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Analysis of cost-optimal minimum energy efficiency requirements for buildings
Endrik Arumägi, Raimo Simson, Kalle Kuusk, Targo Kalamees, Jarek Kurnitski
2017
European Union For the future
Cohesion Fund of Estonia
Foreword This report has been prepared by the Nearly Zero-Energy Buildings Research Group of the Institute of Civil Engineering and Architecture of Tallinn University of Technology within the framework of the project ‘Study on the cost-effective minimum energy efficiency requirements for buildings’. The work was ordered and financed by the Ministry of Economic Affairs and Communications and the KredEx Fund. The research steering group included the following members: Margus Tali (Ministry of Economic Affairs and Communications), Kalle Kuusk (KredEx), Jarek Kurnitski, Endrik Arumägi and Teet Tark (all from Tallinn University of Technology). Reference: Arumägi, E., Simson, R., Kuusk, K., Kalamees, T., Kurnitski, J. (2017). Analysis of cost-optimal minimum energy efficiency requirements for buildings. Tallinn University of Technology.
Copyrights: authors, 2017 Non-exclusive licence for the use of personal copyrights: KredEx Fund, Ministry of Economic Affairs and Communications
Summary In the scope of this study, calculations of cost-optimal energy efficiency levels for new and significantly renovated buildings were performed. According to the Directive on the Energy Performance of Buildings, cost-optimal calculations are to be performed every five years, and the first time these calculations were due to be performed was in 2012 (the calculations for Estonia were completed in 2011). Cost-optimal is the level of energy efficiency at which the total cost of the life cycle is minimised, taking into account the costs of construction, energy and maintenance. According to the methodology, a calculation of the life cycle is performed using the net present value method for a period of 30 years for residential buildings and for a period of 20 years for non-residential buildings. Cost-optimisation calculations are performed as the investor’s financial calculation and a macroeconomic calculation. The financial calculation takes into account appreciation of all taxes, money and energy costs. The macroeconomic calculation is performed without the value added tax but including the cost of CO2 emissions. Calculations are performed at various interest rates to assess sensitivity. Macroeconomic calculations were performed in Estonia for the first time, and their results in most cases overlapped with the results of financial calculations. Only in the case of the smaller residential buildings did the macroeconomic calculations demonstrate a somewhat lower cost-optimal energy performance indicator. There was no difference with regard to other buildings. The results of the financial calculations for new buildings are summarised in the following table. Compared to 2011, cost-optimal energy performance indicators have improved significantly, reaching either very close to nearly zero-energy level or even surpassing it (energy performance class A). According to the results, the nearly zero-energy requirement for terraced and office buildings has become cost-optimal, while that for the apartment blocks is only one unit away. The cost-optimal value of 200 m² small residential buildings remained furthest away (7 units) from the level of the near-zero energy building. In the case of the 100 m² small residential buildings, it is essential to consider that the nearly zero-energy requirement of 100 kWh/(m²·a) applies to all small residential buildings of up to 120 m². This is why the cost-optimal energy efficiency margin is justified, because achieving energy efficiency in smaller buildings is more expensive. Cost-optimal energy performance indicators and additional costs for new buildings. The cost-optimal energy performance indicators and nearly zero-energy requirements for 2011 are included for comparison.
Building
2011 cost-optimal kWh/(m² a)
Cost-optimal kWh/(m² a)
Nearly zero-energy (class A) kWh/(m² a)
Additional cost1 EUR/m²
Small residential buildings 100 m2
- 79 100 55
Small residential buildings 200 m2
140 87 80 67
Terraced buildings - 71 80 36 Apartment buildings 145 103 100 23 Office buildings 140 93 100 23
1Additional cost per square metre of heated area including value added tax, as compared to a reference building. Based on the results for major renovations of small residential buildings, apartment buildings and office buildings, the cost-optimal energy efficiency level has improved by one energy performance class. Therefore, the minimum energy efficiency requirement for major renovations should be reduced by one class to class C.
Given the significant difference between the current minimum requirements for new buildings (class C) and the cost-optimal energy efficiency levels (approximately class A), implementation of the cost-optimal requirements in two stages is justified. With a preparatory period of one year, it is possible to make a transition to class B by 31 December 2018 and to class A by 31 December 2019. It is possible to make a transition to class C in the case of major renovations by 31 December 2018 with a one-year preparatory period as well.
Table of contents
Summary ................................................................................. 3
1 Introduction ..................................................................................................................... 7
1.1 Objective .................................................................................................................. 7
1.2 Description of the study ............................................................................................ 7
2 Methodology used for the analysis ................................................................................... 8
2.1 Energy calculations ................................................................................................... 8
2.2 Cost-effectiveness calculations .................................................................................. 8
2.2.1 Costs of structural solutions and openings ..................................................................... 11
3 Cost-effectiveness of new buildings ................................................................................ 15
3.1 Small residential buildings ....................................................................................... 15
3.1.1 Detached residential building (100 m²) .................................................................... 15
3.1.2 Results of cost-effectiveness calculations ................................................................ 17
3.1.3 Detached residential building (200 m²) .................................................................... 20
3.1.4 Results of cost-effectiveness calculations ................................................................ 23
3.1.5 Terraced building ...................................................................................................... 26
3.1.6 Results of cost-effectiveness calculations ................................................................ 28
3.2 Apartment buildings ............................................................................................... 31
3.2.1 Description of the building ....................................................................................... 31
3.2.2 Results of cost-effectiveness calculations ................................................................ 33
3.3 Office buildings ....................................................................................................... 36
3.3.1 Description of the analysed building ........................................................................ 36
3.3.2 Description of the analysed measures ............................................................................ 39
3.3.3 Results of cost-effectiveness calculations ................................................................ 41
4 Cost-effectiveness of renovated buildings ....................................................................... 45
4.1 Small residential buildings ....................................................................................... 45
4.1.1 Description of the buildings...................................................................................... 45
4.1.2 Description of renovation measures ........................................................................ 45
4.1.3 Results of cost-effectiveness calculations ................................................................ 47
4.2 Apartment buildings ............................................................................................... 48
4.2.1 Description of the buildings...................................................................................... 48
4.2.2 Description of renovation measures ........................................................................ 71
4.2.3 Results of cost-effectiveness calculations ....................................................................... 71
4.3 Office buildings ....................................................................................................... 73
4.3.1 Description of the buildings...................................................................................... 73
4.3.2 Description of renovation measures ........................................................................ 74
4.3.3 Results of cost-effectiveness calculations ....................................................................... 75
References ............................................................................ 76
Annexes ................................................................................. 77
Annex 1. Simulation results for a small residential building (100 m²). .................................... 77
Annex 2. Simulation results for a small residential building (200 m²). .................................... 81
Annex 3. Simulation results for a terraced building. ................................................................ 88
Annex 4. Simulation results for an office building.................................................................... 92
Annex 5. Annex III to Regulation EU 244 (pursuant to EU Directive 2010/31/EU) .................. 96
1 Introduction
1.1 Objective
The aim of the study is to assess the cost-optimal minimum energy efficiency of new buildings, taking into account the energy use of the building and the additional costs associated with achieving the nearly zero-energy level. The energy efficiency requirements applicable at the time of conducting the study were as follows: Minimum requirements for new buildings: • private houses: ≤ 160 kWh/(m² a); • apartment blocks: ≤ 150 kWh/(m² a); • office buildings, libraries and research buildings: ≤ 160 kWh/(m² a). Requirements for low-energy buildings: • private houses: ≤ 120 kWh/(m² a); • apartment blocks: ≤ 120 kWh/(m² a); • office buildings, libraries and research buildings: ≤ 160 kWh/(m² a). Nearly zero-energy level requirements for new buildings: • private houses: ≤ 50 kWh/(m² a); • apartment blocks: ≤ 100 kWh/(m² a); • office buildings, libraries and research buildings: ≤ 100 kWh/(m² a).
1.2 Description of the study
An analysis of cost-optimal energy efficiency levels was performed based on the applicable limit values of the total energy use for the nearly zero-energy buildings provided in the current regulation on minimum energy performance requirements. Calculations for the new and significantly reconstructed buildings are based on the building categories (reference buildings representing their intended use). Over the course of the analysis, the energy use of buildings for compliance with the nearly zero-energy level requirement was calculated. The fulfilment of the nearly zero-energy level requirement requires local production of renewable energy. According to the definition in Regulation No 55 of the Ministry of Economic Affairs and Infrastructure on minimum energy performance requirements for buildings, the nearly zero-energy building status is obtained once a low-energy building acquires a local renewable electricity system with the required productivity, which ensures the achievement of the nearly zero-energy level. During the assessment of cost-effectiveness, the energy savings resulting from the difference in the energy use of a conventional building and a low-energy building were used, as well as the additional investment required for achieving the nearly zero-energy level, the amount of locally produced electricity and its cost. The analysis is based on the results of previous studies and on the representative buildings used in the project for residential nearly zero-energy buildings:
small residential buildings, 100 m²;
small residential buildings, 200 m²;
terraced buildings;
apartment buildings;
office buildings.
The results of the cost-effectiveness calculations are presented as a ratio between the change in the net present value of the building’s expenses and the energy performance indicator.
2 Methodology used for the analysis
The energy demand of a building was calculated according to the methodology for calculating
the energy efficiency of buildings, using dynamic energy simulation software IDA Indoor
Climate and Energy 4.7.1 (IDA-ICE) from the company EQUA Simulations AB. The software
used for calculations meets all the software requirements in the regulation on minimum energy
performance requirements. The results obtained from the dynamic simulations were used to
assess the energy savings potential of different energy efficiency measures and to calculate
the energy consumption of buildings with different structural solutions.
The unit prices required for calculating the additional cost of various structural solutions
affecting the energy use of buildings were obtained from construction companies by the
building type. The budget officers provided unit costs per square metre for various structural
solutions and openings, which also included the costs of material and installation. The costs of
solar panels were estimated. The costs of structures, openings and technical systems were
calculated by the following companies: Merko AS, Timbeco AS, YIT AS, Matek AS, HEVAC
OÜ, Energiamaja OÜ and Kliimaseade OÜ. All calculated costs included VAT.
2.1 Energy calculations
A room-based simulation model was developed for all buildings. The models were designed according to the architectural bases, views and sections of buildings. The solutions for openings and the building envelope were selected according to the building design.
First of all, simulation models were developed to assess the impact of individual components of the building envelope on the energy consumption of the building. In the initial energy simulations, only one component was changed and the result was compared to the energy consumption of the original building. The variable of the individual modifiable components was the thermal transmittance of the relevant component. In addition to the thermal transmittance, the effect of the building’s air permeability was also assessed. The values of thermal transmittance and air leakage of different structural solutions used in simulation models were as follows:
thermal transmittance U of the external wall [W/(m²·K)]: 0.16, 0.14, 0.12, 0.10;
thermal transmittance U of the roofing deck [W/(m²·K)]: 0.12, 0.10, 0.08;
thermal transmittance U of the floor [W/(m²·K)]: 0.18, 0.14, 0.10;
thermal transmittance U of the windows [W/(m²·K)]: 1.1, 0.9, 0.7;
number of air leaks q50 [m³/h·m²]: 6.0, 3.0, 1.5, 1.0.
