

56

61

108

128

170

179

189

195


105.1

159.0

173.2

306.7

363.5

482.5

508.4

536.8

553.8


93.5

141.5

154.1

272.9

323.5

429.6

452.3

477.6

492.8

8

10

10

18

22

27

29

30

34


7.61

6.29

5.77

5.87

6.05

5.59

5.70

5.59

6.14


8.56

7.07

6.49

6.60

6.80

6.29

6.41

6.28

6.90


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1976 – 2000. The embodied energy demand and the reduction in heating energy are compared against the initial, pre-renovated state.

Table 4: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the single-family house, construction period > 2000 Renovation package number

1

2

3

4

5

6

7

8

9

10


21

39

55

74

85

91

100

112

146

156


59.6

110.8

156.2

210.2

241.4

258.4

284.0

318.1

414.6

443.0


53.1

98.6

139.0

187.0

214.8

230.0

252.7

283.0

368.9

394.2

2

10

18

20

21

22

24

29

33

40


3.35

9.03

11.52

9.52

8.70

8.51

8.45

9.12

7.96

9.03


3.77

10.15

12.95

10.70

9.78

9.57

9.50

10.25

8.94

10.15


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1976 – 2000. The embodied energy demand and the reduction in heating energy are compared against the reference construction alternative.

Table 5: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the multi-family house, construction period < 1947 Renovation package number

Ref.

1

2

3

4

5

6

7

8

9


37

64

202

232

240

259

269

270

285

288


105.1

181.8

573.7

658.9

681.6

735.6

764.0

766.8

809.4

817.9


93.5

161.7

510.5

586.3

606.5

654.5

679.8

682.3

720.2

727.8

5

7

14

16

17

18

20

20

25

25

Embodied energy demand's share of the reduced heating energy (oh) [%]

4.76

3.85

2.44

2.43

2.49

2.45

2.62

2.61

3.09

3.08


5.35

4.33

2.74

2.73

2.80

2.75

2.94

2.93

3.47

3.44


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the multi-family house, constrcution period < 1947. The embodied energy demand and the reduction in heating energy are compared against the initial, prerenovated state.

Table 6: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the multi-family house, construction period 1947 - 1975 Renovation package number

Ref.

1

2

3

4

5

6

7

8

9


43

76

103

130

199

216

217

227

230

233


122.1

215.8

292.5

369.2

565.2

613.4

616.3

644.7

653.2

661.7


108.7

192.1

260.3

328.5

502.9

545.8

548.4

573.6

581.2

588.8

7

9

10

11

15

17

17

20

20

24


5.73

4.17

3.42

2.98

2.65

2.77

2.76

3.10

3.06

3.63


6.44

4.69

3.84

3.35

2.98

3.11

3.10

3.49

3.44

4.08


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the multi-family house, csontruction period 1947 – 1975. The embodied energy demand and the reduction in heating energy are compared against the initial, pre-renovated state.

Table 7: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the multi-family house, construction period 1976 - 2000 Renovation package number

Ref.

1

2

3

4

5

6

7


38

57

84

119

129

154

164

168


107.9

161.9

238.6

338.0

366.4

437.4

465.8

477.1


96.0

144.0

212.3

300.7

326.0

389.2

414.4

424.5

7

9

11

18

20

22

23

24


6.49

5.56

4.61

5.33

5.46

5.03

4.94

5.03


7.29

6.25

5.18

5.99

6.14

5.65

5.55

5.65


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period 1976 – 2000. The embodied energy demand and the reduction in heating energy are compared against the initial, pre-renovated state.

Table 8: Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the multi-family house, construction period > 2000 Renovation package number

1

2

3

4

5

6

7

8

9

10


19

30

52

56

64

68

74

116

121

123


27.0

42.6

73.8

79.5

90.9

96.6

105.1

164.7

171.8

174.7


54.0

85.2

147.7

159.0

181.8

193.1

210.2

329.4

343.6

349.3

5

8

10

10

14

16

18

22

25

27


9.27

9.39

6.77

6.29

7.70

8.29

8.56

6.68

7.28

7.73


10.41

10.55

7.61

7.07

8.66

9.31

9.63

7.51

8.18

8.69


Embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period > 2000. The embodied energy demand and the reduction in heating energy are compared against the reference construction alternative.

