epb methodology english

Recommendation

Draft Calculation Methodology for Energy Performance of Buildings

Republic of MoldovaMarch 2011

Draft Methodology recommended as part of the “Regulatory Framework for Energy Efficiency in Buildings” International Project, supported by the Fund of Shareholders of EBRD

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TABLE OF CONTENTS

INTRODUCTION.................................................................................................................................... 4

I. CALCULATION METHODOLOGY FOR THERMAL PROTECTION OF BUILDING

COMPONENTS AND BUILDINGS.................................................................................................7

1. CALCULATION OF ENERGY NEED FOR SPACE HEATING......................................................8

1.1 TERMS AND DEFINITIONS................................................................................................................8

1.2 CALCULATION OF ENERGY NEED FOR HEATING.............................................................................11

1.2.1 Quasi-Continuous Heating at Corrected Internal Set-Point Temperature for Intermitted

Heating.......................................................................................................................... 12

1.2.2 Corrections for Intermittency..........................................................................................12

1.2.3 Corrections for Unoccupied Period (monthly, simple hourly and detailed simulation

methods)........................................................................................................................ 13

1.3 HEAT TRANSFER BY TRANSMISSION.............................................................................................13

1.3.1 Transmission Heat Transfer Coefficient.........................................................................14

1.3.2 Calculation of Thermal Coupling Coefficient for Heated Basement...............................16

1.3.3 Calculation of Thermal Transmittance of Ground Floor.................................................16

1.3.4 Thermal Transmittance (U-value) of Windows...............................................................18

1.4 HEAT TRANSFER BY VENTILATION..................................................................................................19

1.4.1 Simplified Method for Calculation of Heat Transfer Coefficient by Ventilation HV..........20

1.4.2 The Criterion of the Minimum Air Change......................................................................20

1.5 THERMAL GAINS.......................................................................................................................... 21

1.5.1 Internal Heat Gains........................................................................................................21

1.5.2 Solar Heat Gains...........................................................................................................22

1.6 DYNAMIC PARAMETERS................................................................................................................25

1.6.1 Gain Utilization Factor for Heating.................................................................................25

1.6.2 Building Time Constant..................................................................................................27

1.7 TOTAL ANNUAL ENERGY NEED FOR SPACE HEATING....................................................................28

1.7.1 Total Annual Energy Need for Space Heating per Combination of Systems.................28

II. CALCULATION METHODOLOGY FOR ENERGY USE FOR SPACE HEATING.......................30

2. ENERGY USE FOR SPACE HEATING.......................................................................................31

2.1 TERMS AND DEFINITIONS..............................................................................................................31

2.2 HEAT EMISSION SUBSYSTEM........................................................................................................32

2.3 HEAT DISTRIBUTION SUBSYSTEM..................................................................................................36

2.4 HEAT STORAGE SUBSYSTEM........................................................................................................37

2.5 AUXILIARY ENERGY OF HEATING SYSTEM......................................................................................38

III. CALCULATION METHODOLOGY FOR ENERGY USE FOR HOT WATER PREPARATION....39


33. ENERGY USE FOR HOT WATER PREPARATION....................................................................40


3.2 DOMESTIC HOT WATER – VOLUME OF DHW PREPARED................................................................42

3.3 DOMESTIC HOT WATER – DHW DISTRIBUTION SUBSYSTEM AND STORAGE SUBSYSTEM..................42

3.4 DOMESTIC HOT WATER – DHW SYSTEM AUXILIARY ENERGY........................................................44

IV. CALCULATION OF GLOBAL INDICATORS...............................................................................45

4. CALCULATION OF GLOBAL INDICATOR.....................................................................................46


4.2 DELIVERED ENERGY..................................................................................................................... 47

4.2.1 Generation Losses...............................................................................................................48

4.3 Primary Energy and Emissions of CO2.......................................................................................50


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Introduction

This Methodology of Calculation for Energy Performance of Buildings (hereinafter referred to as “Methodology) is supported by an Excel Tool developed for the calculation of energy performance of and issuance of the Energy Performance Certificates for buildings. The Methodology is available for all rated building categories, such as family houses, apartment houses, schools, office buildings and mixed use buildings.

The Methodology focuses on energy (heat) needs for heating, energy use for space heating and energy use for domestic hot water calculation.

For the calculation of energy use the following EN and EN ISO technical standards are used as a basis. They are necessary only as additional information, detailed calculations, and/or for special cases. These are not necessary for standard energy rating. The standard rating calculation is a subject of next chapters in this methodology.

Number of EN Title of the standard

Part 1 – Standard for energy (heat) use for space heating and cooling

EN ISO 13790 Thermal performance of buildings – Calculation of energy use for space heating and cooling (ISO 13790: 2008)

PART 2 – Thermal protection of building components

EN ISO 13789 Thermal performance of buildings – Transmission and

ventilation heat transfer coefficients – Calculation method (ISO 13789: 2007)

EN ISO 6946 Building components and building elements – Thermal resistance and thermal transmittance – Calculation method (ISO 6946: 2007)

EN ISO 13370 Thermal Performance of buildings - Heat transfer via the ground – Calculation methods (ISO 13370: 2007)

EN 13947 Thermal performance of curtain walling – Calculation of thermal transmittance

EN ISO 10077-1 Thermal performance of windows, doors and shutters –

Calculation of thermal transmittance – Part 1: General

EN ISO 10077-2 Thermal performance of windows, doors and shutters – Calculation of thermal transmittance – Part 2: Numerical method for frames

EN ISO 10211 Thermal bridges in building construction – Heat flows and surface temperatures – Detailed calculations (ISO 10211: 2007)

EN ISO 14683 Thermal bridges in building construction - Linear thermal transmittance – Simplified methods and default values (ISO 14683: 2007)

EN ISO 10456 Building materials and products - Hydrothermal properties- Tabulated design values and procedures for determining declared and design thermal values (ISO 10456: 2007)

Part 3 – Standards for heating calculation

EN 15316-1 Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 1: General

EN 15316-2-1 Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 2.1: Space heating emission systems


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EN 15316-4 Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 4-1:: Space heating generation systems, combustion systemPart 4-2: Space heating generation systems, heat pump systemPart 4-3: Space heating generation systems, thermal solar systemsPart 4-4: Heat generation systems, building-integrated cogeneration systemsPart 4-5: Space heating generation systems, the performance and quality of district heating and large volume systemsPart 4-6: Heat generation systems, photovoltaic systems

Part 4-7: Space heating generation systems, biomass combustion systems

EN 15316-2-3 Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies – Part 2.3: Space heating distribution systems

Part 4 – Standards for domestic hot water calculation

EN 15316-3 Heating systems in buildings – method for calculation of system energy requirements and system efficiencies Part 3-1: Domestic hot water systems, characterization of needs (tapping requirements)Part 3-2: Domestic hot water systems, distribution

Part 3-3: Domestic hot water systems, generation

Part 5 – Standards for automation and control

EN 15232 Energy performance of buildings - Impact of Building

Automation, Controls and Building Management

The Methodology is divided into four main separate chapters: I. Calculation methodology for thermal protection of building components and buildings,

including the energy (heat) need for heating; II. Calculation methodology for energy use for space heating; III. Calculation methodology for energy use for hot water preparation;IV. Calculation of global indicator (total delivered energy – total energy use in building),

primary energy and CO2 emissions.

The procedures for thermal protection are based on EN ISO 13790 and on the technical standards referenced in this standard.

Parts of the methodology on heating systems energy requirements for space heating and systems for hot water (DHW) preparation are based on EN 15316.

The last part is focused on calculation of global indicator, energy use, total delivered energy, and primary energy and CO2 emissions. The calculation methodology is based especially on EN 15603.

Calculations have to be performed by two different experts: one for thermal protection and the second one for space heating and DHW. Therefore, the terms, definitions and symbols have been provided for each chapter separately.

The principles of calculation and the connectivity of the calculation results with the certification scheme are reflected in Figure 1 below. The calculation is repeated for actual state and state of the building after realization of proposed energy saving measures for improvement of building thermal protection or measures for improvement of heating system performance. The dot lines in Figure 1 express the repeating of the calculations for the state after realization of proposed energy saving measures.


