DIN V 18599-5 Energy efficiency of buildings — Calculation of the ...

Date: 2007 February
DIN V 18599-5
Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part
5: Delivered energy for heating systems
Energetische Bewertung von Gebäuden — Berechnung des Nutz-, End- und Primärenergiebedarfs für Heizung,
Kühlung, Lüftung, Trinkwarmwasser und Beleuchtung — Teil 5: Endenergiebedarf von Heizsystemen
Supersedes DIN V 18599-5:2005-07

DIN V 18599-5:2007-02
Contents Page
Foreword..............................................................................................................................................................7
Introduction .........................................................................................................................................................9
1 Scope ................................................................................................................................................... 10
2 Normative references ......................................................................................................................... 11
3 Terms and definitions, symbols and units....................................................................................... 13
3.1 Terms and definitions ........................................................................................................................ 13
3.2 Symbols, units and subscripts.......................................................................................................... 17
4 Relationship between the parts of the DIN V 18599 series of prestandards ................................ 20
4.1 Input parameters from other parts of the DIN V 18599 series of prestandards ........................... 21
4.2 Output parameters for other parts of the DIN V 18599 series of prestandards ........................... 22
4.2.1 Generator heat output ........................................................................................................................ 23
4.2.2 Delivered heat ..................................................................................................................................... 24
4.2.3 Auxiliary energy.................................................................................................................................. 25
4.2.4 Uncontrolled heat gains due to the heating system ....................................................................... 25
5 Boundary conditions for the individual subsystems...................................................................... 26
5.1 Part load levels.................................................................................................................................... 26
5.1.1 Heat control and emission................................................................................................................. 26
5.1.2 Heat distribution ................................................................................................................................. 26
5.1.3 Storage................................................................................................................................................. 26
5.1.4 Heat generation................................................................................................................................... 27
5.2 Temperatures ...................................................................................................................................... 27
5.3 Boiler rated output.............................................................................................................................. 29
5.4 Times.................................................................................................................................................... 29
5.4.1 Running times..................................................................................................................................... 29
5.4.2 Distribution of annual values over individual months.................................................................... 32
6 Determination of energy expenditure............................................................................................... 32
6.1 Heat control and emission................................................................................................................. 32
6.1.1 Efficiencies for free emitters (radiators); room heights ≤ 4 m ....................................................... 33
6.1.2 Efficiencies for water based embedded systems (surface heating); room heights ≤ 4 m.......... 35
6.1.3 Efficiencies for electric heating; (room heights ≤ 4 m)................................................................... 36
6.1.4 Efficiencies for air heating/residential ventilation; room heights ≤ 4 m ....................................... 36
6.1.5 Efficiencies for air heating (HVAC systems); room heights ≤ 4 m ................................................ 37
6.1.6 Efficiencies for rooms with heights ≥ 4 m (large indoor spaces) .................................................. 37
6.1.7 Efficiencies for rooms with heights > 10 m...................................................................................... 39
6.1.8 Auxiliary energy Q h,ce,aux ................................................................................................................... 40
6.2 Heat distribution Q h,d – central hot water heating pipe system ..................................................... 43
6.2.1 Auxiliary energy for central hot water heating pipe system .......................................................... 45
6.3 Storage................................................................................................................................................. 50
6.4 Heat generator..................................................................................................................................... 52
6.4.1 Solar systems supporting domestic hot water heating and space heating systems
(combination systems)....................................................................................................................... 53
6.4.1.1 Satisfaction of energy need by solar combination systems.......................................................... 53
6.4.1.2 Energy contribution of solar combination systems........................................................................ 54
6.4.1.3 Calculation procedure for combination systems ............................................................................ 56
6.4.1.4 Calculation procedure for large combination systems .................................................................. 60
6.4.1.5 Auxiliary energy for operation of the solar pump ........................................................................... 60
6.4.2 Heat pump ........................................................................................................................................... 61
6.4.2.1 Principles of the calculation .............................................................................................................. 62
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DIN V 18599-5:2007-02
6.4.2.2 Outdoor air as heat source; average climatic data for Germany ...................................................65
6.4.2.3 Energy need for domestic hot water ................................................................................................69
6.4.2.4 Calculation of the fraction of heating energy to be provided by the second generator
(back-up heating).................................................................................................................................69
6.4.2.5 Heat output and coefficient of performance of the heat pump at full load (steady-state
operation) .............................................................................................................................................73
6.4.2.6 Coefficient of performance in part load operation...........................................................................76
6.4.2.7 Generator thermal losses ...................................................................................................................78
6.4.2.8 Calculation of total energy consumption..........................................................................................79
6.4.2.9 Auxiliary energy...................................................................................................................................80
6.4.2.10Energy consumption of the second generator (back-up heating system)....................................81
6.4.2.11Total energy consumption .................................................................................................................82
6.4.2.12Regenerative energy contribution.....................................................................................................82
6.4.2.13Performance factor to account for the generator subsystem ........................................................82
6.4.3 Conventional boilers ...........................................................................................................................83
6.4.3.1 Multiple boiler systems.......................................................................................................................83
6.4.3.2 Fuel-fired systems (boilers) ...............................................................................................................84
6.4.3.3 Hand stocked biomass combustion systems ..................................................................................94
6.4.3.4 Decentralized fuel-fired systems .......................................................................................................99
6.4.4 Electric heaters..................................................................................................................................101
6.4.4.1 Decentralized electric heaters..........................................................................................................101
6.4.4.2 Central electric heaters.....................................................................................................................101
6.4.5 District heating and local heating....................................................................................................101
6.4.6 Decentralized CHP.............................................................................................................................102
Annex A (normative) Energy use to meet the heating need.......................................................................103
A.1 Electrically driven heat pumps ........................................................................................................103
A.2 Heat pumps with combustion drive.................................................................................................104
A.3 Default values for heat pump calculations .....................................................................................105
A.3.1 Default power values and coefficients of performance for electrically driven heat pumps......105
A.4 Default power values and coefficients of performance for combustion engine-driven heat
pumps.................................................................................................................................................106
A.4.1 Air-to-water heat pumps ...................................................................................................................106
A.4.2 Combustion engine-driven air-to-water heat pumps.....................................................................107
A.4.3 Air-to-air heat pumps ........................................................................................................................107
A.4.4 Absorption heat pumps ....................................................................................................................108
A.5 Correction factor for part load operation........................................................................................110
A.5.1 Electrically driven heat pumps ........................................................................................................110
A.5.2 Absorption heat pumps with modulation burner...........................................................................111
A.6 Calculation procedure for source and sink temperature corrections with a set exergetic
efficiency ............................................................................................................................................111
A.7 VRF systems: relative heat output performance ...........................................................................113
Annex B (informative) Dimensioning of buildings ......................................................................................116
B.1 General information ..........................................................................................................................116
Bibliography....................................................................................................................................................119
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DIN V 18599-5:2007-02
Figures
Figure 1 — Overview of the parts of DIN V 18599 .............................................................................................. 9
Figure 2 — Content and scope of DIN V 18599-5 (schematic diagram) ........................................................... 11
Figure 3 — Subscript system............................................................................................................................. 20
Figure 4 — Designation of pipes in hot water heating pipe systems................................................................. 44
Figure 5 — Distribution of cumulated bin hours for the outdoor air temperature .............................................. 63
Figure 6 — Bin hours and energy fractions of the heat pump and the second generator (back-up
heating) in alternate operation.................................................................................................................... 70
Figure 7 — Bin hours and energy fractions of the heat pump and the second generator (back-up
heating) in parallel operation ...................................................................................................................... 71
Figure 8 — Bin hours and energy fractions of the heat pump and the second generator (back-up
heating) in partly parallel operation ............................................................................................................ 72
Figure A.1 — Energy balance of the generator subsystem (electrically driven heat pump) ........................... 103
Figure A.2 — Energy balance of the generator subsystem (heat pump with combustion drive) .................... 104
Figure A.3 — Heat output of combustion engine-driven air-to-water heat pumps at various source and
sink temperatures ..................................................................................................................................... 106
Figure A.4 — Standard coefficients of performance for combustion engine-driven air-to-water heat
pumps at various source and sink temperatures...................................................................................... 107
Figure A.5 — Heat output of combustion engine-driven air-to-air heat pumps ............................................... 107
Figure A.6 — Standard coefficient of performance of combustion engine-driven air-to-air heat pumps ........ 108
Figure A.7 — Heat output of water-to-water NH 3 /H 2 O absorption heat pumps at various source and sink
temperatures............................................................................................................................................. 108
Figure A.8 — Heat output of water-to-water H 2 O/LiBr absorption heat pumps at various source and sink
temperatures............................................................................................................................................. 109
Figure A.9 — VRF systems: COP heating for load ratios between 10 % and 100 %...................................... 114
Figure A.10 — VRF systems: relative heat output performance ..................................................................... 114
Figure A.11 — VRF systems: relative COP heating for load ratios between 10 % and 100 % ....................... 115
Figure B.1 — Building geometry...................................................................................................................... 116
Tables
Table 1 — Symbols and units............................................................................................................................ 17
Table 2 — Subscripts......................................................................................................................................... 19
Table 3 — Input parameters .............................................................................................................................. 21
Table 4 — Output parameters ........................................................................................................................... 23
Table 5 — Design temperatures........................................................................................................................ 28
Table 6 — Efficiencies for free emitters (radiators); room heights ≤ 4 m .......................................................... 34
Table 7 — Efficiencies for water based embedded systems (surface heating); room heights ≤ 4 m................ 35
Table 8 — Efficiencies for electric heating; (room heights ≤ 4 m) ..................................................................... 36
Table 9 — Efficiencies for air heating (HVAC systems); (room heights ≤ 4 m)................................................. 37
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DIN V 18599-5:2007-02
Table 10 — Efficiencies for rooms with heights from 4 m to 10 m.....................................................................38
Table 11 — Efficiencies for rooms with heights > 10 m .....................................................................................39
Table 12 — Default values for auxiliary energy for the control system..............................................................41
Table 13 — Default values for the auxiliary energy of fans for air supply in rooms where h ≤ 4 m ...................41
Table 14 — Default values for the auxiliary energy of fans and for the control system in rooms h > 4 m
in height (large indoor spaces)....................................................................................................................42
Table 15 — Default values .................................................................................................................................44
Table 16 — Assumptions for heat transfer coefficients U i in W/(m · K) .............................................................45
Table 17 — Constants C P1 ,C P2 for calculation of the expenditure factor of heat pumps ..................................49
Table 18 — Distribution of annual solar contribution over months.....................................................................56
Table 19 — Correction factor for inclination and alignment ...............................................................................57
Table 20 — Correction factor for the solar load ratio (f slr )..................................................................................58
Table 21 — Correction factor for the heat loss rate of the storage tank or tanks (f s,loss )...................................58
Table 22 — Correction factor for the temperature level of the space heating f h,T .............................................59
Table 23 — Energy fraction from the combination system for domestic water heating.....................................60
Table 24 — Hours frequency of outdoor temperature (reference location: Würzburg)......................................66
Table 25 — Monthly hours sum in the individual bins, distributed according to the testing points from
DIN EN 14511 (all parts) .............................................................................................................................69
Table 26 — Mean source temperature for ground and groundwater as a function of the average outdoor
temperature .................................................................................................................................................74
Table 27 — Mean source temperature for ground and groundwater as a function of the average monthly
outdoor temperature....................................................................................................................................74
Table 28 — Correction factors f ∆ϑ to account for deviations in temperature differences in heat pump
measurement and operation .......................................................................................................................75
Table 29 — Boiler temperatures ........................................................................................................................87
Table 30 — Temperature correction factors.......................................................................................................87
Table 31 — Efficiency factors.............................................................................................................................90
Table 32 — Radiation loss factors .....................................................................................................................91
Table 33 — Stand-by heat factors......................................................................................................................92
Table 34 — Auxiliary energy factors ..................................................................................................................93
Table 35 — Default values .................................................................................................................................99
Table 36 — Efficiency factor.............................................................................................................................100
Table 37 — D DS as a function of the primary temperature and type of dwelling substation............................102
Table 38 — Coefficient B DS as a function of the class of insulation and the type of dwelling substation ........102
Table A.1 — Air-to-water heat pumps with a supply temperature of 35 °C .....................................................105
Table A.2 — Air-to-water heat pumps with a supply temperature of 50 °C .....................................................105
Table A.3 — Brine-water heat pumps with supply temperatures of 35°C and 50 °C.......................................105
Table A.4 — Water-water heat pumps with supply temperatures of 35°C and 50 °C .....................................106
Table A.5 — Correction factor for part load operation of electrically driven heat pumps with radiators ..........110
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DIN V 18599-5:2007-02
Table A.6 — Correction factor for part load operation of electrically driven heat pumps with surface
heating systems........................................................................................................................................ 110
Table A.7 — Correction factor for part load operation of absorption heat pumps........................................... 111
Table A.8 — Relative heat output performance .............................................................................................. 113
6