Table 9: Maximum, minimum and mean values of the embodied energy demand's share of the reduced heating energy consumption (expressed in primary energy units). Building type

SFH, CP 1

SFH, CP 2

SFH, CP 3

SFH, CP 4

MFH, CP 1

MFH, CP 2

MFH, CP 3

MFH, CP 4


2.76

2.20

5.59

3.35

2.43

2.76

4.61

6.29


3.10

2.47

6.28

3.77

2.73

3.10

5.18

7.07


3.85

2.92

6.07

8.52

2.98

3.43

5.31

7.79


3.87

3.24

6.82

9.57

3.35

3.85

5.96

8.76


4.93

5.56

7.61

11.52

4.76

5.73

6.49

9.39


5.54

6.25

8.56

12.95

5.35

6.44

7.29

10.55

Maximum, minimum and mean value for the embodied energy demand's share of the reduced heating energy consumption (which is expressed in primary energy units). In case of every building type, two values are indicated; the first one valid for an oil heating system, the second one valid for a wood heating system. Abbreviations: SFH: single-family house; MFH: multi-family house; CP 1: construction period < 1947; CP 2: construction period 1947 – 1975; CP 3: construction period 1976 – 2000; CP 4: construction period > 2000.

Data source for the conversion factor The conversion factor to express the heat demand in primary energy units is derived from the KBOB database (KBOB, 2006).

Annex III The embodied energy demand's share of the total energy demand

Content Table 1: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the SFH, construction period < 1947 Table 2: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the SFH, construction period 1947 – 1975 Table 3: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the SFH, construction period 1976 – 2000 Table 4: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the SFH, construction period > 2000 Table 5: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the MFH, construction period < 1947 Table 6: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the MFH, construction period 1947 – 1975 Table 7: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the MFH, construction period 1976 – 2000 Table 8: The embodied energy demand's share of the total energy demand (expressed in primary energy units) concerning the MFH, construction period > 2000 Table 9: Maximum, minimum and mean values of the embodied energy demand's share of the total energy demand (expressed in primary energy units)

Table 1: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the single-family house, construction period < 1947 Renovation package Initial number state Heat demand [MJ m-2 a-1]

Ref.

1

2

3

4

5

6

7

8

9

509

459

419

382

375

254

243

232

231

213

203

Heating energy consumption oil heating (oh) [MJ m-2 a-1]

1445.6

1303.6

1190.0

1084.9

1065.0

721.4

690.1

658.9

656.0

604.9

576.5

Heating energy consumption wood heating (wh) [MJ m-2 a-1]

1286.2

1159.9

1058.8

965.3

947.6

641.9

614.1

586.3

583.7

538.3

513.0

Total energy demand (oh) [MJ m-2 a-1]

1445.6

1310.6

1200.0

1096.9

1077.0

741.4

712.1

681.9

680.0

633.9

611.5

Total energy demand (wh) [MJ m-2 a-1]

1286.2

1166.9

1068.8

977.3

969.6

661.9

636.1

609.3

607.7

567.3

548.0

7

10

12

12

20

22

23

24

29

35

Embodied energy demand's share of the total energy demand (oh) [%]

0.53

0.83

1.09

1.11

2.70

3.09

3.37

3.53

4.57

5.72

Embodied energy demand's share of the total energy demand (wh) [%]

0.60

0.94

1.23

1.25

3.02

3.46

3.78

3.95

5.11

6.39


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period < 1947. The embodied energy demand is compared against the initial, pre-renovated state.

Table 2: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the single-family house, construction period 1947 - 1975 Renovation package Initial number state Heat demand [MJ m-2 a-1]

Ref.

1

2

3

4

5

6

7

8

9

580

523

453

436

320

247

244

228

218

210

205

Heating energy consumption (expressed in primary energy) oil heating (oh) [MJ m-2 a-1]

1647.2

1485.3

1286.5

1238.2

908.8

701.5

693.0

647.5

619.1

596.4

582.2

Heating energy consumption (expressed in primary energy) wood heating (wh) [MJ m-2 a-1]

1465.7

1321.6

1144.7

1101.8

808.6

624.2

616.6

576.2

550.9

530.7

518.0


1647.2

1494.3

1297.5

1250.2

925.8

722.5

714.0

670.5

646.1

624.4

614.2


1465.7

1330.6

1155.7

1113.8

825.6

109.2

637.6

599.2

577.9

558.7

550.0

9

11

12

17

21

21

23

27

28

32


0.60

0.85

0.96

1.84

2.91

2.94

3.43

4.18

4.48

5.21


0.68

0.95

1.08

2.06

3.25

3.29

3.84

4.67

5.01

5.82


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1947 - 1975. The embodied energy demand is compared against the initial, pre-renovated state.

