Methodology For Calculating The Energy Performance Of Buildings


Published: 2013-01-09

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Methodology for calculating the energy performance of buildings1

Passed 08.10.2012 Annex 63

This regulation is made in accordance with subsection 73 of section 3 of the Building Act.

Chapter 1

GENERAL PROVISIONS

§ 1. Scope of application of the Regulation

This regulation establishes the methods for calculating the energy performance of buildings to prove their compliance with the minimum requirements for energy performance.

§ 2. Definitions

(1) The terms in this regulation are defined as follows:

1) major renovation – renovation is deemed to be major if the costs of modification of the building’s envelope elements and of modification or replacement of the building’s loadbearing or stiffening elements, or of modification of the building envelope and the building’s technical systems or parts thereof, or the complete replacement of a technical system, exceed one quarter of the average building cost of a construction work that is equivalent to the construction work which is being renovated;

2) technical systems – the heating system and the system of hot household water including the corresponding heat sources, the ventilation system, the cooling system, lighting and the systems which generate heat or electricity locally and are included in the energy calculation in accordance with this regulation;

3) indoor climate control – the use of energy for the purpose of ensuring the quality of indoor air, including maintaining, increasing or reducing indoor temperature, in compliance with the ventilation and room temperature requirements established in this regulation, and for the purpose of lighting under the building’s standard use;

4) heated area – net area of rooms with indoor climate control;

5) energy network – a system for the transmission of energy and for the distribution of energy to consumers (such as the power network, district heating and district cooling network, natural gas network);

6) heat gain – solar radiation which enters the building, as well as internal heat gains from occupants, lighting, equipment and technical systems;

7) building leakage rate – the parameter which characterises the air tightness of the building envelope and which is determined by means of an air leakage test at a pressure difference of 50 Pa. The building’s average leakage rate [m3/(h m2)] is expressed per square metre of the buildingenvelope. The area of the envelope is calculated on the basis of the internal dimensions of the building.

8) ESEER – the average cooling season energy efficiency ratio of cooling and refrigeration equipment issued by their manufacturer, calculated according to the European standards and on the basis of the base usage profile and use conditions of an average European cooling device, excluding the electricity use of the fans and pumps of the condenser;

9) SEER – the average cooling season energy efficiency ratio which is stated in the energy performance certificate of air conditioners and air-to-air heat pumps whose capacity is up to 12 kW and which is calculated as the ratio of the energy need for cooling during the cooling season to electricity use under standard conditions;

10) SCOP – the annual average seasonal coefficient of performance which is stated in the energy performance certificate of air conditioners and air-to-air heat pumps whose capacity is up to 12 kW and which is calculated as the ratio of energy need of heating to electricity use under standard conditions.

(2) The terms used in this regulation in relation to energy performance and energycalculation are defined as follows:

1) test reference year for energy calculations – the body of outdoor weather data required for indoor climate and energy calculations and compiled following the Estonian standard EVS-EN ISO 15927–4:2005 on the basis of weather data collected in the entire territory of Estonia during the period 1970–2000;

2) exported energy – the heat or electricity which is generated within the building or on the building site and which is not used in the building but is fed into energy networks;

3) local renewable energy – the heat or electricity generated from solar, wind, water and geothermal energy sources within the building or on the building site. In the case of heat pumps, the renewable energy harvested from the energy source is taken into account in the energy calculation according to the heat pump’s coefficient of performance;

4) delivered energy – the electricity obtained from power networks or the heat obtained from district heating networks in kilowatt-hours per annum (kWh/y) or the energy content (in kilowatt-hours) of fuel which is obtained from fuel suppliers and which is used to cover the building’s annual aggregate energy use in so far as this is not covered by local renewable energy. Any fuel obtained from the building site is deemed to constitute delivered energy;

5) total energy use (kWh/y) of the building – use of heat and electricity by the building’s technical  systems required for indoor climate control, the heating of household water and the operation of electrical equipment, excluding local renewable energy (excepting heat pumps). The building’s total energy use includes all energy losses of the technical  systems, including heat sources and the distribution systems of local energy generation, and the conversion of energy (e.g., coefficient of performance of a heat pump, energy efficiency ratio of a cooling plant,  cogeneration, fuel cell);

6) primary energy – the amount of primary energy from renewable and non-renewable sources which is required for the generation of one kilowatt-hour of delivered energy, including any losses involved in harnessing an energy source and in the generation, transmission and distribution of energy;

7) energy carrier conversion factors – factors which take into account the use of primary energy required for the generation of delivered energy and the environmental impact involved;

8) specific use – the annual energy use in kilowatt-hours per square metre of heated area of a building [kWh/(m2 y)];

9) total weighted specific use of exported energy – the sum of the products, calculated separately for each energy carrier, of the energy fed into the corresponding energy network and the energy carrier conversion factor;

10) total weighted specific use of delivered energ – the sum of the products, calculated separately for each energy carrier, of the delivered energy and the energy carrier conversion factor;

11) standard use of a building – the normal use of a building in relation to the verification of compliance with the minimum requirements for energy performance. The determination of the standard use takes into account the building’s purpose of use, its outdoor and indoor climate, the time during which the building and its technical systems are used, and  heat gains;

12) energy performance indicator [kWh/(m2 y)]– calculated total weighted specific use of delivered energy consumed in the course of standard use of the building, from which  the weighted specific use of exported energy is subtracted;

13) appliances – appliances which belong to the end user, such as home appliances, electronic devices, office appliances, and which do not constitute a part of any technical  system;

14) usage profile – the usage rate of a room, calculated as the ratio of the heat gain from lighting, equipment and  occupants to the maximum heat gain;

15) specific heat loss of the building envelope [W/K]specific heat loss via the building envelope in watts when the difference between outdoor and indoor temperature is one degree Celsius;

16) total  specific heat loss of the building envelope per square metre of heated area [W/(m2K)] – total  specific heat loss via the building envelope per square metre of heated area of the building at a difference of one degree Celsius between indoor and outdoor temperature. The specific heat loss is the sum of the heat losses that result from conduction and infiltration through the building envelope;

17) energy need – the electrical and thermal energy (without taking into account system losses and conversions from one energy type to another) required for indoor climate control, the heating of household water, lighting, and the operation of equipment. The  energy need comprises:  energy need for space heating, space cooling, the heating of ventilation air, the cooling of ventilation air, ventilation, the heating of household water, lighting and the operation of equipment;

18) energy need  for space heating – the amount of thermal energy  required for the heating of rooms to indoor temperature, taking into account  heat gains, heat losses that result from conduction and infiltration through the building envelope and the heating of ventilation supply air to indoor temperature;

19) energy need for space cooling – the amount of thermal energy required for the cooling of rooms to indoor temperature, including both latent and sensible heat, taking into account  heat gain, conduction and infiltration through the building envelope and the temperature of ventilation supply air;

20) energy need for the heating of household water – the amount of thermal energy required for the heating of household water;

21) energy need for the heating of ventilation air – the amount of thermal energy required for the heating of ventilation air to supply temperature, from which recovered heat is deducted; in the case of a ventilation system without heat recovery, the amount of thermal energy required for the heating of ventilation air from the outdoor temperature to indoor temperature.

22) energy need for the cooling of ventilation air – the amount of thermal energy  required for the cooling of air, including both latent and sensible heat;

23) energy use – use of electrical or thermal energy at a given point in the system. Energy use is calculated on the basis of energy need, taking into account system losses and energy conversion losses. At the end-point of a technical system of the building (usually the connection point to the corresponding energy network), the energy use of the utility system equals the sum of delivered energy and local renewable energy;

24) system boundary of delivered and exported energy – the system boundary which is used in energy calculation and which determines the relations between the energy flows to be included in the calculation (Figure 1).

Figure 1. System boundary of delivered and exported energy.