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Figure 1. Principles of Calculation and Connection of Calculation Results with the Certification Scheme

Building data collection(design, inspection, proposal for improvement)

External climate data collection - seasonal

Indoor conditions, zoning, partitioning of building into zones for calculation, building

boundaries

Assessment of building characteristicsTransmission heat transfer coefficients Htr

Ventilation heat transfer coefficients Hve

Seasonal method for calculation of energy need for space heating

Monthly method for calculation of energy need for space heating

External climate data collection - monthly

Seasonal heat gains calculation (solar, internal)

Heat gains calculation (solar, internal)for each month

Dynamic parameters calculation (gain utilization factor for each

month)

Energy need for space heating(actual state, after realisation of proposed

measures)

Data collection on Heating systems for space

heating (design, inspection, proposal)

Energy need for hot water calculation

Exp

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Energy use for space heating – (actual state, after realisation of

proposed measures)

Data collection on hot water preparation

(design, inspection, proposal)

Heating systems losses calculation(distribution, emission, storage,

generation losses)

Energy use for hot water preparation – (actual state, after realisation of proposed measures)

Total delivered energy(actual state, after realisation of proposed measures)

Exp

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fo

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th

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Primary energy calculation(actual state, after realisation of

proposed measures)

CO2 emissions calculation(actual state, after realisation of

proposed measures)

Proposal for energy saving measures

Calculation of energy savings (energy need, energy use, primary energy, CO2 emissions)

Energy rating, energy classes, description(global indicator, buiding thermal protection, space heating,

hot water preparation)

Energy certificate

Print energy certificate

Seasonal gain utilization factor(constant)


HOT WATER PREPARATION

SPACE HEATING

Systems losses calculation(distribution, emission, storage,

generation losses)



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I. Calculation Methodology for Thermal Protection of Building Components and Buildings


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1. Calculation of Energy Need for Space Heating

1.1 Terms and Definitions

calculation step - time interval for the calculation of the energy need and use (one month or one heating season); heating season - period of the year during which a significant amount of energy for heating is needed. In this method seasonal method requires as calculation step a fixed season length that has to be distinguished from the actual season length; unoccupied period - period of several days or weeks without heating, e.g. due to holidays;

heated space - room or enclosure, which for the purposes of a calculation is assumed to be heated to a given set-point temperature; conditioned space - heated space to define the boundaries of the thermal zones and the thermal envelope; unconditioned space - room or enclosure that is not part of a conditioned space;

conditioned zone - part of a conditioned space with a given set-point temperature or set-point temperatures, throughout which the same occupancy pattern is assumed and the internal temperature is assumed to have negligible spatial variations, and which is controlled by a single heating system with equal energy performance;

conditioned area - floor area of conditioned spaces excluding non-habitable cellars or non-habitable parts of a space, including the floor area on all storeys if more than one. External dimensions are used for calculation;

external temperature - temperature of external air;

internal temperature - arithmetic average of the air temperature and the mean radiant temperature at the centre of a zone or space (approximately operative temperature)

set-point (of the internal) temperature - internal (minimum intended) temperature as fixed by the control system in normal heating mode;

Note: The values are specified at national level. For monthly and seasonal methods, the value of the set-point can include adjustment for intermittency.

set-back temperature - minimum internal temperature to be maintained during reduced heating periods;

intermittent heating - heating pattern where normal heating periods alternate with periods of reduced or no heating;

energy need for heating - heat to be delivered to, or extracted from, a conditioned space to maintain the intended temperature conditions during a given period of time;

Note: The energy need is calculated and cannot easily be measured.

energy use for space heating - energy input to the heating system to satisfy the energy need for heating;


9delivered energy for space heating - energy, expressed per energy carrier, supplied to the technical building systems through the system boundary, to satisfy the uses in building;

heat transfer coefficient -heat flow rate divided by the temperature difference between two environments; specifically used for heat transfer coefficient by transmission and ventilation

Note: In contrast with a heat gain, the driving force for heat transfer is the difference between the temperature in the considered space and the temperature of the environment at the other side (in the case of transmission) or the supply air temperature (in the case of ventilation).

transmission heat transfer coefficient - heat flow rate due to thermal transmission through the fabric of a building, divided by the difference between the environment temperatures on either side of the construction;

Note: By convention, the sign is positive if the heat flow is going out of the space considered (heat loss).

ventilation heat transfer coefficient - heat flow rate due to air entering an enclosed space, either by infiltration or ventilation, divided by the difference between the internal air temperature and the supply air temperature;

Note: By convention, the sign of the heat flow is positive if the supply air temperature is lower than the internal air temperature (heat loss).

internal heat gains - heat provided within the building by occupants (sensible metabolic heat) and by appliances such as domestic appliances, office equipment, etc., other than energy intentionally provided for heating or hot water preparation;

Note 1: In this methodology, if not directly taken into account as a reduction to the system losses, the recoverable system thermal losses are included as part of the internal heat gains. Note 2: Included is heat from (warm) process sources that are not controlled for the purpose of heating or domestic hot water preparation.

solar heat gains - heat provided by solar radiation entering, directly or indirectly (after absorption in building elements), into the building through windows;

solar irradiation - incident solar heat on a surface, per area of surface;

heat-balance ratio - monthly or seasonal heat gains divided by the monthly or seasonal heat transfer.


10SYMBOLS

Table 1. Symbols and Units

Symbol Quantity UnitA Area m²C effective heat capacity of a conditioned space J/Kc specific heat capacity J/(kg.K)E Energy MJF Factor 1g total solar energy transmittance of a glazed element 1H heat transfer coefficient W/Kh surface coefficient of heat transfer W/(m²·K)

Isol solar irradiance W/m²Q quantity of heat MJR thermal resistance · m².K/Wt period of time sU thermal transmittance W/(m²·K)V volume of air in a conditioned zone m³ heat-balance ratio 1 efficiency, utilization factor 1 centigrade temperature °C Density kg/m³ time constant h heat flow rate, thermal power W point thermal transmittance W/K linear thermal transmittance W/(m.K)L thermal coupling coefficient W/K

Table 2. Subscripts

A Adjacent (building) Gn Gains nocc unoccupied perioda air Gl glazing, glazed

elementocc occupied period

adj adjusted H Heating red reducedan annual Ht heat transfer s sum, totalB basement Hr Hourly se surface externalb building I internal (temperature) set set-pointbf basement floor Int internal (heat) sh shadingbw basement wall interm Intermittent si surface internalcont

continuous L Length sol solar (heat gains)

D direct m monthly, designated month

tr transmission (heat transfer

e external, exterior, envelope

Mn mean (time or space) TB thermal bridge

F frame Nd Need u unconditionedf floor N Standardized ve ventilation (heat

transfer)g ground 0 base, reference w window

z zone

For calculation quasi-steady-state method calculating the heat balance over month or a whole season is being used. Dynamic effects are taken into account by an empirically determined gain utilization factor.


11Gains utilization factor for the internal and solar heat gains takes account of the fact that only part of the internal and solar heat gains are utilized to decrease the energy need for heating, the rest is leading to an undesired increase of the internal temperature above the set-point.

For calculation of volume and total floor area the external dimensions are used.

Calculation Steps:

a) Choose the type of calculation method (seasonal method for dwelling buildings, monthly method for non-dwelling buildings).

b) Define the boundaries of conditioned spaces and unconditioned spaces.

c) If required, define the boundaries of the different calculation zones (according to temperature, generation, energy carrier , etc.).

d) Define the internal conditions for the calculations, the external climate and other data inputs.

e) Calculate, for each time step and building zone, the energy need (heat need) for heating, QH,nd.

f) Combine the results for different time steps and different zones serviced by the same systems and calculate the energy use for heating taking into account the dissipated heat of the heating systems.

g) Combine the results for different building zones with different systems.

Criteria for Single-Zone Calculation:

a) There are only small, unconditioned spaces.

b) Set-point temperatures for heating of the spaces differ by no more than 4 K.

c) The spaces are serviced by the same heating system (in case of one temperature zone if only parts of building are supplied from different heating systems the heat need can be calculated for whole building and divided according to floor area to separate heating systems).

In other cases building should be divided in more temperature zones calculated separately.

For mixed use buildings the parts with separate use are always a separate calculation zones.

1.2 Calculation of Energy Need for Heating

For each building zone and each calculation step (month or season), the building energy need for space heating, QH,nd, is calculated as:

QH,nd = QH,ht − ηH,gn QH,gn (1)where:

QH,ht is the total heat transfer for the heating in kWh;QH,gn is the total heat gains for the heating in kWh;ηH,gn is the dimensionless gain utilization factor.


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Energy Need for Intermittent Heating

Intermitted heating is applicable only for: office buildings; school buildings.

Possible situations considered are: quasi-continuous heating at constant corrected internal set-point temperature taking into

account intermittency; night-time and/or weekend reduced set-point or switch-off to set-back temperature; unoccupied periods (e.g. holidays) – only for school buildings.

1.2.1 Quasi-Continuous Heating at Corrected Internal Set-Point Temperature for Intermitted Heating

Intermittent heating can be considered as continuous heating with corrected internal set-point temperature if

the set-point temperature variations between normal heating and reduced heating periods are less or equal to 3 K

and/or

if the time constant of the building is less than 0,2 x the duration of the shortest reduced heating period. The set-point temperature for the calculation is the time average of the set-point temperatures.