Foreword
DIN V 18599-5:2007-02
This prestandard has been prepared by DIN Joint Committee NA 005-56-20 GA Energetische Bewertung von
Gebäuden of the Normenausschuss Bauwesen (Building and Civil Engineering Standards Committee), which
also lead-managed the work, and Normenausschuss Heiz- und Raumlufttechnik (Heating and Ventilation
Standards Committee) with the co-operation of the Normenausschuss Lichttechnik (Lighting Technology
Standards Committee).
A prestandard is a standard which cannot be given full status, either because certain reservations still exist as
to its content, or because the manner of its preparation deviates in some way from the normal procedure.
No draft of the present prestandard has been published.
Comments on experience with this prestandard should be sent:
⎯ preferably by e-mail containing a table of the data, to nabau@din.de. A template for this table is provided
on the Internet under the URL http://www.din.de/stellungnahme;
⎯ or as hard-copy to Normenausschuss Bauwesen (NABau) im DIN Deutsches Institut für Normung e. V.,
10772 Berlin, Germany (office address: Burggrafenstrasse 6, 10787 Berlin, Germany).
The DIN V 18599 series of prestandards Energy efficiency of buildings — Calculation of the energy needs,
delivered energy and primary energy for heating, cooling, ventilation, domestic hot water and lighting consists
of the following parts:
⎯ Part 1: General balancing procedures, terms and definitions, zoning and evaluation of energy carriers
⎯ Part 2: Energy needs for heating and cooling of building zones
⎯ Part 3: Energy need for air conditioning
⎯ Part 4: Energy need and delivered energy for lighting
⎯ Part 5: Delivered energy for heating systems
⎯ Part 6: Delivered energy for ventilation systems and air heating systems for residential buildings
⎯ Part 7: Delivered energy for air handling and air conditioning systems for non-residential buildings
⎯ Part 8: Energy need and delivered energy for domestic hot water systems
⎯ Part 9: Delivered and primary energy for combined heat and power plants
⎯ Part 10: Boundary conditions of use, climatic data
The DIN V 18599 series of prestandards provides a methodology for assessing the overall energy efficiency of
buildings. The calculations enable all energy quantities required for the purpose of heating, domestic hot water
heating, ventilation, air conditioning and lighting of buildings to be assessed.
In the described procedures, the DIN V 18599 series of prestandards also takes into account the interactive
effects of energy flows and points out the related consequences for planning work. In addition to the
calculation procedures, the use- and operation-related boundary conditions for an unbiased assessment (i.e.
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DIN V 18599-5:2007-02
independent of the behaviour of individual users and of the local climatic data) to determine the energy needs
are specified.
The DIN V 18599 series of prestandards is suitable for determining the long-term energy needs of buildings or
parts of buildings as well as for assessing the possible use of renewable sources of energy in buildings. The
procedure is designed both for buildings yet to be constructed and for existing buildings, and for retrofit
measures for existing buildings.
Amendments
This prestandard differs from DIN V 18599-5:2005-07 in that it has been revised in form and content.
Previous edition
DIN V 18599-5: 2005-07
8

Introduction
DIN V 18599-5:2007-02
When an energy balance is calculated in accordance with the DIN V 18599 series of prestandards, an
integrative approach is taken, i.e. the building, the use of the building and the building’s technical installations
and equipment are assessed together, taking the interaction of these factors into consideration. In order to
provide a clearer structure, the DIN V 18599 series of prestandards is divided into several parts, each having
a particular focus. Figure 1 provides an overview of the topics dealt with in the individual parts of the series.
Figure 1 — Overview of the parts of DIN V 18599
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DIN V 18599-5:2007-02
1 Scope
The DIN V 18599 series of prestandards provides a methodology for calculating the overall energy balance of
buildings. The described algorithm is applicable to the calculation of energy balances for:
⎯ residential buildings and non-residential buildings;
⎯ planned or new building construction and existing buildings.
The procedure for calculating the balances is suitable for:
⎯ balancing the energy use of buildings with partially pre-determined boundary conditions;
⎯ balancing the energy use of buildings with freely-selectable boundary conditions from the general
engineering aspect, e.g. with the objective of achieving a good comparison between calculated and
measured energy ratings.
The balance calculations take into account the energy use for:
⎯ heating,
⎯ ventilation,
⎯ air conditioning (including cooling and humidification),
⎯ heating the domestic hot water supply, and
⎯ lighting
of buildings, including the additional electric power input (auxiliary energy) which is directly related to the
energy supply.
This document determines the energy use of the heating system for the building according to its different
subsystems. It is also possible to use the results from some subsystems for calculating the delivery of heat to
the sectors covered by DIN V 18599-6, DIN V 18599-8 and vice-versa.
It is also possible to calculate the energy balances of several building zones in which there are several units to
be balanced.
This document describes the energy use of heating systems with their subsystems (control and emission,
distribution, storage and generation). For this purpose, both the thermal losses and the auxiliary energy of the
individual subsystems are determined and, provided these occur within the heated zone, are made available
for the ensuing calculations described in DIN V 18599-1 and DIN V 18599-2. Information is given on the
possible influence of domestic hot water generation according to DIN V 18599-8. Recourse to the heating
system by other systems (e.g. ventilation of residential buildings as in DIN V 18599-6, or ventilation and air
conditioning systems in non-residential buildings as in DIN V 18599-7), that can make demands on certain
subsystems, can accordingly be taken into account and analysed, with DIN V 18599-1 acting as the link
between the Parts.
It is assumed that heating systems are operated as intended and in keeping with accepted best practices.
Special guidance (e.g. with regard to the hydraulic balance of the hot water heating system) is given in
VDMA 24199.
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DIN V 18599-5:2007-02
The required energy use can be calculated using either the methods described in clause 6, or by other
calculation methods (e.g. DIN V 4701-10, DIN V 4701-12 and PAS 1027), provided these alternative methods
deliver equivalent results under comparable boundary conditions (see DIN V 18599-10). The assumptions and
boundary conditions on which these calculations are based shall be recorded systematically and shall apply to
the annual heating need Q h,b .
The energy need values calculated using this procedure cannot be used to size individual components.
Systems not covered by this document shall be assessed by analogy with this document while taking account
of the physics specific to the individual systems.
Figure 2 shows the scope of the present document as a diagram. For the reader’s orientation, all other parts
of the DIN 18599 series of prestandards contain an illustration similar to Figure 2 as shown here, and in which
the respective energy components dealt with are shown in colour.
2 Normative references
Figure 2 — Content and scope of DIN V 18599-5 (schematic diagram)
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
DIN V 4701-10, Energy efficiency of heating and ventilation systems in buildings — Part 10: Heating, domestic
hot water supply, ventilation
DIN V 4701-12, Energetic evaluation of heating and ventilation systems in existing buildings — Part 12: Heat
generation and domestic hot water generation
DIN V 4753-8, Water heaters and water heating installations for drinking water and for service water — Part 8:
Thermal insulation for water heaters with nominal capacity up to 1 000 l — Requirements and testing
11