Chapter 2

INPUT PARAMETERS OF THE ENERGY PERFORMANCE CALCULATION

§ 3. Energy calculation

(1) In order to verify the compliance of a building with the minimum requirements of energy performance, the energy calculation is performed with respect to the standard use of the building, using the input parameters which are set out in this regulation and which characterise the indoor and outdoor climate, the periods of use and operation of the building and the utility systems, heat gains and the building’s air leakage rate. The other necessary input parameters are taken from the building design documentation.

(2) For the purposes of the energy calculation, it is not necessary to perform a detailed division of the building into zones. Small residential buildings and buildings with a single purpose of use may be regarded as a single zone for the purposes of the energy calculation. Large buildings are to be divided into as many zones as required according to their purposes and periods of use.

(3) In this regulation, the buildings’ purposes of use are the purposes of use set out in the regulation entitled Minimum Requirements for Energy Performance enacted in accordance with subsection 72 of section 3 of the Building Act.

§ 4. Outdoor climate

Regardless of the building’s location, the energy calculation and the verification of compliance with the summertime indoor temperature requirement are performed on the basis of the data of the Estonian test reference year. The test reference year represents the typical outdoor climate of three decades (1970–2000) and therefore is not suited to be used for the calculation of the heating power need. Where the test reference year is used for calculating the cooling load, it should be borne in mind that the results are not applicable to the cooling load in the case of a warmer than average summer.

§ 5. Indoor climate

(1) The energy calculation uses the indoor temperature set-points and ventilation air flow rates set out in the regulation entitled Minimum Requirements for Energy Performance enacted in accordance with subsection 72 of section 3 of the Building Act.

(2) In the case of a simplified calculation which treats indoor temperature as a constant, the indoor temperature set-points are used as the indoor temperature value (e.g., in residential buildings 21 °C for heating and 27 °C for cooling). In the case of a dynamic calculation, the relevant values are used as the heating and cooling set-points of a thermostat. Where the building lacks a cooling system, the difference between the summertime indoor temperatures and the cooling set-point must be calculated.

(3) Outside of occupied hours, the ventilation air flow rate of a non-residential building is deemed to be 0.15 l/(sm2) in the out of operation mode of the ventilation system.

(4) In the case of a variable air volume ventilation system in which the air flow rate varies and whose control function operates in accordance with the quality of air (the carbon dioxide (CO2) content or a combination of CO2 content and, for example, temperature or humidity values), the air flow rates set out in the regulation entitled Minimum Requirements for Energy Performance enacted in accordance with subsection 72 of section 3 of the Building Act are used as the maximum air flow rates of the relevant rooms. Where a system with a variable air flow rate is used for the purpose of cooling, the maximum air flow rate is determined according to the cooling need. The minimum air flow rate and the ventilation control function must, in general, be selected such as to avoid exceeding the 1000 ppm maximum volume fraction of CO2 while the corresponding value in outdoor air is 400 ppm.

Chapter 3

STANDARD USE OF THE BUILDING

§ 6.Occupied hoursand  heat gain

(1) The standard use of buildings and the corresponding heat gain from appliances and lighting and from occupants are provided in Table 1 which shows the building’s number of occupied hours per 24-hour day, the number of days of use per week and the maximum heat gain from lighting and appliances and the maximum heat gain from occupants during the building’s occupied hours. The heat gain figures do not include heat gain from the building’s technical  systems, which is calculated as part of the calculations made for the technical  systems according to the requirements set out in Chapter 5 of this regulation.

Table 1. Standard use of buildings and the corresponding maximum values of  heat gain per square metre of heated area

Building’s purpose of use

Occupied hours

Usage rate

Lightinga

W/m2

Appliances

W/m2

Occupantsb

W/m2

Occupants

m2/person

Hours

h/24h

d/7d

Small residential building

00:00-00:00

24

7

0.6

8c

2.4d

2

42.5

Multi-apartment building

00:00-00:00

24

7

0.6

8c

3d

3

28.3

Office building, library or research building

07:00-18:00

11

5

0.55

12

12

5

17.0

Commerce building or  terminal

07:00-21:00

14

7

0.55

20

1

5

17.0

Accommodation building

00:00-00:00

24

7

0.5

8

1

4

21.3

Food service building or service building

12:00-22:00

10

7

0.4

20

4

14

6.1

Public building

08:00-22:00

14

7

0.5

14

0

5

17.0

Educational buildinge

08:00-16:00

8

5

0.6f

15

8

14

5.4

Pre-school institution for children

07:00-19:00

12

5

0.4

15

4

20

3.8

Healthcare building

00:00-00:00

24

7

0.6

9

4

8

10.6

a the figures shown assume the use, in non-residential buildings, of fluorescent lights or other lighting equipment of similar effectiveness. The heat releases shown include both the nominal power of the fluorescent light and the nominal power of the starter which accounts for approximately 25% of the nominal power.

b the internal heat gain from occupants only includes the sensible heat. In order to include latent heat, the relevant values must be divided by the factor 0.6.

c the usage rate of lighting in residential buildings is 0.1.

d to obtain the electricity use of the appliances in residential buildings, the heat release value must be divided by the factor 0.7.

e excluding pre-school institutions for children.

f during the summer break from 15 June to 15 August, the usage intensity is 0.1 and the ventilation operates in the non-use-hours mode.

(2) Usage rate means the average use intensity of lighting and appliances and the average presence of occupants during the building’s occupied hours. The maximum heat release value (usage rate = 1) is used in the calculations of summertime indoor temperatures and cooling loads, except in the case of buildings referred to under subsections 8 and 9. For the purposes of the energy calculation, the maximum heat release value is multiplied by the usage rate value. The annual heat release Q [kWh/(m2y)] of lighting and appliances and the internal heat gain from occupants is calculated using the following formula:

where k is the rate of usage;

P is heat release W/m2;

τd is the building’s number of occupied hours per 24-hour day;

τw is the building’s number of days of occupancy per week.

(3) For the purposes of the energy calculation, the use of electricity by lighting and appliances equals the heat released by the lighting and appliances. In residential buildings, the use of electricity by appliances is obtained by dividing the heat release of appliances with the factor 0.7.

(4) Lighting which is characterised by wattage lower than that given in Table 1 may be used if it provides the same level of illuminance and a separate calculation of illuminance in standard rooms is provided as part of the input parameters of the energy calculation. The general index of illuminance in rooms, uniformity of illuminance, glare and colour rendition and other lighting-related guidelines are provided in the standard EVS-EN 12464-1.

(5) Where the building’s lighting is controlled on a demand basis, the number of use hours of the lighting is calculated using the occupied hours shown in Table 1. The model used for the calculation of the average wattage of lighting must be room-based and the lighting of rooms must ensure the level of illuminance which corresponds to the relevant purpose of use. Where the calculation of the average wattage of lighting is performed in respect of different room types, the average wattage of lighting in heated areas is the weighted average of the areas of the rooms which represent those types.

(6) In calculating the ventilation need, ventilation is held to start one hour before the building’s start hour of use and to switch to the non-use-hours mode one hour after the end hour of use of the building (except for buildings which are used on a 24 hour basis).

(7) The dynamic energy calculations of residential buildings, office buildings, libraries, research buildings, educational buildings (excluding pre-school institutions for children and other educational buildings), and pre-school institutions for children use the detailed usage profiles of buildings set out in Table 2 below.

