i 

 

 

 

 

 

Energy efficiency potential of the European building stock: 

Case study for Germany 
Thesis for the degree in Mechanical Engineering 

 

Tillman GAUER 
Department of Energy and Environment 
Division of Energy Technology 

CHALMERS UNIVERSITY OF TECHNOLOGY 
Göteborg, Sweden, 2013  
Report No. T2013-392



ii 

 

REPORT NO. T2013-392 
 

 

 

 

 

 

Energy efficiency potential of the European building stock: 

Case study for Germany 
Thesis for the degree in Mechanical Engineering 

 

 

 

 

 

Tillman GAUER 

 

 

 

SUPERVISOR 
Érika Mata and Angela Sasic Kalagasidis 

 
 

EXAMINER 
Filip Johnsson 

 
 

 
 

Department of Energy and Environment 
Division of Energy technology 

CHALMERS UNIVERSITY OF TECHNOLOGY 
Göteborg, Sweden, 2013 

  



iii 

 

 

 

 

Energy efficiency potential of the European building stock: 

Case study for Germany 
Thesis for the degree in Mechanical Engineering 

 

 
Tillman GAUER 
 
© TILLMAN GAUER, 2013 
 

 
 
Technical report no T2013-392 
Department of Energy and Environment 
Division of Energy Technology 

Chalmers University of Technology 
SE-412 96 Göteborg 
Sweden 
Telephone + 46 (0)31-772 1000 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
Cover Distribution of annual solar radiation within Germany (1) 

 

Chalmers ReproService 
Göteborg, Sweden 2011 



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Energy efficiency potential of the European building stock: Case study for Germany 

Thesis for the degree in Mechanical Engineering 

Tillman GAUER 
Department of Energy and Environment 
Division of Energy Technology 
Chalmers University of Technology 
Göteborg, Sweden 
 

Abstract  

In developed economies, such as the European Union’s member states, the largest potential 
for energy efficiency improvements lies in retrofitting existing buildings. Thus, a model has 
been developed to assess the energy efficiency potentials for building stocks, the Energy, 
Carbon and Cost Assessment for Building Stocks (ECCABS). It simulates the energy flows in 
buildings and returns the emissions based on the energy demands. Germany in particular is 
interesting as it accounts for nearly 20% of all the population in the European Union, and thus 
also for a major share of its building stock. Thus, in a previous master thesis Wanjani and 
Bauer have already completed the characterisation of the Germany dwelling building stock. 
Now it is possible to simulate individual and aggregated measures and see their results in 
terms of energy and emissions. The model is completed by a cost analysis, as this is the most 
important factor for the house owners on deciding on any measure to take.  
 
The simulations show that all investigated measures can be applied cost efficiently to parts of 
the building stock. The total savings per measure range from 1.24 TWh/a to 380 TWh/a for 
the whole building stock and 0.19 to 120 Mt CO2-equivalent respectively. The cost efficient 
savings rise up to 66 TWh/a which corresponds to 25 Mt CO2-equivalent. Further savings are 
achievable by subsidies, which go up to 150 bn. €/a and save up to 230 TWh/a and 632 Mt 
CO2-equivalent. 
 
Keywords: German building stock, energy demand, energy saving measures (ESM), energy 
simulation, energy efficiency, cost analysis. 

  



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Acknowledgements 

 

First of all I would like to thank my two supervisors Érika Mata and Angela Sasic 
Kalagasidis, without whom this thesis would have never been carried out. I thank you for the 
help during the thesis! 

Also Hanna Lundevall and Tri-Cang Dinh were more than once a big help and great 
colleagues to work with. Thank you as well! 

Furthermore I would like to thank my examiner Filip Johnsson, PhD. 

A special acknowledgment also goes to the teaching staff at my home university Technische 

Universität Kaiserslautern, which has provided me with a good training. Alike the teaching I 
received at the University of Technology Sydney and Chalmers Tekniska Högskola. A very 
special thank you goes to Dr.-Ing. Krätz and Dr. Triebsch which made the exchange possible 
and to all the other people who participated to the exchange. At this point I would also like to 
thank Prof. Dr.-Ing. Hasse who encouraged me by trusting into my abilities. 

A very special thank you goes to the friends I have made and the people I have met during my 
studies and before. Especially mentioned should be Johanna Klos, David Stock and Simon 
Stummann, which always had a helping hand, if it was needed. 

My last and most precious gratitude goes to my family, which has always been there for me, 
what so ever! Vielen Dank! 

  



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Table of abbreviations, acronyms and units 

BMVS Bundesministerium für Verkehr, Bau und Stadtentwicklung (Ministry for traffic, 

construction and urban development 

KfW Kreditanstalt für Wiederaufbau (development bank) 

U heat transfer coefficient [W/m2 K] 

WAvg.EAC Weighted average energy costs [€/a] 

WAvg.S Weighted average savings [€/a] 

WAvg.SNetE Weighted average saved net energy [kWh/a] 

WAvg.EmS Weighted average saved emissions [t CO2-eq./a] 

TotSDelE  Total saved delivered energy [TWh/a] 

TotEmS Total saved emissions [Mt CO2-eq./a] 

WAvg.CE Weighted average energy costs [€/kWh*a] 

WAvg.AC Weighted average abatement costs [€/(tCO2-eq.*a)] 

Cef TotSDelE Cost efficient total saved delivered energy [TWh/a] 

Cef TotEmS Cost efficient total saved emissions [Mt CO2-eq./a] 

COP Coefficient of performance [1] 

SFD Single family dwelling 

MFD Multi family dwelling 

Bldg. Building 

Table of indices 

0 Baseline value /current value 

  



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Table of figures 

Figure 1: Share of energy demand in Germany by sector (2009) (Massen, 2012)................................ 12 

Figure 2: Share of the different fuel used in Germany (import / inland) .............................................. 13 

Figure 3: Energy flows of buildings ........................................................................................................ 20 

Figure 4: Insulation of walls ................................................................................................................... 22 

Figure 5: Insulation of windows and doors ........................................................................................... 24 

Figure 6: Insulation roof / highest ceiling (full) and lowest floor (dashes) ........................................... 24 

Figure 7: Furnace in the buildings energy system ................................................................................. 25 

Figure 8: Characteristics of different furnaces ...................................................................................... 26 

Figure 9: Appliances in the building energy system .............................................................................. 27 

Figure 10: Population growth by county (2009-2030) .......................................................................... 38 

Figure 11: Saved delivered energy depending on the average indoor temperature ............................ 51 

Figure 12: Emission saving potential ventilation ................................................................................... 52 

Figure 13: Delivered energy saving potential ventilation ..................................................................... 52 

Figure 14: Energy saving for different U values and different components ......................................... 54 

Figure 15: Emissions for different U values and different components ............................................... 54 

Figure 16: Delivered energy demand using different envelope insulation standards .......................... 55 

Figure 17: Total emissions applying different envelope standards ...................................................... 55 

Figure 18: Saving potential for hot water production ........................................................................... 56 

Figure 19: Delivered energy saving from different electrical appliances .............................................. 57 

Figure 20: Emissions saved from different electrical appliances .......................................................... 58 

Figure 21: Savings of the different packages ........................................................................................ 59 

Figure 22: Emission saving potential in the current building stock using solar and geothermal heat . 60 

Figure 23: Emission saving potential from oil to biomass substitution ................................................ 60 

Figure 24: Change over to gas ............................................................................................................... 61 

Figure 25: Saved delivered energy by furnace update .......................................................................... 61 

Figure 26: Emission reduction by update of boiler ............................................................................... 62 

Figure 27: Annual emission saving potential ......................................................................................... 63 

Figure 28: CO2-storage potential ........................................................................................................... 64 

Figure 29: Demand for non-renewables delivered energy with different envelope standards ........... 65 

Figure 30: Emission saved by maximum renewables in the different insulation standards ................. 65 

Figure 31: Saving potential for an average building .............................................................................. 66 

Figure 32: Savings of the ESMs mentioned in the pathway project ..................................................... 67 

Figure 33: Result of cost efficient measures ......................................................................................... 67 

Figure 34: Savings by further measures ................................................................................................ 67 

Figure 35: Cost efficient savings by further measures .......................................................................... 68 

Figure 36: Additional savings potential and subsidies I ........................................................................ 68 

Figure 37: Additional saving potential and subsidies for the further measures ................................... 69 

Figure 38: Net cost - intensity diagram of the ESM-package ................................................................ 69 

Figure 39: Net costs over intensity of the german building stock (all ESM) ......................................... 70 

Figure 40: Net costs - intensity diagram for SFDs ................................................................................. 71 

Figure 41: Net costs - intensity diagram for MFD ................................................................................. 71 

Figure 42: Comparison of the different individual insulation measures ............................................... 72 



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Figure 43: Price sensitivity of all PW measures ..................................................................................... 73 

Figure 44: Cumulated investments and delivered energy saved .......................................................... 77 

Figure 45: Emission saving potential per building ................................................................................. 77 

Figure 46: Energy saving potential per building by age ........................................................................ 78 

Figure 47: Emission saving potential per heat floor area and by building age ..................................... 78 

Figure 48: Area specific energy demand ............................................................................................... 80 

 

Table of tables 

Table 1: Fuel supply Germany ............................................................................................................... 13 

Table 2: Share and COP of heat pumps in the German buildingstock (Platt, et al., 2010) ................... 21 

Table 3: Suggested energy saving measures for the Swedish building stock ....................................... 30 

Table 4: Values used for the combined ESM ......................................................................................... 32 

Table 5: Building categorisation (SFD,MFD) .......................................................................................... 32 

Table 6: Installed and potential power of heat pumps (Platt, et al., 2010) .......................................... 34 