Table 3: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the single-family house, construction period 1976 – 2000 Renovation package Initial number state Heat demand [MJ m-2 a-1]

Ref.

1

2

3

4

5

6

7

8

338

301

282

277

230

210

168

159

149

143


959.9

854.8

800.9

786.7

653.2

596.4

477.1

451.6

423.2

406.1


854.1

760.6

712.6

700.0

581.2

530.7

424.5

401.8

376.5

361.4


959.9

862.8

810.9

796.7

671.2

618.4

504.1

480.6

453.2

440.1


854.1

768.6

722.6

710.0

599.2

552.7

451.5

430.8

406.5

395.4

8

10

10

18

22

27

29

30

34


0.93

1.23

1.26

2.68

3.56

5.36

6.03

6.62

7.73


1.04

1.38

1.41

3.00

3.98

5.98

6.73

7.38

8.60


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1976 – 2000. The embodied energy demand is compared against the initial, pre-renovated state.

Table 4: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the single-family house, construction period > 2000 Renovation package RCA number Heat demand [MJ m-2 a-1]

1

2

3

4

5

6

7

8

9

10

242

221

203

198

168

157

151

142

130

96

86


687.3

627.6

576.5

562.3

477.1

445.9

428.8

403.3

369.2

272.6

244.2


611.5

558.5

513.0

500.3

424.5

396.7

381.6

358.8

328.5

242.6

217.3


687.3

629.6

586.5

580.3

497.1

466.9

450.8

427.3

398.2

305.6

284.2


611.5

560.5

523.0

518.3

444.5

417.7

403.6

382.8

357.5

275.6

257.3

2

10

18

20

21

22

24

29

33

40


0.32

1.70

3.10

4.02

4.50

4.88

5.62

7.28

10.8

14.07


0.36

1.91

3.47

4.50

5.03

5.45

6.27

8.11

11.97

15.45


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the single-family house, construction period 1976 – 2000. The embodied energy demand is compared against the reference construction alternative (RCA).

Table 5: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the multi-family house, construction period < 1947 Renovation package Initial number state Heat demand [MJ m-2 a-1]

Ref.

1

2

3

4

5

6

7

8

9

494

457

430

292

262

254

235

225

224

209

206

Heating energy consumption (expressed in primary energy demand) oil heating (oh) [MJ m-2 a-1]

1403.0

1297.9

1221.2

829.3

744.1

721.4

667.4

639.0

636.2

593.6

585.0

Heating energy consumption (expressed in primary energy demand) wood heating (wh) [MJ m-2 a-1]

1248.3

1154.8

1086.6

737.9

662.1

641.9

593.8

568.6

566.0

528.1

520.6


1403.0

1302.9

1228.2

843.3

760.1

738.4

685.4

659.0

656.2

618.6

610.0


1248.3

1159.8

1093.6

751.9

678.1

658.9

611.8

588.6

586.0

535.1

545.6

5

7

14

16

17

18

20

20

25

25


0.38

0.57

1.66

2.11

2.30

2.63

3.03

3.05

4.04

4.10


0.43

0.64

1.86

2.36

2.58

2.94

3.40

3.41

4.52

4.58


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period < 1947. The embodied energy demand is compared with the initial, pre-renovated state.

Table 6: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the multi-family house, construction period 1947 - 1975 Renovation package number Heat demand [MJ m-2 a-1]

Initial state

Ref.

1

2

3

4

5

6

7

8

9

430

387

354

327

300

231

214

213

203

200

197


1221.2

1099.1

1005.4

928.7

852.0

656.0

607.8

604.9

576.5

568.0

559.5


1086.6

977.9

984.6

826.3

758.1

583.7

540.8

538.3

513.0

71.4

70.3


610.6

563.5

519.7

484.3

447.0

356.0

335.9

334.5

325.3

322.0

323.7


153.5

152.2

143.4

136.7

128.1

110.5

108.4

108.0

109.5

109.4

114.3

14

17

20

21

28

32

32

37

38

44


0.63

0.89

1.07

1.27

2.24

2.72

2.73

3.35

3.40

4.11


0.71

1.00

1.20

1.43

2.51

3.05

3.06

3.75

3.81

4.60


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period 1947 – 1975. The embodied energy demand is compared against the initial, pre-renovated state.