Standard corrected set-point temperatures for different building types are reported in the Regulation on Energy Perfromance of Buildings.

1.2.2 Corrections for Intermittency

In the case of intermittent heating, which does not fulfill the conditions in the previous clause for quasi-continuous heating, the energy need for heating, QH,nd,interm expressed in kWh is calculated by using equation:

QH,nd = QH,nd,interm = H,red . QH,nd,cont (2)

where:QH,nd,cont is the energy need for continuous heating in kWh;aH,red is the dimensionless reduction factor for intermittent heating.

The dimensionless reduction factor for intermittent heating, aH,red is calculated using equation:

H,red = 1 bH,red(τH,0/τ)γH(1 fH,hr) (3)

(min. red,H = fH,hr , max. H,red = 1)where:

fH,hr is the fraction of the number of hours in the week with normal (no reduced) set-point temperature, example: (12 5)/(24 7) = 0,357;

bH,red is an empirical correlation factor, bH,red = 3;τ is the time constant of the building in hours;τH,0 is the reference time constant in hours;


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γH is the heat-balance ratio .

1.2.3 Corrections for Unoccupied Period (monthly, simple hourly and detailed simulation methods)

In school buildings, unoccupied periods during the heating season (holiday periods) are taken into account by calculation as follows.

For the month which contains an unoccupied period, the calculation is performed twice: a) for occupied (normal) heating settings; and b) for unoccupied settings and then interpolate the results linearly according to the time

fraction of unoccupied mode versus occupied mode:

QH,nd = (1 fH,nocc) . QH,nd,occ fH,nocc . QH,nd,nocc (4)

where:

QH,nd,occ the energy need for heating either QH,nd,cont or QH,nd,interm, assuming for all days of the month the set-point temperature for occupied period in kWh;

QH,nd, nocc the energy need for heating either QH,nd,cont or QH,nd,interm, assuming for all days of the month the set-back temperature for the unoccupied period in kWh;

fH,nocc the fraction of the month which is the unoccupied (heating) period (e.g. 10/31).

Total Heat Transfer and Heat Gains

For each building zone and each calculation step (month or season), the total heat transfer, Qht is calculated using equation:

QH,ht = Qtr + Qve (5)where:

Qtr the total heat transfer by transmission in kWh;Qve the total heat transfer by ventilation in kWh.

1.3 Heat Transfer by Transmission

The total heat transfer by transmission, Qtr in kWh is calculated for each month or season and for each zone, z, as given by equation:

Qtr = Htr,adj(θint,set,H − θe) . t (6)where:

Htr,adj the overall heat transfer coefficient by transmission of the zone, adjusted for the indoor/outdoor temperature difference (if applicable) in W/K;

θint,set,H the set-point temperature of the building zone in °C; regulation for each building category;

θe the temperature of the external environment in °C; set in regulation;t is the duration of the calculation step (month, season) in hours.


141.3.1 Transmission Heat Transfer Coefficient

The value for the overall transmission heat transfer coefficient, Htr,adj , expressed in W/K shall be calculated in accordance with EN ISO 13789, using the following equation:

Htr,adj = HD +Hg + HU + HA (7)where:

HD the direct heat transfer coefficient by transmission to the external environment in W/K;

Hg the steady-state heat transfer coefficient by transmission to the ground in W/K;

HU the transmission heat transfer coefficient by transmission through unconditioned spaces in W/K;

HA the heat transfer coefficient by transmission to adjacent buildings in W/K.

It can be expressed by equation using the temperature adjustment factor btr,x:

(8)

where:Ai area of element i of the building envelope in m²;Ui thermal transmittance of element i of the building envelope in W/(m².K);lk length of linear thermal bridge k in m;k linear thermal transmittance of thermal bridge k in W/(m.K);btr,x adjustment factor, with value btr,x ≠ 1 if the temperature at the other side of the

construction element is not equal to the external environment, such as in the case of a partition to adjacent conditioned or unconditioned spaces.

Note: For U-value of building components the obviously used method is to be applicated (e.g. according to EN ISO 6946 or appropriate national standard).

Taking into account the simplified calculation of influence of thermal bridges and the thermal coupling coefficient for floor and walls in heated basement the equation for calculation of transmission heat transfer can be expressed as following:

(9)

where:HTB increase of the transmission heat transfer due to thermal bridges in W/K;LB thermal coupling coefficient of heated basement W/K.

Increase of the transmission heat transfer due to thermal bridges HTB is calculated using equation:

(10)

where: U increase of heat transfer coefficient due to thermal bridges in W/(m².K);Ai area of element i of the building envelope in m².

U can be calculated, but in case of not known construction details can default values be used:

U = 0,05 W/(m².K) for constructions with continual thermal insulation on the external side of the envelope;

U = 0,10 W/(m².K) for other structures.


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The adjustment temperature factor btr,x is used instead of the temperature difference and where the summation is done over all the building components separating the internal environment and the environment at the other side of the construction (external, unconditioned space or adjacent conditioned space).

Recommended values of adjustment factor btr,x are reflected in Table 2.

Table 2. Adjustment Temperature Factor btr,x

Heat Transfer viaAdjustment temperature

factor btr,x

External walls, windows, doors 1.0Roof (flat ,slope) 1.0Floor on the ground 1.0Ceiling under loft 0.8

Wall between heated space and loft 0.8

Wall or ceiling between heated and unheated space or basement 0.5

Wall or ceiling between heated space and space heated to lower temperature (garage, adjacent building) 0.35Wall or opening structure between heated and unheated space where unheated space has the opening structure with - single glass 0.7 - double glass 0.6

- double glass with inert glass Ug 2.0 or triple glass 0.5

Floor/ceiling above exterior 1.0

Factor btr,x can be calculated from known temperatures at the other side of the structure using equation:

(11)

where:θint,i set-point temperature in heated building zone in °C;θu temperature in heated or unheated adjacent space in °C;θe temperature of the external environment in °C.

In case of ground floor btr,x =1 is used, while the U-value is calculated according to EN ISO 13370 taking into account the floor on the ground geometry.

In case of basement the steady-state thermal coupling coefficient Ls in W/K is calculated according to chapter 1.3.2 based on EN ISO 13370.

1.3.2 Calculation of Thermal Coupling Coefficient for Heated Basement

Characteristic Dimension of Floor


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To allow for the 3-dimensional nature of heat flow within the ground, the formula in this standard are expressed in terms of the "characteristic dimension" of the floor, B', defined as the area of the floor divided by half the perimeter:

(12)

where:P the exposed perimeter of the floor: the total length of external wall dividing the heated

building from the external environment or from an unheated space outside the insulated fabric;

A total ground-floor area; A is the ground-floor area under consideration;unheated spaces outside the insulated fabric of the building, such as porches, attached garages or storage areas, are excluded when determining P and A (but the length of the wall between the heated building and the unheated space is included in the perimeter: the ground heat losses are assessed as if the unheated spaces were not present).

Equivalent Thickness

The concept of "equivalent thickness" is introduced to simplify the expression of the thermal transmittances.

A thermal resistance is represented by its equivalent thickness, which is the thickness of ground that has the same thermal resistance. In this calculation:

dt is the equivalent thickness for floors; dw is the equivalent thickness for walls of basements below ground level.

1.3.3 Calculation of Thermal Transmittance of Ground Floor

Slab-on-Ground Floor

Slab-on-ground floors include any floor consisting of a slab in contact with the ground over its whole area, whether or not supported by the ground over its whole area, and situated at or near the level of the external ground surface (see Figure 2). This floor slab may be:

uninsulated, or evenly insulated (above, below or within the slab) over its whole area.

Fig. 2

dt is the equivalent thickness for floors:

dt = w + (Rsi + Rf + Rse) (13)

Calculate the thermal transmittance depending on the thermal insulation of the floor.

If dt < B' (uninsulated and moderately insulated floors):


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(14)

If dt > B' (well-insulated floors):1)

(15)

If the floor has horizontal and/or vertical edge insulation, the thermal transmittance can be corrected using the formula:

U = Uo + 2 e /B' (16)

w is the full thickness of the walls, including all layers; Rf thermal resistance of floor construction;Rsi internal surface resistance;Rse external surface resistance; thermal conductivity of unfrozen ground.

Horizontal Edge Insulation

With insulation placed horizontally along the perimeter of the floor formula is used:

(17)

Vertical Edge Insulation

If insulation placed vertically below ground along the perimeter:

(18)

Heated Basement

Fig. 3

The procedures given for basements apply to buildings in which part of the habitable space is below ground level. The basis is similar to that for the slab-on-ground, but allowing for the steady-state thermal coupling coefficient Ls by formula:

Ls = A Ubf + z P Ubw (19)

For basement floor:


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If (dt + 0,5 z) < B' (uninsulated and moderately insulated basement floors):

(20)

If (dt + 0,5 z) B' (well-insulated basement floors):

(21)

For walls of the basement the result Ubw is obtained from formula:

(22)

where z is the depth of the floor of the basement below ground level.