Table 7: Potential of the different renewable energy sources in private sectors ................................. 36 

Table 8: Further energy saving measures ............................................................................................. 37 

Table 9: Fuel substitution order ............................................................................................................ 40 

Table 10: SO2 equivalent (Staiß, 2003) ................................................................................................ 41 

Table 11: SO2 equivalent emssions of different fuels ........................................................................... 41 

Table 12: Costs and cost related data ................................................................................................... 45 

Table 13: Economic parameters ............................................................................................................ 44 

Table 14: Outputs economic analysis per year ..................................................................................... 46 

Table 15: Final energy demand for 2009 [TWh/a] ................................................................................ 48 

Table 16: Energy demands of the baseline by fuel and building type .................................................. 49 

Table 17: Different energy demands and corresponding fuel shares ................................................... 50 

Table 18: U values for windows and their corresponding g values used for the different measures 

(Jagnow, et al.) ...................................................................................................................................... 53 

Table 19: Savings hot water production................................................................................................ 56 

Table 20: Comparison of pathway measures ........................................................................................ 59 

Table 21: Sensitivity coefficients ........................................................................................................... 74 

Table 22: Comparison of the different measures ................................................................................. 75 

Table 23: German building efficiency subsidy programs (2005-2011) .................................................. 76 

Table 26: Characteristics of different insulation materials (MHS) ....................................................... 94 

Table 27: Surface areas (Wanjani and Bauer, 2012) ............................................................................. 96 

Table 28: Emissions storage capacity in building material .................................................................... 97 

Table 29: Close to financial beneficial measures I .............................................................................. 103 

Table 30: Close to beneficial measures II ............................................................................................ 105 

 

  



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Content 

Abstract ................................................................................................................................................... 4 

Acknowledgements ................................................................................................................................. 5 

Table of abbreviations, acronyms and units ............................................................................................ 6 

Table of indices ....................................................................................................................................... 6 

Table of figures ....................................................................................................................................... 7 

Table of tables ......................................................................................................................................... 8 

Content .................................................................................................................................................... 9 

1 Introduction ........................................................................................................................................ 12 

1.1 Background ................................................................................................................................. 12 

1.2 Context of the thesis .................................................................................................................... 14 

1.3 Aim of the thesis .......................................................................................................................... 15 

1.4 Structure of the report .................................................................................................................. 15 

1.5 General considerations ................................................................................................................ 16 

2 Standards and policies ........................................................................................................................ 17 

2.1 Data sources ................................................................................................................................ 17 

2.2 Standards for dwellings ............................................................................................................... 19 

3 Methodology ...................................................................................................................................... 20 

3.1 The Energy, Carbon and Cost Assessment for Building Stocks (ECCABS) model ................... 20 

3.2 Updating the data of the German building stock ......................................................................... 21 

3.3 Construction and efficiencies ...................................................................................................... 22 

3.3.1 Construction ......................................................................................................................... 22 

3.3.2 Furnaces ................................................................................................................................ 25 

3.3.3 Appliances ............................................................................................................................ 27 

3.4 Energy saving measures (ESM) .................................................................................................. 30 

3.4.1 Already in the Pathway Project mentioned measures........................................................... 30 

3.4.2 Emission reduction by fuel change ....................................................................................... 33 

3.4.3 Other measures .................................................................................................................... 37 

3.5 Environmental impact ................................................................................................................. 40 

3.5.1 CO2 equivalent...................................................................................................................... 40 

3.5.2 SO2 equivalent ...................................................................................................................... 41 



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3.6 Costs ............................................................................................................................................ 42 

3.6.1 Measures ............................................................................................................................... 42 

3.6.2 Maintenance ......................................................................................................................... 43 

3.6.3 Variables and fixed values for the cost analysis ................................................................... 43 

3.7 Sensitivity analysis ...................................................................................................................... 46 

4 Results ................................................................................................................................................ 48 

4.1 Validation of the model ............................................................................................................... 48 

4.2 Baseline results ............................................................................................................................ 49 

4.2.1 Current demand and shares .................................................................................................. 49 

4.2.2 Different insulation standard scenarios and corresponding fuel shares ................................ 50 

4.3 Results for ESMs mentioned in the pathway project .................................................................. 51 

4.3.1 Use of thermostats to reduce average indoor air temperature .............................................. 51 

4.3.2 Ventilation with heat recovery (SFD and MFD) .................................................................. 52 

4.3.3 Increase of insulation of the envelope .................................................................................. 53 

4.3.4 Reduction of power used for hot water production .............................................................. 56 

4.3.5 Reduction of power used for appliances, lighting, circulation pumps and packages ........... 57 

4.4 Results for emission reduction by fuel change ............................................................................ 60 

4.5 Results for the further investigated measures .............................................................................. 61 

4.6 Results of increased insulation .................................................................................................... 65 

5 Cost and sensitivity analysis ............................................................................................................... 66 

5.1 Current economic output ............................................................................................................ 66 

5.2 Changing energy prices ............................................................................................................... 73 

5.3. Sensitivity analysis ..................................................................................................................... 74 

6 Discussion .......................................................................................................................................... 75 

6.1 Comparison of different measures with literature ....................................................................... 75 

6.2 Limitations of the results ............................................................................................................. 79 

6.3 Recommendations ....................................................................................................................... 80 

7 Conclusion and further research ......................................................................................................... 82 

8 Bibliography ....................................................................................................................................... 84 

9 Appendixes ......................................................................................................................................... 92 

9.1 Energy standards for dwellings in Germany (and some reference values) ................................. 92 

9.2 Greenhouse gas emissions of different fuels and their efficiencies ............................................. 93 



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9.3 Properties of different insulation materials ................................................................................. 94 

9.4 Energy and emission storage and saving potential from insulation ............................................ 96 

9.5 Energy consumption and emission storage from walls, roofs and floors .................................... 97 

9.6 Energy prices ............................................................................................................................... 98 

9.7 Sensitivity analysis ....................................................................................................................... 99 

9.8 Estimation of subsidies and efficiencies .................................................................................... 100 

9.9 Current input file ....................................................................................................................... 107 

9.10 Changes in the code ................................................................................................................. 137 

Acknowledgement of Original Work .................................................................................................. 138 

 

  



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1 Introduction 

Germany is with a population of about 82 million people the biggest country in the EU and 
correspondingly holds a major share of the buildings. Thus it is a major factor by achieving 
energy and emission saving goals in the housing sector. 
The chapter will give a short introduction into the topic and introduce the Pathway project of 
which the thesis is part of. In addition the structure and the aim of the thesis will be presented. 
Concluded will the chapter be by general considerations and correlations related to the energy 
demand of buildings. 

1.1 Background 

In today’s general discussion about 
energy, climate change and 
greenhouse gases the general public 
tends to simplify it to transportation 
and industry. But in Germany the 
private sector accounts for about one 
third of the German energy demand, 
as indicated in Figure 1. Even though 
much effort is taken, also by private 
persons, to increase the share of 
renewable energies, one may not 
forget that energy not consumed is 
the best energy saving measure. 

The personal use of energy can be 
split up, among many other 
possibilities, into two categories. In 
the first category one can find all the 
consumption which is mainly based on personal habits, e.g. use of different methods of 
transportation. The other group sums up all the topics where no decisions on a daily base are 
made, e.g. type of fuel for heating, insulation of the house. The first group is mainly 
influenced and changed by attitude and psychology. Furthermore the general public moves to 
a greener life style, so a positive trajectory may be assumed. The second group is in a sense 
harder to change, as it in some cases includes major investments with very long lasting 
effects. 

Building or renovation of a house is a demanding business, mentally and financially. But in 
this situation major decisions are to be made, which last for up to a century. ‘How much 
money do I want to spend on insulation or an efficient heating system?’ In the past, where low 
energy prices were assumed to be constant, houses where build rather less insulated and 
faster. 

Transport Privat households

Industry Trade & commerce

Figure 1: Share of energy demand in Germany by sector (2009) 

(Massen, 2012) 



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Besides all that personal issues also national and political issues have to be considered. 
Europe in general and especially Germany are relying on fuel imports. As a consequence 
money leaves the country (or continent) and is not spend locally. By reducing the costs for 
energy and increasing the share of value added in the local economy, also the national (or 
European) economy will benefit. This becomes clearer if one assumes that always the same 
share of salary is saved and the rest spend. So if there is less energy to pay for, there is more 
money to spend on the (local) economy. 

Table 1: Fuel supply Germany
1
 

Country Gas and oil 

(position / share of 

import in %) 

(Berlin, o.a., 2012) 

Coal (position / 

share of import in 

%) (Berlin, o.a., 

2012) 

Uranium (position) 

(Paaßen, 2010) 

Algeria 8 / 2,5 --- --- 

Azerbaijan 9 / 2,5 --- --- 

Columbia --- 2 / 25 --- 

Kazakhstan 5 / 3,6 --- 3 

Libya 7 / 3,4 --- --- 

Niger ---  1 

Nigeria 6 / 5,3 --- --- 

Russia 1 / 37,2 1 / 25 2 

Uzbekistan --- --- 4 

 

The political aspect is that it is much 
harder to convince someone, e.g. to 
more freedom of speech or human 
rights, if you are depending on its 
exports. Looking at the energy fuel 
exporting countries a certain 
coincidence may become obvious. 
This is actually a contradiction with 

                                                           
1the shares for uranium are hard to estimate, as the fuel is reused and resold 

0 20 40 60 80 100

Coal

Gas

Oil

Uranium

Lignite

Renewables

Import

Inland

Figure 2: Share of the different fuel used in Germany (import / inland) 



14 

 

the energy strategic triangle (‘Energetisches Zieldreieck’). The energy strategic triangle 
allows to rate energy sources according to 3 major aspects, security of supply, environmental 
impact and cost-effectiveness; where the first mentioned might be compromised rather easily. 