In addition to assessing the impact of the individual components on the building’s energy consumption, the calculation of the energy efficiency indicator was performed for all combinations by combining various values of thermal conductivity and air leakage of structural solutions.
2.2 Cost-effectiveness calculations
The financial calculations are based on the methodology described in Delegated Regulation (EU) No 244/2012 of the European Commission.
The cost-effectiveness of different structural solutions was estimated using the net present value method:
where:
τ means the calculation period;
CG(τ) means total cost (referred to starting year τ0) over the calculation period;
Ci means initial investment costs for measure or set of measures j; Ca,i (j) means annual cost during year i for measure or set of measures j; Rd(i) means discount factor for year i.
The cost effectiveness of the additional costs related to structural solutions and renewable energy solutions that were needed to meet the requirements of the nearly zero-energy building was assessed in these calculations:
The discount was calculated using the calculated interest rate and a relative price increase during the calculation period. Depending on the uses of the buildings, the cost-effectiveness calculation period was chosen to be 30 years (for residential buildings) or 20 years (for non-residential buildings). The discount was based on the real interest rate of 2.5 %, which corresponds to the rate of return of 3.5 % when inflation is 1 %. The real escalation of energy prices for the calculation period was taken at 1 % per annum.
The initial purchase price of energy carriers was calculated at the following prices (including VAT):
electricity purchase 0.113 EUR/kWh;
electricity sale 0.035 EUR/kWh (re-sale price of electricity from PV panels back to the network);
district heating 0.060 EUR/kWh;
gas 0.048 EUR/kWh;
pellet 0.045 EUR/kWh.
Financial calculations were based on the additional investment needed to achieve the nearly zero-energy levels. When calculating the additional cost of the measure/package, the prices payable by the customer, including all applicable taxes, VAT and support were taken into account in the financial calculations. The calculations did not take into account the potential support that may apply to the introduction of various technologies related to the production of renewable energy.
The cost of building components was calculated by totalling the different expense types and by applying a discount rate to them using the discount factor.
The criterion of profitability is that the net revenue generated and discounted during the economic life of the investment should be greater than the initial investment.
Table 1. Parameter values used for discount. Name Value
Thermal energy (district heating) price,
EUR/kWh
0.05995
Thermal energy (gas) price, EUR/kWh 0.04774
Electricity price, EUR/kWh 0.11316
Electricity price when sold to the network,
EUR/kWh
0.035
Real interest rate, % 2.5
Escalation (electricity), % 1
Escalation (thermal energy), % 1
Calculation period, years
- residential buildings
- office buildings
30
20
The macroeconomic calculations are based on the methodology described in Delegated Regulation (EU) No 244/2012 of the European Commission. The total cost of the measures is calculated as follows:
τ means the calculation period;
CG(τ) means total cost (referred to starting year τ0) over the calculation period;
Ci means initial investment costs for measure or set of measures j; Ca,i (j) means annual cost during year i for measure or set of measures j; Rd(i) means discount factor for year i; Cc,i (j) means annual cost of CO2 emissions during year i for measure or set of measures j.
The calculations are based on the prognosis of the long-term CO2 price variation in the Delegated Regulation (EU) No 244/2012 of the European Commission (see Table 2).
Table 2. Estimated CO2 prices used in macroeconomic calculations.
Carbon price evolution 2020 2025 2030 2035 2040 2045 2050
Reference (frag. action, ref. fossil f. prices)
16.5 20 36 50 52 51 50
Effect. Techn. (glob. action, low fossil f. prices)
25 38 60 64 78 115 190
Effect. Techn. (frag. action, ref. fossil f. prices)
25 34 51 53 64 92 147
Source: Annex 7.10 in the document http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=SEC:2011:0288:FIN:EN:PDF
Calculations of the amounts of CO2 emissions required for macroeconomic calculations are based on the CO2 specific emission rates provided in the report ‘Study on the cost-effective minimum energy efficiency requirements for buildings. Weighting factors for energy carriers’.
The CO2 specific emission factors for the main energy carriers calculated in the report ‘Study on the cost-effective minimum energy efficiency requirements for buildings. Weighting factors for energy carriers’ are given in Table 3.
Table 3. CO2 specific emission factors for the main energy carriers
Energy carrier CO2 specific
emissions
kgCO2/MWh
Electricity 1150
District heating 193
Efficient district heating 39
Extremely efficient district
heating
39
Gas 202
Cost,
(E
UR
/m²)
C
ost,
(E
UR
/m²)
2.2.1 Costs of structural solutions and openings
The costs of the structural solutions for private residential buildings and apartment blocks based on the bids received from builders are shown in the graphs in Figure 1 to Figure 8.
Thermal transmittance U, (W/m²·K)
Figure 1. The dependence of the structure’s estimated cost on thermal transmittance (U): Timber frame walls.
Thermal transmittance U, (W/m²·K)
Figure 2. The dependence of the structure’s estimated cost on thermal transmittance (U): Concrete block walls with rendering.
Min. wool
PIR
Min. wool
PIR
Supplier 1
Supplier 2
Min. wool λ=0.040
Min. wool λ=0.040
Min. wool λ=0.035
Min. wool λ=0.035
EPS λ=0.040
EPS λ=0.040
EPS λ=0.033
EPS λ=0.033
PIR
Supplier 1
Supplier 2
Cost,
(E
UR
/m²)
Co
st,
(E
UR
/m²)
Cost,
(E
UR
/m²)
Thermal transmittance U, (W/m²·K) Figure 3. The dependence of the structure’s estimated cost on thermal transmittance (U): Reinforced concrete walls.
Thermal transmittance U, (W/m²·K)
Figure 4. The dependence of the structure’s estimated cost on thermal transmittance (U): Timber frame roofs.
Min. wool λ=0.040
Min. wool λ=0.035
Min. wool λ=0.035
EPS λ=0.040
EPS λ=0.040
EPS λ=0.033
EPS λ=0.033
PIR
PIR
Supplier 1
Supplier 2
Min. wool
Cellulose fibre wool
PIR
Min. wool
Cellulose fibre wool
PIR
Supplier 1
Supplier 2
Cost,
(E
UR
/m²)
Co
st,
(E
UR
/m²)
Thermal transmittance U,
(W/m²·K)
Figure 5. The dependence of the structure’s estimated cost on thermal transmittance (U): Reinforced concrete roofs.
Thermal transmittance U,
(W/m²·K)
Figure 6. The dependence of the structure’s estimated cost on thermal transmittance (U): Reinforced concrete floor above ambient air.
Min. wool
Min. wool
EPS λ=0.040
EPS λ=0.040
EPS λ=0.033
EPS λ=0.033
PIR
PIR
Supplier 1
Supplier 2
EPS λ=0.040
EPS λ=0.040
EPS λ=0.033
EPS λ=0.033
Min. wool λ=0.040
Min. wool λ=0.035
Supplier 1
Supplier 2
Co
st,
(E
UR
/m²)
Cost,
(E
UR
/m²)
)
Thermal transmittance
U, (W/m²·K)
Figure 7. The dependence of the structure’s estimated cost on thermal transmittance (U): Reinforced concrete floor at ground level.
Thermal transmittance U, (W/m²·K)
Figure 8. The dependence of the estimated cost of windows on thermal transmittance (U).
EPS λ=0.040
EPS λ=0.040
EPS λ=0.033
PIR
PIR
Supplier 1
Supplier 2
Openable wood-aluminium
Unopenable wood-aluminium
Openable wooden
Unopenable wooden
Openable plastic
Supplier 1
Supplier 2
3 Cost-effectiveness of new buildings
The simulations and calculations for assessing the cost-effectiveness of technical solutions are based on the selected sample buildings.
Taking into account the additional investment to improve the structures and the heat energy savings this achieves, energy efficiency indicators which whose costs were still cost-effective were identified. The results of the financial calculations are shown in Figures 12 to 41. Each point on the graph represents one combination of structural solutions and the energy efficiency thus achieved. All points below the baseline relate to combinations that are cost-effective. The points above the baseline relate to combinations for which the original investment to improve energy efficiency exceeds the amount of energy savings.
3.1 Small residential buildings
3.1.1 Detached residential building (100 m²)
The selected building is a single-storey building with a rectangular main plan. The load-bearing part of the building is a wooden structure. The external walls of the building are insulated timber frame walls covered externally with boards, while the internal walls are timber framing walls covered with plasterboard. The plan and views of the building are shown in Figures 9 and 10.
Figure 9. Ground floor plan of a detached residential building (100 m²)
Figure 10. Views of a detached residential building (100 m²) Table 4. Technical characteristics of the building.
Parameter Value
Heated area (m²) 101
Base area of the building (m²) 167
Floors above the ground 1
Floors below the ground -
Height (m) 6.7
Length (m) 14.2
Width (m) 9.6
Closed net area (m²) 101.1
Capacity (m³) 400
Common area (m²)
Dwelling area (m²) 79.1
Total dwelling rooms 4
ΔN
PV
, E
UR
/m²
ΔN
PV
, E
UR
/m²
3.1.2 Results of cost-effectiveness calculations
Figures 11 to 13 reflect the results of cost-effectiveness calculations for a residential building with different combinations of structural solutions and heat sources and real interest rates of 2.0 %, 2.5 % and 3.0 %.
EPI, kWh/(m² a)
Figure 11. Energy performance indicator (EPI) of a detached residential building (100 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.0 %.
EPI, kWh/(m² a) Figure 12. Energy performance indicator (EPI) of a detached residential building (100 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.5 %.
Ground source heat pump
Air-water SP Gas boiler
ΔN
PV
, E
UR
/m²
ΔN
PV
, E
UR
/m²
EPI, kWh/(m² a)
Figure 13. Energy performance indicator (EPI) of a detached residential building
(100 m²) and change in the net present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 3.0 %.
Based on the definition of a nearly zero-energy building given in the Directive on Energy Performance of Buildings, local production of renewable energy is required to reach the nearly zero-energy level. Local generation of renewable energy is added below to the architecturally and technically appropriate combinations. Electricity generation with solar panels was considered as a solution for local production of renewable energy.
In the case of a smaller residential building, the cost-optimal range of energy performance indicators without local production of renewable energy is between 123 and 131 kWh/(m²a), and the additional investment is in the range between 7.4 and 16.9 EUR/m².
Figures 14 to 16 show the results of cost-effectiveness calculations for residential buildings in different combinations of structural solutions, heat sources and local renewable energy production (with PV panels generating solar energy) at the real interest rates of 2.0 %, 2.5 % and 3.0 %.
EPI, kWh/(m² a)
ΔN
PV
, E
UR
/m²
ΔN
PV
, E
UR
/m²
Figure 14. Energy performance indicator (EPI) of a detached residential building (100 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 2.8 kW). Real interest rate 2.0 %.
EPI, kWh/(m² a)
Figure 15. Energy performance indicator (EPI) of a detached residential building (100 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 2.8 kW). Real interest rate 2.5 %.