DIN V 18599-5:2007-02
DIN V 18599-1, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 1: General balancing
procedures, terms and definitions, zoning and evaluation of energy carriers
DIN V 18599-2, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy use for heating, cooling, ventilation, domestic hot water and lighting — Part 2: Energy need for
heating and cooling of building zones
DIN V 18599-3, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 3: Energy need for air
conditioning
DIN V 18599-4, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 4: Energy need and
delivered energy for lighting
DIN V 18599-6, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 6: Delivered energy for
ventilation systems and air heating systems for residential buildings
DIN V 18599-7, Energy efficiency of buildings — Calculation of the energy needs, delivered energy primary
energy for heating, cooling, ventilation, domestic hot water and lighting — Part 7: Delivered energy for air
handling and air conditioning systems for non-residential buildings
DIN V 18599-8, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 8: Energy need and
delivered energy for domestic hot water systems
DIN V 18599-9, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 9: Delivered and
primary energy for combined heat and power plants
DIN V 18599-10, Energy efficiency of buildings — Calculation of the energy needs, delivered energy and
primary energy for heating, cooling, ventilation, domestic hot water and lighting — Part 10: Boundary
conditions of use, climatic data
DIN 18892, Inserts for solid fuel to be built in ceramic stoves ("Kacheloefen/Putzoefen")
DIN EN 297, Gas-fired central heating boilers — Type B boilers, fitted with atmospheric burners of nominal
heat input not exceeding 70 kW
DIN EN 303-5, Heating boilers — Part 5: Heating boilers for solid fuels, hand and automatically stocked,
nominal heat output of up to 300 kW — Terminology, requirements, testing and marking
DIN EN 304, Heating boilers — Test code for heating boilers for atomizing oil burners
DIN EN 308, Heat exchangers — Test procedures for establishing performance of air-to-air and flue gases
heat recovery devices
DIN EN 656, Gas-fired hot water boilers — Type B boilers of nominal heat input exceeding 70 kW but not
exceeding 300 kW
DIN EN 1264, Floor heating — Systems and components (all parts)
DIN EN 12828, Heating systems in buildings — Design of water-based heating systems
DIN EN 12975-1, Thermal solar systems and components — Solar collectors — Part 1: General requirements
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DIN V 18599-5:2007-02
DIN EN 12975-2, Thermal solar systems and components — Solar collectors — Part 2: Test methods
DIN EN 13229, Inset appliances including open fires fired by solid fuels — Requirements and test methods
DIN EN 13240, Roomheaters fired by solid fuel — Requirements and test methods
DIN EN 13410, Gas-fired overhead radiant heaters — Ventilation requirements for non-domestic premises
DIN EN 14511, Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors
for space heating and cooling (all parts)
DIN CEN/TS 14825, Air conditioners, liquid chilling packages and heat pumps with electrically driven
compressors for space heating and cooling — Testing and rating at part load conditions
DIN EN ISO 12241, Thermal insulation for building equipment and industrial installations — Calculation rules
DIN V ENV 12977-3, Thermal solar systems and components — Custom built systems — Part 3:
Performance characterization of stores for solar heating systems
Council Directive 92/42/EEC of 21 May 1992 on efficiency requirements for new hot water boilers fired with
liquid or gaseous fuels
Energieeinsparverordnung (EnEV) (German Energy Saving Ordinance) 2002/2004
VDMA 24199, Regelungstechnische Anforderungen an die Hydraulik bei Planung und Ausführung von
Heizungs-, Kälte-, Trinkwarmwasser- und Raumlufttechnischen Anlagen (Hydraulic system control
requirements in the planning and execution of heating, cooling, domestic hot water and ventilation systems)
3 Terms and definitions, symbols and units
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in the other parts of the DIN V 18599
series of prestandards and the following apply.
3.1.1
expenditure factor
ratio of expenditure to desired use (need) in an energy system
3.1.2
operating range
range indicated by the manufacturer, located within the upper and lower limits (e.g. in respect of temperature,
air humidity, voltage) within which the unit is deemed to be fit for use and has the product data stated by the
manufacturer
3.1.3
operating time
heating time and running time in set-back/cut-out or switch-off mode
3.1.4
reference area
usable area within the conditioned volume of the building
NOTE The net floor area (A NGF ) is used as the reference area.
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DIN V 18599-5:2007-02
3.1.5
calculation period
period for which the balance of relevant energy flows in a building is calculated
NOTE The calculation period for calculating the delivered energy and primary energy is one year; periods of one
month or one day can be used for calculating partial energy characteristics.
3.1.6
balance point temperature
temperature at which the heat output of the heat pump and the energy need of the building are equal
3.1.7
decentralized heating system
heating system in which heat is generated in a unit and is emitted into the same space, with water or air
serving as the heat carrier
3.1.8
delivered energy use (“energy use” in this document)
calculated quantity of energy delivered to the technical building installations (heating system) in order to
ensure the specified room temperature throughout the entire year
NOTE This energy includes the auxiliary energy required to operate the technical building installations. The delivered
energy is transferred at the “interface” constituted by the external building envelope and thus represents the amount of
energy which the connected load requires in order to use the building for its intended purpose under standardized
boundary conditions. Against this background, the energy use is expressed individually for each energy carrier.
3.1.9
generation
subsystem which provides, and may also deliver, the quantity of heat required by the systems (e.g. extract air
heat pump, see DIN V 18599-6)
3.1.10
heat output
Θ g
heat delivered from the unit to the heat carrier per unit of time
NOTE If heat is removed from the internal heat exchanger for defrosting purposes it is taken into account.
3.1.11
heating area
area that encompasses those parts of the building that are supplied by the same heating system; it can extend
over a number of zones, and at the same time one zone can include a number of heating areas
3.1.12
heating time
running time of the heating system to ensure the temperatures specified for use
3.1.13
auxiliary energy
energy (electric power), that is not used to directly satisfy the heating need (e.g. energy for the drive of system
components, circulation pumps, controls, "Carter" heating in the case of heat pumps, etc.)
3.1.14
internal temperature, mean
temperature felt in the interior of a building, given as the internal temperature for the space, averaged over
space and time
NOTE This parameter is specified as part of the planning process.
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DIN V 18599-5:2007-02
3.1.15
combined operation
operation of a heat generator with double service (e.g. for space heating and domestic hot water)
3.1.16
conditioning
generation of defined conditions in spaces by means of heating, cooling, ventilation, humidification, lighting
and domestic hot water supply
NOTE Conditioning aims to meet requirements relating to the room temperature, fresh air supply, light, humidity
and/or domestic hot water.
3.1.17
conditioned space
space and/or enclosure which is heated and/or cooled to a defined set-point temperature and/or humidified
and/or illuminated and/or provided with ventilation and/or domestic hot water
NOTE Zones are conditioned spaces having at least one mode of conditioning. Spaces which have no form of
conditioning are called “unconditioned spaces”.
3.1.18
load factor
ratio between the running time of the compressor and the total time over which the generator is switched on
(stand-by and operation)
3.1.19
coefficient of performance COP
ratio of the heating capacity to the effective power input of a unit
3.1.20
energy need
energy that is supplied by the heating system under standard conditions in order to meet the space heating
need and, if necessary, the heating need for domestic hot water
NOTE See DIN V 18599-8.
3.1.21
heat output
part of the quantity of heat that is transferred to the ensuing system
3.1.22
energy need for heating
calculated heat energy required in order to maintain the specified thermal room conditions within a building
zone during the heating period
NOTE See DIN V 18599-1.
3.1.23
product data
manufacturer-specific data on the basis of
⎯ a declaration of conformity to harmonized European specifications or corresponding European directives,
or
⎯ a declaration of conformity to generally recognized technical standards, or
⎯ a building-inspectorate certificate of usability
that is suitable for this calculation procedure
15

DIN V 18599-5:2007-02
3.1.24
simultaneous operation
simultaneous generation of heat energy for space heating and for domestic water heating
3.1.25
storage
subsystem in which heat contained in a medium is stored
NOTE In heating circuits this is the buffer storage tank (e.g. in heat pump systems).
3.1.26
default value
data which can be used for the calculation if no suitable product data are available for the calculation
procedure
3.1.27
part load operation
operating status of the heat pump in which the actual load requirement lies below the actual load capacity of
the heat pump
3.1.28
control and emission
subsystem in which energy is emitted (e.g. into the space), whilst maintaining the defined requirements
(notably in respect of comfort) (see DIN V 18599-10)
3.1.29
loss
losses (heat emission) occurring in the subsystems between the energy need and the delivered energy, i.e.
losses occurring due to control and emission, distribution, storage and generation. Where such losses occur
within the conditioned spaces, they count as heat sources
3.1.30
distribution
subsystem in which the required quantity of energy is transported from the generator to the heat control and
emission system
3.1.31
heat energy
energy used directly to meet the energy need for heating (e.g. oil, gas, wood or electric power)
3.1.32
heat generator with double service
heat generator which supplies energy to two different systems (e.g. the space heating system and the
domestic hot water system in combined operation)
3.1.33
heat carrier
any medium (water, air, etc.) used for the transfer of heat without changing its state
NOTE In addition to the water circulating in the heating circuits, such media also include:
⎯ the cooled fluid circulating in an evaporator;
⎯ the refrigerant circulating in a condenser;
⎯ the heat recovery medium circulating in a heat recovery heat exchanger.
16