1.3.4 Thermal Transmittance (U-value) of Windows

U-value of windows is calculated using a formula based on EN ISO 10077-1:

(23)

where:Uf thermal transmittance in W(m².K); Ugl thermal transmittance of the glazing in W(m².K); Af area of the frame in m²;Agl area of the glazing in m²;ygl linear thermal transmittance (join between glazing and sash) in W(m.K); lgl perimeter of the glazing in m.

Table 3. Input Values for Linear Thermal Transmittance of Aluminium and Steel Profiles Between Glasses W/(m.K)

Type of Window

Double glass, triple glass, without

coating with air or gas layer

Double glass, triple glass, with coating

with air or gas layer

Wooden or plastic frame 0.04 0.06Steel frame with interruption of the thermal bridge 0.06 0.08Steel frame without interruption of the thermal bridge 0 0.02

Table 4.Thermal Transmittance of Glazing for Windows Ugl W/(m²·K)

Type of Glazing Dimension mm

Ugl-value


19Glazing

air argon krypton SF61. Single glazing1.1 Simple glass 3-4 mm 5.2 - - -1.2 Polycarbonate 8 4.8 - - -

2. Double glazing2.1 Double glazing, closed air layer 3–40-3 2,7 - - -

4–40-4 2,7 - - -

3. Double glass3.1 Two clear glasses, 1 = 2 = 0,89 4–12–4 2.9 2.7 2.6 3.1

4–16-4 2.7 2.6 2.6 3.13.2 Clear + selective glass 2 0,4 4–12–4 2.4 2.1 2.0 2.7

4-16-4 2.2 2.0 2.0 2.73.3 Clear + selective glass 2 0,2 4–12–4 1.9 1.7 1.5 2.4



4-16-4 1.5 1.2 1.1 2.2

Triple glass4.1 3 clear glasses, 1 = 2 = 3 = 0,89 4-6-4-6-4 2.3 2.1 1.8 2.0

4-12-4-12-4 1.9 1.8 1.6 2.04.2 Clear + two selective glasses 0,4 4-6-4-6-4 2.0 1.7 1.4 1.6




4-12-4-12-4 1.0 0.8 0.5 1.1

Table 5. Input Values for Thermal transmittance of the Frame of the Window Uf in W/(m²·K)

Type of FrameUf

W/(m²·K)Wooden or plastic frame 2,0Steel frame with interruption of the thermal bridge 2,0 < Uf ≤ 2,8Steel frame without interruption of the thermal bridge > 2,8

1.4 Heat Transfer by VentilationFor each building zone, z, and for each calculation step (month, season) the total heat transfer by ventilation, Qve, in kWh, is calculated as given by equation:

Qve = Hve,adj(int,set,H,z e)t (24)

where: Hve,adj the overall heat transfer coefficient by ventilation, adjusted for the indoor-

outdoor temperature difference (if applicable), expressed in W/K;

int,set,H,z the set-point temperature of the building zone for heating in °C; set in for each building category;

e the temperature of the external environment in °C, set in regulation for each building category;


20t the duration of the calculation step (month, season) in hours.

1.4.1 Simplified Method for Calculation of Heat Transfer Coefficient by Ventilation HV

Heat transfer coefficient by ventilation HV in W/K without taking into account the adjacent unheated spaces, without the pre-heating or heat recovery is calculated using equation:

(25)where:

a . ca heat capacity of air per volume Wh/(m³.K); a.ca = 1200 J/(m³.K) = 1200 / 3600 = 0,333 Wh/(m³.K)

n average ventilation rate determined in accordance with equation (26) or (27) in 1/h;

Vm volume of the internal air, estimated as 80% of building volume calculated from external dimensions Vm = 0,8 . Vb in m³.

Average ventilation rate n in 1/h is calculated using equation (26) or (27):

(26)

or (27)

where: B the characteristic value for the building location, (B=12 for detached/single buildings

in windy country, B = 8 for other buildings);M the characteristic value for the room type (standard value M = 0,7);Vb building volume (external dimensions) in m³;Vi,a volume of the internal air, estimated as 80% of building volume calculated from

external dimensions Vm = 0,8 . Vb in m³;il,ve coefficient of the gap permeability m²/(s.Pa0,67);l the length of the opening structures gaps (joints) in m.

Time-average airflow rate in m³/s is calculated using equation:

qve,k,mn = n. Vm (28)where:

n average ventilation rate determined in accordance with equation (26) or (27) in 1/h;Vm volume of the internal air, estimated as 80% of building volume calculated from

external dimensions Vm = 0,8 . Vb in m³.

1.4.2 The Criterion of the Minimum Air Change

Minimum average air change rate for dwelling and non-dwelling buildings is required on level nN = 0,5 1/h. Minimum this value shall be used for calculation of heat transfer coefficient by ventilation Hve.

Table 6. Input Values for the Coefficient of Gap Permeability il,ve

Type of windowCoefficient of gap permeability ilv

m²/(s.Pa0,67)Old steel doors and windows 1,8 . 10-4

Old wooden doors and windows 1,4 . 10-4

New doors and windows 1,0 . 10-4


21

1.5 Thermal Gains The total thermal gains in kWh are the sum of solar heat gains and internal heat gains given by equation:

QH,gn = Qint + Qsol (29)

where:Qint, internal heat gains;Qsol, solar heat gains.

1.5.1 Internal Heat Gains

The internal heat gains, heat gains from internal heat sources, including negative heat gains (dissipated heat from internal environment to cold sources or “sinks”), consist of any heat generated in the conditioned space by internal sources other than the energy intentionally utilized for space heating or hot water preparation.

The internal heat gains include: metabolic heat from occupants and dissipated heat from appliances; heat dissipated from lighting devices; heat dissipated from, or absorbed by, hot and mains water and sewage systems; heat dissipated from, or absorbed by, heating, cooling and ventilation systems; heat from or to processes and goods.

Internal heat gains per m² of total floor area calculated from the external dimensions:family house qi 4 W/m²;apartment building qi 5 W/m²;public building qi 6 W/m².

Values are time average power of the internal heat sources for all calculation period. They include metabolic heat from occupants, dissipated heat from appliances, lighting, and hot water systems.

Values are used in equation:

Qint = i . t = qi . Ab . t (30)

where: i time average heat flow rate from internal heat sources in W; qi average power of the internal heat sources W/m²;Ab total floor area in m²;t length of the considered calculation period (month or season) in hours.

1.5.2 Solar Heat Gains

Heat gains from solar heat sources depend on the solar radiation available in the locality, the orientation of the collecting areas, the permanent shading, the solar transmittance and absorption and thermal heat transfer characteristics of collecting areas.

The calculation procedure and input data depend on the type of calculation method (monthly seasonal).


22For the monthly and seasonal method, the sum of the heat gains from solar sources in the considered building zone for the considered month or season, Qsol, expressed in kWh, are calculated using equation:

(31)

where: btr,l adjustment factor for the adjacent unconditioned space with internal heat

source;

sol,mn,k time-average heat flow rate from solar heat source k, in W;sol,mn,u,l time-average heat flow rate from solar heat source l in the adjacent

unconditioned space in W;

t length of the considered month or season in hours.

Only if a huge part of solar gains is presented due to adjacent big sungardens the flow from solar heat source in the adjacent unconditioned space is taken into account.

The extra heat flow due to thermal radiation to the sky is neglected.

If flow from solar heat source in the adjacent unconditioned space and heat flow due to thermal radiation to the sky are neglected:

(32)

The heat flow by solar gains through building element k, Φsol,k expressed in watts, is given by equation: Φsol,k = Asol,k Isol,k

Heat gains from solar heat sources are

(33)

where:Asol,n is the effective collecting area of surface n with a given orientation and

tilt angle, in the considered zone or space in m²; Isol,k the mean energy of the solar irradiation over the time step of the

calculation, per m² of collecting area of surface k, with a given orientation and tilt angle in W/m²,´set in the Regulation on Energy Performance of Buildings;

t is the length of the considered month or season in hours, set in the Regulation on Energy Performance of Buildings.

Values for duration of calculation step (season or month) Isol,k . t per m² of collecting area of surface k, with a given orientation and tilt angle in kWh/m² is set in the Regulation on Energy Performance of Buildings.

1.5.2.1 Effective Collecting Area

Effective collecting area is a coefficient that includes the characteristics and the area of the collecting surface (including the impact of shading).