EPI, kWh/(m² a) Figure 16. Energy performance indicator (EPI) of a detached residential building (100 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 2.8 kW). Real interest rate 3.0 %.
ΔN
PV
, EU
R/m
²
According to the current requirements, the limit value of the nearly zero-energy level for a
residential building is the EPI of 50 kWh/(m²a). The results of the calculations show that the cost-optimal levels of energy performance indicators for selected buildings exceed the current nearly zero-energy limit value.
With local renewable energy production, the cost-optimal range of energy performance indicators for a detached residential building (100 m²) is from 77 to 83 kWh/(m²a), and the additional investment is between 51.0 and 58.3 EUR/m².
The calculation results of the macroeconomic total expenditure are presented in Figure 17.
EPI, kWh/(m² a)
Figure 17. Results of cost-effectiveness calculations for a detached residential building (100 m²) at the macroeconomic level.
Real interest rate 2.5 %.
At the macroeconomic level, the cost-optimal range of energy performance indicators for a detached residential building (100 m²) with a geothermal pump and generation of local renewable energy is 60 to 70 kWh(m² a); in the case of a gas boiler, the figure is between 115 and 119 kWh(m² a).
3.1.3 Detached residential building (200 m²)
The selected building has two floors. This building has a rectangular main plan. The bearing part of the building is a stone structure with ceiling slabs of reinforced concrete elements. The external walls of the building are externally insulated concrete block walls, while the internal walls are plasterboard on a metal frame. The building plans are shown in Figures 18 and 19, with the views given in Figure 20.
Figure 18. First floor plan of a detached residential building (200 m²).
Figure 19. Second floor plan of a detached residential building (200 m²).
Figure 20. Views of a detached residential building (200 m²) Table 5. Technical characteristics of the building.
Parameter Value
Heated area (m²) 206
Base area of the building (m²) 179
Floors above the ground 2
Floors below the ground -
Height (m) 7
Length (m) 19.9
Width (m) 12.8
Closed net area (m²) 190.3
Capacity (m³) 1252
Common area (m²)
Dwelling area (m²) 160.8
Total dwelling rooms 4
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
3.1.4 Results of cost-effectiveness calculations
Calculations for a larger residential building were performed in a similar way to the calculations for a small residential building. Figures 21 to 23 reflect the results of cost-effectiveness calculations for residential buildings in different combinations of structural solutions and heat sources at the real interest rates of 2.0 %, 2.5 % and 3.0 %.
EPI, kWh/(m² a) Figure 21. Energy performance indicator (EPI) of a detached residential building (200 m²) and change in the net present value (∆NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.0 %.
EPI, kWh/(m² a)
Figure 22. Energy performance indicator (EPI) of a detached residential building (200 m²) and
change in the net present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.5 %.
Ground source heat pump Air-water SP Gas boiler
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
EPI, kWh/(m² a)
Figure 23. Energy performance indicator (EPI) of a detached residential building (200 m²) and
change in the net present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 3.0 %.
In the case of a detached residential building (200 m²), the cost-optimal range of energy performance indicators without local production of renewable energy is between 137 and 141 kWh/(m²a), and the additional investment is in the range between 13.6 and 17.1 EUR/m².
Figures 24 to 26 show the results of cost-effectiveness calculations for a detached residential building (200 m²) in different combinations of structural solutions, heat sources and local renewable energy production (with PV panels generating solar energy) at the real interest rates of 2.0 %, 2.5 % and 3.0 %.
EPI, kWh/(m² a) Figure 24. Energy performance indicator (EPI) of a detached residential building (200 m²) and
change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.0 kW). Real interest rate 2.0 %.
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
EPI, kWh/(m² a) Figure 25. Energy performance indicator (EPI) of a detached residential building (200 m²) and
change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.0 kW). Real interest rate 2.5 %.
EPI, kWh/(m² a) Figure 26. Energy performance indicator (EPI) of a detached residential building (200 m²)
and change in the net present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.0 kW). Real interest rate 3.0 %. With local renewable energy production, the cost-optimal range of energy performance indicators for a detached residential building (200 m²) is from 87 to 91 kWh/(m²a), and the additional investment is between 63.2 and 66.7 EUR/m².
ΔN
PV
, EU
R/m
²
EPI, kWh/(m² a) Figure 27. Results of cost-effectiveness calculations for a detached residential building (200 m²) at the macroeconomic level. Real interest rate 2.5 %.
At the macroeconomic level, the cost-optimal range of energy performance indicators for a detached residential building (200 m²) with a geothermal pump and generation of local renewable energy is 55 to 65 kWh(m² a), with an air-water heat pump and generation of local renewable energy it is 85 to 90 kWh(m² a); in the case of a gas boiler and generation of local renewable energy, the figure is between 115 and 119 kWh(m² a).
3.1.5 Terraced building
The selected building has two floors. The building is divided into six sections with separate entrances. It has a rectangular base plan with some protruding parts on the façade. External walls of the building are made of wall elements on a wooden frame, and these are covered with plasterboard on the inside. Partition walls between the sections of the building are made of wall elements on a wooden frame, with the internal walls made of plasterboard on a metal frame. The details of the building are given in Table 6, with the plans shown in Figure 28 and the views in Figure 29. Table 6. Details of the terraced building.
Parameter Value
Building footprint (m²) 643.4
Floors above the ground 2
Floors below the ground -
Height (m) 6.6
Length (m) 53.2
Width (m) 22.9
Net enclosed area (m²) 676.8
Heated area (m²) 565.8
Capacity (m³) 2180
Common area (m²) 16
Dwelling area (m²) 676.8
Total dwelling rooms 6
Figure 28. Plans of the first and second floors of the terraced building.
Figure 29. Views of the terraced building.
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
3.1.6 Results of cost-effectiveness calculations
The results of cost-effectiveness calculations for the terraced building are provided in Figures 30 to 35.
EPI, kWh/(m² a) Figure 30. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.0 %.
EPI, kWh/(m² a) Figure 31. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 2.5 %.
Ground source heat pump
Air-water SP
Gas boiler
ΔN
PV
, EU
R/m
²
ΔN
PV
, EU
R/m
²
EPI, kWh/(m² a) Figure 32. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources. Real interest rate 3.0 %.
In the case of a terraced building, the cost-optimal range of energy performance indicators without local production of renewable energy is between 84 and 86 kWh/(m²a), and the additional investment is in the range between 22.7 and 31.4 EUR/m².
Figures 33 to 35 show the results of cost-effectiveness calculations for terraced buildings in different combinations of structural solutions, heat sources and local renewable energy production (with PV panels generating solar energy) at the real interest rates of 2.0 %, 2.5 % and 3.0 %.
EPI, kWh/(m² a) Figure 33. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.5 kW). Real interest rate 2.0 %.
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
EPI, kWh/(m² a)
Figure 34. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.5 kW). Real interest rate 2.5 %.
EPI, kWh/(m² a) Figure 35. Energy performance indicator (EPI) of a terraced building and change in the net
present value (NPV) for different combinations of structural solutions and heat sources with local renewable energy production (PV panels with a nominal power of 4.5 kW). Real interest rate 3.0 %.
With local renewable energy production, the cost-optimal range of energy performance indicators for a terraced building is from 71 to 73 kWh/(m²a), and the additional investment is between 35.9 and 44.6 EUR/m².
3.2 Apartment buildings
3.2.1 Description of the building
The selected building is a 5-storey apartment block with underground parking. This building has a U-shaped main plan. The building has a 5-storey main section and 3- or 4-storey wings. There is an enclosed parking area under the building and additional parking spaces located under the projecting parts of the building facing the courtyard. The building has a concrete bearing structure with stone and concrete walls. The plans of the ground floor and the top floor of the building are shown in Figure 36, while the front and side views of the building are demonstrated in Figure 37.
Figure 36. Plans of the ground floor and the top (fifth) floor of the apartment block.
Figure 37. Front and side views of the apartment block.
ΔN
PV
, EU
R/m
²
The technical characteristics of the sample residential buildings are given in Table 7.
Table 7. Technical characteristics of the building.
Parameter Value
Heated area (m²) 6373
Base area of the building (m²) 1618
Floors above the ground 5
Floors below the ground 1
Height (m) 17.8
Length (m) 54.3
Width (m) 35.7
Closed net area (m²) 6373
Capacity (m³) 25900
Common area (m²) 2009.2
Dwelling area (m²) 3713.8
Total dwelling rooms 51
3.2.2 Results of cost-effectiveness calculations
Figures 38 to 40 reflect the results of cost-effectiveness calculations for apartment blocks in different combinations of structural solutions at the real interest rates of 2.0 %, 2.5 % and 3.0 %. Figures 41 to 43 show the cost-effective energy performance indicators that can be achieved by different combinations of structural solutions and local renewable energy production (with PV panels generating solar energy) at various real interest rates.
EPI, kWh/(m² a) Figure 38. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions. Real interest rate 2.0 %.
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
ΔN
PV
, EU
R/m
²
EPI, kWh/(m² a)
Figure 39. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions. Real interest rate 2.5 %.
EPI, kWh/(m² a)
Figure 40. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions. Real interest rate 3.0 %.
Without local renewable energy production, the cost-optimal range of energy performance indicators for an apartment block is approximately from 115 to 117 kWh/(m²a), and the additional investment is between 6.2 and 9.6 EUR/m².
EPI, kWh/(m² a)
Figure 41. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions with local renewable
ΔN
PV
, EU
R/m
²
ΔN
PV
, EU
R/m
²
energy production (PV panels with a nominal power of 53 kW). Real interest rate 2.0 %.
EPI, kWh/(m² a)
Figure 42. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions with local renewable energy production (PV panels with a nominal power of 53 kW). Real interest rate 2.5 %.
EPI, kWh/(m² a)
Figure 43. Energy performance indicator (EPI) of an apartment block and change in the net
present value (NPV) for different combinations of structural solutions with local renewable energy production (PV panels with a nominal power of 53 kW). Real interest rate 3.0 %.
According to the current requirements, the limit value of the nearly zero-energy level for a
section of an apartment block is an EPI of 100 kWh/(m²a). The results of the calculations
show that the cost-optimal levels of energy performance indicators exceed the current nearly zero-energy limit value.
With local renewable energy production, the cost-optimal range of energy performance indicators for an apartment block is from 101 to 103 kWh/(m²a), and the additional investment is between 22.9 and 26.3 EUR/m².
The calculation results of the macroeconomic total expenditure for an apartment block are presented in Figure 44.
ΔN
PV
, EU
R/m
²
EPI, kWh/(m² a)
Figure 44. Results of cost-effectiveness calculations of an apartment block at the macroeconomic level. Real interest rate 2.5 %.
3.3 Office buildings
3.3.1 Description of the analysed building
The analysed office building has six floors (five in some parts) with an underground unheated parking area (Figure 45). The underground parking area makes up about 20 % of the gross floor area of the building, which has been treated as unheated space in this study. Approximately 75 % of the building is made up of office and commercial premises (Figure 46).