A part of the security of supply is the duration, how long the fuel can be supplied. It is widely 
assumed that we already passed peak oil, the maximum oil banking capacity, and along with 
that declining oil resources. Also a simple change form one fossil fuel to another is not doing 
the trick, as peak (natural) gas and peak uranium will also come. Such changes in fuel might 
at most be seen to buy some time. 

The last aspect, which is probably the most important one, is the 2°C climate target UNFCCC. 
As Germany is a big country, in terms of population and economy, also major saving 
potentials exist. As energy is a driving cost in the major companies, which account for the 
majority of the non-residential energy demand in Germany, they have applied measures to cut 
back on their consumption. Furthermore the emission trade scheme encourages the major 
energy consumer (and along with that greenhouse gas emitter) to reduce their impact on the 
environment. (Umweltbundesamt, 2013) The EN 1600 helps the industry, which uses a major 
amount of energy, to cut back in consumption and to optimise their production in terms of 
energy and emissions. Depending on the size of the energy used a whole team of engineers 
might be occupied. Thus a focus on the German housing stock seems more legit. All those 
problems are address in the ‘Pathways to Sustainable European Energy Systems’ project. 

In addition small and medium-sized companies may also benefit from the measures proposed 
in this thesis and otherwise, as they often are based in a housed build for residential purpose. 
Especially the small businesses, and mainly the craftsmen among them, might benefit more 
from a specialised optimisation by their guild than from a rather general work like this. 

Big companies, which account for the second third of the German energy demand, use 
individual energy optimisations; the suggestions made later can be seen as optimisation for 
the last third, private houses, and also small businesses. 

As already stated by Vahlenkamp private houses have the biggest additional saving potential. 
Unlike onshore wind, which has a similar local added value and volume, the efficiency in the 
private houses has negative costs for reducing emissions. (Vahlenkamp, et al., 2012) 

All the above stated arguments allow the reduction to the German dwelling stock. 

1.2 Context of the thesis 

The thesis itself is part of the ‘Pathways to Sustainable European Energy Systems’, in the 
following abbreviated as Pathway (PW), a broad research project concerning all topics related 
to the future of energy in Europe. In this project several energy saving measures (ESMs) for 
dwellings have already been introduced and tested for the Swedish building stock. Those 
measures will now be introduced to the German building stock, if applicable. The impact of 
this introductions will be measured in costs, energy and emissions saved. 



15 

 

1.3 Aim of the thesis 

The aim of this thesis is to estimate the energy and cost saving potential in the German 
dwelling stock, with respect to several technical and non-technical restrictions and the 
resulting reduction in greenhouse gas emissions, in the following emissions. Based on this, 
suggestions of what actions to take will be given. 
Besides the saving and efficiency measures directly related to everyday consumption also 
further measures are investigated. Those measures apply either to the planning phase or to the 
upstream chain e.g. building material. They are of special interest, as they consume the energy 
within a short time and are used for a long period of time. A good example of such is 
insulation material which is produced and used within weeks, but lasts for decades. 

1.4 Structure of the report 

In a first step the data sources will be investigated, which were used for the simulations. This 
is the first and most critical step, as all further steps are based on that information gathered 
and fixed in the very beginning of the project. Along with the data, also currently in place 
(and finished) programs, policies and projects are presented. 
The following chapter deals with the ECCABS model which will be presented in the first 
subchapter, followed by the updated values. Then follows a deeper look into efficiencies, as 
they are the major contributors to the success of any energy related project. These efficiencies 
also include the energy demand of building materials, as they also contribute to the total 
emissions of a building. The chapter will be concluded by introducing already broad up 
energy saving measures (ESM) during other work in the ‘Pathways to Sustainable European 
Energy Systems’ project and further suggestions. As the main aim is to reduce the emissions 
the change in fuels and the increase in efficiency are investigated on a more detailed level. 
The results are presented in the following part of the report. The results will split up the usage 
of the different fuels used and the corresponding emissions will be presented. A comparison 
with similar work will be drawn to validate the results received. 
The subsequent sensitivity analysis compensates for the uncertainty in predicting data and 
other values into the future. 
The report then is concluded with a discussion, a conclusion and a suggestion for further 
work. 

  



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1.5 General considerations 

As Germany decided to shut down all the nuclear power plants till 2020 and mainly new gas 
and coal power plants are in planning, the (average) emissions per kWh electricity will 
increase, assuming renewables will not be able to compensate. From this perspective, and that 
electricity has the highest exergy2 of the considered energies, to reduce emissions electricity 
should only be considered the last option to choose. 

To supply the same comfort to the inhabitants, which can be expressed as final energy, there 
are several ways to change/reduce the current system: 

1) Increase efficiency 
By increasing the efficiency, less primary energy is needed to supply the same amount 
of final energy or comfort. 

2) Substitute fossil fuels 
To reduce the emissions for the same final energy, less CO2 intense fuels must be 
used, even though their (theoretical) primary energy demand might be higher. This can 
also be seen as an efficiency measure, as the emissions per final energy are reduced. 

3) Decrease the demand 
The demand can be decreased either by decreasing the wasting, which is another form 
of efficiency or by changing habits, in this case of the inhabitants. This is mainly 
subject to psychological aspects which shall only be mentioned along the main 
argumentation, but not further investigated. 
 

The expression of comfort as final energy can be shown by some simple examples, e.g. 
opening a can or drying laundry. 
So, put in an easy expression, one could say: Demand and supply must be improved! 

Along with increasing efficiencies and decreasing demands renewable energy sources need to 
be used, even if these result in a higher delivered energy demand. As they are renewable, this 
still decreases the emissions. 

The report will group the type of fuel into two groups, fossil and renewable. The first group 
covers oil, gas, district heating, coal, electricity and others. Whereas the second group 
accounts for the rest, solar, biomass & waste, geothermal and other heat pumps. Whereas gas, 
district heating and electricity can be produced from renewable sources, they are mostly not. 
Thus the grouping is used in the following report. Even though the term renewable is not 
exactly right for solar, as the sun does not ‘renew’, but ‘only’ will exceed the lifetime of 
humanity, it follows the most common categorisation.  

                                                           
2 Exergy describes the ability to change one from of energy in another. The higher the exergy 
is the easier it is to change it into energies with lower exergies. 



17 

 

2 Standards and policies 

In the following chapter the sources mainly used are introduced. There sources provide the 
data, which is the basis for the following simulations. 
The second part introduces shortly the major regulations which refer to the building stock. 

2.1 Data sources 

As already mentioned above the data used are crucial and fundamental for the simulation, as 
they have a major influence on the outcome. The influence can also be seen in the sensitivity 
analysis. 
To assure a sufficient precision of the numbers used, they were taken from official national 
and international statistics and cross checked if possible. Furthermore, earlier studies from 
universities and other recognised institutions have been included. A detailed list, of the studies 
referred to, can be found in the bibliography at the end of the report. 

For the convenience of the reader the different sources are merged into two groups:  
official (national and international) and universities & other research facilities. 
 

The group of official sources consists of the following: 

• Eurostat  
Eurostat is the statistical office of the European 
Union (based in Luxembourg) and provides data 
of all the member states and important neighbouring countries and trading partners. 
 

• DESTATIS: Statistisches Bundesamt (Federal statistics agency)  
The DESTATIS is the federal department for statistics in Germany 
and it is supplemented by the 16 state departments for statistics. 
They provide statistic data for Germany and its major trading 
partners and neighbours.  
 

• KfW: Kreditanstalt für Wiederaufbau (government-owned development bank)  
The KfW is a government owned bank in Germany 
which only purpose it is to provide money to the 
general public and industry in fields of special 
interest, e.g. education, local infrastructure or 
energy saving. All the government aid programs in 
that field are run by the KfW. The KfW also 
publishes all funding they have given and is therefore an excellent source for statistical 
data in the field of energy in the private dwelling sector. 

  



18 

 

• UBA: Umweltbundesamt (Federal environment agency)  
The UBA is part of the federal German ministry for 
environment, nature conservation and reactor safety. It 
funds and publishes research in different fields related to 
environment and is thus a valuable source for information, 
especially on the impact and potential of renewable 
energies. 

• EEA: European environment Agency  
The European environment agency is one of the EU agencies 
and is run in cooperation with several neighbouring countries. 
The EEA provides as well the EU and other governmental 
boards, as well as the broad public with data concerning a broad 
variety of information related to environmental questions. 
 

The second (academic) group consists of the following members: 

• IWU Institut Wohnen und Umwelt 

(Institute for living and environment)  
The IWU is a state funded (and owned) 
institute for research in the fields of 
living, energy and integrated, sustainable development. It is also a major source for the 
prevenient work by WANJANI and BAUER, on which this research is based. 

• ifeu - Institut für Energie- und Umweltforschung(Institute 

for research in the field of energy and environment)  
The IFEU is a private owned research facility (GmbH), which 
was a spin-off from the nearby University of Heidelberg. The 
institute looks back on over 30 years of independent research 
in the fields of energy and ecology and their economic 
consequences. 
 

• Schwäbsich Hall AG 
Schwäbsich Hall is a cooperative 
owned building society, which 
finances housing related project, 
like new buildings and (energy) 
renovations. As one of the biggest building finances in Germany is a good source for 
actual average cost for certain measures. 

  



19 

 

2.2 Standards for dwellings 

EU regulations apply to a various number of fields related to buildings. One of the major ones 
is the energy efficiency of appliances. This rates the different appliances on a scale3 and gives 
the consumer the chance to choose an energy efficient product. This also allows further to ban 
products from certain classes from the market, e.g. light bulbs. This regulation is influencing 
this research, as electric appliances are treated as heat sources. As those regulations are 
already in place, only their influence (reduced heat gains from the electric appliances) will be 
investigated. 

