Analysis of cost-optimal minimum energy efficiency requirements … · 2018. 5. 28. · Analysis of...

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


3.1.5 Terraced building ...................................................................................................... 26


3.2 Apartment buildings ............................................................................................... 31

3.2.1 Description of the building ....................................................................................... 31


3.3 Office buildings ....................................................................................................... 36

3.3.1 Description of the analysed building ........................................................................ 36

3.3.2 Description of the analysed measures ............................................................................ 39


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


4.2 Apartment buildings ............................................................................................... 48



4.2.3 Results of cost-effectiveness calculations ....................................................................... 71

4.3 Office buildings ....................................................................................................... 73



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;


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.


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.


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.


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


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)





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





Height (m) 7

Length (m) 19.9

Width (m) 12.8

Closed net area (m²) 190.3

Capacity (m³) 1252

Common area (m²)



ΔN

PV

, EU

R/m

² Δ

NP

V, E

UR

/m²


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 %.


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



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



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


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 %.




Air-water SP

Gas boiler

ΔN

PV

, EU

R/m

²

ΔN

PV

, EU

R/m

²



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 %.


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




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




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




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


EPI, kWh/(m² a)



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)


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)


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)


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.


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)


Dynamic shading

EPI, kWh/(m² a)

ΔN

PV

, EU

R/m

² Δ

NP

V, E

UR

/m²

EPI, kWh/(m² a)


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


with heat recovery


(pellet boiler)


with heat recovery


(pellet boiler), heating system

based on radiator heating

Additional insulation of the roof


External wall additional insulation


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


(geothermal heat pump)

Additional insulation of the attic

dropped ceiling (50 mm of cellulose

fibre wool)


W/(m²K))


W/(m²K))


with heat recovery


(geothermal heat pump), heating

system based on radiator heating

Additional insulation of the

roofing deck (250 mm of

mineral wool)




W/(m²K))


W/(m²K))


with heat recovery


(geothermal heat pump)

Solar panels for making hot water

Additional insulation of the roofing


with heat recovery


(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)



Floor insulation (300 mm of

expanded polystyrene)


W/(m²K))


W/(m²K))

Additional insulation of the roofing

deck (300 mm of mineral wool)



Floor insulation (300 mm of

expanded polystyrene)

Replacement of windows (U =

0.7 W/(m²K))


W/(m²K))


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


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.


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 %.


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


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)


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);



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:


roof additional insulation 200 mm;


ventilation system with heat recovery;

lighting management.

Energy performance class C:


roof additional insulation 300 mm;


ventilation system with heat recovery;

lighting management.


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:


Heated

area:

182 m²

Bearing

structure –

small block


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:


Heated

area:

1154 m²

Bearing

structure –

brick


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


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:



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

-

http://www.kredex.ee/energiatohususest/kraadpaevad-4/



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-


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-


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



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



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



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



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



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



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



Table 5

kWh/a

Other (biomass, district

heating/cooling, etc.)

Energy

consumption using



Table 5

kWh/a

Primary energy

Energy

consumption using



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


(W/m²K)

0.17

0.16


0.12

0.12

U-value of floor (structure)

at ground level, W/(m²K)

0.21

0.18


(total)

1.1

0.9

G-value

0.58

0.55


m3/(h∙m²)

3.0

1.5

Ventilation system


0.8/1.8

0.8/1.5


-

PV panels

-

87

energy sources

88

Office

Current

building

practices

Nearly zero-energy level


W/(m²K)

0.23

0.10


0.18

0.06

U-value of floor at ground

level, W/(m²)

0.18

0.06


(total)

1.2

0.9

G-value

0.63

0.46


m3/(h∙m²)

3.0

0.6

Ventilation system


0.75/2.0

0.8/1.5


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


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


1.4 / 1.8

0.8 / 0.8

Heating source

Pellet boiler


Ventilation system

Heat recovery 80 %

Heat recovery 80 %

Measures based on

renewable energy sources

-

-

Apartment buildings


renovation




W/m²K

0.20

0.15


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 %


energy sources

-

-

Office


renovation



U-value of external

wall, W/m²K

0.16

0.14


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/


Table 4)

Energy consumption, kWh/m²a

Delivered energy


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/


Table 4)


Delivered energy


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/


Table 4)



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)


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)


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)


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


177 133

Energy

performance

class C

45 30 7.5 6 10 37.6 Electricity: 54

Heating + hot water


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.

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