The Effective Solar Collecting aAea of a Glazed Envelope Element (e.g. a window), Asol, expressed in m², is in simplified way given by equation:

Asol = Aw . Fsh . Fc . FF . ggl (34)


23where:

ggl total solar energy transmittance of the transparent part of the element;FF frame factor - transparent part of the element (clear glazing) fraction; ratio of

the projected transparent part area to the overall projected area of the glazed element (e.g. window);

Aw overall projected area of the glazed element in m²;Fsh shading reduction factor;FC shading devices reduction factor.

For the glazed parts of external walls the solar transmittance of radiation normal on the glazing area gn, which is higher than the average value of the total solar energy transmittance of solar energy ggl, therefore is this value adjusted by the correction factor Fw.

ggl = Fw ggl,n (35)

where Fw is a correction factor for glazing without shading Fw = 0,90.

Table 7. Typical Values of Total Solar Energy Transmittance at Normal Incidence for Common Types of Glazing

(according to the Table G.2 EN ISO 13790:2008)

Type of glazing ggl,n Fw ggl

Single glazing 0,85 0,9 0,765

Double glazing 0,75 0,9 0,675

Double glazing with selective low-emissivity coating 0,67 0,9 0,603

Triple glazing 0,70 0,9 0,630

Triple glazing with two selective low-emissivity coatings 0,50 0,9 0,450

Double window 0,75 0,9 0,675

1.5.2.2 Shading Reduction Factors for External Obstacles

The shading correction factor for external obstacles can be calculated from:

Fsh = Fhor . Fov . Ffin (36)where:

Fhor partial shading correction factor for the horizon;Fov partial shading correction factor for overhangs;Ffin partial shading correction factor for fins.

Shading from Horizon

Fhor - the partial shading correction factor for the horizon.

The effect of shading from the horizon depends on horizon angle, latitude, orientation, local climate and heating season.

Typical horizontal obstacles are for exemple: the ground; trees; other buildings.

Shading correction factors for typical average Northern hemisphere climates and the heating season from October to April are given in Table 8.


24

The horizon angle is an average over the horizon facing the façade considered.

- horizon angle

Table 8. Partial Shading Correction Factor for Horizon, Fhor

Horizon Angle45° N Latitude

S E/W N

0° 1,00 1,00 1,0010° 0,97 0,95 1,0020° 0,85 0,82 0,9830° 0,62 0,70 0,9440° 0.46 0,61 0,90

Shading from Overhang and Fins

Fov is the partial shading correction factor for overhangs.

Typical obstacles are for exemple: roof overhang; attics overhangs; balconies, loggias; side walls of balconies, loggias.

Table 9. Partial Shading Correction Factor for Overhang, Fov

Horizon Angle45° N Latitude

S E/W N

0° 1,00 1,00 1,0030° 0,90 0,89 0,9145° 0,74 0,76 0,8060° 0,50 0,58 0,66

Shading from Fins

Ffin is the partial shading correction factor for fins.

Table 10. Partial Shading Correction Factor for Fins, Ffin

Horizon Angle 45° N Latitude

overhang angleoverhang angle


25

S E/W N

0° 1,00 1,00 1,0030° 0,94 0,92 1,0045° 0,84 0,84 1,0060° 0,72 0,75 1,00

The values are valid for fins on one side.

For south-facing windows, with fins on both sides, the two shading correction factors shall be multiplied.

1.6 Dynamic ParametersThe dynamic effects are taken into account by the gain utilization factor H,gn. It is dimensionless factor for decrease of heat gains to compensate the situation when the heat gains are higher then thermal losses and therefore the gains contribute to increase of internal temperature instead of decrease of energy consumption. This situation occurs especially in the transitional period (spring, autumn).

1.6.1 Gain Utilization Factor for Heating

The dimensionless gain utilization factor for heating,H,gn is a function of the heat-balance ratio H and a numerical parameter, aH, that depends on the building inertia.

For standard energy rating for dwelling buildings (apartment buildings, family houses) and for seasonal calculation the gain utilization factor for heating is to take H,gn=0,95.

In other cases the gain utilization factor for heating is calculated for each month as given by next equations:

if H 0 and H 1: (37)

if H = 1: (38)

if H 0: (39)

where H is a heat-balance ratio for heating mode during the calculation period

(40)QH,ht total heat transfer for the heating mode in kWh;QH,gn total heat gains for the heating mode in kWh;aH dimensionless numerical parameter depending on the time constant, H.

Numerical parameter aH is given by equation:

(41)where:

Example 1: Cold months, building without insulation = 24 h,

= 0,3 H,gn = 0,95

Example 2:Transitional months, well insulated building: = 24 h, = 1,0 H,gn = 0,7

Legend1 time constant 8 h 2 time constant 1 d3 time constant 2 d4 time constant 7 d5 time constant infinite (high inertia)


26aH,0 dimensionless reference numerical parameter; time constant of the building zone expressed in hours;H,0 a reference time constant in hours.

The parameter values are empirical values and may also be determined at national level. If there are no national values available the values from Table 11 may be used.

Table 11. Values of the Numerical Parameter, a 0,H, and Reference Time Constant, H,0

Type of Method aH,0H,0

hMonthly calculation method 1,0 15Seasonal calculation method *) 0,8 30

Note: The values for seasonal method are only informative.

Illustration of gain utilization factor for different time constants with example is in Figure 3.

Figure 3. Example of Gain Utilization Factor Estimation(using the figure in EN ISO 13790: 2008.)


27

Source : EN ISO 13790: 2008

The gain utilization factor is defined independently of the heating system characteristics, assuming perfect temperature control and infinite flexibility. A slowly responding heating system and a less-than-perfect control system can significantly affect the use of the heat gains.

1.6.2 Building Time Constant

The time constant of the building zone expressed in hours, characterizes the internal thermal inertia of the conditioned zone both for the heating and cooling periods. It is calculated by using equation:

(42)

where:Cm internal heat capacity of the building or building zone kWh/K;Htr,adj a representative value of the overall heat transfer coefficient by transmission,

adjusted for the indoor-outdoor temperature difference W/K;Hve,adj a representative value of the overall heat transfer coefficient by ventilation,

adjusted for the indoor-outdoor temperature difference W/K.

Internal Heat Capacity of the Building

For the monthly and seasonal method, the internal heat capacity of the building zone Cm

expressed in J/K is calculated by summing the heat capacities of all the building elements in direct thermal contact with the internal air of the zone under consideration, as given by Equation:

(43)

where: j internal heat capacity per area of the building element j in J/(m².K) or in kWh/(m².K);Aj area of the element j in m².

The values may be approximately estimated using the values in Table 12

Table 12. Internal Heat Capacity(according EN ISO 13790: 2008 for monthly and seasonal method)

Type of ConstructionInternal Heat Capacity

C(J/K)

Very light 80 000. Ab

Light 110 000. Ab

Medium 165 000. Ab

Heavy 260 000. Ab


28

Very heavy 370 000. Ab

1.7 Total Annual Energy Need for Space Heating

The annual energy needs for heating for the given building zones, QH,nd,an expressed in kWh is calculated as given by equation (44), by summing the calculated energy

(44)

where:QH,nd,i energy need for heating of the considered zone per calculation step (month) in

kWh

The standard length of heating season (number of months) is defined in the Regulation on Energy Perfromance of Buildings.

1.7.1 Total Annual Energy Need for Space Heating per Combination of Systems

In the case of a multi-zone calculation (with or without thermal interaction between zones), the annual energy needs for a given combination of heating and different zones, QH,nd,an,zs is calculated as the sum of the energy needs over the zones, that are serviced by the same combination of systems, as given by Equation:

(45)

where:QH,nd,an,z annual energy need for heating of zone z, serviced by the same

combination of systems in kWh.

Specific heat need is heat need for all heating season per m² of total floor area in kWh/m² estimated as given by equation:

(46)

where: Ab total floor area in m²,QH,nd,an,s total annual energy need in kWh.


29

II. Calculation Methodology for Energy Use for Space Heating


30

2. Energy Use for Space Heating


Technical Building Systems

technical building subsystem - part of a technical building system that performs a specific function (e.g. heat generation, heat distribution, heat emission);

system thermal loss - thermal loss from a technical building system for heating (cooling), domestic hot water (humidification, dehumidification or ventilation) that does not contribute to the useful output of the system;

Note 1: A system loss can become an internal heat gain for the building if it is recoverable.

Note 2: Thermal energy recovered directly in the subsystem is not considered as a system thermal loss but as heat recovery and directly treated in the related system standard.