DIN V 18599-5:2007-02
3.1.34
central heating system
heating system in which the heat is generated in a unit and is transported via distribution piping to a number of
rooms in a building, with water serving as the heat carrier
3.1.35
zone
basic unit of space for calculating energy balances
NOTE 1 A zone is a cumulative term for a section of the floor area or certain part of a building having uniform boundary
conditions of use and which does not exhibit any relevant differences in the mode of conditioning and other zone criteria.
NOTE 2 DIN V 18599-10 contains a compilation of boundary conditions of use.
3.1.36
cycle time
time for one cycle of the generator, consisting of an ON period t ON , where the generator is running, and an
OFF period t OFF , where the generator is in stand-by mode
3.2 Symbols, units and subscripts
Table 1 — Symbols and units
Symbol Meaning Common unit
Ac collector area m 2
b factor –
B width m
Bezugsgröße reference quantity –
c specific heat capacity kWh/(kg · K)
C constant –
COP coefficient of performance –
d time d/a, d/mth
e expenditure factor –
f factor –
FC load factor –
h height m
HDH heating degree hours Kh
IAM incidence angle modifier –
k coefficient –
L length m
n number –
p pressure kPa
P power, energy output W, kW
PE power input, power consumption W, kW
q loss –
17

DIN V 18599-5:2007-02
18
Table 1 (continued)
Symbol Meaning Common unit
Q energy kWh/mth
R heat loss rate –
SPF seasonal performance factor –
t time, period h/d, h/mth, h/y
U heat transfer coefficient (thermal transmittance) W/m · K
UA heat loss rate W/K
V volume m 3
V & volume flow m 3 /h
W auxiliary energy kWh/mth
z daily running time h/d
α time component –
β part load level, (load factor) –
η efficiency, conversion factor –
Θ energy W, kW
ϑ temperature °C
ρ density kg/l

Table 2 — Subscripts
DIN V 18599-5:2007-02
Subscript Meaning Subscript Meaning
a year, over- mth monthly, in the respective month
A connection, branching, design n nominal, rated, index, exponent
Abgl balance N night-time set-back/switch-off
App unit NA inclination, night
aux auxiliary energy outg generator heat output
b need, use P pump
B stand-by, shut down, components pl part load
Betrieb operation PM pump management
bin bin prim primary
Bio biomass PS buffer storage tank
bp balance point Q heat quantity
bu back up heating rB design operating time
C space temperature control rd recovered
ce control and emission, over-heating reg regenerative
combi
combination of heating and domestic hot
rl recoverable
water
d distribution rL design running time
DS dwelling substation RL return, outlet
e electric, efficiency, external, outdoor rv residential ventilation system
ex exhaust air, extract air RV reverse flow inhibitor
f delivered energy, factor s storage, emitted radiation, upper
FBH underfloor heating S main supply pipe
fl full load SB stand-by
G building/zone Sch circuit
ges total, overall sek secondary
Grenz limit sin heating mode only
GZ base cycle SL stub pipe, branching
h heating slr solar load ratio (system utilization)
H heating system sol solar
HK heating circuit soll required value, set-point
hours hours sys reference, system
Hs/Hi gross calorific value/net calorific value T day
hydr hydraulic Test test condition
i interior, serial counter, lower, bin TH thermostat valve
I internal, indoor upper upper
in consumption, input v loss
int intermittent V vertical distribution
intern internal VL supply
Itc cut-out point w domestic hot water
k cold water, boiler W heat
K combination system WA weekend set-back/switch-off
km mean boiler (temperature) WE heat generator
L air temperature profile, running time WP heat pump
loss loss WRG heat recovery
lower lower z circulation circuit
m average, mean 70 temperature boundary condition
max maximum 100 % at rated load
mot engine
19

DIN V 18599-5:2007-02
Subscript system
Figure 3 shows the system of subscripts used for the characteristic values of the building’s technical
installations and equipment. The various types of system, subsystem and energy are also listed.
20
Figure 3 — Subscript system
4 Relationship between the parts of the DIN V 18599 series of prestandards
The following two subclauses
⎯ summarize the input parameters to be used in this document,
⎯ provide an overview of how the part-balances calculated using the method explained here are applied in
other parts of the DIN V 18599 series.
For simplification, neither the parameters nor the reasons why the data are needed in other calculations are
explained here.
This document is intended to be used in the calculation of the thermal losses and the auxiliary energy for
⎯ the control and emission of heat to the space or to air as the heat carrier, or to an ensuing system such
as in DIN V 18599-7,
⎯ distribution in the heating circuit, or to an ensuing system such as in DIN V 18599-6 or DIN V 18599-7,
⎯ storage and
⎯ heat generation
of heating systems for the ensuing balancing procedures according to DIN V 18599-1.

4.1 Input parameters from other parts of the DIN V 18599 series of prestandards
Table 3 — Input parameters
DIN V 18599-5:2007-02
Symbol Meaning Source
B G Width of building, in m –
h G Storey height, in m –
f Hs/Hi
Ratio of gross calorific value to net calorific value according to
energy carrier
L G Length of building, in m –
n G Number of heated storeys –
Qh, max
& Maximum heat load, in kW
see DIN V 18599-1
see DIN V 18599-2,
Annex B
Q h,b Energy need (in the respective month), in kWh see DIN V 18599-1
Q rv,h,outg
Q h*,b
Generator heat output of residential ventilation unit (in the
respective month), in kWh
Generator heat output of air handling unit
(in the respective month), in kWh
see DIN V 18599-6
see DIN V 18599-7
Q c,f Delivered energy for chiller (in the respective month), in kWh see DIN V 18599-7
Q w,outg
Generator heat output to domestic hot water system (in the
respective month), in kWh
see DIN V 18599-1
t w,100% Daily running time of boiler for domestic hot water heating, in h see DIN V 18599-8
t c,op Daily operating time of space cooling system, in h see DIN V 18599-10
t h Heating hours (in the respective month), in h see DIN V 18599-2
t h,op Daily duration of heating operation, in h see DIN V 18599-10
t h*,op Daily operating time of HVAC heating coil, in h see DIN V 18599-10
d mth Number of days per month, in d/mth see DIN V 18599-10
t Nutz,d Daily usage period, in h see DIN V 18599-10
d Nutz,a Number of usage days per annum see DIN V 18599-10
ϑ e Monthly average outdoor temperature, in °C see DIN V 18599-10
ϑ e,min
Daily average outdoor temperature on a design reference day
for heating, in °C
see DIN V 18599-10
ϑ i a Ambient temperature, in °C see DIN V 18599-2
21

DIN V 18599-5:2007-02
22
Table 3 (continued)
Symbol Meaning Source
ϑ i,h,soll Internal set-point temperature for heating, in °C see DIN V 18599-10
ϑ h*
ϑ r,Nutz
Mean heating medium temperature for heating coil during the
usage time, in °C
Mean heating medium temperature for absorption chiller during
the usage time, in °C
see DIN V 18599-7
see DIN V 18599-7
a — ϑ i,h , is to be used for system components in a heated zone, taking into account reduced heating operation (without taking into
account weekends and holidays).
— ϑ i,c is to be used for system components in a cooled zone (the user shall decide whether a cooled zone exists).
— ϑ u is to be used for system components in an unheated and uncooled zone.
— If a zone is heated and cooled in the same month, it shall be determined which occurred more often and the appropriate
temperature used.
NOTE Examples of the dimensioning of buildings are to be found in Annex B.
Daily operation shall be considered the normal case and is to be taken into account by the heating time
(operating hours/duration) t h,op . Calculations are to be based on the assumption that there is always only one
connected load. Where there are a number of different loads a differentiation shall be made between the
individual requirements for each case.
The illustrations in Annex B may be helpful when determining L G and B G .
Heating is only necessary if the monthly energy need Q h,b,i is greater than 1 kWh.
4.2 Output parameters for other parts of the DIN V 18599 series of prestandards
Values are calculated for the zones specified in DIN V 18599-1.
If components are used in more than one subsystem, values are to be added together for use in the ensuing
calculations, taking into account the fact that the thermal data relate to the gross calorific value unless the
heat is generated by electric power or district heating.
In the following, the fractions of thermal and auxiliary energy in the different subsystems are determined for
use in the ensuing calculations in DIN V 18599-1.

Table 4 — Output parameters
DIN V 18599-5:2007-02
Symbol Meaning Used in
dh,rB Monthly design operating time, in d see 5.4.1
Q h,ce
Q h,ce,aux
Q h,d
Q h,d,aux
Q I,h,d
Q h,s
Q h,s,aux
Q I,h,s
Q h,g
Q h,g,aux
Q I,h,g
Q h,reg
Control and emission thermal losses of heating system to the surrounding
environment (e.g. space, room, zone, basement) (in the respective month),
in kWh
Auxiliary energy for heating system control and emission (in the respective
month), in kWh
Distribution thermal losses of heating system to the surrounding
environment (e.g. room, zone, basement) (in the respective month), in kWh
Auxiliary energy for heating system distribution (in the respective month),
in kWh
Uncontrolled internal heat gains in the zone due to heating system
distribution (in the respective month), in kWh
Storage thermal losses of heating system to the installation space (in the
respective month), in kWh
Auxiliary energy for heating system storage (in the respective month), in
kWh
Uncontrolled internal heat gains in the zone due to heating system storage
(in the respective month), in kWh
Generation thermal losses of heating system to the installation space (in
the respective month), in kWh
Auxiliary energy for heating system generation (in the respective month), in
kWh
Uncontrolled internal heat gains in the zone due to heating system heat
generation (in the respective month), in kWh
Regenerative energy contribution (in the respective month), in kWh
see 6.1
see 6.2
see 6.3
see 6.4
If there are different configurations for individual components of the heating system within one zone (e.g.
underfloor heating, radiators, air heating) an overall value is to be used in the calculations that is determined
by calculating the proportion of each parameter in relation to the net floor area.
4.2.1 Generator heat output
The generator heat is obtained from the energy need and from the losses from the individual subsystems.
Q h, outg Qh,
b + Qh,
ce + Qh,
d + Qh,
s
= (1)
For the heating of heating coils in HVAC systems the generator heat output is determined as follows:
Q h, outg Qh*,
b + Qh,
d + Qh,
s
= (2)
For the heating of absorption chillers in HVAC systems the generator heat output is determined as follows:
Q h, outg Qc,
f + Qh,
d + Qh,
s
= (3)
23