Table 2. Detailed usage rate  values for the energy calculation

Time

Residential building, lighting

Residential building, lightning

Residential building occupants

Office building, library, research building

Educational building

Pre-school institution for children

00:00-01:00

0

0.5

1

0

0

0

01:00-02:00

0

0.5

1

0

0

0

02:00-03:00

0

0.5

1

0

0

0

03:00-04:00

0

0.5

1

0

0

0

04:00-05:00

0

0.5

1

0

0

0

05:00-06:00

0

0.5

1

0

0

0

06:00-07:00

0.15

0.5

0.5

0

0

0

07:00-08:00

0.15

0.7

0.5

0.2

0

0.4

08:00-09:00

0.15

0.7

0.5

0.6

0.6

0.8

09:00-10:00

0.15

0.5

0.1

0.6

0.6

0.8

10:00-11:00

0.05

0.5

0.1

0.7

0.6

0.3

11:00-12:00

0.05

0.6

0.1

0.7

0.4

0.3

12:00-13:00

0.05

0.6

0.1

0.4

0.3

0.8

13:00-14:00

0.05

0.6

0.2

0.6

0.6

0.1

14:00-15:00

0.05

0.6

0.2

0.7

0.6

0.1

15:00-16:00

0.05

0.5

0.2

0.7

0.3

0.4

16:00-17:00

0.2

0.5

0.5

0.6

0

0.3

17:00-18:00

0.2

0.7

0.5

0.2

0

0.3

18:00-19:00

0.2

0.7

0.5

0

0

0.3

19:00-20:00

0.2

0.8

0.8

0

0

0

20:00-21:00

0.2

0.8

0.8

0

0

0

21:00-22:00

0.2

0.8

0.8

0

0

0

22:00-23:00

0.15

0.6

1

0

0

0

23:00-00:00

0.15

0.6

1

0

0

0

(8) The verification of compliance of residential buildings and open office rooms with the summertime indoor temperature requirement is performed using the detailed energy calculation usage profiles of buildings as set out in Table 2.

(9) The verification of compliance of single room offices, conference rooms, classrooms and the rooms of pre-school institutions with the summertime indoor temperature requirement and the dynamic calculation of the cooling load of such premises are performed using the detailed usage profiles of rooms as set out in Table 3. For classrooms and conference rooms, the  heat gain values provided in Table 4 are used. For other rooms, the  heat gain values provided in Table 1 are used.

Table 3. Usage rate values for the verification of compliance with summertime indoor temperature requirement

Time

Single-room office

Conference room

Classroom

Playing room in a pre-school institution for children

Sleeping room in a pre-school institution for children

00:00-01:00

0

0

0

0

0

01:00-02:00

0

0

0

0

0

02:00-03:00

0

0

0

0

0

03:00-04:00

0

0

0

0

0

04:00-05:00

0

0

0

0

0

05:00-06:00

0

0

0

0

0

06:00-07:00

0

0

0

0

0

07:00-08:00

0

0

0

0.5

0.2

08:00-09:00

1

1

0.8

1

0.2

09:00-10:00

1

1

0.8

1

0.2

10:00-11:00

1

1

0.8

0.4

0.2

11:00-12:00

1

1

0.8

0.4

0.2

12:00-13:00

0

0

0.5

1

0.2

13:00-14:00

1

1

0.8

0.2

1

14:00-15:00

1

1

0.8

0.2

1

15:00-16:00

1

1

0.8

0.5

0.5

16:00-17:00

1

1

0

0.4

0.2

17:00-18:00

0

0

0

0.4

0.2

18:00-19:00

0

0

0

0.5

0.2

19:00-20:00

0

0

0

0

0

20:00-21:00

0

0

0

0

0

21:00-22:00

0

0

0

0

0

22:00-23:00

0

0

0

0

0

23:00-00:00

0

0

0

0

0

Table 4. Internal  heat gain values for the verification of compliance with summertime indoor temperature requirement

Purpose of use of the room

Lighting
W/m2

Appliances
W/m2

Occupants
W/m2

Occupants
m2/person

Conference room

15

50

25

3.4

Classroom

15

12

35

2.1

Computer class

15

75

35

2.1

(10) In dynamic calculations, the total internal heat gain from one occupant is taken to amount to 125 W (sensible heat 85 W). In educational buildings, including pre-school institutions for children, the total internal heat gain fromoccupants is held to amount to 110 W (sensible heat 75 W) per occupant. These values correspond to 1.2 and 1.0 metabolic units (met), with body surface area amounting to 1.8 m2. The thermal resistance of clothing is held at 1.1 clo in wintertime and 0.6 clo in summertime. The  heat gain from occupants is calculated in relation to heated area using the  heat gain values given in Table 1 in respect of occupants.


§ 7.Domestic hot water use

For the specific use of hot household water, the figures to be used are given in Table 5 in litres per square metre of heated area per annum. The temperature difference between hot and cold water is taken to amount to 50°C.

Table 5. Specific use of hot household water and energy need per square metre of heated area

Building’s purpose of use

Specific use of hot water
l/(m2 y)

Energy need
kWh/(m2 y)

Small residential buildings

430

25

Multi-apartment buildings

520

30

Office buildings, libraries and research buildings

100

6

Commerce buildings and terminals

65

4

Accommodation buildings

520

30

Food catering and service buildings

400

23

Public buildings

340

20

Educational buildings (excl pre-school institutions for children)

180

10

Pre-school institutions for children

460

27

Healthcare buildings

520

30

§ 8. Stoves, fireplaces and sauna stoves

(1) The stoves and fireplaces may be included in the energy calculation as part of a combined heating system, provided the fireplaces store heat and are equipped with a combustion air duct. Fireplaces which do not store heat and which use indoor air for combustion are not included in the energy calculation. Stoves which use indoor air for combustion are not included in the energy calculation. Where stoves are used as the main heating system, they are included in the energy calculation regardless of whether or not they have a combustion air  duct.

(2) In calculating the heat release of the stoves and fireplaces which are taken into account in the energy calculation those stoves and fireplaces are deemed to be heated once every 24 hours.

(3) Wood-burning sauna stoves are not included in the energy calculation. The electricity use of electric sauna stoves of small residential buildings and apartments is deemed to amount to 500 kWh per year. The heat release of electric sauna stoves is not taken into account as  heat gain.

§ 9. Air leakage of buildings

Where the building’s air leakage rate has not been measured or proved in any other manner, the energy calculation uses the base values of air leakage of buildings given in Table 6. Where the design air leakage value is greater than the base value in Table 6, the design air leakage value is used. Where air leakage is measured according to the standard EVS-EN 13829 or has been proved by the supplier of the house, the measured or proved value is used in the energy calculation.

Table 6. Base values of air leakage of buildings per square metre of building envelope.

Purpose of use

Base value of air leakage m³/(hm²)

New building, major renovation

Renovation, existing building

Detached houses

6

9

Other buildings

3

6

Chapter 4

CALCULATION OF ENERGY NEED

AND SUMMERTIME INDOOR TEMPERATURES

Division 1

Calculation of energy need

§ 10. Principles of calculation of energy need and summertime indoor temperatures

(1) The calculation of energy need follows the principles of the standard EVS-EN ISO 13790 which are applied in accordance with this section.

(2) The calculation of the energy need for space heating takes into account the need to heat infiltration air and the heating of ventilation supply air in the room from supply air  temperature to indoor temperature.

(3) When calculating the energy need for the heating of ventilation air, the heat recovery of the ventilation system is taken into account. The energy need for the heating of ventilation supply air includes the heating of the ventilation air before and/or after heat recovery or, in ventilation systems without heat recovery, the heating of the supplied outdoor air from the outdoor temperature to indoor temperature.

(4) Heat gain is calculated following the requirements specified in section 6. The calculation of solar radiation which enters the building through glass surfaces takes into account different solar protection solutions (such as solar protection glass, internal and external window blinds, grates, awnings) as provided in the design solution, as well as the shadows cast on glass surfaces by surrounding objects and by parts of the building itself.

(5) The energy need for the heating of household water is calculated in accordance with section 7. 