Table 7: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the multi-family house, construction period 1976 - 2000 Renovation package number Heat demand [MJ m-2 a-1]

Initial state

Ref.

1

2

3

4

5

6

7

330

292

273

246

211

201

176

166

162


937.2

829.3

775.3

698.6

599.2

570.8

499.8

471.4

460.1


833.9

737.9

689.9

621.6

533.2

507.9

444.8

419.5

409.4


937.2

836.3

784.3

709.6

617.2

590.8

521.8

494.4

484.1


833.9

744.3

698.9

109.8

551.2

527.9

466.8

442.5

433.4

7

9

11

18

20

22

23

24


0.84

1.15

1.55

2.92

3.39

4.22

4.65

4.96


0.94

1.29

1.74

3.27

3.79

4.71

5.20

5.54


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period 1976 – 2000. The embodied energy demand is compared against the initial, pre-renovated state.

Table 8: Embodied energy demand's share of the total energy demand (expressed in primary energy units) for the multi-family house, construction period > 2000 Renovation package number Heat demand reduction [MJ m-2 a-1]

RCA

1

2

3

4

5

6

7

8

9

10

209

190

179

157

153

145

141

135

93

88

86

Heating energy consumption (expressed in primary energ y demand) oil heating (oh) [MJ m-2 a-1]

593.6

539.6

508.4

445.9

434.5

411.8

400.4

383.4

264.1

249.9

244.2


528.1

480.1

452.3

396.7

386.6

366.4

356.3

341.1

235.0

222.4

217.3


593.6

544.6

516.4

455.9

444.5

425.8

416.4

401.4

286.1

274.9

271.2


528.1

485.1

460.3

406.7

396.6

380.4

372.3

359.1

257.0

247.4

244.3

5

8

10

10

14

16

18

22

25

27


0.92

1.55

2.19

2.25

3.29

3.84

4.48

7.69

9.09

9.95


1.03

1.74

2.46

2.52

3.68

4.30

5.01

8.56

10.11

11.05


Embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units) for the different renovation packages in case of the multi-family house, construction period > 2000. The embodied energy demand is compared against the reference construction alternative (RCA).

Table 9: Maximum, minimum and mean values of the embodied energy demand's share of the total energy demand (expressed in primary energy units). Building type

SFH, CP 1

SFH, CP 2

SFH, CP 3

SFH, CP 4

MFH, CP 1

MFH, CP 2

MFH, CP 3

MFH, CP 4


0.53

0.60

0.93

0.32

0.38

0.63

0.84

0.92


0.60

0.68

1.04

0.36

0.43

0.71

0.94

1.03


2.66

2.74

3.92

5.63

2.39

2.24

2.96

4.53


2.97

3.07

4.39

6.26

2.67

2.51

3.31

5.05


5.72

5.21

7.73

14.07

4.10

4.11

4.96

9.95


6.39

5.82

8.60

15.54

4.58

4.60

5.54

11.05

Maximum, minimum and mean value of the embodied energy demand's share of the total energy demand (sum of the heating energy consumption and of the embodied energy demand, expressed in primary energy units). In case of every model building, two values are indicated; the first one valid for an oil heating system, the second one valid for a wood heating system. Abbreviations: SFH: single-family house; MFH: multi-family house; CP 1: construction period < 1947; CP 2: construction period 1947 – 1975; CP 3: construction period 1976 – 2000; CP 4: construction period > 2000.

Annex IV Detailed information about the data base and the calculation methods for the renovation material comparison

Content Embodied energy data for renovation materials Embodied energy data for window systems Embodied energy data for controlled air exchange systems Embodied energy data for heating systems Embodied energy content per metre square renovated area, calculated for different materials and material thicknesses Embodied energy calculation methodology for the material comparison Information on the used data sources

Embodied energy data for renovation materials Table 1: Compilation of the renovation materials that are considered for the renovation material comparison. Application area, heat conductivity, density, regional validity, functional unit, embodied energy per kilogramme, embodied energy per functional unit and data source are indicated. Abbreviations: CH: embodied energy values are valid under Swiss production conditions; RER: embodied energy values are valid under European conditions. The abbreviation RER refers to all European countries and not only to the countries of the European Community (ecoinvent, 2006). Insulating material

Application area

Heat Density conductivity λ ρ [W m-1 K-1] [kg m-3]

Regional validity

Functional Embodied unit (FU) energy content [MJ kg-1]