Note 3: Heat dissipated by the lighting system or by other services (e.g. appliances of computer equipment) is not part of the system thermal losses, but part of the internal heat gains.

auxiliary energy - electrical energy used by technical building systems for heating (cooling, ventilation) and/or domestic water to support energy transformation to satisfy energy needs;

Note: This includes energy for fans, pumps, electronics, etc. Electrical energy input to the ventilation system for air transport and heat recovery is not considered as auxiliary energy, but as energy use for ventilation.

system thermal loss - thermal loss from a technical building system for heating (cooling), domestic hot water (humidification, dehumidification or ventilation) that does not contribute to the useful output of the system;




recoverable system thermal loss - part of a system thermal loss which can be recovered to lower either the energy need for heating (or cooling) or the energy use of the heating (or cooling) system;

recovered system thermal loss - part of the recoverable system thermal loss which has been recovered to lower either the energy need for heating (or cooling) or the energy use of the heating (or cooling) system.


31


Symbol Quantity UnitA Area m²C, c specific heat capacity J/(kg.K)D Diameter mE system performance coefficient (expenditure factor) -E energy generally (energy use, primary energy) kWhF conversion factor – Factor mL length mM Mass kgM mass kgN number of operating times –O Occupancy personsP electrical power WQ quantity of heat, energy kWhT time, period of time ST thermodynamic temperature KV Volume m³W electrical auxiliary energy kWhZ running time h/d heat conductivity W/(m.K) Efficiency – Celsius temperature °CΦ thermal power W density of water kg/m³

Table 14. Subscripts

a Air gl generation losses pr produced, generationan Annual gs Gains ren renewable energyaux Auxiliary H,h heating energy rbl recoverablec Control i Internal rvd recoveredCO2 Related to CO2

emissionsin Input system r recovered

d Distribution l Loss sys systemdh district heating nd Need s storagee External ngen without generation t totalem Emission nrvd non recovered V ventilationexp Exported nren non renewable w domestic hot waterf Final out output from systemgen Generation p Primary

2.2 Heat Emission Subsystem

Calculation of heat emission subsystem allows the combination of four heat emission subsystems per building. In case of more types of heat emission subsystems the calculation has to be performed either in more excel sheets or by reducing the calculation to three (four) major types of subsystem used.

For calculation of heat emission subsystem efficiency following procedure can be used.


32The heat losses in kWh of heat emission are calculated as:

Q l,em = Q em,str + Q em,emb + Q em,c (47) where:

Q em,str heat loss due to non-uniform temperature distribution in (kWh);Q em,emb heat loss due to emitter position (e.g. embedded) in (kWh);Q em,c heat loss due to control of indoor temperature in (kWh).

(48)

where:

heat loss from the heat emission subsystem over time period (year) in kWh;

calculated heat demand for heating for solved period of time in kWh. This value is available in building characteristics;

is the factor for the hydraulic equilibrium;

Value of factor of hydraulic equilibrium depends on system configuration:

f hydr = 1.00 when hydraulic balanced by automatic balancing valves at each raiser and group of 8 emitters;1.03 documented hydraulic balancing at installation or by commissioning;1.05 for others;

is the factor for intermittent operation (as intermittent operation is to be understood the time dependent option for temperature reduction for each individual room space);

is the factor for the radiation effect (only relevant for heating of large indoor spaces with h > 4 m);

is the total efficiency level for the heat emission in the room space;

for continuous operation, 0,75 (to be used for electrical heating systems with an integrated feedback control system);

is to be set to 1.

The total efficiency level is fundamentally evaluated as:

(49)

where:

the part efficiency level for a vertical air temperature profile;

ithe part efficiency level for room temperature regulation;

the part efficiency level for specific losses of the external components.

The part and total efficiencies levels prescribed in the following tables are based on the following assumptions:

standard room heights h ≤ 4m (with the exception of large indoor space buildings with h > 4 m);

domestic and non-domestic buildings; different heat protection levels;


33 continuous mode of operation (intermittent modes of operation are taken into account

by means of the factor fint ); reference to one room space in each case.

In this section system solutions not covered are to be taken from other documented sourcesor are to be interpolated or matched in a suitable manner.

Table 15. Efficiencies Air Heating (non-domestic ventilation systems) (room heights ≤4 m)

System Configuration Control Parameter ηh,ce

low quality ofcontrol

high quality ofcontrol

Additional heating inthe incoming air(additional heater)

Room space temperature 0.82 0.87Room space temperature(cascade control of incomingair temperature)

0.88 0.90

Exhaust air temperature 0.81 0.85Recirculation airheating (inductionequipment, ventilatorconvectors)

Room space temperature 0.89 0.93

Table 16. Efficiencies for Room Spaceswith heights ≥4 m (large indoor space buildings)

Influence ParametersPart Efficiencies

ηL ηC ηB

4 m 6 m 8 m 10 mRoomSpace

Unregulated0.80

temp.regulation

Two-step controller 0.93P-controller (2 K) 0.93P-controller (1 K) 0.95PI-controller 0.97PI-controller with optimization 0.99

HeatingSystems

Warm air heatingAir distribution with normalinduction ratio, radiators

Air outlet at the side 0.98 0.94 0.88 0.83 1

Air outlet above 0.99 0.96 0.91 0.87 1

Warm air heatingAir distribution additionally withregulated vertical recirculation

Air outlet at the side 0.99 0.97 0.94 0.91 1

Air outlet above 0.99 0.98 0.96 0.93 1

Hot water ceiling-mounted radiant panels 1 0.99 0.97 0.96 1

Dark radiators (radiator tubes) 1 0.99 0.97 0.96 1Bright radiators 1 0.99 0.97 0.96 1Floor heating (high heatprotection level)

Floor heatingcomponent integrated

1 0.99 0.97 0.96

0.95

Floor heating thermallydecoupled

1

Table 17. Efficiencies for Electrical Heating


34(room heights ≤4 m)

Influence Parameters Total Efficiencyηh,ce

Ext

erna

l wa

ll re

gion

E- direct heating P-controller (1 K) 0.91E- direct heating PI-controller (with optimization) 0.94Storage heating unregulated without external temperature dependent charging and static/dynamic discharging

0.78

Storage heating P-controller (1 K) with external temperature dependent charging and static/dynamic discharging

0.88

Storage heating PID-controller with optimization with externaltemperature dependent charging and static and continuous dynamic discharging

0.91

Inte

rnal

wal

l reg

ion

E- direct heating P-controller (1 K) 0.88E- direct heating PI-controller (with optimization) 0.91Storage heating unregulated without external temperature dependent charging and static/dynamic discharging

0.75

Storage heating P-controller (1 K) with external temperature dependent charging and static/dynamic discharging

0.85

Storage heating PID-controller with optimization with externaltemperature dependent charging and static and continuous dynamic discharging

0.88

Table 18. Efficiencies for Component Integrated Heating Surfaces (panel heaters, room heights ≤4 m)

Influence Parameters Part EfficienciesηL ηC ηB

Room spacetemperatureregulation

Heat carrier medium water Unregulated 0.75 unregulated, with central supply temperatureregulation

0.78

unregulated with average value formation (ΘV –ΘR) 0.83 Master room space 0.88 two-step controller/P-controller 0.93 PI-controller 0.95Electrical heating two-step controller 0.91 PI-controller 0.93

System Floor heating ηB1 ηB2

wet system 1 0.93 dry system 1 0.96 dry system with low cover 1 0.98Wall heating 0.96 0.93Ceiling heating 0.93 0.93

Specific heatlosses via layingsurfaces

Panel heating without minimum insulation in accordancewith DIN EN 1264

0.86

Panel heating with minimum insulation in accordance with DIN EN 1264

0.95

Panel heating with 100% better insulation than required by DIN EN 1264

0.99

Table 19. Efficiencies for Free Heating Surfaces (Radiators)


35room heights ≤4 m

Influence Parameters Part EfficienciesηL ηC ηB

Room spacetemperatureregulation

unregulated, with central supply temperature regulation

0.80

Master room space 0.88P-controller (2 K) 0.93P-controller (1 K) 0.95PI-controller 0.97PI-controller (with optimization function, e.g. presence management, adaptive controller)

0.99

Over-temperature(reference Θi = 20 °C)

ηL1 ηL2

60 K (e.g. 90/70) 0.8842.5 K (e.g. 70/55) 0.9330 K (e.g. 55/45) 0.95

specific heat losses via external components GF = glass surface area)

radiator location internal wall0.87 1

radiator location external wall GF without radiation protection 0.83 1 GF with radiation protection 0.88 1 normal external wall

0.95 1a The radiation protection must prevent 80% of the radiation losses from the heating body to the glass surface area by means of insulation and/or reflection.

2.3 Heat Distribution Subsystem

Overall recoverable heat loss from the heat distribution system – represents loses from heat distribution subsystems that are emitted in the heated space of the building. The majority of these losses can be recovered for heating, which is expressed by the Heat recovery factor from distribution subsystems.