DIN V 18599-5:2007-02
If the heat generator delivers heat to several subsystems Q h,outg is the sum of the values of Q h,outg from the
individual subsystems, taking into account the fact that the data relate to the gross calorific value (unless the
heat is generated by electric power).
In the above,
24
Q h,outg is the generator heat output to the heating system (see DIN V 18599-1, DIN V 18599-6 or
DIN V 18599-7);
Q h,b
Q h*,b
Q c,f
Q h,ce
Q h,d
Q h,s
4.2.2 Delivered heat
where
is the energy need (see DIN V 18599-2);
is the generation heat output of the air handling unit (see DIN V 18599-7), in kWh;
is the delivered energy for the chiller (in the respective month) (see DIN V 18599-7), in kWh;
are the control and emission thermal losses of the heating system to the surrounding
environment (e.g. room, zone, basement) (in the respective month) (see 6.1), in kWh;
are the distribution thermal losses of the heating system to the surrounding environment (e.g.
room, zone, basement) (in the respective month) (see 6.2), in kWh;
are the storage thermal losses of the heating system to the surrounding environment (in the
respective month) (see 6.3), in kWh.
Qh, f ( Qh,
outg + Qh,
g)
⋅ fg,
PM − Qh,
reg
= (4)
with Q h,reg = Q h,sol + Q h,in
Q h,f
is the delivered energy for the heat generator (see DIN V 18599-1);
Q h,outg is the generator heat output to the heating system (see DIN V 18599-1);
Q h,g
Q h,reg
Q h,in
Q h,sol
f g,PM
are the generation losses of the heating system to the installation space (in the respective
month) (see 6.4), in kWh;
is the regenerative energy contribution (in the respective month) (see 6.4), in kWh;
is the ambient heat (in the respective month) (see 6.4), in kWh;
is the solar energy contribution (in the respective month), in kWh;
is the correction factor for heat generators with integrated pump management.
It shall be taken into account that the data relate to the gross calorific value unless the heat is generated by
electric power. If the delivered energy is electric power, there is no difference between gross calorific value
and net calorific value.
For the purposes of this document, integrated pump management is the coupling of the heating circulation
pump with the operation of the burner in the generator for control purposes.

DIN V 18599-5:2007-02
The correction factor for heat generators with integrated pump management takes into account the energy
used for operation at a higher temperature over shorter pump running times. Pump running times are
considered in 6.2.1.
Heat generators with integrated pump management f g,PM
⎯ For heat generators with integrated pump management, f g,PM is equal to 1.
⎯ For heat generators with integrated pump management and boiler temperature control with outdoor
sensors, f g,PM is equal to 1,03.
⎯ For heat generators with integrated pump management and boiler temperature control with indoor
sensors, f g,PM is equal to 1,06.
4.2.3 Auxiliary energy
where
Q h, aux Qh,
ce, aux + Qh,
d, aux + Qh,
s, aux + Qh,
g, aux
Q h,aux
= (5)
is the auxiliary energy for the heating system (see DIN V 18599-1);
Q h,ce,aux is the auxiliary energy for heating system control and emission (in the respective month) (see
6.1), in kWh;
Q h,d,aux
Q h,s,aux
Q h,g,aux
is the auxiliary energy for heating system distribution (in the respective month) (see 6.2), in
kWh;
is the auxiliary energy for heating system storage (in the respective month) (see 6.3), in kWh;
is the auxiliary energy for heating system generation (in the respective month) (see 6.4), in
kWh;
4.2.4 Uncontrolled heat gains due to the heating system
It shall be identified which subsystems are located in the respective zone and are to be taken into account
accordingly:
where
Q I, h QI,
h, d + QI,
h, s + QI,
h, g
Q I,h
Q I,h,d
Q I,h,s
Q I,h,g
= (6)
are the uncontrolled internal heat gains in the zone due to the heating system (in the respective
month), in kWh (see DIN V 18599-2);
are the uncontrolled internal heat gains in the zone due to distribution (in the respective month)
(see 6.2), in kWh;
are the uncontrolled internal heat gains in the zone due to storage (in the respective month) (see
6.3), in kWh;
are the uncontrolled internal heat gains in the zone due to generation (in the respective month)
(see 6.4), in kWh.
25

DIN V 18599-5:2007-02
Values shall be calculated for the zones specified in DIN V 18599-1.
5 Boundary conditions for the individual subsystems
If the specifications result in a usage time t h,Nutz = 0, the associated part load β i is similarly zero. If
requirements from DIN V 18599-7 exist, then t h,Nutz shall be determined according to the times specified in
that document.
5.1 Part load levels
5.1.1 Heat control and emission
The mean part load for a heating circuit in the control and emission subsystem is
where
26
Qh,
b
h, ce =
Q&
h, max ⋅th
β (7)
Q h,b
is the energy need in the calculation period (in the respective month) (see 4.1), in kWh;
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW;
t h
5.1.2 Heat distribution
is the number of heating hours in the respective month (see 4.1).
The mean part load in the distribution subsystem is
where
Qh,
b + Qh,
ce
h,d =
Q&
h, max ⋅ th
β (8)
Q h,b
Q h,ce
is the energy need in the calculation period (in the respective month) (see 4.1), in kWh;
are the monthly control and emission thermal losses of the heating system to the surrounding
environment (e.g. room, zone, basement) (see 4.2), in kWh;
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW;
t h
5.1.3 Storage
is the number of heating hours in the respective month (see 4.1).
The design temperature required for the storage tank is the mean heating circuit temperature as specified in
5.2. The mean part load of the storage tank in the heating circuit is:
Qh,
b + Qh,
ce + Qh,d
h,s =
Q&
h, max ⋅th
β (9)

where
Q h,b
Q h,ce
Q h,d
is the monthly energy need in the calculation period (see 4.1), in kWh;
DIN V 18599-5:2007-02
are the monthly control and emission thermal losses of the heating system (in the respective
month) (see 4.2), in kWh;
are the monthly distribution thermal losses of the heating system (in the respective month) (see
4.2), in kWh;
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW;
t h
5.1.4 Heat generation
is the number of heating hours in the respective month (see 4.1).
Distribution losses Q h,d and thermal losses from any storage tank that may be present, Q h,s , result in an
increase in the mean generation part load, as a result of which the distribution subsystem has to be fed at a
higher temperature. The mean generation part load in the heating circuit is:
where
Qh,
b + Qh,
ce + Qh,d
+ Qh,s
h,g =
Q&
h, max ⋅th
β (10)
Q h,b
Q h,ce
Q h,d
Q h,s
is the energy need in the calculation period (in the respective month) (see 4.1), in kWh;
are the heating system control and emission thermal losses (in the respective month) (see 4.2),
in kWh;
are the heating system distribution thermal losses (in the respective month) (see 4.2), in kWh;
are the heating system storage thermal losses (in the respective month) (see 4.2), in kWh;
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW;
t h
5.2 Temperatures
is the number of heating hours in the respective month (see 4.1).
For automatic temperature-controlled heating circuits the following shall apply for the individual subsystems as
a function of the mean part load and the mean temperature difference under design conditions:
and
ϑ HK,m (β i ) = 0,5 · (ϑ VL,m (β i ) + ϑ RL,m (β i )) (11)
∆ϑ HK (β i ) = ϑ VL,m (β i ) – ϑ RL,m (β i ) (12)
VL, m
1
i
( β ) ( ϑ −ϑ
) ⋅ β n ϑi,
h,soll
ϑ = +
(13)
i
VA
i, h,soll
27

DIN V 18599-5:2007-02
where
28
RL, m
1
i
( β ) ( ϑ −ϑ
) ⋅ β n ϑi,
h,soll
ϑ = +
(14)
β i
ϑ VA
ϑ RA
i
RA
i, h,soll
is the mean part load in the subsystem;
is the supply temperature of the heating medium under design conditions;
is the return temperature of the heating medium under design conditions;
n is the emitter exponent (default values: 1,33 for radiators; 1,1 for underfloor heating);
ϑ i,h,soll is the room temperature during the usage time (see 4.1), in °C.
The mean over-temperature of the heating medium is obtained as follows:
where
ϑVA
+ ϑ
∆ ϑ RA
A =
−ϑi,
h,soll
(15)
2
∆ϑ A
is the mean over-temperature of the heating medium under design conditions.
For constant temperature boilers with mixers, over-temperatures shall be used for distribution and control and
emission, while a mean temperature of 70 °C shall be assumed for boilers without mixers.
The design temperatures can be adjusted where existing buildings have been refurbished.
If no new detailed design is to be carried out and the existing emitters are retained, the design temperatures
from Table 5 can be roughly adjusted as a function of the old and new heat load according to DIN V 18599-2,
Annex B. In the case of intermediate values, the next higher pair of temperatures shall be selected.
Old design temperatures
Table 5 — Design temperatures
70/55 °C
Q&
N, neu / Q&
N, alt
at new design temperatures
55/45 °C 35/28 °C
90/70 °C 63,8 % 40,6 % 11,3 %
70/55 °C − 63,7 % 17,8 %
55/45 °C − − 27,9 %
The mean required (supply and return) temperatures for heat generators without a storage tank are calculated
according to equation (11). If a buffer storage tank is interposed, the required temperatures shall be calculated
using equation (11) unless other provisions are given in 6.3 or are dependent on the system (see 6.4.3.3).
This temperature is assumed to be the storage temperature and the supply pipe temperature.
If different heating circuits are operated, the maximum temperature is dependent on the requirement to be met
by the heat generator.