Embodied energy content [MJ FU-1]

Data source

Polystyrene (EPS)

Interior insulation of floors, ceilings and walls, insulation of the embrasures, exterior insulation of the façacde, insulation of the steep roof

0.035

30

RER

1.05

100.2

105.2 ecoinvent (2006)

Glass wool mat


0.032

40

CH

1.28

48.1

61.6 ecoinvent (2006), Sager (2007)

Glass wool slab


0.036

70

RER

2.52

39.4

99.3 IBO (2000), Sager (2007)

Extruded polystyrene solid foam, foamed with CO2 (XPS)

Interior insulation of ceilings, floors and walls, exterior insulation of the façacde (in the base region of the façade)

0.035

30

CH

1.05

67.2

70.6 ecoinvent (2006), Sto (2007)

Cork slab

Interior insulation of ceilings, floors and walls

0.045

120

RER

5.40

26.3

142.0 ecoinvent (2006), KBOB (2006), IBO (2000)

Foam glass


0.045

110

CH

4.95

27.1

134.1 IBO (2000), KBOB (2006)

Isofloc


0.039

60

CH

2.34

7.8

18.3 ecoinvent (2006), KBOB (2006)

1

Embodied energy data for window systems Table 2: Description of the window components, which are used for the assessment of the relevance of embodied energy. The table includes information on the thermal transmission coefficient (U-value), the embodied energy demand per square metre and on the data source. Description of the window component

Thermal transmission coefficient, U-value [W m-2 K-1]

Embodied Regional energy demand validity

Data source

[GJ m-2]

Wooden window frame

1.5

2.67

CH KBOB (2006)

Sheet glass, dual vitrification

1.1

0.65

CH KBOB (2006)


0.7

1.00

CH KBOB (2006)


0.5

1.12

CH KBOB (2006)

Embodied energy data for controlled air exchange systems Table 3: Description of the controlled air exchange system, which is used for the assessment of the relevance of embodied energy. In the table a short description of the system, the data source and the regional and the plane validity for the embodied energy values are indicated. Description of the controlled single room air exchange system

ERA

Embodied Regional energy demand validity [GJ]

Data source

[m2] Controlled air exchange system, peripheral 6 x 120 m3 h-1, steel tubes, with earth register

780

146


Controlled air exchange system, peripheral 6 x 120 m3 h-1, steel tubes, with earth register

810

152


Controlled air exchange system, peripheral 6 x 120 m3 h-1, steel tubes, with earth register

195

37


Embodied energy data for heating systems Table 4: Compilation of embodied energy values for different heating systems. These embodied energy values allow to convert the heat demand that is offered by the model building descriptions into the primary heating energy consumption. Heating system

Embodied energy demand [MJ/ MJ useful heat]

Regional validity

Data source


1.42

CH KBOB (2007)


1.28

CH KBOB (2007)


0.36

CH KBOB (2007)

Heat pump, earth sensor, 10 kW

0.82

CH KBOB (2007)

2

Embodied energy content per square metre renovated area [MJ m-2] Table 5: Embodied energy content values of the renovation materials that are described in the renovation material comparison. For each renovation material, the embodied energy content is indicated for several material thicknesses. The grey embodied energy values indicate that the insulating capacity of polystyrene (EPS) is used as a reference insulating capacity. The black embodied energy values indicate that the insulating capacity of glass wool mat is used as a reference insulating capacity. Thus, the embodied energy content values are not offered for a certain material thickness, but for a certain insulating capacity. The abbreviations indicate the building components areas that are insulated. Abbreviations: E: embrasures; I: interior ceilings, floors and walls; SR: steep roof; F: façade. Thickness [mm]

0.04 E

0.08 I

0.1 I

0.12 F

0.12 I

0.14 SR

0.16 F

0.16 I

0.16 SR

0.2 F

0.2 I

0.2 SR

0.3 F

0.3 I

0.3 SR

Material EPS

120

240

300

EPS/ XPS

360

360

337

XPS

161

201

480

480

242

113

Foam glass

153

322

340 306

383

460

460

613

405

486

658

900

386

767 91

579 850

767

104

648

986

604

567 613

900

843

309

80 324

600 403

453

Isofloc

600 562

270

Glass wool mat

526

449

Glass wool slab

Cork slab

460

1150 1150 114

810

171 1215

Embodied energy calculation methodology for the material comparison Calculation of the essential material thickness Calculation of the essential material thickness of the material A to obtain the insulating capacity of EPS: (functional unit of the material A) [-] / (functional unit of EPS) [-] = Y [-] {(Y [-]) / (density of the material A)} [kg-1 m3] / (1/ density of EPS) [kg-1 m3] = Z [-] Z [-] x material thickness of EPS [m] = material thickness of the material A [m]