(6) The parameters set out in section 6 are used in calculating the summertime indoor temperature and the energy need for space cooling. The cooling of rooms by air change achieved through the opening of windows is not taken into account in the calculations  for non-residential buildings. In the case of residential buildings, only the opening of windows to the airing position and the air change driven by the difference between outdoor and indoor temperature are taken into account (the windows are closed when the temperature falls to the heating set-point). The verification of compliance with the summertime indoor temperature requirement provided in the regulation entitled Minimum Requirements for Energy Performance established in accordance with subsection 72 of section 3 of the Building Act takes into account the fact that the degree hours requirement applies to the occupied hours of the building and that outside those hours the indoor temperature may be higher, but will not be taken into account.

Division 2

Calculation of heat loss through the building envelope

§ 11. Principles of calculation of heat loss through the building envelope

(1) In the calculation of heat losses, the area of the building envelope is calculated on the basis of internal dimensions of the building (the dimensions between internal surfaces of walls or ceiling and floor together with rooms and load-bearing and non-load-bearing partitions). Where heat losses are calculated separately for each room, the area of the relevant envelope section is calculated using the centre-line measures of partitions and inserted ceilings.

(2) The heat losses of the building envelope (exterior walls, floors and roofs) are calculated on the basis of the thermal transmittance of the envelope and its area as calculated on the basis of the internal dimensions of the building. Regular thermal bridges (e.g., stiffeners, masonry anchors) are taken into account in accordance with their thermal transmittance values. The heat losses of  irregular thermal bridges (e.g., the junctions of exterior wall and exterior wall, exterior wall and inserted ceiling, floor and exterior wall, warm roof and exterior wall, as well as window to wall fixing junctions) are taken into account separately in accordance with the thermal transmittance values of linear and point thermal bridges. If necessary, the total specific heat loss (heat loss in watts at a temperature difference of one degree) of the building envelope calculated according to the method described above is converted into average thermal transmittance of the building envelope by dividing the total specific heat loss of the envelope with the area of the envelope which is determined according to the rules of the calculation software used.

(3) The thermal transmittance of the building envelope is based on the data obtained from the building design documentation. The specific thermal conductivity of materials should be calculated according to the standard EVS-EN ISO 10456:2008 and the thermal resistance of homogeneous and non-homogeneous material layers according to the standards EVS-EN ISO 6946 and EVS 908-1.

(4) The building’s heat loss to the ground is determined on the basis of a dynamic one-dimensional calculation which assumes a heat-accumulating soil layer whose thickness is at least one metre and below which the temperature remains constant at 7 °C, or on the basis of a dynamic three-dimensional calculation, or by using tabulated values of the temperature of the ground beneath the building, or according to the standard EVS-EN ISO 13370. Where more precise data are unavailable, the following parameters may used in for calculation purposes: for drained surfaces, specific thermal conductivity 1.4 W/(m K) and specific heat 1.5 MJ/(m3K); for undrained surfaces, specific thermal conductivity 2.0 W/(m K) and specific heat 2.0 MJ/(m3K); for homogeneous rock, specific thermal conductivity 3.0 W/(m K) and specific heat 2.0 MJ/(m3K).

§ 12. Thermal bridge calculation

(1) The thermal transmittance values of thermal bridges are obtained from the building design documentation. The thermal transmittance of thermal bridges should be calculated using either the detailed or simplified method in accordance with the corresponding standard (e.g., EVS-EN ISO 10211, EVS-EN ISO 10077, EVS-EN ISO 14683, ISO 15099), or the thermal transmittance values provided by the manufacturer of the material or construction product. Where more precise data are unavailable, the values provided in Table 7 may be used in respect of residential buildings.

Table 7. Thermal transmittance values of linear thermal bridges of the building envelope

 

Thermal transmittance of linear thermal bridges , W/(m·K)

New buildings

Buildings undergoing major renovation

Buildings undergoing renovation

Existing buildings

External corner of an exterior wall

0.2

0.3

0.5

1.0

Internal corner of an exterior wall

-0.1

-0.2

-0.2

0.3

Junction of an exterior and an interior wall

0.1

0.1

0.2

0.9

Junction of an exterior wall and an inserted ceiling

0.1

0.2

0.3

0.8

Junction of the roof and an exterior wall

0.2

0.2

0.4

0.4

Junction of an exterior wall and the slab floor  

0.3

0.3

0.4

0.4

Junction of an exterior wall and the  floor  above vented crawl space

0.3

0.3

0.4

0.4

Junction of a window and an exterior wall (window in the insulation layer, its frame covered with insulation which amounts to at least 40% of the total thickness of the insulation layer)

0.1

0.1

0.2

0.2

Junction of a window and an exterior wall (window in the load-bearing layer)

0.2

0.3

0.4

0.5

Junction of a balcony and an exterior wall

0.3

0.5

0.6

0.8

(2) The thermal transmittance ΔΨ (W/K) of the thermal bridges of the building envelope is calculated by means of the following formula:

where Ψj is the thermal transmittance of the linear thermal bridge in W/(mK);
ljis the length of the linear thermal bridge in metres;
χp is the thermal transmittance of the point thermal bridge in W/K;
np is the number of similar point thermal bridges in the building envelope.

(3) The thermal transmittance of windows Ua (W/(m2K)) is obtained from the data provided by the manufacturer. Where no such data are available, thermal transmittance is calculated using the detailed method provided in the standards (for example, EVS-EN ISO 10077 or EVS-EN ISO 15099) or by means of the following simplified formula:

where Uk is the thermal transmittance of the glazing in W/(m2K);
Ak is the area of the glazing in m2;
Ur is the thermal transmittance of the frame and the sash in W/(m2K);
Ar is the area of the frame and the sash in m2;
Ψk is the thermal transmittance of the linear thermal bridge of the glazing unit (largest perimeter of the visible limit of the glazed area) in W/(mK);
lk is the length of the perimeter of the glazing unit in metres.

(4) The thermal transmittance of the glazing and frame and the parameters of the linear thermal bridge of the glazing unit are obtained from the data provided by the manufacturer. If more precise data are unavailable, the thermal transmittance of the frame unit is held at 1.6 W/(m2K) in the case of plastic windows; at 1.7 W/(m2K) in the case of timber windows whose frame and sash unit are 70 mm thick; 1.7 W/(m2K) in the case of timber-aluminium windows whose frame and sash unit are 110–130 mm thick; 1.1 W/(m2K) in the case of timber-aluminium windows whose frame is 130 mm thick and whose sash is 170 mm thick; 4.0 W/(m2K) in the case of metal profiles with a thermal break; 7.0 W/(m2K) in the case of metal profiles without a thermal break.

(5) The thermal resistance of the frame and sash unit of timber windows may be calculated as the thermal resistance of a layer which consists of homogeneous material with an average thickness of the frame and sash unit and which is multiplied by the factor 0.7 to account for two-dimensional heat conduction.

(6) Where more precise data are unavailable, the linear thermal bridge of the glazing unit is taken to be 0.06W/(mK); in the case of plastic and timber windows, 0.08W/(mK); in the case of metal profiles without a thermal break; 0.02W/(mK); in the case of metal profiles with a thermal break.

Division 3

 Infiltration

§ 13. Determination of the infiltration air flow rate

(1) The infiltration air flow rate qi (l/s) is calculated by means of the formula:

where q50 is the average air leakage rate in m3/(h·m2) of the building envelope, calculated in accordance with section 9 of this regulation;
A is the area of the building envelope (including floors) in m2;
x is the factor which is 35 in the case of a single-storey building, 24 in the case of a two-storey building, 20 in the case of a three or four-storey building and 15 in the case of a five-storey or higher building, the height of a storey being 3 metres;
3,6 is the factor which converts the airflow rate unit from m3/h to l/s.

(2) Where exhaust  air flow rate exceeds supply air flow rate, the infiltration air flow rate may be calculated by means of the following formula:

where q50 is the average air leakage rate in m3/(h·m2) of the building envelope, calculated in accordance with section 9 of this regulation;
A is the area of the buildings envelope in m2;
qv is the exhaust air flow rate in l/s;
qs is the supply  air flow rate in l/s.