Figure 45. Views of the office building.
Büroo Office
Tehnoruum Technical area
Äprind Commercial premises
Kohvik Café
Abiruum Utility room
Figure 46. Standard floor plans of an office building with zones. These plans were used to compile a simulation model of energy calculations. First floor plan (top left); plan of the floors 2 to 5 (top right); sixth floor plan (bottom). The general details of the building are given in Table 8, with the details of structures shown in Table 9. The 3D simulation model of the building is shown in Figure 47.
Table 8. Details of the studied building.
Parameter Value
Heated area of the building, Aheated, m²
4191.2
Gross floor area of the building, Agross, m²
5820.0
Number of floors, - 6
Proportion of windows in the façade,
%
55.1
Ratio of the building envelope to the
heated area
Aenv/Aheated, -
1.23
Specific heat loss, ∑H/Aheated, 0.49
W/(K·m²)
Source of heat supply for
heating and for warming up of
domestic water and ventilation
air
district heating
Heating elements steel panel radiators
Cold source compressor-cold machine
Room equipment for cooling active cooling pads
Ventilation systems mechanical SP-VT in
office rooms and the
parking area; VT system
in toilets
Ventilation heat recovery rotor heat exchanger
Table 9. Description of the boundary structures of the building.
Boundary structure Thermal
conductivity Ui,
W/(m²·K)
Surface area
Ai, m²
Specific heat
loss H, W/K
Proportion of
H, %
External wall 0.20 1077.1 247.7 10.4 %
Roofing deck 0.13 813.1 105.7 5.1 %
Ceiling slab above
ambient air
0.12 139.0 16.7 0.8 %
Ceiling slab above
ambient air
0.24 27.9 6.7 0.3 %
Ground floor (parking
area)
0.13 1056.2 137.3 6.7 %
Ceiling slab (between
the parking area and
the first floor)
0.24
611.4
146.7
7.1 %
Windows 0.70 1319.6 923.7 44.7 %
Doors 1.50 15.3 22.9 1.1 %
Thermal bridges b - - 137.6 6.7 %
Infiltration c - - 352.0 17.1 %
Total / Average 0.41 5059.7 2064.8 100 %
Figure 47. South view (left) and north view (right) of the building’s simulation model.
3.3.2 Description of the analysed measures
The analysis of an office building was focused on the façade design of the building, efficient technical systems and local renewable energy options. The volumetric solution in the project design for the studied building and its energy supply mode formed the basis of the analysis. The following parameters were examined with regard to the façade design:
the insulation thickness of the external wall and roofing deck;
window transparency, size and number of insulated glass units;
static and dynamic solar shielding. The following parameters were analysed for the technical systems;
heat exchanger temperature ratio (ηT) and specific power (SFP) of ventilation units;
power of the building’s cooling system (kW) depending on the façade solutions;
specific power (W/m²) and control of the lighting system.
The thickness of the insulating material for the external wall was changed by 30 mm increments and the roofing deck was changed by 50 mm increments. Unit pricing for the boundary structures was calculated based on the data in Table 10, taking into account the cost of materials and installation.
Table 10. Insulation thickness, thermal conductivity and cost of the boundary structures. Boundary structure diso, mm Ui, W/(m²·K) Unit price, EUR/m²
External wall
140 0.30 358.6 170 0.24 361.3 200 0.20 364.0 230 0.17 366.7 260 0.15 369.4 290 0.13 372.1
Roofing deck
200 0.16 91.5 250 0.13 94.0 300 0.11 96.5 350 0.10 99.0 400 0.09 101.5
In addition to the triple sun protection glazing in the project design, windows with clear glazing, both triple and quadruple, were also analysed. The thermal conductivity of the aluminium window frame was 1.0 W/(m²·K) for each solution. Table 11 describes all window options and their costs.
Table 11. Analysed insulated glass units.
Option No of
glass
panes, pcs
Ug,
W/(m²·K)
Utot,
Rfr=30 %,
W/(m²∙K)
Utot,
Rfr=10 %,
W/(m²∙K)
Selective
coating
Solar
factor g, -
Glass
unit
filling
Window
cost,
EUR/m²
3xSPG 3 0.62 0.73 0.66 SKN 165 0.22 Ar 125.0
3xCG
3
0.62
0.73 0.66 PLT
ULTRA N
0.39
Ar
120.0
4xCG
4
0.33
0.53 0.39 PLT
ULTRA N
0.28
Kry
195.0
* SPG – sun protection glazing; CG – clear glazing.
The building is designed with a rotor heat recovery ventilation unit that has the specific power
(SFP) of 1.82 kW/(m3/s) and the heat recovery temperature ratio ηT of 73.9 %. In order to reduce the energy use of ventilation, an alternative solution was analysed that uses ventilation units 1-2 times larger than conventional units [SFP = 1.57 kW/(m3/s); heat recovery temperature ratio ηT = 76.1 %].
A summary of the selected lighting fixtures is provided in Table 12.
Table 12. Type, specific power and cost of lighting fixtures.
Lighting fixture Type Power,
W
Average
specific
power,
W/m²
Cost,
EU
R/pc
Fluorescent light TRILUX Solvan C2-L UXP-S
228 03 E Solvan
64 11.90 195
LED ZUMTOBEL Mirel-L LAY
LED3800-840 M600L LDO KA
38 6.02 187
For the production of local renewable electricity, the installation of PV panels was analysed on the roofs of buildings that have approximately 620 m² of spare roof space. The technical data and cost of the selected PV panel are given in Table 13, while its output was simulated in the IDA-ICE calculation programme. The maximum surface area of PV panels is 328.1 m² (205 pcs). Three systems of different sizes were studied:
1) PV panels with an area of 70.4 m² (44 pcs) and a total output of 11 kW (micro producer) 2) PV panels with an area of 211.2 m² (132 pcs) and a total output of 33 kW (small producer) 3) PV panels with an area of 328.1 m² (205 pcs) and a total output of 51.25 kW (small producer)
The pricing of a PV panel includes the cost of an inverter (approximately 15 % of the final price), installation and material costs (30 %).
Table 13. Technical data, optimal installation and cost of the PV panel.
Parameter Value
Nominal power, W 250
Efficiency factor, % 15.9
Surface area of the PV panel, m² 1.60
Width of the PV panel, m 0.986
Angle of inclination, ° 45
Angle to the south direction, ° 24
Simulated productivity per PV panel, kWh/a 261
Cost of the PV panel (without VAT), EUR 149.50
System cost (without VAT), EUR/W 1.14*
System cost (without VAT), EUR/W 1.20**
System cost (without VAT), EUR/W 1.22***
* - system’s total power under 11 kW (44 pcs);
** - system’s total power under 33 kW (132 pcs);
*** - system’s total power over 33 kW.
Measures used in the reference model:
external wall insulation thickness 140 mm;
roofing deck insulation thickness 200 mm;
triple-glazed windows with clear glazing;
ventilation unit according to the main design (SFP = 1.82; ηT = 73.9 %);
manually time-controlled T5 fluorescent lamps.
3.3.3 Results of cost-effectiveness calculations
Local renewable energy production reduces the building’s energy performance indicator by 5.5, 16.4 and 25.5 kWh/(m²∙a) in accordance with the total power of the PV panels studied, which was 11 kW (70.4 m²), 33 kW (211.2 m²) and 51.25 kW (328.1 m²). The ratio of exported to produced electricity was calculated as falling between 14 % and 25 %. Figure 48 reflects the ratio of the additional investment in the building to the saved EPI.
Lisainvesteering/säästetud ETA Additional investment / saved EPI
VÄLISSEINA SOOJUSTUSE PAKSUS EXTERNAL WALL INSULATION THICKNESS
KATUSLAE SOOJUSTUSE PAKSUS ROOFING DECK INSULATION THICKNESS
AKNAD JA VARJESTUS WINDOWS AND SHADING
VENT VENT
VALGUSTUSSÜSTEEM LIGHTING SYSTEM
PV PANEELID PV PANELS
3x KK 3xCG
3x PK 3xSPG
3x PK + stat. verjestus 3xSPG + static shading
4xKK väikesed aknad 4xCG small windows
dün varjestus dynamic shading
SFP SFP
Luminofoorvalgusti Fluorescent light
Figure 48. Additional investment for saved EPI.
Figure 49 shows the results of a cost-effectiveness analysis that illustrate the energy performance indicators of the analysed options, the change in net present value and the amount of additional investment in comparison to the original solution.
ΔN
PV
, EU
R/m
²
Ad
dit
ion
al in
vest
men
t fo
r th
e o
rigi
nal
so
luti
on
, %
ΔN
PV
, EU
R/m
²
Figure 49. Energy performance indicator of the studied options, change in the net present value and additional investment in relation to the original solution for an office building.
Achieving the level of 112.6 kWh/(m²∙a) of a low-energy building only requires an additional investment of 0.1 %.
The additional investment required to achieve the energy efficiency level of a nearly zero-energy building is 1.6 % of the cost of the original solution (22.9 EUR/m²). The ΔNPV for this option is approximately -40 EUR/m² (savings) compared to the reference solution, therefore the achieved level of the nearly zero-energy building can be called the cost-optimal level, and the cost-optimal energy consumption range is between 90 and 95 kWh/(m²∙a). Figures 50 to 53 provide cost-effectiveness calculations for all analysed options at the real interest rates of 2.0 %, 2.5 % and 3.0 %.
nZEB with dynamic sun shading
Minimum
requirement
nZEB
Low-energy building II
Low-energy building I
Original solution
Strong class C
Additional investment EPI, kWh/(m² a)
NPV
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
ΔN
PV
, EU
R/m
²
ΔN
PV
, EU
R/m
²
Figure 50. Results of cost-effectiveness calculations for an office building. Real interest rate 2.0 %.
EPI, kWh/(m² a)
Figure 51. Results of cost-effectiveness calculations for an office building. Real interest rate 2.5 %.
Dynamic shading
EPI, kWh/(m² a)
ΔN
PV
, EU
R/m
² Δ
NP
V, E
UR
/m²
EPI, kWh/(m² a)
Figure 52. Results of cost-effectiveness calculations for an office building. Real interest rate 3.0 %.
EPI, kWh/(m² a) Figure 53. Results of macroeconomic cost-effectiveness calculations for an office building.
Real interest rate 2.5 %.
4 Cost-effectiveness of renovated buildings
4.1 Small residential buildings
4.1.1 Description of the buildings
This part of the analysis considers the options for improving the energy efficiency of small residential buildings on the basis of two sample buildings:
a newer, small residential building that only requires renovation of the technical building systems;
an older, small residential building that also requires renovation of the building envelope.
Table 14. Technical characteristics of the sample residential buildings.