Calculation of the embodied energy content per area Calculation of the embodied energy content per area for the material A. The insulating capacity of EPS is considered as reference insulating capacity: embodied energy content per area [MJ m -2] = material thickness of EPS [m] x Z [-] x density of the material A [kg m-3] x embodied energy content per kilogramme [MJ kg-1]

3

Data sources ecoinvent: Geschäftsleitung ecoinvent: EMPA, Eidgenössische Materialprüfungs- und Forschungsanstalt, Rolf Frischknecht, Annette Köhler KBOB: www.kbob.ch KBOB c/o BBL Bundesamt für Bauten und Logistik, Holzikofenweg 36, 3003 Bern Ökologie: Daten aus „Ökologie der Dämmstoffe“ vom IBO Sager: http://www.sager.ch/, SAGER AG, Dämmstoffe/ Kunststoff-Profile, Leutwilerstrasse 281, CH-5724 Dürrenäsch SIA: Kontrollausschuss Wärmedämstoffe der Kommission SIA 279, SIA Schweizerischer Ingenieur- und Architektenverein, Generalsekretariat, Postfach, 8039 Zürich Sto: www.stoag.ch Sto AG, Südstrasse 14, CH-8172 Niederglatt

4

Annex V Detailed information on the 16 renovation material compositions for the renovation material comparison Content (can be found on the attached CD) Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 1 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 2 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 3 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 4 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 5 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 6 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 7 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 8 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 9 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 10 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 11 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 12 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 13 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 14 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 15 Excel workbook concerning the SFH, construction period 1947 – 1975, and the material composition number 16

Annex VI Embodied energy calculation procedure for heating energy generation assuming district heating systems

Embodied energy calculation procedure for heating energy generation assuming district heating systems

Assumptions Used energy sources to produce heat using a district heating system: Share of industrial oil heating: 0.2 Share of industrial gas heating: 0.1 Share of heat produced by a waste incineration installation: 0.7 Total efficiency factor for the district heating system: 0.85 10 % of the produced heat are lost during the transport from the district heating system to the customer Per 1 MJ produced useful heat, 0.02 MJ are used as electricity for the pump operation Embodied energy content of 1 MJ useful heat produced by the industrial oil heating: 1.36 MJ Embodied energy content of 1 MJ useful heat produced by the industrial gas heating: 1.36 MJ Embodied energy content of 1 MJ useful heat produced by the waste incineration installation: 0 MJ. The embodied energy content can be allocated completely to the waste disposal. Embodied energy content of 1 MJ electricity (Swiss strom mix): 2.89 MJ

Calculation of the embodied energy demand Calculation of the embodied energy demand that has to be invested to produce 1 MJ useful heat using a district heating system: Embodied energy demand [MJ] = [(0.2 * 1.36 + 0.1 * 1.28) / (0.85 * 0.9)] + 0.02 * 2.89 = 0.581

Annex VII Detailed information about the procedure to calculate the primary energy demand based on heat demand values and final energy demand values

Data concerning the primary energy calculation Table 1: Compilation of the embodied energy demand values per heat demand and per final energy demand. In addition, the efficiency factors of various heating systems are indicated. Finally, the primary energy demand values per final energy demand and per heat demand are indicated. The data are restricted to Swiss conditions. Heating system

Embodied energy demand per heat demand [MJ/MJ]

Embodied energy demand per final energy demand [MJ/MJ]

Efficiency Primary factor energy demand per final energy demand [MJ/MJ]

Primary energy demand per heat demand

Data source

[MJ/MJ]


1.420

1.29

0.91

1.29



1.280

1.25

0.98

1.24

1.27 KBOB (2007), Koschenz & Pfeiffer (2005), Kost (2006),

Electric heating, Swiss strom mix

3.041

2.89

0.95

2.91

3.06 KBOB (2007), Koschenz & Pfeiffer (2005), Kost (2006),


0.357

0.21

0.58

1.26


District heating

0.582

0.45

0.77

1.52

1.97 Frischknecht (2007), Koschenz & Pfeiffer (2005)

Solar heating

0.061

0.06

1.0

6.69