DIN V 18599-5:2007-02
Where constant temperature boilers and biomass boilers are used, a mean temperature of 70 °C can be
assumed for heat generation.
Fuel conversion and solid fuel boilers shall be treated in the same way as constant temperature boilers.
Return temperatures shall be taken into account when calculating efficiencies of condensing boilers.
For all low temperature and condensing boilers the stand-by loss shall be related to the mean heating circuit
temperature.
5.3 Boiler rated output
The rated output QN & of boilers to be installed in newly erected buildings is calculated as follows:
Firstly, the rated output of the boiler and the required maximum output for all connected loads (consumers)
are determined. Depending on the extent to which requirements need to be met simultaneously, the boiler
rated output QN & shall be determined either from the largest individual output or by adding together the
simultaneous requirements according to 6.4.3. The value of QN, h
& for space heating generation is obtained as
follows:
where
QN, h
& = 1,3 · h, max
Q & (16)
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW.
For existing buildings the rated output of the existing heat generation system is used. If this cannot be
established, then for heat generators that have been installed before 1994, the required heat output shall be
calculated according to equation (17):
QN, h
& = 2,5 h, max
Q & in kW (17)
The maximum generator output required by a building or building zone for space heating, central domestic
water heating, residential ventilation and air conditioning is the sum of all outputs that are required
simultaneously ( ∑QN, gleichzeitig)
& , or from the largest output in prioritized operation ( QVorrang ) & :
&
N max( Q&
N, gleichzeitig,
Q&
∑
Vorrang )
Q
5.4 Times
= (18)
5.4.1 Running times
If in DIN V 18599-2 night-time or weekend set-back or switch-off has been taken into account, this shall also
be included when considering the heating system. Boost operation is taken into account in the time data given
in DIN V 18599-10.
Design running time of a heating system
The design running time shall be used for determining thermal losses from distribution piping and, where
applicable, a heat generator. It takes into account both the reduced running time as a result of night-time or
weekend set-back or switch-off and also the set-back temperatures and, alternatively, continuous operation.
29

DIN V 18599-5:2007-02
Daily design heating running time
where
30
t = − f ⋅ ( 24 − t )
(19)
h, rL, T
t h,rL,T
f L,NA
t h,op
24 L, NA h, op
is the daily design running time, in h;
is the running time factor for night-time set-back or switch-off;
is the daily heating time, in h.
The running time factor taking into account night-time set-back or switch-off, f L,NA is as follows:
⎯ for continuous night-time operation: f L,NA = 0;
⎯ for night-time switch-off: f L,NA = 1;
⎯ for night-time set-back:
where
ϑNA,
Grenz − ϑe
f L, NA = 1−
with f L, NA ≤ 1
(20)
ϑNA,
Grenz − ϑe,
min
ϑ NA,Grenz
ϑ e
ϑ e,min
Monthly design operating days
where
is the night-time set-back temperature limit of 10 °C;
is the monthly average outdoor temperature (see 4.1), in °C;
is the daily mean design temperature (see 4.1), in °C.
365 − fL,WA
⋅ ( 365 − dNutz,
a ) th
d h, rB = dmth
⋅
⋅
(21)
365
d ⋅ 24
d h,rB
d mth
f L,WA
d Nutz,a
t h
is the design number of operating days in the respective month;
mth
is the number of days in the respective month (see 4.1);
is the factor taking into account weekend set-back or switch-off;
is the annual usage time (see 4.1), in d;
is the number of heating hours in the respective month (see 4.1), in h.
The running time factor taking into account weekend set-back or switch-off, f L,WA is as follows:
⎯ for continuous operation over the weekend: f L,WA = 0;

⎯ for weekend switch-off: f L,WA = 1;
⎯ for weekend set-back:
where
DIN V 18599-5:2007-02
ϑWA,
Grenz − ϑe
f L,WA = 1−
with f L,WA ≤ 1
(22)
ϑWA,
Grenz − ϑe,
min
ϑ WA,Grenz
ϑ e
ϑ e,min
is the weekend set-back temperature limit of 15 °C;
is the monthly average outdoor temperature (see 4.1), in °C;
is the daily mean design temperature (see 4.1), in °C.
Monthly design heating running time
where
t = t ⋅ d
(23)
h, rL
t h,rL
t h,rL,T
d h,rB
h, rL, T
h, rB
is the monthly design running time, in h;
is the daily design running time, in h;
is the monthly design number of operating days.
If different heating circuits are operated differently, or if other loads in addition to the heating system are
connected to a heat generator or to a distribution (e.g. a chiller or air handling unit) then accordingly the
longest operating time shall be taken into account for the heat generators. Domestic water heating is dealt
with in DIN V 18599-8.
The number of heating days in the respective month is given by
where
th
d h, mth = (24)
24
t h
is the number of heating hours in the respective month.
The monthly number of usage days is given by
where
dNutz,
a
dNutz, mth ⋅ dmth
365
d Nutz,a
d mth
= (25)
is the annual usage time, in d;
is the number of days in the respective month.
31

DIN V 18599-5:2007-02
5.4.2 Distribution of annual values over individual months
The energy use of components (e.g. for circulation pumps) can take the form of an annual mean if this is not
needed in the balance for individual zones according to DIN V 18599-2.
If the energy use in the zone is to be balanced monthly, the annual values shall be converted by means of the
following equation.
32
Wh,
d, e, M
=
Wh,
d, e, a
βh,
d, M ⋅ tNutz,
mth
h, d, a ⋅ th,
op ⋅ dNutz,
a
β
6 Determination of energy expenditure
The energy need from 6.4 shall be used as the input parameter for calculation of the characteristic values
relating to the heating system.
If there are additional requirements from another part of the DIN V 18599 series (e.g. for HVAC systems
according to DIN V 18599-7) this is also to be considered taking into account the required temperature,
compared with that of conventional heating systems (provided it is higher). The different subsystems shall be
analysed according to their usage, in the same way as for the heating system.
6.1 Heat control and emission
In the following, the energy characteristics required to determine the losses associated with the transfer of
heat to the room are specified.
Q h,ce is calculated for each month according to equation (27).
Q
where
h, ce
Q h,ce
Q h,b
f hydr
f int
⎛ f
= ⎜
⎝
Radiant
η
f
int
h, ce
f
hydr
⎞
− 1⎟Q ⎟
⎠
h, b
is the additional loss due to control and emission (in the respective month), in kWh;
is the energy need (in the respective month) (see 4.1), in kWh;
is the factor to account for hydraulic balance, currently equal to 1;
is the factor to account for intermittent operation (intermittent operation is understood to be the
option of reducing the temperature in individual rooms at certain times);
f Radiant is the factor to account for the effect of radiation (only relevant when heating large indoor spaces
where h > 4 m);
η h,ce
is the overall efficiency for heat emission in the room.
f int and f Radiant shall be set at 1, unless described in more detail in the following clauses.
(26)
(27)

The overall efficiency η h,ce is generally calculated as follows:
where
DIN V 18599-5:2007-02
1
ηh,
ce = (28)
( 4 − ( ηL
+ ηC
+ ηB
))
η L is the partial efficiency for a vertical air temperature profile;
η C is the partial efficiency for room temperature control;
η B is the partial efficiency for specific thermal losses via external components.
In some cases a breakdown of the efficiency is not required. The annual expenditure for heat emission in the
space is calculated as
where
∑
h, ce, a = Q h, ce
Q (29)
Q h,ce,a is the annual heat loss due to control and emission, in kWh;
Q h,ce
is the heat loss due to control and emission (in the respective month) according to equation (27),
in kWh.
The partial and the overall efficiency given in the following tables are based on the following assumptions:
⎯ standard room heights h ≤ 4m (with the exception of large indoor spaces where h > 4 m);
⎯ residential and non-residential buildings;
⎯ different levels of thermal insulation;
⎯ continuous operating mode (intermittent operation in excess of that specified in DIN V 18599-2 is
accounted for by the factor f int );
⎯ reference is to one room in each case.
System solutions not covered in this clause
⎯ are dealt with in 6.4
NOTE The systems dealt with here are mainly heating equipment or individual fireplaces in which a differentiation
between heat generation and heat control and emission is not appropriate.
or
⎯ shall be interpolated or adjusted in a suitable manner.
6.1.1 Efficiencies for free emitters (radiators); room heights ≤ 4 m
Table 6 specifies the efficiencies for free emitters.
33

DIN V 18599-5:2007-02
Room temperature
control
Over-temperature
(reference ϑ i =
20 °C)
Specific thermal
losses via external
components
(GF = glazing
surfaces)
34
Table 6 — Efficiencies for free emitters (radiators); room heights ≤ 4 m
Parameters
Efficiencies
η L η C η B
Uncontrolled, with central supply temperature control 0,80
Master space 0,88
P controller (2 K) 0,93
P controller (1 K) 0,95
PI controller 0,97
PI controller (with optimum tuning function, e.g. presence
management, adaptive controller)
0,99
ηL1 ηL2 60 K (e.g. 90/70) 0,88
42,5 K (e.g. 70/55) 0,93
30 K (e.g. 55/45) 0,95
Radiator located on internal wall
Radiator located on external wall
0,87 1
— glazing surface (GF) without radiation protection 0,83 1
— glazing surface (GF) with radiation protectiona 0,88 1
— normal external wall 0,95 1
a Radiation protection must prevent 80 % of the radiation losses from the radiator to the glazing surface by means of insulation
and/or reflection.
The overall efficiency η h,ce is obtained by means of equation (28).
For η L a mean value shall be calculated from the data for the main parameters “over-temperature” and
”specific thermal losses via external components”.
η L = (η L1 +η L2 )/2 (30)
EXAMPLE Radiator on external wall; over-temperature 42,5 K; P controller (2 K)
η L = (η L1 + η L2 )/2 = (0,93 + 0,95)/2 = 0,94
η C = 0,93
η B = 1
η h,ce = 1/(4 – (0,94 + 0,93 + 1)) = 0,88
Factor to account for intermittent operation: f int = 0,97
NOTE For continuous operation f int is given a value of 1.
Factor to account for the effect of radiation: f Radiant = 1,0