Newer building (renovation of the technical building
systems only)
Older building (renovation of the structures and
technical building systems)
Number of floors: 2
Net enclosed area: 217.8 m²
Heated area: 182.3 m²
Thermal transmittance of external walls: 0.25
W/(m²K)
Thermal transmittance of roofs: 0.16 W/(m²K)
Thermal transmittance of windows: 1.8 W/(m²K)
Heating system: gas boiler + radiators
Number of floors: 1
Net enclosed area: 164.5 m²
Heated area: 164.5 m²
Thermal transmittance of external walls: 0.54
W/(m²K)
Thermal transmittance of roofs: 0.48 W/(m²K)
Thermal transmittance of windows: 2.8 W/(m²K)
Heating system: stove heating + electricity
4.1.2 Description of renovation measures
Energy efficiency packages are made up of combinations of various individual measures. Individual measures analysed:
heat recovery ventilation system η – 0.8;
replacement of the heat source: air-water heat pump, pellet boiler, geothermal heat pump;
external wall insulation: 50/100 mm, 150/200 mm, 250/300 mm;
roof insulation: 50/100 mm, 150/200 mm, 250/300 mm;
replacement of windows: U = 0.7 W/(m²K), U = 1.1 W/(m²K), U = 1.5 W/(m²K);
floor insulation: 100 mm, 200 mm, 300 mm;
installation of solar thermal collectors.
The note ‘50/100’ for the insulation layer thickness of the external wall and roofing deck refers to a situation where 50 mm of additional insulation has been used for a newer sample building and 100 mm of additional insulation has been used for an older building in order to equalise the thermal transmittance of the structures in post-renovation conditions. When evaluating the cost of the measures, the cost estimates provided by general contracting companies in the field of construction were used, which were compared with the unit prices based on EKE Nora unit prices.
Table 15. Description of reconstruction measures.
Energy
performance
class
Newer building Older building
E
Ventilation system
with heat recovery
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(pellet boiler), heating system
based on radiator heating
Additional insulation of the roof
(250 mm of mineral wool)
Replacement of doors (U = 1.0 W/(m²K))
D
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(pellet boiler)
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(pellet boiler), heating system
based on radiator heating
Additional insulation of the roof
(250 mm of mineral wool)
External wall additional insulation
(200 mm of mineral wool)
Replacement of windows (U = 0.7
W/(m²K))
Replacement of doors (U = 1.0
W/(m²K))
C
Installation of a ventilation system with
heat recovery
Replacement of the heat source
(geothermal heat pump)
Additional insulation of the attic
dropped ceiling (50 mm of cellulose
fibre wool)
Replacement of windows (U = 0.7
W/(m²K))
Replacement of doors (U = 1.0
W/(m²K))
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(geothermal heat pump), heating
system based on radiator heating
Additional insulation of the
roofing deck (250 mm of
mineral wool)
External wall additional insulation
(300 mm of mineral wool)
Replacement of windows (U = 0.7
W/(m²K))
Replacement of doors (U = 1.0
W/(m²K))
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(geothermal heat pump)
Solar panels for making hot water
Additional insulation of the roofing
Installation of a ventilation system
with heat recovery
Replacement of the heat source
(geothermal heat pump), heating
system based on radiator heating
Solar panels for making hot water
ΔN
PV
, EU
R/m
²
B
deck (250 mm of cellulose fibre
wool)
External wall additional insulation
(250 mm of mineral wool)
Floor insulation (300 mm of
expanded polystyrene)
Replacement of windows (U = 0.7
W/(m²K))
Replacement of doors (U = 1.0
W/(m²K))
Additional insulation of the roofing
deck (300 mm of mineral wool)
External wall additional insulation
(300 mm of mineral wool)
Floor insulation (300 mm of
expanded polystyrene)
Replacement of windows (U =
0.7 W/(m²K))
Replacement of doors (U = 1.0
W/(m²K))
4.1.3 Results of cost-effectiveness calculations
The results of financial calculations of the total expenditure are shown in Figures 54 and 55.
EPI, kWh/(m² a)
Figure 54. Results of cost-effectiveness calculations for a newer small residential sample building.
ΔN
PV
, EU
R/m
²
EPI, kWh/(m² a)
Figure 55. Results of cost-effectiveness calculations for an older small residential sample building.
The cost-optimal range for the reconstruction of a newer building only requiring the renovation of technical systems is the energy performance indicator between 240 and 260 kWh/(m²a). The cost-optimal range for the reconstruction of an older building also requiring the renovation of the building envelope is the energy performance indicator between 250 and 260 kWh/(m²a). Reconstruction of technical systems only is not a case of major renovation, therefore the minimum energy efficiency requirement for a major renovation should be set on the basis of the buildings that require renovation of the building envelope. The current minimum energy efficiency requirement for a major renovation of small residential buildings is 210 kWh/(m²a). When laying down the new requirements, the energy efficiency requirement for a major renovation should be increased by one energy performance class, that is, the energy efficiency requirement for a major renovation could be equal to the minimum energy efficiency requirement of 160 kWh/(m²a) that applies to the new small residential buildings. This is because the cost-effective range for the reconstruction of small residential buildings is quite large and the changes in the total cost are relatively small up to the energy performance value of 150 kWh/(m²a).
4.2 Apartment buildings
4.2.1 Description of the buildings
Two different sizes of buildings have been selected in order to take into account the difference in energy use due to the compactness of a building: a smaller building made of brick and a larger reinforced concrete building made with assembled elements. The brick building and the reinforced concrete building were chosen as samples because the existing apartment blocks are mainly the construction types made of brick and of reinforced concrete (Figure 56).
Pro
po
rtio
n
Ne
t a
rea
of
ap
art
me
nt b
locks,
mill
ion m
²
Bri
ck
Rei
nfo
rced
co
ncr
ete
– la
rge
pan
el
Larg
e b
lock
Wo
od
Oth
er
Figure 56. Net area of apartment blocks.
Details of the technical characteristics of the existing situation with the sample buildings are given in Table 16 and in Figure 57.
Table 16. Technical characteristics of the sample apartment blocks.
Smaller Larger
Bearing structure Brick Reinforced concrete
Number of floors 4 5
Net floor area, m² 1383 3519
Heated area, m² 1154 2968
Number of apartments
Thermal conductivity of the
Building envelope, W/(m²·K)
32 60
External wall 1.0 0.9
Roof 1.1 0.8
Windows 2.0 2.0
Surface area of the building
envelope, m²
External wall 760 1410
Roof 320 610
Windows 260 520
Figure 57. Photos illustrating the sample apartment blocks.
4.2.2 Description of renovation measures
Energy efficiency packages are made up of combinations of various individual measures. Individual measures analysed:
External wall insulation 150 mm, 200 mm and 300 mm
Roofing deck insulation 300 mm, 400 mm and 500 mm
Basement ceiling insulation 150 mm
New windows with thermal transmittance of U = 1.1 W/(m²K) and U = 0.8 W/(m²K)
New double-pipe heating system
Installation of a mechanical ventilation system
o mechanical exhaust without heat recovery; o mechanical exhaust with heat recovery by an exhaust air heat pump; o mechanical intake exhaust with a central unit.
Installation of solar panels (PV)
o smaller house 16 kW; o larger house 32 kW.
The calculations for the costs of measures were based on the budgets for reconstruction work of the apartment buildings that have applied for a renovation grant from the government. The costs of measures only include the energy saving works. The cost of electricity, water, sewerage and other works is not included and would increase the cost of the package by approximately 20 %.
4.2.3 Results of cost-effectiveness calculations
The results of financial calculations of the total expenditure are shown in Figures 58 and 59.
ΔN
PV
, E
UR
/m²
ΔN
PV
, E
UR
/m²
EPI, kWh/(m² a)
Figure 58. Results of cost-effectiveness calculations for a smaller sample apartment block.
EPI, kWh/(m² a)
Figure 59. Results of cost-effectiveness calculations for a larger sample apartment block.
For a smaller apartment block, the cost-optimal energy consumption range is between 130 and 160 kWh/(m²a). For a larger apartment block, it is between 110 and 130 kWh/(m²a). Taking into account the largely varying sizes and technical conditions of the existing apartment blocks, the cost-optimal energy efficiency requirement for a major renovation would be equal to the 150 kWh/(m²a) minimum energy efficiency requirement for new apartment buildings.
The results of the macroeconomic total cost calculations are shown in Figures 60 and 61.
ΔN
PV
, E
UR
/m²
ΔN
PV
, E
UR
/m²
EPI, kWh/(m² a)
Figure 60. Results of macroeconomic cost-effectiveness calculations for a smaller apartment block.
EPI, kWh/(m² a)
Figure 61. Results of macroeconomic cost-effectiveness calculations for a larger apartment block.
The macroeconomic cost-optimal calculations also support the equalisation of the energy efficiency requirement for a major renovation with the current minimum energy efficiency requirement of 150 kWh/(m²a) for new apartment blocks.
4.3 Office buildings
4.3.1 Description of the buildings
The analysis of the energy savings potential of office buildings was based on two sample buildings (Figures 62 and 63).
Figure 62. Office building 1.
Figure 63. Office building 2.
All calculations were performed on both building samples. The final results were the weighted average values of the two buildings’ surface areas.
The building envelopes and air circulation of the existing buildings were characterised by the following main indicators:
Thermal transmittance of external walls
U ≈ 1.1 W/(m²·K)
Thermal transmittance of roofs
U ≈ 1.0 W/(m²·K)
Thermal transmittance of windows
U ≈ 1.8 W/(m²·K)
4.3.2 Description of renovation measures
The following simulations were performed:
existing thermal transmittance, temperature ratio of the ventilation heat recovery 0.7;
existing thermal transmittance of windows U=1.2, temperature ratio of the ventilation heat recovery 0.7;
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 15 cm, on the roof 20 cm; window U = 1.2 W/(m²·K);
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 20 cm, on the roof 25 cm; window U = 1.2 W/(m²·K);
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 25 cm, on the roof 30 cm; window U = 1.2 W/(m²·K);
ΔN
PV
, E
UR
/m²
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 15 cm, on the roof 20 cm; window U = 0.9 W/(m²·K); more efficient lighting;
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 25 cm, on the roof 30 cm; window U = 0.9 W/(m²·K); more efficient lighting;
temperature ratio of the ventilation heat recovery 0.7; additional insulation on the walls 25 cm, on the roof 30 cm; window U = 0.9 W/(m²·K).
Energy performance class D:
external wall additional insulation +200 mm;
roof additional insulation +250 mm;
thermal conductivity of windows U = 1.2 W/(m²·K);
ventilation system with heat recovery.
Energy performance class C:
external wall additional insulation +150 mm;
roof additional insulation 200 mm;
thermal conductivity of windows U = 0.9 W/(m²·K);
ventilation system with heat recovery;
lighting management.
Energy performance class C:
external wall additional insulation +250 mm;
roof additional insulation 300 mm;
thermal conductivity of windows U = 0.9 W/(m²·K);
ventilation system with heat recovery;
lighting management.
4.3.3 Results of cost-effectiveness calculations
The results of financial calculations of the total expenditure are shown in Figure 64.
EPI, kWh/(m² a)
Figure 64. Results of cost-effectiveness calculations for an office building.
The cost-optimal energy efficiency requirement for a major renovation is 160 kWh/(m²a) and is equal to the minimum requirements for energy efficiency of new office buildings.