(3) Where the formulae set out in subsections 1 and 2 are used simultaneously, the infiltration air flow rate is determined on the basis of the formula which yields the lower air flow rate.

Chapter 5

RULES FOR THE CALCULATION OF THE ENERGY USE OF THE BUILDING’S TECHNICAL SYSTEMS

Division 1

Heating systems

§ 14. Principles of calculations concerning heating systems

(1) The calculations concerning heating systems include the calculation of the energy use for space heating, of the heating of ventilation air and of household water. The corresponding energy use (kWh/y) values are calculated on the basis of the relevant energy need. Rather than totalling the use of heat and electricity, these are treated separately in order to make it possible to calculate use figures by source of delivered energy.

(2) The use of electrical and thermal energy by a heating system is calculated on the basis of the efficiency of the heating system (or, where a heat pump system is used, that system’s coefficient of performance) and of the electricity use of any auxiliary devices. The inclusion in the calculation of the efficiency factor of the heating system allows losses in the thermal energy source (e.g., losses in the boiler or the heat exchanger of the district heating system) as well as losses related to the distribution and output of heat and to inaccuracies in regulating room temperature to be taken into account. The energy use of the heating system is obtained by dividing its energy need by its efficiency factor. The efficiency factor of the heating system is obtained as the product of the efficiency factor of the thermal energy source and the efficiency factor of the distribution and output of heat. In heat pump systems, the coefficient of performance is used instead of the efficiency factor. The efficiency factor of the thermal energy source is calculated on the basis of the data provided by the manufacturer; the efficiency values provided in Table 8 may be used instead of the calculated value. The efficiency of the distribution and output of heat and the electricity use of auxiliary devices are calculated using a computer simulation; the parameters provided in Table 9 may be used instead of the calculated value. Where the radiators of the system are not equipped with thermostatic valves, the efficiency values listed in Table 9 are reduced by 0.1 units.

Table 8. Efficiency factors of thermal energy sources on the basis of the lowest calorific value of the consumable substance of the fuel

Thermal energy source

Efficiency factor

District heating substations

1.0

Oil or gas boilers

0.85

Oil, condensing boilers

0.90

Gas, condensing boilers

0.95

Pellet boilers

0.85

Other types of solid fuel boilers

0.75

Electric boilers

1.0

Stoves

0.6

Table 9. Efficiency factors of the distribution and output of heat and the electricity use of auxiliary devices

Building type

Manner of heating

Efficiency factor

Electricity use of the circulation pumps of hydronic systems1, kWh/(m2 y)

Small residential buildings

Radiators

0.97

1

 

Floor heating slab floors or floors above vented crawl space

0.85

2

 

Floor heating in inserted ceiling

1.0

2

 

Ceiling heating in a warm roof

0.90

2

 

Ceiling heating in an inserted ceiling

1.0

2

Other buildings

Radiators

0.97

0.5

 

Floor heating slab floors or floors above vented crawl space

0.85

1

 

Floor heating in inserted ceiling

1.0

1

1 electricity use per square metre of heated area, in the case of electric radiators, cables and electric ceiling heating and heat pump systems, kWh/(m2 y)

(3) The losses of the heating system and the electricity use of auxiliary devices are not taken into account as internal heat gain in the energy calculation. The losses accounted for in the efficiency factor of the heating system are not utilisable.

§ 15. Calculations concerning heating systems incorporating heat pump systems

(1) The calculation concerning the heat pump system is based on the coefficient of performance that shows how many kWh of thermal energy are obtained for each kWh of electrical energy consumed by the heat pump.

(2) A heat pump operated as part of a combined heating system is taken into account in the calculation if a part of the peak thermal power need is satisfied by another heat source (e.g., an electric heating element or an oil or gas-fired boiler). Geothermal heat pumps which produce thermal energy from water or ground energy may satisfy the entire thermal power need or a part of it. Other heat pumps are always considered part of a combined heating system.

§ 16. Calculations concerning combined heating systems incorporating heat pump systems

(1) In combined heating systems, the heat generated by the heat pump is calculated on the basis of the heat pump’s thermal capacity, instant heating need and the heat gain which reduces heating need in accordance with section 6. With respect to space heating and the heating of ventilation air, the instant power need (which for the purposes of this subsection does not mean the dimensioning capacity of the heat pump system) depends on the outdoor temperature.

(2) The thermal power need of the heating system is calculated for each hour. The thermal energy produced by the heat pump (kWh/y) is the sum of the power needs of the hours during which the capacity of the heat pump exceeds or equals the power need (calculated for each hour of the test reference year). The calculation takes into account the reduction of peak capacity as a function of the drop in outdoor temperature and the calculations are conducted for the relevant temperature ranges.

(3) The thermal energy produced by another source of such energy (kWh/y) consists of the power need that is not covered by the heat pump and is calculated as the sum of the differences between the power need and the heat pump’s power (for each hour of the test reference year, taking into account the fact that the power of the heat pump is equal to or less than the power need of the heating system). The energy use of the other source of thermal energy is calculated in accordance with the requirements set out under subsection 2 of section 14.

(4) To calculate the use of electrical energy by the heat pump system, the thermal energy produced by the heat pump is divided by the average coefficient of performance which characterises the heat pump system during the heating period, and which accounts for the electricity use of the circulators and any other auxiliary devices connected to the heating system, as well as, in accordance with section 14, the efficiency factor of the distribution and emission of heat. The coefficient of performance is determined on the basis of the values set out in Table 10 or of the calculation performed using data provided by the manufacturer, which account for the operation of the heat pump at part load and at different outdoor temperatures. When using the data set out in Tables 9 and 10, the average coefficient of performance of the heat pump system equals the product of the coefficient of performance value set out in Table 10 and the efficiency factor value set out in Table 9.

Tabel 10. Average values of the coefficient of performance of heat pumps for the heating period and for the heating of household water1

Type of heat pump

Average coefficient of performance for the heating period2

Performance coefficients at different outdoor temperatures (°C) and different part load values (%) -15°C/100%; -7°C/100%;
2°C/50%; 7°C/50%

Geothermal heat pump, Geothermal heat pump, 40°C/33°C

3.6

3.4

 

Geothermal heat pump, 5°C/35°C
Geothermal heat pump, 50°C/35°C

3.2

3.0

 

Geothermal heat pump, heating of household water

2.7

 

Exhaust air heat pump3

3.0

 

Air-to-air heat pump4

-

        2.0             2.4             3.0             4.0

Air-to-water heat pump, 40°C/33°C4

-

        1.7             2.1             2.7             3.5

Air-to-water heat pump, heating of household water

2.0

 

1 The coefficient of performance accounts for the use of electricity by the pump unit, circulators and auxiliary devices.

2 In relation to the heating of household water the coefficient of performance reflects the year’s average value.

3 The temperature difference of exhaust air before and after entering the heat pump amounts to 21-5=16 °C and a part of the heat pump capacity is utilised for the heating of household water.

4 The capacity and the coefficient of performance of the heat pump depend considerably on the outdoor temperature.

(5) In the case of heat pumps which extract thermal energy from outdoor air the calculation of electrical energy use is performed separately for the relevant temperature ranges. With respect to air-to-air heat pumps whose capacity is up to 12 kW the calculation of electrical energy use may be performed using the yearly average coefficient of performance which for the present purposes is to be found in the energy performance certificate of the heat pump as the SCOP value corresponding to the coldest climate zone. The use of SCOP value requires that the air-to-air heat pump is dimensioned to a load that corresponds to the oudoor temperature of -7 °C.