Along with those EU regulations also national regulations apply, which are mostly based on 
the EU regulations, but refer to the national institutions. 
In Germany the federal founding is, as mentioned before, executed by the KfW. The KfW set 
standards whether a refurbishment is funded and/or subsidiesed or not and at which 
conditions. These standards vary with the laws concerning the energy use in dwellings. In 
addition the German laws from the late ‘70s to ‘90s have a similar character and must be 
included. The different regulations have different bases. While the laws refer to the net 
heating demand, the early KfW-standards use the primary energy demand as a reference. The 
newer standards, 2007 and later, also limit losses due to transmission. 
The passive house standard and the Effizienzhaus Plus standard are not based on laws, but on 
architectural / civil engineering concepts. They both limit the primary energy demand and the 
Effizienzhaus Plus also the total energy demand. The fact that they use different bases for 
calculation makes them different from the standards mentioned above. 
A detailed table can be found in appendix 9.1. 

  

                                                           
3 Scale going from A – F with A+, A++, etc. for different types of appliances. 



20 

 

3 Methodology 

Whereas the last chapters introduced the context and the data used in this research, the 
following chapter deals with the methods and models used. The chapter is starting with the 
introduction of the core model and the updating of different characteristics of the German 
building stock. It then focusses on the efficiencies of different parts of the model. 
Following the investigated measures are introduced shortly and also the way of investing their 
financial and environmental impact is described. 

3.1 The Energy, Carbon and Cost Assessment for Building Stocks 

(ECCABS) model 

The energy demand of a building 
is defined by its balance of the 
different energies, so influx 
minus outflow. An overview of 
the major heat gains and flows is 
given in Figure 3.  
To estimate the heat and energy 
fluxes through the boundaries of 
a building basic heat and mass 
transfer is used. The ECCABS 
model uses two boundaries. All 
renewable and fossil fuels need to 
be converted into useful energy 
in the furnace. So the furnace is 
treated as an independent system, which has the (fossil and renewable) fuels, for which the 
owner is charged for, as an influx and the heat gains and waste heat as outflows. Together 
with the other influxes and outflows they form the net energy balance of the system 
(building). In contrast the sum of all solar, fossil and renewable fuels is called delivered 
energy. 
The simulation consists of two parts using two different programs, MATLAB and Simulink to 
calculate those balances. While Simulink is used to solve the energy balance of each building 
type, MATLAB handles the in- and output of the simulation. Additionally the emissions and 
costs of fuels are calculated, based on an input file. As the simulation is a projection in the 
future certain uncertainties occur, e.g. energy prices. These uncertainties can be used as an 
advantage by manipulating several values, e.g. taxes on emissions, to see the influence of the 
different parameters. 

The output of the model is a file, which list the different energies: 

1. Heat use: Space heating and hot water 4 
                                                           
4 Cooling is also possible, but it is neglected for Germany, as there are only a neglectable 

number of housings that are featured with air conditioning systems. (~0.5 %) 

Figure 3: Energy flows of buildings 

Transmission losses 



21 

 

2. Heat gains: radiation, lighting, electrical applications, occupants 
3. Heat losses and free cooling 
4. Heat recovery: transmission, air conditioning systems 
5. Electricity consumption: fans and hydronic pumps 

The total energy demand can then be calculated by summing up 1 – 3 and 5 and subtracting 4. 
Furthermore, the demand for the different fuels and energies is presented, along with the costs 
and emissions associated to them. (Mata, et al., 2011) 

3.2 Updating the data of the German building stock 

To get an as accurate result as possible the data used for the simulation, especially the shares 
of the different fuels and the houses have to be as new as possible. As the data provided by 
Wanjani and Bauer are from December 2012, so just several weeks old, no major differing 
information where found. And thus, except for the introduction of heat pumps, no major 
changes were made. 
The used values where compared with other data available, e.g. (Diefenbach, et al., 2011). 
Those values show similar magnitudes for the different types, but different shares in used 
fuels. This is reasonable, as those data is extracted from subsidies for renewing of furnaces. 
So the high shares of coal and electric heating are plausible, as they are much older and much 
more likely subject to change. Also the higher share of oil furnaces than of gas fuelled is 
plausible, as gas furnaces are more efficient and come with some other benefits and thus are 
preferred nowadays by the general public over oil furnaces within the last years. 
Additional data for the heat pump is available for the different types of heat pumps and their 
average COP, but not for the type of building they are installed in. The following data was 
extracted and introduced: 

Table 2: Share and COP of heat pumps in the German buildingstock (Platt, et al., 2010) 

Heat pump Type Number Share [%] COP 

A Air-water 88,000 0.49 3.4 

B Brine-water 155,000 0.86 4.5 

C Water-water 26,000 0.14 4.9 

 

As the share is rather small and the COP is depending on the temperature differences 
available in the specific application, an average COP was introduced on the base of the 
different COPs stated above and the shares they represent (COPav = 4.179). (Platt, et al., 2010) 

Also the share of solar space heating and solar hot water production was introduced to 0.53% 
of the total production each. (Wasserstoff-Forschung, 2011) 

More detailed information on the technique can be found in chapter 3.4.2. 



22 

 

To balance the energy the other fuels where degreased to fit a 100% (±1%) heat supply to the 
building class. 

As mentioned earlier Germany is going through a change in its electricity supply and thus the 
emissions per (average) kWh electricity will change. To be consistent all emission data used 
was taken from the GEMIS project. This data also includes the upstream chain for the 
different fuels. The data used can be found in the9 Appendixes appendix. ((IINAS)) 

3.3 Construction and efficiencies 

Reducing the energy consumption does not necessarily also result in a reduction of 
greenhouse gasses. For this reason the overall emissions of different insulation types are 
compared shortly. Also the efficiencies of different energy converters will be investigated, 
which also play a major role in the delivered energy demand. 
These efficiencies can be split up into two groups, due to construction or appliances. The 
construction ones are due to the civil engineering design of the building and mostly harder to 
change. The efficiencies to appliances are, in general, easier to change, but also much more 
depending on changing everyday habits. 

3.3.1 Construction 

The construction efficiencies are dominated by the (outer) envelope. The envelope mainly 
consists, in terms of energy, of four different elements: 

• Facade / (outer) walls 

• Windows (and doors) 

• Roof / attic (ceiling of the highest heated room) 

• Basement (floor of lowest heated room) 

The facades are in today’s 
discussion the main topic if it 
comes to energy efficiency in 
(private) buildings. On the one hand 
this is reasonable, as the outer walls 
contribute the majority of the 
envelope. On the other hand their 
heat transfer value is (already) 
rather low, compared to the one of 
windows. In addition strengthening 
of the envelope is generally 
considered a rather expensive and 
time consuming method. But 
nevertheless it is crucial, especially 
for older dwellings built before the 
first laws concerning energy 

efficiency in November 1977. As it is seen by a lot of inhabitants as a major disturbance an 

Figure 4: Insulation of walls 



23 

 

energy makeover of the outer envelope might be combined with aesthetic improvements, e.g. 
new painting. By this one could also make use of several synergies, e.g. only one scaffold 
needs to be erected. 

The insulation increases the thermal resistance of the building against the environment. It 
attempts to keep the inside of the building at a constant and comfortable temperature. Never 
the less how big and good the insulation is, it will never be able to block all heat being 
transferred from the inside out (or the other way around). But this is not totally necessary, as 
minor air circulation increases the quality of the air, e.g. in terms of oxygen level or 
unpleasant odour. Furthermore the insulation, including the facades, also has the ability to 
store and supply heat over a longer time5. The same applies for 'cooling' in summer, when the 
insulation is not only a resistance to the heat flowing into the building, but also stores heat 
from the outside and thus keeps the inner of the building cooler. The facades can then purge 
the heat stored during the night or cooler times of the day. 
The ECCABS model itself only accounts for the heat transfer coefficient, but not in which 
way it is achieved in the actual building. This is absolutely sufficient, as the heat demand is 
only depending on that. But as mentioned above, the insulation (including the facades) has a 
huge influence on the comfort inside a building. One can experience that by being in an old 
house (some centuries ago built) where at a hot day a pleasant climate can be found, whereas 
a building of newer construction dates, assuming the very same conditions, needs some kind 
of air conditioning to maintain the same comfort. This little example shows the influence of 
the heat capacity of the facades insulation system. 
Another aspect is the energy balance of such insulation, because there is no point in investing 
more energy in transport, production etc., than it is saved later. If it comes to insulation 
material, two materials come in mind, as they are used widely: mineral wool and polystyrene 
panels. Besides those two there is a variety of different other materials and systems available. 
Besides the energy consumption of the different materials, also their availability is important. 
Availability in this sense means if the basic material is renewable or fossil, where renewable 
also includes otherwise waste materials from other processes. A detailed list can be found in 
the appendix. 

The choice of the preferable material should also be depending on the local availability to 
reduce transport emissions, similar to the choice of roof covering before the introduction of 
standardised roof tiles. A good example of such are thatched roofs in Northern Germany. As 
the insulation will be not removed it may also be of interest how to recycle the materials. 
From that perspective two attributes would be perfect: reusable and easy to split in its basic 
compounds. All the renewable materials have the advantage that they are decomposable. This 
might be seen as the optimal solution, from today’s point of view, as most of the left overs of 
a building are landfilled. 