References
Directive 2010/31/EU of the European Parliament and the Council of 19 May 2010 on the energy performance of buildings (EPBD). Delegated Regulation (EU) No 244/2012 of the European Commission, 16 January 2012. Regulation No 55 of the Minister for Economic Affairs and Infrastructure of 3 June 2015 on minimum energy performance requirements for buildings.
Regulation No 58 of the Minister for Economic Affairs and Infrastructure of 5 June 2015 on the methods for calculating the energy performance of buildings.
Annexes
Annex 1. Simulation results for a small residential building (100 m²).
Annex 2. Simulation results for a small residential building (200 m²).
Used energy
Annex 3. Simulation results for a terraced building.
Annex 4. Simulation results for an office building.
Annex 5. Annex III to Regulation EU 244 (pursuant to EU Directive 2010/31/EU)
ANNEX
III
Reporting template that Member States may use for reporting to the Commission
pursuant to Article 5(2) of Directive 2010/31/EU and Article 6 of this Regulation
1. REFERENCE BUILDINGS
The building types used as the basis for the analysis of building stock energy efficiency
improvement in ‘ENMAK: Estonia’s long-term energy management development plan 2030+’
were used as reference buildings for existing buildings.
Representative buildings used:
1. small residential buildings;
2. apartment buildings;
3. office buildings.
When selecting the reference buildings, the existing building stock was taken into account, and
the most common types of buildings were used in simulation calculations.
In these simulation calculations, the following variables were set at different levels:
- thermal transmittance of external walls;
- thermal transmittance of roofs;
- thermal transmittance of the floor at ground level;
- thermal transmittance of windows;
- number of air leaks;
- ventilation system type;
- heat source type (small residential buildings).
This report sets out in detail the source data and results of energy simulations and cost-optimal
calculations for small residential buildings, apartment blocks and offices. A more detailed
description of the cost-effectiveness calculations is provided in Annex 1 ‘Cost optimal and
nZEB energy performance levels for buildings’.
Table 1. Reference building for existing buildings (major renovation)
For existing
buildings
Building
geometry1
Ratio of
window
area over
the building
envelope
and
windows
with no
solar access
Floor area, m², as used in the Building Code
Descriptio
n of the
building2
Description
of the
average
building
technology3
Average
energy
performanc
e kWh/m² a (prior to
investment)
Component
level
requirement
s (typical
value)
1. Single family buildings and subcategories
Component
level
requirements
have not been
defined. The
regulation on
minimum
energy
performance
requirements
sets out
general
requirements
for building
envelopes,
technical
systems and
heating
systems.
Older small residential buildings
External wall:
142 m²
Attic ceiling
138 m²
Floor at
ground level:
138 m²
Number of
floors: 1
Windows:
22 m² (14 % of façade area)
Heated
area:
165 m²
Bearing
structure –
wood
External wall: U = 0.54
W/(m²K)
Roof:
U = 0.48 W/(m²K) Windows: U = 2.8
W/(m²K)
Heating
system:
stove
heating
520
Newer
small
residential
buildings
External wall:
206 m²
Attic ceiling
237 m²
Floor at
ground level:
237 m²
Number of
floors: 2
Windows:
50 m² (20 % of façade area)
Heated
area:
182 m²
Bearing
structure –
small block
External wall: U = 0.25
W/(m²K)
Roof: U = 0.16
W/(m²K)
Windows:
U-
1.8
W/(m²K)
Heating
system: gas
boiler
310
2. Apartment blocks and multifamily buildings and subcategories
Smaller
apartment
blocks
External wall:
760 m²
Attic ceiling
320 m²
Floor at
ground level:
320 m²
Windows:
260 m² (34 % of façade area)
Heated
area:
1154 m²
Bearing
structure –
brick
External wall: U = 1.0
W/(m²K)
Roof:
U = 1.1
W/(m²K)
Windows:
U = 2.0
W/(m²K)
242
1 S/V (surface to volume), orientation, area of N/W/S/E façade.
2 Construction material, typical air tightness (qualitative), use pattern (if appropriate), age (if appropriate).
3 Technical building systems, thermal transmittance of building elements, windows – area, thermal transmittance (U-
value), shading, passive systems, etc.
Number of
floors: 4
Heating
system:
district
heating
Larger
apartment
blocks
External wall:
1410 m²
Attic ceiling
610 m²
Floor at
ground level:
610 m²
Number of
floors: 5
Windows:
520 m²
(37 % of
façade
area)
Heated
area:
2968 m²
bearing
structure –
assembled
reinforced
concrete
External wall:
U = 0.9
W/(m²K)
Roof:
U = 0.8
W/(m²K)
Windows:
U = 2.0
W/(m²K)
Heating
system:
district
heating
202
3. Office
buildings
and
subcategori
es
External wall: U = 1.1
W/(m²K)
Roof:
U = 1.0
W/(m²K)
Windows:
U = 1.8
W/(m²K)
Heating
system:
district
heating
310
5. Other
non-
residential
building
categories
In connection with the definition of a nearly zero-energy building provided in Directive
2010/31/EU and with the updates to the minimum energy performance requirements, the
Ministry of Economic Affairs and Infrastructure commissioned an analysis to determine
the nearly zero-energy levels of new buildings. The study was conducted by the Tallinn
University of Technology. The following six building types were analysed:
small residential buildings, 100 m²;
small residential buildings, 200 m²;
terraced buildings;
apartment buildings;
office buildings.
The factors taken into consideration when selecting the reference buildings included the
number of floors, the net area, and the window to façade area ratio. The aim was to select
buildings that the architects considered to be characteristic of newly planned buildings. On
the basis of the selected buildings, calculation models were developed to simulate energy
consumption.
In these simulation calculations, the following variables were set at different levels:
- thermal transmittance of external walls;
- thermal transmittance of roofs;
- thermal transmittance of the floor at ground level;
- thermal transmittance of windows;
- solar factor of the insulating glass unit (g-value);
- number of air leaks;
- window to façade area ratio (office buildings);
- heat source type (small residential buildings).
Descriptions of the calculation models can be found in Table 1. The area covered by the
models is presented in the form of the heated area, since energy consumption is presented in
relation to the heated area. The heated area is deemed to be the net area for which the indoor
climate is conditioned.
Table 2. Reference building for new buildings
For new
buildings
Building
geometry4
Ratio of
window area
over the
building
envelope and
windows with
no solar access
Floor area,
m²,
as used in the
Building Code
Typical
energy
performance
kWh/m² a
Component
level
requirement
s
1. Single-
family
buildings and
subcategories
External wall: 137 /
157 m²
Roof: 130 /
114 m²
Floor at ground
level:
100 / 115 m²
Windows: 19 /
104 m² (12 % /
66 % of façade
area)
Heated area:
101 / 206 m²
Component
level
requirements
have not been
defined. The
regulation on
minimum
energy
performance
requirements
sets out
general
requirements
for building
2. Apartment
blocks and
multifamily
buildings and
External wall:
1906 m²
Ceiling:
Windows:
1232 m² (39 %
of façade area)
Heated area:
6373 m²
4 S/V, area of N/W/S/E façade. Please note: the orientation of the building can constitute an energy efficiency measure in
itself in the case of new buildings.
subcategories 1493 m²
Floor at ground
level:
1364 m²
envelopes,
technical
systems and
heating
systems.
3. Office
buildings and
subcategories
External wall:
1077 m²
Ceiling: 813 m²
Floor at ground
level:
1056 m²
Windows:
1320 m² (55 %
of façade area)
Heated area:
4191 m²
4. Other non-
residential
building
categories
Table 3. Basic reporting table for energy performance relevant data
Quantity
Unit
Description
Calculation
Method and tool(s)
Energy performance calculations are carried out in
accordance with the Government of the Republic
Regulation No 55 on minimum energy performance
requirements1 and Regulation No 58 of the Minister
for Economic Affairs and Communications on the
methods for calculating the energy performance of
buildings1
Primary energy
conversion factors
Weighting factors for energy carriers:
1) fuels obtained from renewable raw materials (wood and
wood-based fuels and other biofuels, with the exception of
peat and peat briquettes) 0.75;
2) district heating 0.9;
3) liquid fuels (fuel oil and liquefied gas) 1.0;
4) natural gas 1.0;
5) solid fossil fuels (coal and other similar) 1.0;
6) peat and peat briquettes 1.0;
7) electricity 2.0.
The values assigned to primary energy conversion factors (per
energy carrier) used for the calculation
Climate conditions
Location
Tallinn, 59.35 N and 24.8 E
Name of the city with indication of latitude and longitude
Heating degree-days
Degree-days are
calculated for the
whole year. The
number of degree-
days depends on the
location of the
building and the
bivalent
temperature. Estonia
is divided into six
regions. For
instance, the number
of degree-days in a
HDD
(heating
degree-day)
To be evaluated according to EN ISO 15927-6, specifying the
period of calculation
standard year in the
Tallinn region at the
bivalent temperature
17 °C is 4220.
When calculating
with a simulation
programme, the
‘Estonian Test
Reference Year’ is
used as external
climate data
Cooling degree-days
Not used in Estonia
CDD
(cooling
degree-day)
Source of climatic dataset
Data for degree-days is supplied
by the Estonian Meteorological
and Hydrological Institute and are
available to the public on the
KredEx website
http://www.kredex.ee/energiatohus
usest/kraadpaevad-4/
The external climate test reference
year [1] used in the simulation
programmes has been compiled
using climate data covering
30 years.
Provide references on climatic dataset used for the calculation
Terrain
description
The terrain has not been described.
The calculation method does not
require consideration to be taken of
buildings located nearby.
E.g. rural area, sub-urban, urban. Explain if the presence of
nearby buildings has been considered or not
Building geometry
Length × Width × Height
see Annexes 1
and 2
m × m × m
Related to the heated/conditioned air volume (EN 13790) and
considering as ‘length’ the horizontal dimension of the south-
oriented façade.
Number of
floors
see Annexes 1
and 2
-
S/V (surface-to-volume) ratio
see Annexes 1
and 2
m2/m
3
Ratio of window
area over total
building envelope
area
South
see Annexes 1
and 2
%
East
see Annexes 1
and 2
%
North
see Annexes 1
and 2
%
West
see Annexes 1
and 2
%
Orientation
see Annexes 1
and 2
°
Azimuth angle of the south façade (deviation from the South
direction of the ‘south’ oriented façade).
Latent heat
sources
Building utilisation
Small residential buildings: 0.6
Apartment blocks: 0.6
Office buildings: 0.55
In accordance with the building categories proposed in Annex 1
to Directive 2010/31/EU.