Division 2

Ventilation systems

§ 17. Calculation of air flow rates of ventilation systems

(1) For the purpose of using it in the energy calculation, the value of the outdoor air flow rate of the building’s ventilation system is calculated according to the regulation entitled Minimum Requirements for Energy Performance established in accordance with subsection 72 of section 3 of the Building Act. Heat recovery and the electricity use of the ventilation system are calculated for ventilation units that correspond to those described in design documentation and produce the air flow rate described in the previous sentence (ventilation units which correspond to those described in design documentation have sufficient capacity to guarantee the required air flow rates). The calculation takes into account the possible difference in the flow rates of supply and exhaust air, both with respect to the given ventilation unit and in the case of separate fans. Where the volume of exhaust air exceeds the volume of supply air, the difference between the exhaust and supply air flow rates is regarded as an additional supply of outdoor air without heat recovery.

(2) The energy use of ventilation units whose hours of operation differ is calculated separately. The air flows of ventilation units with identical hours of operation are usually totalled.

(3) The infiltration air flow is not included in the air flow calculation of the ventilation system and is calculated separately according to section 13, which makes provision for accounting for the possible difference between the supply and exhaust air flow rates by introducing the corresponding adjustment in the formula of the infiltration air flow rate.

§ 18. Calculation of heat recovery

(1) Heat recovery in the ventilation system is calculated simultaneously with the energy need for space heating and for the heating of ventilation air.

(2) The calculation of heat recovery is based on the temperature ratio value of the heat exchanger (the difference between the temperature of the heated  air stream before and after the heat exchanger divided by the maximum temperature difference over the heat exchanger), the temperature of supply air and the measures designed to limit frost formation on the heat exchanger. Where manufacturer’s data are unavailable, the following ratios are used:

1) cross-flow plate heat exchangers, 0.6;

2) counterflow plate heat exchangers, 0.7;

3) rotary heat exchangers, 0.7;

4) run-around coil heat exchangers, 0.4.

(3) In order to avoid frost growth on the heat exchanger at low outdoor temperatures, the minimum temperature of exhaust air (the air leaving the ventilation unit) is usually controlled by reducing the efficiency of the ventilation unit. Where more precise data are unavailable, the minimum temperature of exhaust air is controlled as follows:

1) in residential buildings, to +5 °C in the case of a plate heat exchanger and to 0 °C in the case of a rotary heat exchanger or a plate heat exchanger with humidity recovery;

2) in other non-residential buildings without humidification and significant humidity production, to 0 °C in the case of a plate heat exchanger and to –5 °C in the case of a rotary heat exchanger.

(4) The additional power need and energy which are required for avoiding frost formation on the heat exchanger are included in the calculation concerning the ventilation system.

(5) In order to avoid the overheating of rooms, the temperature of supply air is set below the indoor temperature. In systems in which the temperature of supply air is kept constant, it is usually set at 18 °C. The heating of supply air to the indoor temperature is included in the calculation of the energy need for space heating.

§ 19. Calculation of the electricity use of ventilation systems

(1) The electricity use of a ventilation system mainly consists of the electricity use of the ventilation units and their control devices and to a lesser extent of the electricity use of pumps and other auxiliary devices. The efficiency of electricity use is assessed on the basis of specific fan power of the ventilation system at a calculated air flow rate. Specific fan power is the ratio of the total power of the system to the air flow rate (either supply or exhaust air flow rate, the higher to be selected) [(kW/(m3/s)].

(2) In the case of bigger ventilation units (air flow rate over 0.25 m3/s), electricity use is calculated separately in respect of each fan. The electricity use of a fan Ev (kWh/y) is calculated by means of the following formula:

where Pv is the wattage of the fan in kW;
τd is the number of the operating hours of the fan at a calculated air flow rate per 24-hour period;
τw is the number of the fan operating days per week at a calculated air flow rate d;
t is the period of 8760 hours in respect of which the calculation is performed.

(3) The wattage of the fan Pv (W) is calculated by means of the following formula:

where Δpv is the fan pressure rise in Pa;
V is the fan’s air flow rate in m3/s;
ηft is the fan’s total efficiency which includes the efficiency of the fan, the efficiency of the belt transmission, the efficiency of the motor and the efficiency of the control of the possible rotation speed.

(4) The total  efficiency of the fan is obtained from the data provided by the manufacturer; the values set out in Table 11 may be used instead of relying on the manufacturer’s data.

Table 11. Aggregate efficiency ηft of the fan

Air flow V m3/s

ηft

< 0.25

0.20

0.25 – 0.5

0.35

0.5 – 1

0.40

1 – 5

0.45

> 5

0.50

§ 20. Calculation concerning the pressure rise of the fan

(1) The pressure rise of the fan Δpv (Pa) is calculated by means of the following formula:

Δpv = Δpm + Δpt,

where Δpm is the pressure drop of the ventilation unit in Pa;
Δpt is the pressure drop of the ducts in Pa.

(2) The pressure drop of the ventilation unit Δpm includes the total pressure drop of the unit’s components and the pressure drop at the juncture of the fan and the ventilation unit. The pressure drop of filters is deemed to equal the average pressure drop over their period of use, to be calculated by adding to the initial pressure drop one third of the difference between the final and initial pressure drop values.

(3) The pressure drop of ducts Δpt represents the total pressure drop of the ducts and of the terminal devices, including the pressure drop in the ducts leading both to and from the ventilation unit.

(4) Where no data are available in the building design documentation concerning the pressure drop values, those values are calculated using the data set out in Table 12.

Table 12. Pressure drop values for ventilation units and duct segments in systems whose air flow rate is ≥ 0,25 m³/s. The terminal surface velocity of ventilation unit components corresponding to low, normal and high pressure drop values is, respectively, 1.5, 2 and 2.5 m/s.

Component

Pressure drop in Pa

Supply

Low

Normal

High

Heating element

40

80

120

Cooling element

60

100

140

Heat recovery unit

100

150

200

Coarse filter

30

60

100

Fine filter

70

100

200

Noise suppressor

30

50

80

Juncture of ventilation unit and ducts

20

50

70

Ducts:

       

-constant air flow rate

100

200

300

-variable air flow rate

200

300

400

Terminal device

50

50

100

Exhaust

Low

Normal

High

Heat recovery unit

100

150

200

Filter

50

100

150

Noise suppressor

30

50

80

Juncture of ventilation unit and ducts

20

50

70

Ducts:

     

Constant air volume

100

200

300

Variable air volume

200

300

400

Terminal device

20

30

50

(5) In performing the calculation of a variable air volume system in accordance with the simplified method, the pressure drop value of the ductwork is assumed to remain constant. The pressure drop of the variable air volume system Δpv (Pa) is calculated by means of the following formula:

Δpv = Δpt + Δpmxp,

where Δpt is the pressure drop of the ductwork and the terminal device in Pa;
Δpm is the pressure drop of the ventilation unit in Pa;
xp is the pressure drop factor of the variable air volume system, xp = 0,65.

§ 21. Auxiliary devices of ventilation systems

(1) The wattage Phr (kW) of the pump of a run-around coil heat exchanger is calculated by means of the following formula:

where  VSK is the flow rate of the heat exchange fluid in m3/s;
ηp is the efficiency factor of the pump;
Δpr is the pressure drop of the liquid side of the heat exchanger in kPa (kilopascal);
Δpp is the pressure drop in kPa of the pipework which contains the heat exchange fluid ;
Δpv is the pressure drop of the regulator valve in kPa.

(2) The estimated pressure drop value of 0.2 kPa/m may be used as the pressure drop value of the pipework  run-around coil. The pressure drop values of the fluid side of the heat recovery unit fall into the following ranges: 60 kPa (low), 100 kPa (normal) and 150 kPa (high). The pressure drop of the three-way valve (the regulator valve of the heat exchange fluid) may be deemed to equal 40% of the pressure drop for the entire system (including the pressure drop of the valve). Where the system is controlled by adjusting the rotation speed of the pump, the pressure drop of the regulator valve Δpp = 0 kPa.