DIN V 18599-5:2007-02
6.1.2 Efficiencies for water based embedded systems (surface heating); room heights ≤ 4 m
Table 7 specifies the efficiencies for water based embedded systems (surface heating) for room heights
≤ 4 m.
Table 7 — Efficiencies for water based embedded systems (surface heating); room heights ≤ 4 m
Room
temperature
control
System
Specific thermal
losses via laying
surfaces
Parameters
Part efficiencies
η L η C η B
Water as heat transfer medium
— uncontrolled 0,75
— uncontrolled, with central supply temperature control 0,78
— uncontrolled, with mean value (ϑ V –ϑ R ) 0,83
— master space 0,88
— two-step controller/P controller 0,93
— PI controller 0,95
Electric heating
— two-step controller 0,91
— PI controller 0,93
Underfloor heating η B1 η B2
— wet system 1 0,93
— dry system 1 0,96
— dry system with thin cover 1 0,98
Wall heating 0,96 0,93
Ceiling heating 0,93 0,93
Underfloor heating without minimum insulation to
DIN EN 1264
Underfloor heating with minimum insulation to DIN EN 1264 0,95
Underfloor heating with 100 % better insulation than
required by DIN EN 1264
The overall efficiency η h,ce shall be determined using equation (28).
For η B , a mean value shall be calculated from the data for the parameters “system” and “specific thermal
losses via laying surfaces”.
η B = (η B1 + η B2 )/2 (31)
EXAMPLE Underfloor heating – wet system (water); two-step controller; underfloor heating with a high level of
thermal insulation
η L = 1,0
η C = 0,93
η B = (η B1 + η B2 )/2= (0,93 + 0,95)/2 = 0,94
η h,ce = 1/(4 – (1,0 + 0,93 + 0,94)) = 0,88
0,86
0,99
35

DIN V 18599-5:2007-02
Factor to account for intermittent operation: f int = 0,98
NOTE For continuous operation f int is given a value of 1.
Factor to account for the effect of radiation: f Radiant = 1,0
6.1.3 Efficiencies for electric heating; room heights ≤ 4 m
Table 8 specifies the efficiencies for electric heating for room heights ≤ 4 m.
At external wall
At internal wall
36
Table 8 — Efficiencies for electric heating; room heights ≤ 4 m
Parameters
Overall efficiency
η h,ce
P controller (1 K) for direct electric heating 0,91
PI controller (with optimum tuning) for direct electric heating 0,94
Storage heating uncontrolled without outdoor-temperature-dependent charging
and static/dynamic discharging
Storage heating P controller (1 K) with outdoor-temperature-dependent charging
and static/dynamic discharging
Storage heating PID controller (with optimum tuning) with outdoor-temperaturedependent
charging and static and continuous dynamic discharging
P controller (1 K) for direct electric heating 0,88
PI controller (with optimum tuning) for direct electric heating 0,91
Storage heating, uncontrolled without outdoor-temperature-dependent charging
and static/dynamic discharging
Storage heating P controller (1 K) with outdoor-temperature-dependent charging
and static/dynamic discharging
Storage heating PID controller (with optimum tuning) with outdoor-temperaturedependent
charging and static and continuous dynamic discharging
Factor to account for intermittent operation: f int = 0,97 (to be used for electric heating systems with
integrated backward charging)
NOTE For continuous operation f int is given a value of 1.
Factor to account for the effect of radiation: f Radiant = 1,0
6.1.4 Efficiencies for air heating/residential ventilation; room heights ≤ 4 m
Residential ventilation systems are systems that supply and/or extract air, supplying residential buildings with
outdoor air, possibly combined with heat recovery and air handling.
Efficiencies η h,ce for air heating and residential ventilation are described in DIN V 18599-6.
0,78
0,88
0,91
0,75
0,85
0,88

6.1.5 Efficiencies for air heating (HVAC systems); (room heights ≤ 4 m)
DIN V 18599-5:2007-02
Table 9 specifies the efficiencies η h,ce for air heating (non-residential HVAC systems) for room heights ≤ 4 m.
Table 9 — Efficiencies for air heating (HVAC systems) for room heights ≤ 4 m
System configuration Control parameter
Supply air back-up
heating (additional
heater)
Recirculation air heating
(induction terminal units,
fan convectors)
Low quality of control
η h,ce
High quality of
control
Room temperature 0,82 0,87
Room temperature (cascade control
of supply air temperature)
0,88 0,90
Extract air temperature 0,81 0,85
Room temperature 0,89 0,93
The auxiliary energy for recirculation air heating shall be taken from Table 9. The data for residential
ventilation systems from DIN V 18599-6 can be used as the values for ventilation systems with a partial
heating function.
6.1.6 Efficiencies for rooms with heights ≥ 4 m (large indoor spaces)
Efficiencies for rooms with heights from 4 m to 10 m are specified in Table 10.
37

DIN V 18599-5:2007-02
Space
temp.
control
Heating
systems
38
Table 10 — Efficiencies for rooms with heights from 4 m to 10 m
Parameters
Part efficiencies
ηL 4 m 6 m 8 m 10 m
Uncontrolled 0,80
Two-step controller 0,93
P controller (2 K) 0,93
P controller (1 K) 0,95
PI controller 0,97
PI controller with optimum tuning 0,99
Warm air heating Air outlet at the side 0,98 0,94 0,88 0,83 1
Air distribution with normal induction
ratio
Air outlet above 0,99 0,96 0,91 0,87 1
Warm air heating Air outlet at the side 0,99 0,97 0,94 0,91 1
Air distribution with controlled vertical
recirculation
Air outlet above 0,99 0,98 0,96 0,93 1
Ceiling mounted radiant panels 1,00 0,99 0,97 0,96 1
Radiant tube heaters 1,00 0,99 0,97 0,96 1
Luminous radiant heaters 1,00 0,99 0,97 0,96 1
Underfloor heating (with a high level of
thermal insulation)
1,00 0,99 0,97 0,96
Integrated floor heating 0,95
Thermally decoupled
underfloor heating
Evaluation of heating systems for large indoor spaces with radiators (existing buildings):
Assumptions shall be based on warm air heating with a normal induction ratio and side air outlet.
Warm air heating systems with high air distribution induction ratio:
Characteristic values shall be determined by calculating the arithmetic mean of the values of the systems with
air outlets at the side and above.
When ceiling mounted radiant panels are used in rooms with a height of less than 4 m, the overall efficiency
η h,ce for a room height of 4 m shall be used. Furthermore, the factor f Radiant is equal to 1.
The overall efficiency η h,ce is determined using equation (28).
EXAMPLE Room height 8 m, warm air heating with air outlet above, P controller (1 K)
ηL = 0,91
ηC = 0,95
ηB = 1
ηges = 1/(4 – (0,91 + 0,95 + 1)) = 0,88
η C
η B
1

DIN V 18599-5:2007-02
Factor to account for the effect of radiation: f Radiant = 0,85 for ceiling mounted radiant panels, luminous
radiant heaters, radiant tube heaters and underfloor heating.
The efficiencies of heating systems in large indoor spaces and the factor f Radiant are mean values based on a
heating system and product typology, which can also be used as a basis for approximations of deviating
configurations.
6.1.7 Efficiencies for rooms with heights > 10 m
Table 11 specifies efficiencies for room heights > 10 m.
Space
temp.
control
Heating
systems
Table 11 — Efficiencies for rooms with heights > 10 m
Parameters
Part efficiencies
η L
12 m 15 m 20 m
Uncontrolled 0,80
Two-step controller 0,93
P controller (2 K) 0,93
P controller (1 K) 0,95
PI controller 0,97
PI controller with optimum tuning 0,99
Warm air heating Air outlet at the side 0,78 0,72 0,63 1
Air distribution with normal induction ratio Air outlet above 0,84 0,78 0,71 1
Warm air heating Air outlet at the side 0,88 0,84 0,77 1
Air distribution with controlled vertical
recirculation
Air outlet above 0,91 0,88 0,83 1
Ceiling mounted radiant panels 0,94 0,92 0,89 1
Radiant tube heaters 0,94 0,92 0,89 1
Luminous radiant heaters 0,94 0,92 0,89 1
Underfloor heating (with a high level of
thermal insulation)
Warm air heating systems with high air distribution induction ratio:
0,94 0,92 0,89
Integrated floor heating 0,95
Thermally decoupled
underfloor heating
1
The characteristic values shall be determined by calculating the arithmetic mean of the values of systems with
an air outlet at the side and above.
The overall efficiency η h,ce is calculated using equation (28).
EXAMPLE Room height 12 m, radiant tube heaters, P controller (2 K)
η L = 0,94
η C = 0,93
η C
η B
39

DIN V 18599-5:2007-02
40
η B = 1
η ges = 1/(4 –(0,94 + 0,93 + 1)) = 0,88
Factor to account for the effect of radiation: f Radiant = 0,85 for ceiling mounted radiant panels, luminous
radiant heaters, radiant tube heaters and underfloor heating.
The characteristic values of the efficiencies of heating systems in large indoor spaces and the factor f Radiant
are mean values for the heating systems and product types, which can also be used as a basis for
approximation of deviating configurations.
6.1.8 Auxiliary energy Q h,ce,aux
The auxiliary energy that is used to improve heat transfer processes in the room and is not dealt with in 6.1.2
and 6.1.4 is calculated according to equation (32).
where
Q h, ce, aux QC
+ QV,
P
Q h,ce,aux
Q C
Q V,P
= (32)
is the auxiliary energy (in the respective month), in kWh;
is the auxiliary energy of the control system (in the respective month), in kWh;
is the auxiliary energy of fans and additional pumps (in the respective month), in kWh.
The individual fractions Q C and Q V,P shall be determined using equations (33) and (34) respectively.
where
PC
⋅ dmth
⋅ 24
Q C =
(33)
1000
( P ⋅ n + P ⋅ n )
V V P P ⋅ th,
rL
QV,
P = (34)
1 000
P C
d mth
n V
n P
P V
P P
is the electrical rated power consumption of the control system with auxiliary energy (from
Table 12 or product data), in W;
is the number of days in the respective month (see 4.1);
is the number of fan units;
is the number of additional pumps;
is the electrical rated power consumption of the fans (from Table 13 or product data), in W;
is the electrical power consumption of the pump from manufacturer’s data, in W
or
[ ] 08 , 0 &
P
50 ⋅ QLH
= (35)