                                                           
5 Assuming the insulation is applied outside. 



24 

 

The earlier mentioned example shows another alternative to extra insulation, thicker walls. 
Due to low energy prices in the past and faster constructing processes, demanded by the 
customers, the walls became thinner and thinner and less thermal resistant materials have 
been used. Now this time saving during the construction must be paid back with both higher 
energy demands (and costs) or an additional construction period. Thicker walling does not 
only apply to the new build dwellings, but also to the existing building stock. This insulation 
has several requirements, e.g. sufficient space, if the additional wall is to be erected inside. 
This might be necessary because of heritage status of the storefront or insufficient space in the 
direct area. 

From table 9.3 in the appendix one can see that no matter which material will be used for 
insulation (e.g. to a standard of U = 0.2 W/m2*K) the primary energy will pay back within 
only some month or years at most. Also in terms of thickness all the materials result in a 
corridor between 20 and 30 cm, except for PU, wood 
wool slab and calcium silicate. 

A much bigger effort needs to be taken by 
improving the thermal resistance of the 
windows (and doors, see Figure 5). As the 
windows can hardly be exchanged within a 
day, the inhabitants have to face major 
drawbacks in their comfort. In addition an 
exchange can only be done at good weather, 
no or just a little rain, and not to cold 
temperatures, as those would cause too 
much discomfort for the inhabitants. 

The highest roof or insulating ceiling is the 
ceiling/wall which separates the heated area 

of the dwelling from the unheated area 
above, see Figure 6. In most cases this is 
the ceiling of the top room. The basic 
method of insulation is rather simple, as 
mostly mineral wool is used. Today we 
see an increasing share of renewable, 
biomass based materials. 

Much less effort needs to be taken to 
improve the insulation o the lowest floor. 
This is due to the fact that most houses 
have an unheated basement and the 
requirements in terms of tightness and 
(weather) durability are much lower (see 
Figure 6). 

Figure 5: Insulation of windows and doors 

Figure 6: Insulation roof / highest ceiling (full) and lowest 

floor (dashes) 



25 

 

Another aspect is the so called a/v ration. This characteristic of building is the ratio of the 
outer surface area and the volume enclosed. This ratio is very interesting from an energy point 
of view, as heat needs area to be transferred. So the more volume per dwelling, hence more 
people, are covered by the same outer surface, the less heat is transferred. This assumes the 
same temperatures and heat transfer rates. This is a planning aspect of a house, which can not 
be changed after the construction. As this aspect only applies to new dwellings it will not be 
further investigated in the discussion. 

3.3.2 Furnaces  

Furnaces, in this case, are all 
appliances, which aim it is to 
convert delivered energy6 or 
electricity into heat or in a more 
general net7 energy, see Figure 
7. This unit varies a lot within 
the German building stock, 
whereas gas and oil boilers are 
most common and electrical 
furnaces are in the down. Also 
an increasing share of 
renewables can be found. 
A study shows that in Germany 
about 88% of all used furnaces 
are not up to date. (Discher, 
2010). Another crucial aspect, 
concerning the heating device, is the right dimensioning. Like all other appliances also heaters 
have an optimal operation condition. The further away from such point a heater is operated 
the lower is the actual efficiency. This dimensioning is very much depending on the size of 
the dwelling, the climate and its inhabitants need for heat. This load varies during the year and 
along with that the efficiency of the heater. The more units are heated with one heating system 
the more average the heat demand will be, always considering the naturally given temperature 
changes over the year. From this one can see that heating systems covering one floor, or even 
less, are not very effective. Those systems can be found in rather simple multi-storey 
dwellings. 

  

                                                           
6 Delivered energy is sometimes also referred to as secondary energy. 

7 Net energy is sometimes also named tertiary energy. 

Figure 7: Furnace in the buildings energy system 



26 

 

Figure 8 below shows the degree of utilisation of different boiler types. This shows how much 
heat is gained per energy delivered as fuel, upper heating value.  

A further benefit which comes 
along with every change of a 
furnace is the readjustment to the 
actual heating demand. As stated 
above about 88% of all furnaces 
in Germany are out dated. As a 
result of rather cheap energy 
prices in the past, furnaces where 
over dimensioned. This wastes a 
lot of energy, specially keeping 
in mind that old furnaces have 
only in peak loads good 
efficiencies, but in lower loads 
the efficiency declines rapidly, as 
indicated in Figure 8. The 
dimensioning is also very much 
depending on the number of 
inhabitants, which may change 
over time. Also a simple 
readjustment of the heating 
program and regular maintenance 
increase the efficiency. (NRW) 
All those characteristics are far 
too much depending on the 
specific case and may thus not be 
further investigated in this 
research. But rather they may be 
seen as an additional benefit. 

From Figure 8 the current 
average furnace efficiency can be 
estimated to about 90%. An 

update of the furnaces to condensate boilers can increase that efficiency to 96%. The numbers 
in Figure 8 refer to the lower heating value, which are thus about 5 % lower than the 
efficiency (referring to the upper heating value), which is used in this thesis. These values 
correspond to the values found in up to date furnaces, e.g. BUDERUS. 

Another crucial part of the heating system is the circulation pump, which circulates the water 
from the furnace to the radiator and back. While old models run constantly new models run 
only when needed and at lower energy demand per heated floor area.  

D
eg

re
e 

o
f 

u
ti

li
sa

ti
o
n

 

Utilised capacity 

Outdoor temperature 

Share annual 

heating 

demand 

Outdated furnace 

Low temperature boiler 

Condensing boiler (70/50) 

Condensing boiler (40/30) 

Figure 8: Characteristics of different furnaces 



27 

 

3.3.3 Appliances 

Appliances are all further 
electrically powered units, except 
for heat pumps, which do not 
have the purpose of heating, see 
Figure 9. Appliances might be in 
this case split up into two 
different groups. The first group 
are all kind of (electric) lighting. 
The second group includes all the 
other machines used in (private) 
dwellings, e.g. oven, TV, stereo. 

Other heat supplying units, as 

stoves, water boilers etc., should 
also be considered, as they are 
mostly used on a daily basis and for a rather long time. Cooking is the second major energy 
consumer in buildings. In Germany mostly electric fire place can be found after a change over 
in 80’s. In general there a three types of stoves commercially available. As mentioned above 
the most common one is the electric oven. This converts all the electric energy supplied into 
heat. Where this heat is transferred then is very much depending on the size of the bottom of 
the pot or pan used. This needs to fit perfectly to use all the heat and be of matching type. The 
second type is gas ovens, they can be found in older and commercial kitchens, as they come 
with certain benefits for cooking. In Germany gas ovens have a rather bad image as they are 
seen as old fashioned and dangerous (leakage of gas). Depending on the fitting of the pot or 
pan nearly all the energy is transferred from the gas to the food. The third and last is the 
induction oven. This converts also all the electric energy supplied into heat. As it requires 
special pots and pans they fit perfectly and nearly 100% of the heat is transferred.  

The major difference, in terms of energy, is the source of energy. As the German electricity 
generation system has an average efficiency of about 33% this needs to be considered in the 
energy balance. Assuming for all three types same negligible losses for transportation and 
maintenance, the gas stove provides the highest efficiency. 

Another often discussed aspect is the lighting. The EU commission adopted two regulations 
concerning the efficiency of lighting in 2009. Till 2012 all types of conventional filament 
lamp were banned from selling in the EU. The expected outcome of this is a reduction of 
about 15 million tonnes of CO2 emissions. (EC45/2009, 2009) A further often neglected 
aspect is the transportation, production and recycling of the bulbs. Even though the new bulbs 
maybe a little more difficult to handle, the reduction of emissions and energy in transport (and 
other parts of the life cycle) are most favourable, as their lifetime is, even for the ones of 
poorest lifetime, more than six times higher. The best ones achieves up to 19 times the 
lifetime of a conventional bulb. This means saving 18 times the transport with trucks. The 

Figure 9: Appliances in the building energy system 



28 

 

annual energy demand is 88 kWh compared to 480 kWh for conventional bulbs. (Salzburg, 
2013) 

While dryers provide a certain comfort for the users, they also consume a lot of energy. The 
producers give values between 2 and 4 kWh per load (dena). The 42% efficiency of the 
average German power plant (Bundesumweltamt, 2013) more than doubles those values. 
Those values are for the up to date models, but not for the thousands of machines in current 
use, purchased 15 or more years ago using 30 kWh or more. 
Clothes lines in contrast consume no electric energy at all during operation, but require more 
time and space. In addition the maintenance, production and recycling of dryers needs to be 
taken into account as well. 

The use of dryers (in private households) is not only due to the personal comfort of the user, 
but also due to space available. So this issue should be kept in mind by the design of new 
dwellings. 

The other mentioned appliances are subject to the European Union energy label. This label 
was introduced in directive 92/75/EEC and updated with directive 2010/30/EU. The label 
informs the consumer about the energy demand of the product. The rating is based on an 
average reference model or a fixed value (based on the category) and thus up to date. 
Nevertheless the differentiation in the high efficiency is rather poor, as all products above 
certain efficiency are grouped together whether they use 30% or 5% of an average model. A 
new, more detailed scale seems necessary. 

In terms of energy all (electric) appliances can be represented by an energy or heat source in 
the model used in this thesis. This might suggest that there is no real need to improve 
anything from a bigger point of view. But one needs to keep in mind that all the electrical 
appliances use electricity, which is produced at about 42% efficiency in Germany. 

The aim of the EU 20-20-20 project and this thesis is to reduce the CO2 emissions, which are 
most often coupled to the energy demand, but not always. Also a change to climate neutral 
fuels, e.g. wood, or more efficient supply/production of tertiary energy also reduce the GHG 
emissions.  
It can be summarised that all fuels need to be used as close to the area of production and the 
consumers to reduce emissions based on transportation. As the availability of sustainable, 
renewable fuels vary between the different regions within Germany, also the tertiary energy 
production as to be adjusted. Furthermore the political borders (at least within the EU) should 
be overstepped, to provide an optimal supply. 