(3) The efficiency factor ηp of the pump may be deemed to equal 0.3.

§ 22. Electrical energy use of ventilation units in small residential buildings and apartments

(1) The electrical energy use Ev (kWh/y) of small ventilation units whose air flow rate is lower than 0,25 m3/s is calculated by means of the following formula:

Ev = Pvs tvsn xp,

where Pvs is the wattage of the ventilation unit in kW at design air flow rate;
tvsn is the annual number of operating hours of the ventilation unit at design air flow rate (in general, the value of tvsn is 8760 h, except in the case of systems controlled on a demand basis);
xp is the pressure drop factor of the ducts.

(2) The wattage Pvs of the ventilation unit is deemed to equal the value which is provided by the manufacturer of the ventilation unit for the design  air flow rate and which has been measured in accordance with the standard EVS-EN 13141-7.

(3) The pressure drop factor xp of the ducts is determined on the basis of the data set out in Table 13 of this regulation.

Table 13. Pressure drop factor xp of the ducts

Pressure drop factor

Pressure drop level in ductwork

Pressure drop in supply ductwork

Low
35 Pa

Normal
50 Pa

High
100 Pa

xp

0.8

1.0

1.2

Division 3

Cooling systems

§ 23. Calculation of the energy use of cooling systems

(1) The energy use of a cooling system is composed of the energy use for the production of cooling energy and the electrical energy use by the auxiliary devices required for the distribution and emission  of cooling energy.

(2) The energy use for cooling during the cooling period Qj (kWh/y) including condensation losses and the thermal losses related to the distribution and emission  of cooling energy is calculated on the basis of the energy need for cooling as follows:

where Qje is the energy need of the cooling coils  of ventilation units in kWh/y;
Qrs is the energy need of room conditioning  units in kWh/y;
βje is the factor describing heat losses related to the cooling coils  of ventilation units;
βrs is the factor describing heat losses related to the distribution of cooling energy between room  units and the emission  of cooling energy.

§ 24. Calculation concerning single-stage cooling systems

(1) For compressor-driven cooling systems, the electrical energy delivered to the cooling system during the cooling period EQ (in kWh/y) is calculated by means of the following formula:

where Qj is the energy use for cooling in kWh/y, including condensation and heat loss;

Ea is the electricity use of auxiliary devices in kWh/y;

ε is the energy efficiency ratio  of the cooling energy production process during the cooling period.

(2) The thermal energy Qjt (in kWh/y) delivered to absorption cooling systems is calculated by means of the following formula, to which the electricity use Ea of auxiliary devices is added:

where ε is the energy efficiency ratio  of the cooling energy production process during the cooling period;

Qj is the energy use for cooling in kWh/y, including condensation and heat loss in kWh/y.

(3) The energy efficiency ratio ε of the cooling period is calculated on the basis of the full load and part load value given by the manufacturer of the unit respectively in accordance with the standards EVS-EN 14511-2 and EVS-EN 14825 or on the basis of the ESEER value given by the manufacturer; or taken to equal the value given in Table 14. When calculating the cooling factor on the basis of the ESEER value, the fact that that value is based on the capacity of the compressor module and does not include the electricity use of the condenserfans and pumps must taken into account and the corresponding amount deducted from the ESEER value.

Table 14. Energy efficiency ratios describing the cooling energy production process during the cooling period

Manner of production of cooling energy

ε

Compressor-driven cooler

3.5

Natural cooling, liquid cooler

Natural cooling, ground loop (horizontal)

Absorption cooling

5

30

0.7

(4) System losses are determined by means of a simulation calculation or by using the values given in Table 15. Where the calculation concerning the energy need of the cooling coil already accounts for condensation, the factor βje that states the relevant value without condensation losses must be used. If condensation has not been accounted for, the factor βjek that includes condensation losses must be used.

Table 15. Factors describing the condensation losses of the cooling process and the heat loss of the distribution and emission  of cooling energy

Cooling water supply temperature

βje

βjek

βrs

7 °C

0.3

0.6

0.2

10 °C

0.2

0.5

0.15

15 °C

0.1

0.2

0.1

18 °C

0.0

0.0

0.0

(5) The βje and ja βrs factors of split and VRV type units (local units with separate cooler and condenser elements) are deemed to equal zero because their heat losses have been accounted for as part of the energy efficiency ratio.

(6) The SEER value stated in the energy performance certificate of air conditioning units and air-to-air heat pumps (split and VRV type) of up to 12 kW capacity may be used as the energy efficiency ratio with respect to the cooling period. The condensation losses of such units may be accounted for by using the values corresponding to the supply temperature +7 °C of cooling water as stated in Table 15.

§ 25. Calculation of the electrical energy use of cooling systems that utilise free cooling

Where the cooling energy that is consumed in a building is derived from free cooling and harvested by means of a compressor-driven cooling unit, the delivered energy of the cooling system during the cooling period is calculated by means of the following formula:

where α1 is an estimated proportion of the yearly cooling energy produced by means of production process 1;
α2 is an estimated proportion of the yearly cooling energy produced by means of production process 2 (α1 + α2 = 1.0);
ε1 is the energy efficiency ratio  of production process 1 for the cooling period;
ε2 the energy efficiency ration  of production process 2 for the cooling period;
Qj is the cooling energy use during the cooling period in kWh/y including any condensation losses and heat losses;
Ea is the electrical energy use of auxiliary devices in kWh/y.

§ 26. Calculation of electrical energy use by auxiliary devices of cooling systems

(1) Where it is not possible ot calculate the electrical energy use Ea (in kWh/y) of auxiliary devices which consume electrical energy (such as the pumps in the cooling system, the fans of fancoils  as well as other auxiliary devices) with a higher accuracy, that use is calculated by means of the following formula:

where βa is the electricity use factor of the auxiliary devices of the system during the cooling period;

Qj is the energy need in kWh/y for cooling the space served by the system during the cooling period.

(2) The electricity use factor may be deemed to equal the following values:

1) for hydronic systems with chilled  beams, 0.05

2) for hydronic systems with fancoils, 0.08

3) for VAV (variable air volume) ventilation systems, 0.05

4) for split and VRV (variable refrigerant volume) units, 0 (auxiliary devices are accounted for in the cooling factor).

Division 4

Local renewable energy systems

§ 27. Use of solar energy for the production of thermal energy

(1) The thermal energy produced by a solar collector and the electrical energy used by the circulation pump is calculated either by means of the relevant software or the formula set out under subsection 2 below. The software must allow the use of climatic parameters of the test reference year of the Estonian energy calculations, permit the accounting of the solar radiation flow which reaches the collector surface as a function of the collector’s orientation, tilt and shading, make provision for the heat loss of the collector and the system, take into account the particular manner of charging the accumulation tank and the use of thermal energy in the building, and include in the calculation the technical parameters provided by the manufacturer.

(2) Where more precise data are not available, the thermal energy of the hot household water provided by the collector may be calculated by means of the following formula:

where Qkol is the yearly thermal energy in kWh/y of the hot household water provided by the solar collector;
210 is the thermal energy in kWh/(m2y) produced by the collector for the active surface of the collector;
Akol is the active surface of the collector (in m2) which is not overshadowed;
kik is the factor describing the orientation of the collector with respect to the cardinal points (for kik values, see Table 16);
knurk is the factor describing the collector’s tilt with respect to the horizon (for knurk values, see Table 17).

Table 16. Collector or panel orientation factor, kik

Orientation

kik, -

South-east/South/South-west

1.0

East/West

0.8

North-west/North/North-east

0.6

Table 17. Collector or panel tilt factor, knurk

Tilt angle

knurk, -

70 o

1

(3) When the formula set out under subsection 2 is used to perform the relevant calculation, the maximum thermal energy of the hot household water provided by the solar collector equals 50 % of the yearly energy use for the production of hot household water. Any quantity by that threshold is exceeded is not taken into account in the energy calculation.