Average thermal gain from occupants
Small residential
buildings: 2
Apartment blocks: 3
Offices: 5
W/m²
Specific electric power of the lighting system
Small residential
buildings: 8
Apartment blocks: 8
Offices: 12
* In residential
buildings, lighting
utilisation is 0.1
W/m²
Total electric power of the complete lighting system of the
conditioned rooms (all lamps + control equipment of the
lighting system)
Building
elements
Specific electric power of electric equipment
Small residential
buildings: 2.4
Apartment blocks: 3
Offices: 12
W/m²
Average U-value of walls
Small residential
buildings: New - 0.14
Existing - 0.25 / 0.54
Apartment blocks:
New - 0.17
Existing - 0.8 / 1.1
Offices: New - 0.17
Existing - 1.0
Weighted U-value of all walls: U_wall =
(U_wall_1 · A_wall_1 + U_wall_2 · A_wall_2 + … +
U_wall_n
· A_wall_n) / (A_wall_1 + A_wall_2 + … + A_wall_n); where
U_wall_i = U-value of wall type i; A_wall_i = total surface area
of wall type i
Average U-value of roof
Small residential
buildings: New - 0.09
Existing - 0.16 / 0.48
Apartment blocks:
New - 0.14
Existing - 0.7 / 1.1
Offices: New - 0.14
Existing - 1.0
W/m²K
Similar to walls.
Average U-value of foundation
Small residential
buildings: 0.09
Apartment blocks:
0.14
Offices: 0.14
W/m²K
Similar to walls.
Small
residential
Average U-value of windows
buildings:
New - 0.8
Existing - 2.1
Apartment
blocks: New -
1.1
Existing - 2.0
Offices:
New -
1.1
Existing - 1.6
W/m²K
Similar to walls; it should take into account the thermal bridge
due to the frame and dividers (according to EN ISO 10077-1)
Thermal bridges
Total length
Additional
conductivities of
thermal bridges are
added to simulation
calculations in
accordance with
the regulation on
the methods for
calculating the
energy
performance of
buildings1
m
Average linear
thermal
transmittance
W/mK
Thermal capacity per unit
area
External walls
Not defined in the
calculation method
J/m²K
To be evaluated according to EN ISO 13786
Internal walls
Not defined in the
calculation method
J/m²K
Slabs
Not defined in the
calculation method
J/m²K
Type of shading systems
Not included in cost-optimal
calculations
E.g. sun blind, roll-up shutter, curtain
Total solar energy transmittance of glazing (for radiation
Average g-value
Glazing 0.63-0.46 - perpendicular to the glazing), here: weighted value according
to the area of different windows (to be evaluated according to
EN 410)
Glazing + shading
Shading not
included in cost-
optimal calculations
-
Total solar energy transmittance for glazing and an external
solar protection device must be evaluated according to EN
13363-1/-2
Infiltration rate (air changes per hour)
Number of air leaks q50
Small
residential
buildings:
New - 1.0
Existing - 6.0 / 15
Apartment
blocks: New -
1.5
Existing - 4.4
Offices:
New -
1.5
Existing - 6.0
m3/(hm²)
E.g. calculated for a pressure difference inside/outside of 50 Pa
Building systems
Ventilation system
Air flow rate
Small residential
buildings: 0.42
Apartment blocks:
0.5
Offices: 2.0
l/(cm²)
Heat recovery
efficiency
New buildings:
80
Reconstruction:
60-80
%
Efficiency of heating system Generation District heating 100 %
Gas,
oil condensation
boiler 95
Pellet boiler 85
Electric heating 100
Ground source heat
pump
(COP) 3.5
Air-water heat pump
(COP)
2.4
Evaluated in accordance with EN 15316-1, EN 15316-2-1,
EN 15316-4-1, EN 15316-4-2, EN 15232, EN 14825 and
EN 14511 standards
Distribution
Underfloor
heating 90 %
Radiators 97 %
%
Emission
Not defined in the
calculation method
%
Control
If the radiators do not
have thermostats, the
distribution
efficiency is reduced
by 0.1 units.
%
Efficiency of cooling system
Generation
Compressor - 3.5
Fluid cooler - 5.0
Absorption cooling -
0.7
Evaluated in accordance with EN 14825, EN 15243,
EN 14511 and EN 15232 standards
Distribution
Depends on the
temperature of the
cooling water flow
0.2-0.6
%
Emission
Not defined in the
calculation method
%
Control
Not defined in the
calculation method
%
Efficiency of DHW system
Generation
District heating 100
Gas, oil
condensation
boiler 92
Pellet boiler 85
Electric heating 100
Ground source heat
pump (COP) 2.7
Air-water heat pump
(COP)
2.0
%
Evaluated in accordance with EN 15316-3-2, EN 15316-3-3
Distribution
Not defined in the
calculation
method
%
Building setpoints
and schedules
Temperature setpoint
Wint
er
Small residential
buildings: ≥ 21
Apartment blocks: ≥
21
Offices: ≥ 21
°C
Indoor operative temperature
Sum
mer
Small residential
buildings: ≤ 27
Apartment blocks: ≤
27
Offices: ≤ 25
°C
Wint
Not defined in the
%
Indoor relative humidity, if applicable: ‘Humidity has only a
Humidity setpoint
er calculation method small effect on thermal sensation and perceived air quality in the
rooms of sedentary occupancy’ (EN 15251) Sum
mer
Not defined in the
calculation method
%
Operation schedules and
controls
Occupancy In accordance with Table 2 in
Section 6 of Regulation No 63 of
the Minister for Economic
Affairs and Communications of
8 October 2012 on the methods
for calculating the energy
performance of buildings1. The
table provides detailed usage data
for lighting in residential buildings,
appliances in residential buildings,
people in residential buildings, and
for offices, buildings used for
educational purposes and pre-school
care establishments.
Provide comments or references (EN or national standards, etc.)
on the schedules used for the calculation Lighting
Appliances
Ventilation
Heating system
Cooling system
Energy building
need/use (Thermal) energy contribution
of main passive strategies
implemented
1) … Not included in cost-
optimal calculations
kWh/a E.g. solar greenhouse, natural ventilation, day lighting 2) … kWh/a 3) … kWh/a
Energy need for heating
Energy consumption
using different
calculation variants is
given in Table 5
kWh/a
Heat to be delivered to or extracted from a conditioned space to
maintain the intended temperature conditions during a given
period of time
Energy need for cooling
Energy consumption
using different
calculation variants is
given in Table 5
kWh/a
Energy need for DHW
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Heat to be delivered to the needed amount of domestic hot water
to raise its temperature from the cold network temperature to the
prefixed delivery temperature at the delivery point
Other energy need (humidification,
dehumidification)
Not included in cost-
optimal calculations
kWh/a
Latent heat in the water vapour to be delivered to or extracted
from a conditioned space by a technical building system to
maintain a specified minimum or maximum humidity within the
space (if applicable)
Energy use for ventilation
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Electrical energy input to the ventilation system for air transport
and heat recovery (not including the energy input for preheating
the air) and energy input to the humidification systems to satisfy
the need for humidification
Energy use for internal lighting
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Electrical energy input to the lighting system and
other appliances/systems
Other energy use (appliances, external lighting,
auxiliary systems, etc.)
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Energy generation
directly in or near
the building
Thermal energy from renewable sources
(e.g. thermal solar collectors)
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Energy from renewable sources (that are not depleted by
extraction, such as solar energy, wind, water power, renewed
biomass) or co-generation Electrical energy generated in the building and used on-
site
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Electrical energy generated in the building and exported to the market
Not included in the
cost-optimal
calculation model
kWh/a
Energy consumption
Delivered energy
Electricity
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Energy, expressed per energy carrier, supplied to the technical
building systems through the system boundary, to satisfy the
uses taken into account (heating, cooling, ventilation, domestic
hot water, lighting, appliances, etc.)
Fossil fuel
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Other (biomass, district
heating/cooling, etc.)
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Primary energy
Energy
consumption using
different calculation
variants is given in
Table 5
kWh/a
Energy that has not been subjected to any conversion or
transformation process
86
4. Selecting variants/measures/packages
Table 4.1. Data on selected energy efficiency packages (new buildings)
Small residential buildings
Current
building
practices
Nearly zero-energy
level
(100 m²)
Nearly zero-energy
level
(200 m²)
U-value of external wall,
W/m²K
0.20
0.16
0.14
U-value of roof, W/m²K
0.12
0.10
0.14
U-value of floor (structure)
at ground level, W/m²K
0.27
0.18
0.18
U-value of window, W/m²K
(total)
1.1
1.1
0.9
G-value
0.55
0.55
0.55
Number of air leaks q50,
m3/(h∙m²)
3.0
1.5
1.5
Ventilation system
(temperature ratio/SFP)
0.8/1.8
0.8/1.5
0.8/1.5
Measures based on renewable
energy sources
-
Air-water heat pump +
PV panels
Air-water heat pump +
PV panels
Apartment buildings
Current
building
practices
Nearly zero-energy
level
U-value of external wall,
(W/m²K)
0.17
0.16
U-value of roof, W/m²K
0.12
0.12
U-value of floor (structure)
at ground level, W/(m²K)
0.21
0.18
U-value of window, W/m²K
(total)
1.1
0.9
G-value
0.58
0.55
Number of air leaks q50,
m3/(h∙m²)
3.0
1.5
Ventilation system
(temperature ratio/SFP)
0.8/1.8
0.8/1.5
Measures based on renewable
-
PV panels
-
87
energy sources
88
Office
Current
building
practices
Nearly zero-energy level
U-value of external wall,
W/(m²K)
0.23
0.10
U-value of roof, W/m²K
0.18
0.06
U-value of floor at ground
level, W/(m²)
0.18
0.06
U-value of window, W/m²K
(total)
1.2
0.9
G-value
0.63
0.46
Number of air leaks q50,
m3/(h∙m²)
3.0
0.6
Ventilation system
(temperature ratio/SFP)
0.75/2.0
0.8/1.5
Measures based on renewable
energy sources
-
PV panels
-
Table 4.2. Data on selected energy efficiency packages (existing buildings)
Small residential buildings
Older/newer
Existing requirement for a major
renovation
Energy performance class D
Energy performance class C
U-value of external
wall, W/m²K
0.3 / 0.25
0.15 / 0.25
U-value of roof, W/m²K
0.2 / 0.16
0.12 / 0.10
U-value of floor at
ground level, W/m²K
1.0 / 0.34
0.25 / 0.34
U-value of window, W/m²K
1.4 / 1.8
0.8 / 0.8
Heating source
Pellet boiler
Ground source heat pump
Ventilation system
Heat recovery 80 %
Heat recovery 80 %
Measures based on
renewable energy sources
-
-
Apartment buildings
Existing requirement for a major
renovation
Energy performance class D
Energy performance class C
U-value of external wall,
W/m²K
0.20
0.15
U-value of roof, W/m²K
0.12
0.12
U-value of floor at first
floor level, W/m²K
0.6
0.18
Thermal transmittance of
window, W/m²K
(glass/frame/total)
1.1
1.1
Heating system
New double-pipe system
New double-pipe system
Ventilation system
Without heat recovery
Heat recovery 80 %
Measures based on renewable
energy sources
-
-
Office
Existing requirement for a major
renovation
Energy performance class D
Energy performance class C
U-value of external
wall, W/m²K
0.16
0.14
U-value of roof, W/m²K
0.14
0.12
U-value of floor at
ground level, W/m²K
Thermal transmittance of
window, W/m²K
(glass/frame/total)
1.2
0.9
Ventilation system (temperature
ratio/SFP)
Heat recovery 80 %
Heat recovery 80 %
Measures based on
renewable energy sources
-
-
3. Calculation of the primary energy demand of the measures
Energy performance calculations are carried out in accordance with Regulation No 55 of the
Minister for Economic Affairs and Infrastructure on minimum energy performance
requirements1 and with Regulation No 58 of the Minister for Economic Affairs and
Infrastructure on the methods for calculating the energy performance of buildings.1
The primary energy demand of a building is expressed using the energy performance indicator. This
figure shows the gross energy needs per square metre of heated area per year, multiplied by
weighting factors. The unit in which the energy performance indicator is measured is kWh/m²a.