The calculation of total heat loss from heating distribution subsystem is based on the known temperature conditions and types of pipe and insulation materials of the pipelines.

For water heating, the nominal temperature is assumed to be the average temperature of heat carrier (water).


36

The heat loss coefficient can be calculated by:

(50)

where:λiz heat conductivity of the thermal insulation (W/(m.K));λt heat conductivity of the pipe (W/(m.K));D external diameter of insulated pipe (including insulation) D = d + 2siz (m);d pipe diameter (m);st thickness of the pipe;he heat transfer coefficient (W/(m².K)), value for insulated pipes = (10 - 15 W/(m².K)).

Heat recovery factor from distribution subsystems – value can float from 0,00 to 1,00 depending on the amount of heat emitted from the system. The higher the number of Heat recovery factor the more of heat losses are recovered.

NON-recoverable losses from the distribution system outside building – if applicable for building assessment, all thermal losses outside the considered building need to be assessed and filled.

NON-recoverable losses from the distribution system outside heated space – if applicable for building assessment, all thermal losses from heating distribution system outside the heated space need to be assessed and filled.

Total NON-recoverable heat loss from the heat distribution system is calculated, based on the filled inputs.

2.4 Heat Storage Subsystem

Overall recoverable heat loss from the heat storage subsystem – value is the annual sum of recoverable heat losses from the heat storage subsystem in the building (if installed). Values from storage vessel data sheets (manufacturer’s data) may be used for determination of the annual loss of the device and thus the recoverable heat loss. (daily loss x number of heating days).

Heat recovery factor from storage subsystems – value can float from 0,00 to 1,00 depending on the amount of heat emitted from the system. The higher the number of Heat recovery factor is the more of heat losses are recovered from the storage subsystem for heating purposes.

Overall NON-recoverable heat loss from the heat storage subsystem – value is the annual sum of NON-recoverable heat losses from the heat storage subsystem, either in the building (outside heated space or related to the heating system, although outside the building). Values of storage vessel manufacturers may be used for determination of the annual loss of the device, which depending on device location represent NON-recoverable heat loss.

2.5 Auxiliary Energy of Heating System

Total electrical input of heat generators – enter the sum of all electrical inputs of heat generators.


37

Total electrical input of auxiliary devices (pumps, ventilators) – enter the sum of all electrical inputs of other auxiliary devices (pumps, ventilators, operation systems, etc.) related to heating system.

Heating system annual operation time – value is dependent on the heating period duration, which is related to geographical position of calculated building.

Operation factor – default value is set to 0,75. Based on the type of system and operation, value can vary from 0,5 – 0,9.


38

III. Calculation Methodology for Energy Use for Hot Water Preparation


39

3. Energy Use for Hot Water Preparation


Technical Building Systems

technical building subsystem - part of a technical building system that performs a specific function (e.g. heat generation, heat distribution, heat emission);

system thermal loss - thermal loss from a technical building system for heating, cooling, domestic hot water, humidification, dehumidification or ventilation that does not contribute to the useful output of the system;




auxiliary energy - electrical energy used by technical building systems for heating, cooling, ventilation and/or domestic water to support energy transformation to satisfy energy needs;

Note 1: This includes energy for fans, pumps, electronics, etc. Electrical energy input to the ventilation system for air transport and heat recovery is not considered as auxiliary energy, but as energy use for ventilation.

system thermal loss - thermal loss from a technical building system for heating, cooling, domestic hot water, humidification, dehumidification or ventilation that does not contribute to the useful output of the system;




recoverable system thermal loss - part of a system thermal loss which can be recovered to lower either the energy need for heating or cooling or the energy use of the heating or cooling system;

Note: This depends on the calculation approach chosen to calculate the recovered gains and losses (holistic or simplified approach).

recovered system thermal loss - part of the recoverable system thermal loss which has been recovered to lower either the energy need for heating or cooling or the energy use of the heating or cooling system.

Note: This depends on the calculation approach chosen to calculate the recovered gains and losses (holistic or simplified approach).


40


Symbol Quantity UnitA Area m²

C, c specific heat capacity J/(kg.K)D Diameter mE system performance coefficient (expenditure factor) -E energy generally (energy use, primary energy) kWhF conversion factor – Factor mL Length mM Mass kgM Mass kgN number of operating times –O Occupancy personsP electrical power WQ Quantity of heat, energy kWhT time, period of time sT thermodynamic temperature KV Volume m³W electrical auxiliary energy kWhZ running time h/d heat conductivity W/(m.K) Efficiency – Celsius temperature °CΦ thermal power W density of water kg/m³

Table 21.Subscripts

a Air F Final out output from systeman Annual Gen Generation p primaryaux auxiliary Gl generation losses pr produced, generationc Control Gs Gains ren renewable energyCO2 related to CO2

emissionsH,h Heating energy rbl recoverable

d distribution I Internal rvd recovereddh district heating In Input system r recovereddel delivered L Loss sys systeme external nd Need s storageem emission ngen without generation t totalexp exported nrvd Non recovered V ventilation

nren Non renewable w domestic hot water


41

3.2 Domestic Hot Water – Volume of DHW Prepared

For three types of buildings – tabulated values per area are (informative values, calculation is automatic, according to the type of building, while the heat demand reflects the chosen type of building as shown in the table below).

Table 22

Type of building Qw,A,day

kWh/(m².a)

Apartment building 20Office building 6School building 10

(51)where:

Qw, A, day specific heat demand for heated water based on 60 °C of heated water and 10 °C of cold water at the inlet of the boiler.

Calculation of DHW heated volume for Family Houses (informative values, calculation is performed using the formula below, in case when the type of building “Family house” is chosen).

The volume of prepared hot water is calculated according to the heated floor area:

( m³/a) (52)

For calculation of heat needs:QW = 1,16 . VW,f . (ΘW, t – ΘW, o)

QW energy supplied to hot water per year (kWh/a);VW,f the volume of prepared hot water [dm³/day];ΘW, t temperature of water leaving the boiler (ºC);ΘW, o temperature of water entering the boiler (ºC).

3.3 Domestic Hot Water – DHW Distribution Subsystem and Storage Subsystem

The DHW distribution subsystem losses are calculated by dividing the total heat loss from

DHW distribution subsystem , ,W dis lsQ in two components

(kWh/a) (53)

Sum of losses from different parts of distribution network (kWh/a). Total heat loss from various tapping conditions (in heated space)


42Total heat loss from various tapping conditions (in heated space) is calculated by excel:

(kWh/a) (54)where:

specific mass of water in kg/m³;

specific heat of water in kJ/(kg.K);

water volume behind the circulation loop in m³;

average ambient temperature, average internal temperature around pipe in °C;

nominal temperature of DHW in pipes in °C;

number of DHW deliveries during the day.

Heat losses from different parts of circulation loop network (kWh/a), value is calculated knowing the heat losses from the pipes of the circulation loop. These loses need to be calculated and filled in the table see below

Total heat loss from DHW distribution subsystem: calculation is based on knowing the temperature conditions and types of pipe and insulation materials of the pipelines. For DHW the nominal temperature is assumed to be 60 °C.

The heat loss coefficient can be calculated by:

(55)

where:λiz heat conductivity of the insulation (W/(m.K));λt heat conductivity of the pipe (W/(m.K));D external diameter of insulated pipe (including insulation) D = d + 2siz (m)d pipe diameter (m);


43st thickness of the pipehe heat transfer coefficient (W/(m²K)), value for insulated pipes = (10 W/(m².K)).

Heat recovery factor from DHW distribution – value can float from 0,00 to 1,00 depending on the amount of heat emitted from the system, which can be recovered for heating. The value depends on the location of the DHW distribution system in or outside the heated space of the building. The higher the number of Heat recovery factor the more of heat losses are recovered for heating.

3.4 Domestic Hot Water – DHW System Auxiliary Energy

Use the characteristic data for electrical power inputs of DHW auxiliary devices, including the generator power input.

The values of Auxiliary energy of DHW subsystems are being calculated according to the all year operation of the DHW preparation system (8760 hrs/a).


44

IV. Calculation of Global Indicators


45

4. Calculation of Global Indicator


primary energy - energy that has not been subjected to any conversion or transformation process;

Note 1: Primary energy includes non-renewable energy and renewable energy. If both are taken into account it can be called total primary energy.

Note 2: For a building, it is the energy used to produce the energy delivered to the building. It is calculated from the delivered and exported amounts of energy carriers, using conversion factors.

energy carrier - substance or phenomenon that can be used to produce mechanical work or heat or to operate chemical or physical processes;

Note: The energy content of fuels is given by their gross calorific value.

total primary energy factor - for a given energy carrier, non-renewable and renewable primary energy divided by delivered energy, where the primary energy is that required to supply one unit of delivered energy, taking account of the energy required for extraction, processing, storage, transport, generation, transformation, transmission, distribution, and any other operations necessary for delivery to the building in which the delivered energy will be used;

Note: The total primary energy factor always exceeds unity.