(4) Where more precise data are not available, the electricity use of the circulation pump of the solar collector may be calculated by means of the following formula:

where Ekol.pump  is the yearly electricity use in kWh/y of the circulation pump of the solar collector;
Akol is the active surface of the collector (in m2) that is not overshadowed;
tkol.pump is the yearly number of operating hours (h) of the circulation pump of the collector.

Where more precise data are not available, the number of operating hours of the circulation pump tkol.pump may be deemed to equal 2000 h/y.

§ 28. Use of solar energy for the production of electrical energy

(1) The electrical energy produced by means of solar panels in a year is calculated by means of the following formula:

where Epan is the electrical energy (in kWh/y) produced by the solar panels during the year;
Qpäike is the yearly solar energy (in kWh/y) which reaches the surface of the panels that is not overshadowed;
Pmax is the maximum capacity in kW of the solar panels at standard operating conditions (Iref= 1 kW/m2, temperature 25 oC);
kkas is the factor describing the use conditions of the solar panels;
Iref is the standard value of solar irradiance, 1 kW/m2.

(2) The yearly solar energy that reaches the surface of solar panels is calculated by means of the following formula:

where 960 is the yearly solar radiation in kWh/(m2y) that reaches a horizontal surface;
kik is the factor describing the orientation of solar panel with respect to the cardinal points (for kik values, see Table 16);
knurk is the factor describing the collector’s tilt with respect to the horizon (for knurk values, see Table 17).

(3) The maximum capacity of the solar panel Pmax at standard operating conditions depends on the type of the panel and is calculated on the basis of the manufacturer’s data. The use conditions factor kkas accounts for the environmental parameters that prevail on the site (temperature, installation parameters) and for losses related to converting the harvested energy to alternating current. Where specific data are not available, the values stated in Table 18 may be used.

Table 18. Solar panel efficiency factor, kkas

Installation type

kkas, -

No air-cooling

0.7

Moderately air-cooled

0.75

Intensely air-cooled

0.8

§ 29. Electricity generated from wind

(1) The calculation of the electricity generated from wind must be based on wind parameters at the location of the wind turbine and take into account the efficiency of the turbine and the size of its blades. The data of the Estonian test reference year for energy calculations cannot be used for calculating the electricity generated from wind.

(2) The annual electricity generated by a wind turbine is calculated by means of the following formula:

where Etuul is the annual electricity in kWh/y generated by the wind turbine;
Atiivik is the area in m2 formed by the turbine blades against the air flow;
vi is the wind speed in m/s at which the wind turbine generates electricity;
vmin is the lowest wind speed in m/s at which the wind turbine generates electricity;
vmax is the highest wind speed in m/s at which the wind turbine generates electricity;
ρ is the density of air, 1.2 kg/m3;
ηgen,iis the aggregate efficiency of the wind turbine at specific wind speed vi that is obtained from the data provided by the manufacturer;

ti is the number of the operating hours (h) of the turbine corresponding to the wind speedvi.

(3) The annual electricity generated by a wind turbine may also be calculated by means of the following simplified formula:

where Etuul is the annual electricity in kWh/y generated by the wind turbine;
Atiivik is the area in m2 formed by the turbine blades against the air flow;
vk is the average wind speed in m/s;
ρ is the density of air, 1.2 kg/m3;
ηk.gen is the annual aggregate efficiency of the wind turbine, which is obtained from the data provided by the manufacturer;
B is the factor describing the distribution of wind speed during the operation of the wind turbine throughout the year (1.5 where more precise data are unavailable);
t is the number of operating hours of the turbine per year.

Chapter 6

REQUIREMENTS FOR THE PRESENTATION OF THE RESULTS OF ENERGY CALCULATION

§ 30. Requirements for the presentation of calculation results

(1) The input parameters used in the energy calculation are presented in the format provided in Annex 1 of this regulation. In the case of proving the compliance of a small residential building with the limit value of the energy performance indicator in accordance with the simplified method, the input parameters and calculation results are presented in the format provided in Annex 2 of this regulation.

(2) The results of the energy calculation are presented in the format provided in Annex 3 of this regulation. A summary of delivered and exported energy must be presented with respect to all energy carriers used in the provision of the building’s energy supply (electricity, district heating and/or various fuels) in accordance with the results of the calculations concerning its utility systems.

(3) The results of the calculations concerning the utility systems are entered in the table of total energy use provided in Annex 3 of this regulation. The energy use of the ventilation system, lighting, appliances and, in general, also of the cooling system consists solely of electrical energy, and is entered, together with the electrical energy use of the heating system, into the corresponding fields in the electricity column. The thermal energy use of the heating system is presented in accordance with the energy supply solution of the heating system in the thermal or electrical energy column, by way of allocations to space heating, the heating of ventilation air and the heating of household water. Local renewable energy, the electricity fed into the power network and the thermal energy fed into the supply or return pipeline of the district heating network are presented in the table of local renewable energy and exported energy.

(4) The quantities of obtained fuels are calculated as the product of delivered thermal energy and the lower calorific value of the fuel. The lower calorific values of consumable substances are deemed to equal the data provided by the manufacturer or the values provided in Annex 4 of this regulation.

(5) The energy carrier conversion factors are set out in the regulation entitled Minimum Requirements for Energy Performance established in accordance with subsection 72 of section 3 of the Building Act. Weighted energy use is calculated as the product of the difference between delivered energy and exported energy and of the energy carrier conversion factor.

(6) The energy performance indicator ETA is calculated by dividing the difference between the total delivered energy use and the total exported energy by the number of square metres of heated area:

where ETA is the energy performance indicator expressed in kWh/(m2 y);
Etar,i is the energy delivered (in kWh/y) by means of the energy carrier i;
Eeks,i is the energy exported (in kWh/y) by means of the energy carrier i;
fi is the weighting factor of the energy carrier i; -
Aneto is the heated area in m2.

When presenting the results of the calculation of delivered and exported energy, the following formula is considered to hold with respect to each energy carrier:

where Esum,i is the building’s total energy use in kWh/y in relation to the energy carrier i;
Elok,i is the local renewable energy in kWh/y related to the energy carrier i.

(7) The results of the verification of summertime indoor temperature with regard to all calculated rooms which represent room types are presented in the format provided in Annex 5 of this regulation. With respect to residential buildings, the presentation of the duration curve is not compulsory. Where the verification calculation of summertime indoor temperature is not performed with respect to a small residential building, the data proving the exemption of the rooms representative of room types from the temperature verification requirement are presented in the format provided in Annex 6 of this regulation.

(8) When presenting the results, the fields in coloured rows and the columns in Annexes 1–3 and 5–6 must be completed.

Chapter 7

IMPLEMENTING PROVISIONS

§ 31. Implementation of this regulation

(1) Where the application for a building permit is submitted before 9 January 2013, but the building permit is issued after that date, the requirements established in this regulation do not apply.

(2) This regulation enters into force on 9 January 2013.

1 Directive 2002/91/EC of the European Parliament and of the Council on the energy performance of buildings (OJ L 1, 4.01.2003, pp. 65–71), amended by Directive 2010/31/EU of the European Parliament and of the Council on the energy performance of buildings (OJ L 153, 18.06.2010, pp. 13–35)

Juhan Parts
Minister

Marika Priske
Secretary-General

Annex 1 Presentation of input parameters of the energy calculation

Annex 2 Presentation of input parameters of the energy calculation concerning the proving of compliance, in the case of small residential buildings and in accordance with the simplified method, with the limit value of the energy performance indicator

Annex 3 Presentation of the results of the energy calculation

Annex 4 Lower calorific values of the consumable substances of fuels

Annex 5 Presentation of the results of the verification of summertime indoor temperature

Annex 6 Data concerning rooms representative of room types in small residential buildings