Weighting factors for energy carriers:
1) fuels obtained from renewable raw materials (wood and wood-based fuels and other biofuels,
with the exception of peat and peat briquettes) 0.75;
2) district heating 0.9;
3) liquid fuels (fuel oil and liquefied gas) 1.0;
4) natural gas 1.0;
5) solid fossil fuels (coal and other similar) 1.0;
6) peat and peat briquettes 1.0;
7) electricity 2.0.
90
Table 5.1. Energy demand calculation output table (new buildings)
Small residential building (100 m²)
Measure/package/
variant (as described in
Table 4)
Energy consumption, kWh/m²a Delivered energy
specified by source,
kWh/m²a
(gas boiler; air-water
heat pump + PV panels)
Primary energy
demand, kWh/m²a
Reduction in
demand for
primary energy
compared to the
reference building,
kWh/m²a
Heating
Cooling
Ventilation
exhaust air
heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
Current building
practices
59.1
-
3.1
26.3
6.3
25
Electricity: 34.4;
Gas: 85.4
154 (gas boiler)
-
Cost-optimal level
16.6
-
3.1
12.5
6.3
25
Electricity: 63.5
PV output: 24.0
79 (air-
water heat
pump + PV
panels)
75
Small residential building (200 m²)
Measure/package/
variant (as described in
Table 4)
Energy consumption, kWh/m²a
Delivered energy
specified by source,
kWh/m²a (gas boiler;
geothermal heat pump
+ PV panels)
Primary energy
demand, kWh/m²a
Reduction in
demand for
primary energy
compared to the
reference building,
kWh/m²a
Heating
Cooling
Ventilation
exhaust air
heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
91
Current building
practices
96.3
-
3.2
26.3
6.3
25
Electricity: 34.5;
Gas: 122.6
192 (gas
boiler)
-
Cost-optimal level
21.5
3.2
12.5
6.3
25
Electricity: 43.5
87 (air-
water heat
pump + PV
panels)
105
Apartment buildings
Measure/package/
variant (as described in
Table 4)
Energy consumption, kWh/m²a
Delivered energy
specified by source,
kWh/m²a (district
heating and
radiators) + PV
panels
Primary energy
demand, kWh/m²a
(district heating)
Reduction in
demand for
primary energy
compared to the
reference building,
kWh/m²a
Heating
Cooling
Ventilation
exhaust air
heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
Current building
practices
26.1
-
3.2
30.0
6.3
29.5
Electricity: 39.1
District heating:
56.1
127
-
Cost-optimal level
13.6
-
3.2
30.0
6.3
29.5
Electricity: 39.1
District heating:
43.6
103
24
92
Office
Measure/package/
variant (as described in
Table 4)
Energy consumption, kWh/m²a Delivered energy
specified by source,
kWh/m²a (district
heating and
radiators)
Primary energy
demand, kWh/m²a
(district heating)
Reduction in
demand for
primary energy
compared to the
reference building,
kWh/m²a
Heating
Cooling
Ventilation
exhaust air
heating
Domestic
hot water
Fans,
pumps
Lighting,
appliances
Current building
practices
25.8
3.0
9.5
5.8
13.8
37.9
Electricity: 55.7
District heating: 41.1
149
-
Cost-optimal level
32.0
3.0
10.2
5.8
12.9
22.3
Electricity: 37.8
District heating:
48.0
93
56
93
Table 5.2. Energy demand calculation output table (existing buildings)
Small residential building (older)
Measure/package
/variant (as
described in
Table 4)
Energy consumption, kWh/m²a Delivered energy
specified by
source, kWh/m²a
Primary energy
demand, kWh/m²a
Reduction in
demand for
primary energy
compared to the
reference building,
kWh/m²a
Heating
Cooling
Ventilatio
n exhaust
air heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
Existing
requirement for
a major
renovation
Energy
performance
class D
150
-
6.0
electric
heater
25
6.5
25.5
Electricity:
38
Heating + hot
water
(pellet): 175
208
312
Energy
performance
class C
30
-
6.0
electric
heater
10
6.5
25.5
Electricity:
38
Heating + hot
water
(geothermal heat):
40
156
364
Small residential building (newer)
Measure/package
/variant (as
described in
Table 4)
Energy consumption, kWh/m²a Delivered energy
specified by
source, kWh/m²a
Primary energy
demand, kWh/m²a
Reduction in
demand for primary
energy compared to
the reference
building, kWh/m²a
Heating
Cooling
Ventilatio
n exhaust
air heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
94
Existing
requirement for
a major
renovation
Energy
performance
class D
150
-
6.0
electric
heater
25
6.5
25.5
Electricity:
38
Heating + hot
water (pellet):
175
207
103
Energy
performance
class C
30
-
6.0
electric
heater
10
6.5
25.5
Electricity:
38
Heating + hot
water
(geothermal
heat): 40
156
154
Apartment buildings Measure/package
/variant (as
described in
Table 4)
Net energy use, kWh/m²a
Delivered energy
specified by
source, kWh/m²a
(gas boiler and
underfloor
heating)
Primary energy
demand, kWh/m²a
Reduction in
demand for
primary energy
compared to the
reference
building,
kWh/m²a
Heating
Cooling
Ventilatio
n exhaust
air heat
Domestic
hot water
Fans,
pumps
Lighting,
appliances
Existing
requirement for
a major
renovation
Energy
performance
class D
115
-
-
30
5.0
29.5
Electricity:
35
Heating + hot
water (district
heating): 70
174
68
95
Energy
performance
class C
45 - 5.0
electric
heater
30 5.0 29.5 Electricity:
40
Heating + hot water
(district heating): 70
148 94
Office Measure/package
/variant (as
described in
Table 4)
Energy consumption, kWh/m²a
Delivered energy
specified by source
Primary energy
demand, kWh/m²a
Reduction in demand
for primary energy
compared to the
reference building,
kWh/m²a
Heating Cooling Ventilation
exhaust air
heat
Domestic
hot water Fans, pumps Lighting,
appliances
Existing
requirement for a
major renovation
Energy
performance
class D
65 35 7.5 6 10 37.6 Electricity: 59
Heating + hot water
(district heating): 71
177 133
Energy
performance
class C
45 30 7.5 6 10 37.6 Electricity: 54
Heating + hot water
(district heating): 51
154 156
96
4. Calculation of total cost
New buildings
The economic calculations included construction cost calculations and discounted energy cost
calculations for 30 years in the case of residential buildings and 20 years in the case of non-
residential buildings. The cost of construction was calculated only for construction work and
components linked to improving energy performance.
Construction work and components to improve energy performance:
• adding insulation;
• replacing existing windows with windows with a lower thermal transmittance;
• installing a ventilation system with a better temperature ratio (without pipes);
• changes in the source of heat (boilers, heat pumps, etc.).
Labour costs, materials, overhead expenses, part of the project-management costs, design costs and
VAT were included in the construction costs relating to energy performance.
The energy prices used were as follows:
• Electricity, purchase EUR 0.113/kWh (incl. VAT @ 20 %)
• Electricity, sale EUR 0.035/kWh (incl. VAT @ 20 %)
• Natural gas EUR 0.048/kWh (incl. VAT @ 20 %)
• District heating EUR 0.060/kWh (incl. VAT @ 20 %)
The discount was calculated using the calculated interest rate and a relative price increase during
the calculation period. Depending on the uses of the buildings, the cost-effectiveness calculation
period was chosen to be 30 years (for residential buildings) or 20 years (for non-residential
buildings). The discount was based on the real interest rate of 2.5 %, which corresponds to the rate
of return of 3.5 % when inflation is 1 %. The real escalation of energy prices for the calculation
period was taken at 1 % per annum.
Financial calculations were based on the additional investment needed to achieve the nearly zero-
energy levels. When calculating the additional cost of the measure/package, the prices payable by
the customer, including all applicable taxes, VAT and support were taken into account in the
financial calculations. The calculations did not take into account the potential support that may
apply to the introduction of various technologies related to the production of renewable energy.
The cost of building components was calculated by totalling the different expense
types, and a discount rate was applied to them using the discount factor.
The criterion of profitability is that the net revenue generated and discounted during
the economic life of the investment should be greater than the initial investment.
Existing buildings
The economic calculations included construction cost calculations and discounted energy cost
calculations for 20 years. All renovation work costs were included in the calculation of construction
costs. For example, costs of additional roof insulation were added to the costs of roofing
installation.
The energy prices used, including value added tax, were as follows:
97
• Electricity EUR 0.11/kWh
• Natural gas EUR 0.05/kWh
• Pellet EUR 0.045/kWh
• District heating EUR 0.06/kWh
5. Cost-optimal level for reference buildings
Table 6.1. Comparison table for new buildings
Reference building
Cost-optimal level,
kWh/m²a
Current requirements for
reference buildings,
kWh/m²a
Gap
Small residential
building (200 m²)
87
160
46 %
Apartment buildings
103
150
31 %
Office buildings
93
160 42 %
Justification of the gap: In the case of small residential buildings, the cost-optimal level
depends on the heat source used. Since energy carriers are weighted differently, there is no
direct correlation between delivered energy and primary energy use, and so the cost-optimal
level established through primary energy can change.
Plan to reduce the non-justifiable gap: Class B requirements will start applying in 2018, and
class A – or nearly zero-energy requirements – will be in force as of 31 December 2019, which
means 80 for small residential buildings and 100 for apartment blocks and office buildings. As
a result, the differences between cost-optimal and nearly zero-energy will be -8 % in small
residential buildings, -3 % in apartment blocks and 8 % in office buildings.
Table 6.2. Comparison table for existing buildings
Reference building
Cost-optimal level,
kWh/m²a
Current requirements for
reference buildings,
kWh/m²a
Gap
Small residential
buildings
250
210
16 %
Apartment buildings
130
180
38 %
Office buildings
160
210
31 %
Justification of the gap: When laying down the new requirements, the energy efficiency
requirement for a major renovation should be increased by one energy performance class, i.e.
the energy efficiency requirement for a major renovation could be equal to the minimum
energy efficiency requirement of 160 kWh/(m²a) that applies to new small residential
98
buildings. This is because the cost-effective range for the reconstruction of small residential
buildings is quite large and the changes in the total cost are relatively small up to the energy
performance value of 150 kWh/(m²a).
Plan to reduce the non-justifiable gap: the transition to the class C requirements will take place
in 2018. As a result, the differences will disappear.