CO2 emission coefficient - for a given energy carrier, quantity of CO2 emitted to the atmosphere per unit of delivered energy.

Note: The CO2 emission coefficient can also include the equivalent emissions of other greenhouse gases (e.g. methane).


46

SYMBOLS


Symbol Quantity UnitE energy generally (energy use, primary energy) kWh Factor -K Coefficient -M Mass kg

Table 24. Subscripts

CO2 Related to CO2 emissions exp exportedDel Delivered p primary

4.2 Delivered Energy

Delivered energy Edel,i is energy, expressed per energy carrier, supplied to the technical building systems inside building through the system boundary, to satisfy the uses taken into account (space heating, domestic hot water preparation) or to produce electricity.

In delivered energy Edel,i are included emission, distribution and storage heating system losses including also auxiliary energy for pumps and fans of distribution system in building. Solar thermal energy produced on site is extracted from the delivered energy Edel,i .

Total delivered energy as a global indicator for energy class in energy certificate is a sum of delivered energy Edel,i for all energy carriers.

(56)

Example of calculation of delivered energy per energy carrier is in Table 25.

Table 25. Delivered Energy Calculation


47

4.2.1 Generation LossesGeneration losses are calculated from the delivered energy to the system Edel,i considering the efficiency of heat production suggested in Table 26:

(57)

where:Edel,i delivered energy after extraction of solar thermal energy produced on site for

energy carrier i;Egl,i energy loss of the generation system;ηgen,i generator’s efficiency of heat production for carrier i.

4.2.1.1 Systems for Space Heating

Generation Losses for Space Heating System are calculated from the delivered energy to the system, considering the efficiency of heating generator suggested in Table 26:

(58)

where:Eh,del,I is the delivered energy to the heating system after extraction of solar thermal

energy produced on site for energy carrier i;Eh,gl is the energy loss of the space heating generation system;ηh,gI is the generator’s efficiency of heat production for carrier i. η h,gen,I < 0, listed in

Table 26.


48

4.2.1.2 Systems for Hot Water Preparation

Generation losses for DHW system are calculated from the delivered energy to the DHW system, considering the efficiency of DHW generator suggested in Table 26:

(59)

where:E W,del.i delivered energy to the heating system after extraction of solar thermal energy

produced on site for energy carrier i;EW,gl energy loss of the DHW generation system;η W,gen,i DHW generator’s efficiency of heat production for carrier i. η W,gen,I < 0, listed in

Table 26.


49

4.3 Primary Energy and Emissions of CO2

Primary energy is calculated from the delivered energy Edel,p,i including generation losses and the losses outside building in case of district heating for each energy carrier i.

In case of district heating the heating distribution losses Edh,d,l,outside and heat exchange losses outside building Edh,em,l,outside are taken into account by default values:

4% from delivered energy Edel,i for distribution losses; 2% from delivered energy Edel,i for heat exchange losses.

Note: Other values can be used if are known or in case the national method for calculation of distribution and emission losses outside the building for district heating are available at national level.

Delivered energy for primary energy calculation for space heating is calculated using equation:

(60)

where:

E h,del.i delivered energy to the heating system for space heating after extraction of solar thermal energy produced on site for energy carrier i without generation losses;

Eh,gl energy loss of the space heating generation system;

Eh,dh,d,l,outside space heating distribution losses outside building in case of district heating;

Eh,dh,em,l,outside space heating emission losses outside building in case of district heating.

Delivered energy for primary energy calculation for DHW is calculated using equation:

(61)

where:

E W,del.i delivered energy to the heating system for hot water preparation after extraction of solar thermal energy produced on site for energy carrier i without generation losses;

EW,gl energy loss of the DHW generation system;

EW,dh,d,l,outside DHW heating distribution losses outside building in case of district heating;

EW,dh,em,l,outside DHW heating emission losses outside building in case of district heating;

For each energy carrier i the delivered energy for primary energy calculation is a sum of energy use for space heating and delivered energy for primary energy calculation for hot water preparation:


50

(62)

where:E W,del.p,i delivered energy to the heating system for primary energy calculation after

extraction of solar thermal energy produced on site for energy carrier i and including generation losses – for hot water preparation;

E h,del.p,i delivered energy to the heating system for primary energy calculation after extraction of solar thermal energy produced on site for energy carrier i and including generation losses – for space heating.

Primary energy is calculated from the delivered energy Edel,p,i and exported energy Eexp,i for each energy carrier:

(63)

where:Edel,p,i delivered energy including generation losses and after extraction of solar

thermal energy produced on site for energy carrier i;Eexp,i exported energy for energy carrier i;fP,del,i primary energy factor for the delivered energy carrier i; fP,exp,i primary energy factor for the exported energy carrier i.

The emitted mass of CO2 is calculated from the delivered energy Edel,p,i and exported energy Eexp,i for each energy carrier:

(64)

where:Edel,p,i delivered energy including generation losses and after extraction of solar

thermal energy produced on site for energy carrier i;Eexp,i exported energy for energy carrier i;Kdel,i CO2 emission coefficient for delivered energy carrier i;Kexp,i CO2 emission coefficient for the exported energy carrier i.

Table 26.Transformation and Conversion Factors (acording to the Regulation for Energy Performance of Buildings)

Energy Carrier Way of ConversionSpecific Unit

(s.u.)

Caloric ValueGJ/s.u. Efficiency of

Production and

Distributionin %

Emission Coefficient

CO2 kg/kWhCoefficient of Primary

PnergyFp

Natural gas

Standard boiler – old)a) 1000 m³34,28

83 – 890,277

1,36

Standard boiler – newa) 1000 m³

34,2887 – 89

0,2771,36

low temperature boiler 1000 m³ 34,28 90 – 93 0,277 1,36

Condensing boiler 1000 m³34,28

98 – 103c)0,277

1,36

Coke (blackcoaled)

Solid fuel boiler ton28,03

70 – 720,467

1,53

Black coal Solid fuel boiler ton 25,17 69 – 82 0,394 1,19


51Brown coal graded

Solid fuel boiler ton15,50

67 – 720,433

1,40

Light heating oil

Standard boiler – old ton 42,00 80 0,330 1,35

Standard boiler – new ton 42,00 85 0,330 1,35Low temperature boiler – old

ton42,00

860,330

1,35

Low temperature boiler – new

ton42,00

910,330

1,35

Wood pellets

biomass boiler ton17,00

850,020

1,06

Wood chipsbiomass boiler ton

11,5076

0,0201,06

biomass boiler ton 11,50 68 0,020 1,09

Lump woodbiomass boiler with gasification s

ton11,50

830,020

1,09

Natural gas district heating kWh 88 0,277 1,36

Black coal district heating kWh 82 0,394 1,19

Brown coal district heating kWh 73 -78 0,433 1,40

Wood chipsdistrict heating kWh 75 – 85

0,0201,06

Heavy heating oildistrict heating

kWh85 0,330 1,35

Natural gas

district heating – combined heat and power production

kWh80 – 85

0,277 1,36

Brown coaldistrict heating – combined heat and power production

kWh 70 – 80 0,433 1,40

Black coal district heating– combined heat and power production

kWh 70 – 80 0,394 1,19

Nuclear energydistrict heating combined heat and power production

kWh 80,5d) 0,016 1,00

Electricity

Electric heating, cooling

kWh 99 0,275g) 2,789e)

electric water heater kWh 99 0,275g 2,789e)

heat pump - water, air, soil(electric engine)

kWh 270 0,275g 2,789e)

Notices:a) old boiler - boiler older than 10 years from the date of manufacture/date of entry into service;

new boiler – boiler not older than 10 years (incl.) from the date of manufacture / date of entry into service;

b) if the building is supplied with heat and hot water from the source in the building, then the energy need, primary energy and CO2 emissions are defined for the known conditions of heat and hot water preparation; if there is an information on evaluation of the performance of the source, then the stated data need to be taken into consideration;

c) in the case of natural gas condensing boiler, the assessment of efficiency of source fuel value is done taking into account the fuel value;

d) efficiency from the point of water vapor emission from the vapor generator until the heat entry into the evaluated building ;

e) primary energy factor is defined while taking into account the energy mix in Moldova (98% natural gas, 1% water power plants and 1% oil);

f) in the efficiency of heat production, no losses caused by secondary distribution and influence of heat-transfer station efficiency are considered (98% natural gas, 2% water power plants);

g) CO2 emission coefficient is defined while considering the energy mix in the Republic of Moldova.

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