Special attention needs to be brought to residential accommodations, retirement homes and 
such. Those institutions have a mainly social goal rather than an economic. This suggests that 
there is some saving potential left. Even though only about 5% of all Germans live in such an 
accommodation, the potential might not be neglected. This is mainly due to the ownership, as 
it is owned not by a private person, but a legal entity. Such entities are mainly interested in a 
higher profit (whether it keeps the profit or not). Also long term investments are more likely, 



29 

 

as they can be seen as financial investments, without the drawbacks8 of such investment in 
their own dwellings. (Jochum, et al., 2012) 
These types of dwellings are also very interesting as they mostly come with in the rent 
included water, heat and electricity. This might reduce the effort to save on services which are 
already included in the rent. Rather simple methods, as motion detectors instead of switches, 
water efficient taps, toilets and showers will increase the efficiency of such dwellings.  

  

                                                           
8 These drawbacks are mostly due to the reduced comfort during the construction period. 



30 

 

3.4 Energy saving measures (ESM) 

After establishing the model and creating a baseline, the current demand and the influence of 
different measures is tested. The measures can be grouped into three groups. The first one 
consists of the measures already mentioned in the pathway project. The second group 
investigates the changes in fuels and the inclusion of alternative energy sources. And the last 
group sums up all which are not mentioned by then. For all three groups a short list is given in 
the beginning and then a more detailed description of the different measures is presented. 
Depending on the measure, either a single simulation is done, or a sensitivity analysis. 

The approach follows the idea of first to reduce the demand and then reduce the emissions 
(per kWh). 

3.4.1 Already in the Pathway Project mentioned measures 

For single- and multi-family dwellings a list of measures has been published, with respect to 
the Swedish housing stock. This list is investigated first, as Germany has partly some 
common aspects with Sweden, like climate and building style. 
The list is sorted by the energy saving potential of every measure (for Sweden): 
 
Table 3: Suggested energy saving measures for the Swedish building stock 

No Measure 

PW1 Use of thermostats to reduce indoor air temperature to 20°C 

PW2 Ventilation with heat recovery (SFD) 

PW3 Ventilation with heat recovery (MFD) 

PW4 Increase of insulation of the facades 

PW5 Increase of insulation of windows 

PW6 Increase of insulation of cellar/basement 

PW7 Increase of insulation of attics/roofs 

PW8 Reduction of power used for the production of hot water to 0.8 W/m2 

PW9 Reduction of power used for the production of hot water to 1 W/m2 

PW10 50% power reduction of appliances 

PW11 Reduction of power demand of circulation pumps 

PW12 50% power reduction of lighting 

PWA Combination of all above 

 



31 

 

The German building stock differs from the Swedish one, specially keeping in mind the 
programs run in Germany within the last years to increase the share of renewable energies 
used and strengthen the insulation. Nevertheless it is a reasonable start as a rather large 
number of buildings might still be in their original (-energy-) setup. 
 
The heat transferred through the wall (by conduction and convection) is direct proportional to 
the temperature difference and the U value of the wall. As the outer temperature is fixed only 
the inner temperature can be changed. This can be done by thermostats, which control the 
indoor temperature automatically, and thus reduce the heat transfer through the envelope. 
Model representation: Reduced Tmin 
Ventilation systems exchange the air inside a building to guarantee a pleasant climate inside. 
The air going out is warmer as the air flowing in and the inflowing air must be heated to the 
inside temperature. The energy required for this could partly be gained from the outgoing air. 
As only 0.5% of all dwellings in Germany have an air conditioning system this method must 
been seen as a new investment, rather than a technical upgrade of an existing system. 
Model representation: HRec_eff = 0.5 

The insulation has a major influence on the heat demand of a building, as mentioned before. 
By increasing the thermal resistance less heat is transferred out of the building. The envelope 
consists, as mentioned above of several components with specific thermal resistances and 
shares in area. Special attention should be brought to heat bridges, which bridge the 
surrounding insulation of the (outer) envelope. 
The (outer) envelope of a building consists of four main parts (from an energy perspective): 
(Outer) walls, windows, roof / attic and basement / lowest floor. The heat transfer is, as 
already mentioned depending on the U value of the envelope. This average U value can be 
decreased, so less heat is transferred, continuously. This means not all building from a certain 
class are insulated better, only the overall average. This allows to pick the buildings most 
promising, or best suiting by other aspects. Thus measures four to seven will be investigated 
as a sensitivity analysis. 
Model representation: Reduced overall U value 
The reduction of energy needed to produce hot water can be mainly achieved by using a 
more efficient (newer) boiler. Instead of reducing the (primary) energy demand to produce hot 
water, also the demand for hot water can be reduced by using inlets for taps, showers, etc. 
This saving potential is estimated to about 10%. (Kirchner, et al., 2009) Both reductions have 
the same representation in the model. 
Model representation: Reduced Hw 

The electric appliances in a building work as a (electric) heater, as they transform a part of 
their electricity consumption direct into heat and the rest indirectly, with another step in 
between. This may be good in the first attempt, as it does not matter, for the temperature of 
the building, where the heat comes from. But as they are powered by electricity, the most 
exegetic energy available in private households (with a poor efficiency over the whole 
process) it becomes obvious, why the input of electricity should be reduced as much as 
possible. 
Model representation: Ac 
Circulation pumps circulate the transport medium though the heating system. Up to date 
models run when heat is needed, whereas older models run continuously. The saving potential 
by replacement of the 18.1 mio. pumps can be up to 90% of the original required energy (per 
year and unit) and about 50% in average. About 52% of all circulations pumps used in 
Germany are older than 10 years. Furthermore those pumps are mostly over dimensioned. In 
addition to the saved electricity also 10-15% heat is saved, as rooms are not heat 



32 

 

unnecessarily. (Wohlauf, et al., 2005)  
A case study by Grundfos emphasises that the real savings from a new circulation pump are 
bigger than the savings calculated based on the technical data. The average saving in the study 
was about double. (GRUNDFOS, 2011) 
Model representation: HyP 

 
The combination of all the ESMs above is also investigated. As not all ESMs are using 
definite numbers, the up to date values are used. The following Table 4 gives an overview 
over the values used: 
Table 4: Values used for the combined ESM 

ESM 4-7 11 

value 
Uoverall: 0.339 to 0.665 

(g: 0.59) 
80% 

 
As measures 2-5 only apply for certain groups of houses Table 5 gives an overview of the 
grouping. 
Table 5: Building categorisation (SFD,MFD) 

 SFD MFD 

Building ID X10-X29 X30-X511 
 
As several measures mentioned above have similar effects on their fuelling system, namely 
the electric grid, their influence will be investigated together. Those aggregations of measures 
will be called packages, where the first package includes the reduction of demand for lighting, 
appliances and the circulation pump to the up to date level (Electricity I). The next package, 
called Electricity II) includes furthermore a heat recovery of 50% and a lowering of the 
average indoor temperature to 20°C. A further benefit from reduced electric consumption is 
smaller peaks in the electric grid and an unloading of the grid. This then reduces the emissions 
from the grid, e.g. for storage and back up capacity. 
Also the insulation measures (PW4 – PW7) will be investigated as a package. This is due to 
the fact that such measures are state subsidised and are mostly carried out by one company. 

An additional measure will simulate the upscale effect of a typical renovation, where besides 
new insulation also the furnace is renewed and a solar thermal system is introduced to the 
building. (Up to date I) 

A more ambitious variation is the up to date II package, where it is assumed to make us of all 
the geo- and solar thermal potential. And the other fuels reduced accordingly to the 3.4.1. 
Also the higher efficiency of the gas boilers is considered (0.96) and a higher efficiency for 
oil boilers (0.94) due to exchange of the old furnace. Also an additional share of 2.5% of 
biomass fuels is introduced to the building stock. Even though this scenario seem quiet 
ambitious in the first place, the subsidies and cheap loans by granted by the government. 
(KfW) 



33 

 

3.4.2 Emission reduction by fuel change 

The second group covers all the measures which are based on a change in fuel. This does not 
reduce the net energy demand of a building but can reduce the delivered energy demand of a 
building. In most cases high emissive fuels, e.g. oil and coal, are substituted by low emissive 
ones e.g. solar heating. 

To cover the full scope of all energy sources available, one can start with the basic energy 
sources available. There are two energy sources which are infinite, with respect to mankind: 
the sun and geothermal energy. 

Geothermal energy is making use of the temperature gradient along the radius of the earth. 
The extracted heat can be used directly for heating purposes (either space heating or warm 
water) by using downhole heat exchangers. Downhole processes can also be used to produce 
electricity, as their cycle transports big amounts of energy. The heat which can not be used for 
electricity generation can then be used for space and hot water heating. In areas with a low 
heat gradient in the surface near areas heat pumps can make use of the small temperature 
difference, by using a process similar to the one in refrigerators. This is constantly possible, as 
the temperature in about 6 m depth does not change significantly during the year. Also 
included in this group are heat pumps using air as a heat source, which is obviously not a 
geothermal source, but uses similar techniques and may thus be included in this group.  
The electric potential of geothermal energy is assumed to be 6.4 GWel, which corresponds to 
50 TWh/a (Klaus, et al., 2010). This potential considers ecological, financial and technical 
restrictions. Assuming such a plant delivers energy at a share of 50% heat and 50% electricity, 
gives 6.4 GWth, which corresponds to 50 TWh/a heat (Geox)9. This heat, which would else be 
wasted, can then be used in a district heating system. On the one hand it must be argued that 
this heat is also partly used for commercial purposes, which are not covered here. On the 
other hand this reduction may be compensated by assuming that companies feed excess heat 
into a district heating system. 

Besides this large-scale geothermal heat usage, one can also use the geothermal heat on a 
much smaller scale. This is done by heat pumps, which work in the same way as the ones to 
produce electricity. Only the scale and temperatures are different, as they only require much 
smaller amounts of heat and at lower temperatures. The following Table 6 shows the current 
installed heat pumps and the estimated potential in 2020. This potential is with respect to 
technical and economic aspects. 

                                                           
9 This geothermal power plant has the capacity assumed in the BMVS study and therefore 

the efficiencies can be used. 



34 

 

Table 6: Installed and potential power of heat pumps (Platt, et al., 2010) 

Type 

Av. 

heating 

power 

[kW] 

Number 

installed 

2008 

Heat 

produced 

[TWh/a] 

Installed 

power 

[GW] 

Est. 

number 

installed 

2020 

Est. 

installed 

power 

2020 

[GW] 

Est. heat 

delivered 

(2200 h/a) 

[TWh/a] 

Brine-

water 
10 155,000 3.41 1.55 

820,000 26.8 58.96 
Air-

water 
12 88,000 2.32 1.056 

Water-

water 
14 26,000 0.8 0.364 

Sum N/A 269,000 6.53 2.974 820,000 26.8 58.96 

 

Adding up both measures this gives a total geothermal power of 33.2 GWthermal and  
108.96 TWh/a heat. 

All the other energies, available for heating purposes, are due to the sun. The sun can be used 
either directly or indirectly. A form of direct use is the use of solar thermal panel. Those 
transfer the solar radiation into heat, which then can be used to heat spaces or to support warm 
water production. The potential for this is rather low, compared to other regions in the world, 
as the angle of the incoming beams of sunlight is rather flat. As already seen on the cover the 
available (direct) solar energy decreases from the South to the North of Germany. In 2012 
11.5 GWtherm where installed. ((BSW-Solar), 2013) Future expected produced heat is 36 
TWh/a in 2030, using 99 mio. m2 of collector area. (Ebert, et al., 2012). The area limitation is 
mainly due to shading and orientation of the roof areas. This potential will be introduced as a 
(renewable) fuel in the simulation. 

The second way to make (rather) direct use of the sun is to convert the solar radiation into 
electricity. The same limitations apply as for solar thermal use. Photovoltaic is a direct 
competitor to the solar thermal energy, as the space available on roof tops is limited. Using 
other not used areas is done, but exceeds the scoop of the thesis, as this is more a type of 
(micro) power plant, rather than a supporting energy source. Another often brought forward 
limitation of photovoltaic is the, compared to conventional fuels, rather unpredictable 
production and the unsteady availability. But it is shown that photovoltaic is no threat to the 
electric grid and thus shall not be discussed further here. The second argument, that the 
production is unsteady is partly right, but as the electricity is produced during high load times, 
photovoltaic even reduces the load on the electric grid during that time. (Burger, 2011) The 
total potential for Germany is estimated between 161 GWp and 275 GWp, which corresponds 



35 

 

to 66 TWh/a and 248 TWh/a respectively. The 66 TWh/a includes only a use of 34% of the 
available area, where the rest is given to the solar thermal use. ((BSW-Solar), 2013) and 
(Klaus, et al., 2010) This potential is not directly included in the model, as it is fed into the 
grid, but puts the electricity consumed (in the model) in a relation. The fed in into the grid 
influences the emissions of the electricity of the grid. 

The third big group is biomass and waste. The combination of this group is based on technical 
reasons, as both can be burned as a solid or gasified. Also waste can be seen as a renewable 
source of fuel, as it will always appear. Also some components of that group are both, 
biomass and waste, e.g. wood chips from a saw mill. Biomass is a direct competitor, in terms 
of area, to food, which must be seen as a problem. The potential for biomass in Germany is 
also limited to the material use of biomass, e.g. wood for boards and beams. Also the potential 
for energy from waste, burned in a CHP and then supplied to the customers, can be seen as 
constant, as no further resources are available. One might argue that old landfills might be a 
source for ‘new’ waste (and other valuable resources), but this potential seems rather limited, 
as those landfills would need to be older than the introduction of the recycling system to have 
a sufficient energy potential. The sustainable biomass potential for Germany is estimated to 
202 TWh/a, assuming an (slightly increased) CHP efficiency of 60% result in 121.2 TWh/ael 

and 80.8 TWh/atherm. This is a theoretical potential, which accounts all the potential available 
for energy production and not for material use. Excluding the use for other purposes, e.g. 
transportation etc., the potential is estimated to 23 TWh/a. (Klaus, et al., 2010) Other sources 
see the maximum potential for biomass already reached. (Nitsch, et al., 2010) This 
corresponds to the current data used in the ECCABS model. Thus further increase of biomass 
will not be investigated. 
In this thesis the potential for biomass and waste will be limited to Germany, so no net 
imports are considered. It might be argued, that neighbouring countries, which have more 
capacities than they need, could supply Germany with biomass, e.g. Poland, Ukraine. This 
should be neglected anyways, as those transports require energy and the energy demand in 
those neighbouring countries will rise within the next years and thus they might be only able 
to supply for short terms. An area based perspective, rather than one restrained by political 
borders is to be applied, as only then optimal supply can be guaranteed. 
Model representation: P_HP, P_Sh_X and P_Hw_X (corresponding to the added fuels) 

  



36 

 

To get a better overview of the stated potentials above the following Table 7 will conclude 
this section: 

Table 7: Potential of the different renewable energy sources in private sectors 

Energy source 
Potential [TWh/a] 

Promising areas 
Electric Thermal 

Solar 66 36 South 

Direct geothermal none 108.96 South and Rhine 

Biomass / Waste None 23 Rural areas 

Geothermal heat 

from electricity 

production 

50 50 Rhine 

sum 116 217.96  

 

To get a better overview over the different potentials available in the different regions a 
bottom up characterisation seems to be ideal, as performed by the University of Technology 
Munich for the municipality of Ismaning. (Hausladen, et al., 2012) Thus a maximum supply 
with local renewable energies could be applied much easier, as they might be more easily 
implemented in the energy planning of to be build and renovated houses. 

The other potentials, e.g. electricity from geothermal heat or biomass and waste, for energy 
exploitations may not be investigated in this report, as they are not applicable to the housing 
sector and may be seen as part of the German generation system. Nevertheless a sustainable 
exploitation of these resources reduces the greenhouse gas footprint of every dwelling, which 
relies on the (inter-)national grid. 

  



37 

 

3.4.3 Other measures 

The third group of measures consists of those recommended by official and other sources, and 
the measures coming from the model itself. Those measures are mostly based on 
mathematical considerations and the sensitivity analysis of (Wanjani, et al., 2012).This 
subchapter will deal with the energy saving measures, which are obviously directly related to 
buildings, but can not be fully assed with the ECCABS model. Table 8 gives an overview 
over these further measures, which are then described in detail. 

Table 8: Further energy saving measures 

Number Measure 

O1 Increase the share of wood in building materials 

O2 Water management 

O3 District heating 

O4 Development area and population 

O5 Update furnaces 

O6 Reduced humidity 

O7 Use wood based insulation material 

 

Buildings not only consume energy and emit GHG during operation, but also during 
construction (and the production of the materials used). Walls have a major share in buildings 
and thus account for a majority of the emissions during construction. The emissions10 for 1 m2 

of conventional wall varies between 63 to 127 kg CO2 equivalent, whereas wood based types 
vary between 42 to 54 kg CO2 equivalent. (Die Nachhaltigkeit von Fassadenbaustoffen im 
Vergleich - Ökobilanz von zehn Außenwandtypen, 2012) In addition the wood stores 1 t CO2 
per 1m3 and acts as a CO2-storage during the lifetime of the building. 

Another interesting idea is the reuse of water within a building. As most such 
accommodations are built in the style of high-rise buildings, same floor plan for each level, 
the water used for showering or hand washing, may be used to flush the toilet of the next 
lower level (or even the own). The reuse of water across apartments can only be introduced in 
new buildings and, because of this not be further investigated in this thesis. The second one 
can be retrofitted to an existing bathroom. 
As reuse of water, as described before, not only reduces the amount of fresh water used, but 
also along with that the energy used to pump water. 

                                                           
10 including production, installation and end-of-life 



38 

 

Growth [%] 

Below -15 

-15 to below -10 

-10 to below -5 

-5 to below 0 

0 to below 5 

5 or more 

The development of 
new housing areas is 
also a major 
potential, as a big 
movement from the 
city centers and rural 
areas, here especially 
eastern Germany, to 
the suburban areas is 
expected. The direct 
potential can be 
estimated by an 
interpolation between 
several housing 
standard models 
(EnEV 09, PHPP 
etc.). Along with 
those direct saving 
potentials also 
indirect potentials are 
available, e.g. by 
smart infrastructure, 
which allows short 
distances or good 
public transport for 
everyday ways. This reduces the emissions and energy demand, which are not directly 
reflected in the gas, oil or electricity bill. The change in population density (per county) is 
indicated in Figure 10 and shows the major potentials in and sorrounding the major cities and 
the South of Germany. 
Furthermore the total population of Germany is expected to shrink till 2050 to 71.5 mio.. This 
is a reduction of 12.6%. Thus the total energy demand for heating in germany can be expected 
to decrease by that percentage. 

Another measurement, which does not directly influence the demand of the building stock, 
but the primary energy demand (PED) is the increase of district heating capacity. A district 
heating system supplies a number of heat sinks with heat which are within certain distance. 
One of the advantages of such a system is that already over 20,000 systems have been set up. 
In 2011 those have supplied 344,412 customers/dwellings. The expansion and aggregation of 
those existing nets is estimated to 17.1 TWh/a, 84 TWh/a respectively. This numbers increase 
to 20.7 and 130.1 TWh/a by moving from a low price to a high price level and a changing 
from microeconomic to a (national) macroeconomic perspective. This difference, which is 
only due to economic reasons, might be bridged by government funding. The environmental 
benefit of such systems is that they are independent from the actual fuel and have an average 

Figure 10: Population growth by county (2009-2030) 



39 

 

loss of about 12% in the net. (AGFW | Der Energieeffizienzverband für Wärme, Kälte und 
KWK e.V., 2012) This loss can be compensated by much more efficient furnaces. More often 
updated furnaces also give the possibility to adjust the fuel to local opportunities, with fewer 
restrictions due to the inhabitants, e.g. smell, technical skills, noise. This heat might be gained 
from wood chips, waste or other renewable fuels from a combined heat and power system 
(CHP). To assure a continuous supply, when needed, also fossil fuel can be burned (either in 
one furnace or more). Also the overall efficiency of the whole system, as only very little 
losses occur from the incineration, transport and transfer of heat to the dwellings, is rather 
high. Another advantage of such a system is that also other sources can feed in heat, e.g. from 
geothermal or solar thermal systems, or waste heat from nearby industries. Those potentials 
will be presented below. Some buildings can not directly benefit from local renewable 
sources, e.g. no geothermal source available or they are situated in a valley and can not use 
solar thermal energy. These buildings could then be supplied indirectly using a district heating 
system. Other obstacles could be unfavorable direction of the roof or monumental restrictions. 
Other arguments, brought forward in favor of district heating, are an easier handling for the 
customer, as heat itself is supplied. In addition the reduced number of total parts may also 
suggest a reduced total effort for the same amount of heat supplied. Furthermore the district 
heating requires much less space in the dwelling than a normal furnace, especially when 
considering also tanks. A benefit for the general public might be a reduced amount of effort in 
defrosting streets and sidewalks, as e.g. in Iceland. 
The biggest advantage from an energy point of view is that only the heat is delivered, so 
furnace ‘growths and shrinks’ with the demand of the building, e.g. due to more inhabitants or 
a better insulation. 

In this model the potential is combined with the one using waste heat, as they both use the 
same carrier system. Furthermore it is assumed that 50% is produced at the current price and 
emissions and 50% are waste heat, which are sold at the current price, but their emissions are 
already accounted. 
Model representation: P_Sh_DH and P_Hw_DH 

As already mentioned in chapter 3.3.2 Furnaces the vast majority of the furnaces used in 
German dwellings are outdated. A replacement of those, as the efficiency has increased, will 
reduce the demand for delivered energy, while the net energy demand stays constant. 

As mentioned above, also the insulation material itself consumes energy produces and 
emissions during its lifetime. A change to wood based material can thus reduce the energy 
demand and corresponding emissions. It furthermore stores CO2 during its lifetime. As the 
lifetime of insulation material is much longer than the one of fuels, an import will (over the 
lifetime) decrease the saved emissions only very little. 

  



40 

 

3.5 Environmental impact 

As everything has an impact in its (direct) environment, also the energies used in dwellings 
have. As shown in Table 9 and Table 11 every form of fuel impacts the environment. To rate 
the different fuels and energy sources most often the CO2 equivalent is used. In this report 
also the SO2 equivalent is introduced. 

3.5.1 CO2 equivalent 

Similar to the merit order for power plants an order for fuels (for heating and hot water) is 
introduced. In contrast to the merit order, which is based only on the costs, this ranking is 
based on the emissivity, availability and the competing demands, e.g. used as material. This is 
important as only this allows comparing different measures against each other. This order is 
mainly based on the total emissions (per kWh), but also on the ability to substitute a certain 
fuel. The data is also taken from the GEMIS database, which was introduced in chapter 3.2 
above. Fuel with a top rank will be replaced by fuel with a lower rank. The following Table 9 
gives the ranking used and a short explanation, if the order differs from the emissivity. 

Table 9: Fuel substitution order 

Rank Fuel 
Emissions 

[g CO2-eq. / kWh] 
Comment 

1 Coal 330 
Heavily subsidised in Germany 

and mining is determined 

2 Electricity 579 
Can hardly be stored and used for 

other purposes 

3 Oil 313.5  

4 Gas 245 

Emissions can be reduced by 
increasing the share of biogas or 

hydrogen; also a good energy 
storage 

5 Biomass / waste 91.4  

6 District heating 251 
Emissions can be reduced by 

change of fuel 

7 
Solar / geothermal 

energy 
75 (photovoltaic) , 

others neglectable11 
 

                                                           
11 CO2-Emissionen der Stromerzeugung - Ein ganzheitlicher Vergleich verschiedener 

Techniken, 2007 



41 

 

Another problem comes along with the use of gas, or to be more precise the methane in the 
gas. Its impact on the atmosphere is about 25 times more damaging than CO2. As methane is 
mostly not produced at the place of final use, it needs to be transported, in Germany mostly 
pumped through pipelines, to the place of combustion. The leakage during transportation is at 
the moment at about 36 g CO2 equivalent / kWh. It must be argued that with increasing 
absolute amount, also the absolute emissions increase, but it must then also be considered that 
a local production of this gas reduces the losses, as they occur per km pipeline. (E.ON, 2005) 

A further major discussable factor is the emission factor of biomass. They reach in literature 
from -575 to 100 g/kWh, which is due to the different assumptions. The negative values result 
from avoided methane emissions, which results from the natural decomposing of the biomass. 
(CO2-Emissionen der Stromerzeugung - Ein ganzheitlicher Vergleich verschiedener 
Techniken, 2007) 

3.5.2 SO2 equivalent 

SO2 is one of the main causes for acid rain, forest decline and acidification on foil. After the 
introduction of strippers in the late 1980’s it went out of the public focus, as the impacts 
mentioned upfront declined rapidly. But nevertheless every combustion emits SO2 and similar 
substances. The SO2 equivalent, analogous to the CO2 equivalent, rates the impact of different 
substances on the environment, as indicated in Table 10.  

Table 10: SO2 equivalent (Staiß, 2003) 

Substance SO2 NOx HCl HF NH3 H2S 

SO2 

equivalent 
1 0.696 0.878 1.601 3.762 0.983 

 

For the further calculations the following values for the different fuels are used (Life Cycle 
Umweltbilanz von österreichischen Heizsystemen, 2000) and (Zech, et al.): 

Table 11: SO2 equivalent emssions of different fuels 

 

G
a

s 

O
il

 

C
o

a
l 

B
io

m
a

ss
 

D
is

tr
ic

t 

h
ea

ti
n

g
 

E
le

ct
ri

ci
ty

 

G
eo

th
er

m
a

l 

en
er

g
y

 

P
h

o
to

-

v
o

lt
a

ic
 

S
o

la
r 

th
er

m
a

l 
 

SO2 equivalent 

[g/kWh] 
0.25 0.65 4 1.2 0.4 0.8 0.045 0.676 0.25 

 



42 

 

This value might either be used as another major indicator to rate heating systems, or as a 
secondary to decide between two CO2-equivalent wise similar options. 

 

As well as for CO2-equivalent as for SO2 equivalent emissions it must be kept in mind that 
those emitted by biomass are part of the regular cycle, whereas those from fossil have been 
stored and excluded from circulation for millions of years. These emissions have a high 
impact on the present climate. In contrast the biomass fuels add no quantities to the natural 
circulation. 

3.6 Costs 

For the dwelling owner the costs and revenues are the major factor to either decide on 
applying a measure or not. The above investigated measures represent an update of a part of 
the current building stock. These can either be done by using less efficient materials or the 
measures only to a share of buildings. The first alternative is most unlikely to happen, as only 
investments in to an at least up to date level are made. As the discomfort is the same for the 
inhabitant, more efficient measures are chosen, if they return a cost saving. A applying of 
measures with up to date materials in just a part of the building stock, can be simulated by 
interpolating the different measures. 
From a technical and national point of view especially the maximum potentials are of most 
interest and are thus investigated mainly in the following chapters. 

An investigation of small, medium and big saving potential will show the relation between 
costs and saved energy and emissions. 

3.6.1 Measures 

Besides the measures summed up in the pathway project, also the costs for retrofitting the 
whole envelope are investigated. This is due to the fact that such massive renovations are 
aggregated and it is made use of synergies. Furthermore some components (e.g. furnace) of 
the new energy system must be dimensioned according to other parts (e.g. insulation). In 
addition those measures with the biggest reduction in emissions and delivered energy are 
considered. 

The costs for certain measures are marginal costs. This is due to the fact that nearly all of the 
energy renovations will be done when a ‘cosmetic’ renovation or a replacement due to failure 
is performed. The costs for the measures to save electricity from appliances and lighting are 
set to 0 as well, as EU regulations ban more and more inefficient products from the market, as 
stated above. 

The costs for certain measures were mostly taken from the Schwäbsich Hall bank, which 
finances housing related projects, as renovations. If not indicated other. 



43 

 

The costs for packages are the sum of all individual measures, so synergies are not accounted 
for. As measures have different lifetimes, the costs for each sub-measure was up scaled to the 
lifetime of the longest measure, mostly the insulation with 40 years. 

3.6.2 Maintenance 

The maintenance costs for buildings and its components depend much on the age of the 
building, its construction complexity and the type of building. 

As the calculated values are average across the whole building stock also average values for 
maintenance must be applied. Also no inflation needs to be considered, as it is calculated with 
respect to the reference year 2009. 

The effects of the age of a building may be neglected in thi