where
QLH & is the electrical rated power consumption of the heating coil, in kW;
t h,rL
is the monthly design running time (see 5.4.1), in h.
DIN V 18599-5:2007-02
The electrical rated power consumption of an additional pump can only be used in the calculations if the
hydraulic circuit of the heating coil requires an additional pump (e.g. an injection circuit), which is not already
taken into account in the heat distribution.
The operating time of the fan and/or pump is assumed to be equal to the operating time of the heating system.
Control with auxiliary
energy P C
Table 12 — Default values for auxiliary energy for the control system
Parameters
Power
W
Electrical control with electromotoric actuation 0,1 (per drive)
Electrical control with electrothermal actuation 1,0 (per drive)
Electrical control with electromagnetic actuation 1,0 (per drive)
Table 13 — Default values for the auxiliary energy of fans for air supply in rooms where h ≤ 4 m
Fan P V
Parameters
Power
W
Fan convector 10
Fan convector for direct electric heating 10
Storage heating with dynamic discharge 12
Storage heating with continuous dynamic discharge 12
Auxiliary energy in large indoor spaces (h > 4 m) – systems with direct heating
Most notably in large indoor spaces, heaters are used whose functions cannot be easily divided into the
subsystems heat generation and heat control and emission, and which are installed in the space in which they
are used. Examples of such heaters are gas and infrared radiators. The total auxiliary energy of these
systems is credited to the heat requirement of the space in which the heaters are installed (see top of
Table 14).
Q
h, ce, aux
Ph,
aux ⋅ th,
rL
= (36)
1 000
Auxiliary energy in large indoor spaces (h > 4 m) – systems without direct heating
Where heating systems used in large indoor spaces have a central heat generator and a separate unit for
emission of heat into the space in which it is required, only the auxiliary energy for the heat emission of these
systems is credited to the heat requirement of the space (see bottom of Table 14).
Q
h, ce, aux
Ph,
ce, aux ⋅ th,
rL
= (37)
1 000
41

DIN V 18599-5:2007-02
In equations (36) and (37)
42
Q h,ce,aux is the monthly auxiliary energy (heat emission and, if necessary, heat generation according to
equation (36)), in kWh;
P h,aux
is the rated power consumption of the equipment from Table 14 or manufacturer’s data (heat
generation and heat emission), in W;
P h,ce,aux is the rated power consumption of the equipment from Table 14 or manufacturer’s data (heat
emission), in W;
t h,rL
is the monthly design running time (see 5.4.1), in h.
The operating time of the fan including the control system is assumed to be equal to the operating time of the
heating system.
Table 14 specifies the default values for the auxiliary energy of fans and for the control system in rooms where
h > 4 m (large indoor spaces).
Table 14 — Default values for the auxiliary energy of fans and for the control system in rooms h > 4 m
in height (large indoor spaces)
Ph,aux Direct fired heat generators
(installed in the space they heat)
Ph,ce,aux Heat control and
emission system:
air heating
Luminous radiant heaters
(control and regulation)
Parameters
Radiant tube heaters up to 50 kW
(control, regulation and fan for combustion air distribution)
Radiant tube heaters above 50 kW
(control, regulation and fan for combustion air distribution)
Warm air generator with atmospheric burner and recirculation air axial fan
(control, regulation and fan for combustion air distribution)
Warm air generator with fan-assisted burner and recirculation air radial fan
(control, regulation and fan for combustion air distribution, fan for warm air
distribution)
Heating coil installed in room it heats (room height < 8 m)
(central heat generator with indirect-fired heating coil)
Heating coil installed in room it heats (room height > 8 m)
(central heat generator with indirect-fired heating coil)
Vertical recirculation fan (room height < 8 m)
Vertical recirculation fan (room height > 8 m)
Power
W
25 (per unit)
80 (per unit)
100 (per unit)
0,014 · Q h,b
0,022 · Q h,b
0,012 · Q h,b
0,016 · Q h,b
0,002 · Q h,b
0,013 · Q h,b
NOTE The power requirements specified in Table 14 are mean values. Characteristic values for auxiliary energy heat
generators are only introduced if not taken into account in 6.4.3.4.
Q h,b shall be determined as specified in 4.1.
The annual expenditure is determined according to equation (29).

6.2 Heat distribution Q h,d – central hot water heating pipe system
Heat loss from central hot water heating piping
The following general equation applies for losses from piping:
where
( HK, m − ϑi
) ⋅ Li
th,
rL, i
Qh, d = ∑ U i ⋅
⋅
U i
ϑ HK,m
ϑ i
DIN V 18599-5:2007-02
ϑ (38)
is the linear heat transfer coefficient, in W/m · K;
is the mean heating medium temperature from 5.4, in °C;
is the ambient temperature (see 4.1 or Table 15), in °C;
L is the length of the piping, in m;
t h,rL
is the monthly design running time (see 5.4.1), in h.
If, for a HVAC system, a heating coil is provided with heat by the heating system, the mean heating medium
temperature ϑ h* and the operating time th*,op for the distribution system shall be taken from 4.1.
If an absorption chiller is provided with heat by the heating system, the mean heating medium temperature
ϑ r, Nutz and the operating time tc,op for the distribution system shall be taken from 4.1.
In the zones through which the pipes pass, the loss corresponds to the uncontrolled heat gains:
where
i i Q QI, h,
d, = h, d,
(39)
Q I,h,d
Q h,d
are the uncontrolled losses to the zone via the heating distribution system (in the respective
month), in kWh
is the heat output from distribution piping (in the respective month), in kWh.
The value shall be summated with the values for the other zones and used in the ensuing calculations
according to DIN V 18599-2.
Boundary conditions for default values
If no detailed heating piping layout plan is available, the thermal losses can be approximated using the values
in Table 15. It is assumed that average piping comprises three different zones: V, S and A: Zone V is the
horizontal distribution of heat from the generator to the main supply pipes, zone S comprises the vertical main
supply pipes (if necessary up to the local distribution system for each dwelling) and zone A comprises the
branching pipes (that can be sealed off) to the radiators within the dwelling.
Length of piping for hot water heating pipe systems (see Figure 4)
L V Pipe section between heat generator and main supply pipes. This (horizontal) pipework can be located in
the unheated area (such as a basement or attic) or in the heated area (such as in the screed);
43

DIN V 18599-5:2007-02
L S main supply pipes (vertical and, in some cases, horizontal). These pipes are located in the heated area,
either in the external walls (external distribution) or mainly in the interior of the building (internal
distribution). Continuous circulation of the heating medium;
L A branching pipes: pipes that can be sealed off in the heated area. Connection between the circulating pipe
sections and the radiators.
44
Figure 4 — Designation of pipes in hot water heating pipe systems
Table 15 — Default values
Parameter Symbol Unit Zone V Zone S Zone A
Ambient temperature ϑ i °C from DIN V 18599-2
Ambient temperature
outside the heating
season (if no values are
calculated from
DIN V 18599-2)
Ambient temperature in
the heating season (if
no values are
calculated from
DIN V 18599-2)
Length of external main
supply pipe sections
Length of internal main
supply pipe sections
Length of internal main
supply pipe sections
Building/zone data are taken from DIN V 18599-2.
In the above table
ϑ i °C 22 °C
ϑ i
°C
13 °C in the unheated zone
and 20 °C in the heated
zone
Two-pipe heating
20 °C in the heated zone
L m 2 · LG + 0,016 25 · LG · B2 G 0,025 · LG · BG · hG · nG 0,55 · LG · BG · nG L m 2 · LG + 0,032 5 · LG · BG + 6 0,025 · LG · BG · hG · nG 0,55 · LG · BG · nG One-pipe heating
L m 2 · L G + 0,032 5 · L G · B G + 6 0,025 · L G · B G · h G · n G +
2 · (L G + B G ) · n G
L G is the largest extended length of the building (see 4.1), in m;
B G is the largest extended width of the building (see 4.1), in m;
0,1 · L G · B G · n G

n G is the number of heated storeys (see 4.1);
h G is the height of the storeys, in m (see 4.1).
DIN V 18599-5:2007-02
If a building is not rectangular in shape, the pipe lengths to be used in the calculations shall be determined by
dividing the building into rectangles, adding together the lengths of the individual rectangles and taking their
mean width. The values thus calculated shall be inserted in the formulae in Table 15.
Heat supply piping for air handling units
Lengths of pipework used for the heating of decentralized air handling units shall be calculated in the same
way as for hot water heating systems. For central air handling units, the length of piping shall be specified to
suit the location.
Determining the length of piping in buildings extending over more than one zone
If a building comprises a number of zones (see DIN V 18599-2), then for simplification the length of the
branching and main supply pipes is determined from the geometrical dimensions of each zone. The lengths of
the distribution pipes are determined from the geometrical dimensions of the building as a whole.
Alternatively, the distribution system can be calculated for the whole building and the thermal losses assigned
to the zones proportionately to their areas.
Age class of building
Table 16 — Assumptions for heat transfer coefficients U i in W/(m · K)
Distribution External main supply pipes Internal main supply pipes
V S A S A
From 1995 0,200 0,255 0,255 0,255 0,255
1980 to 1995 0,200 0,400 0,400 0,300 0,400
Up to 1980 0,400 0,400 0,400 0,400 0,400
Non-insulated piping
A NGF ≤ 200 m 2 1,000 1,000 1,000 1,000 1,000
200 < A NGF ≤ 500 m 2 2,000 2,000 2,000 2,000 2,000
A NGF > 500 m 2 3,000 3,000 3,000 3,000 3,000
Located in external wall
(EW)
total/usable a
EW, non-insulated 1,35/0,80
EW, externally insulated 1,00/0,90
EW (U = 0,4 W/(m 2 · K)) 0,75/0,55
a Total = total heat output; usable = output of heat that is usable in the space.
6.2.1 Auxiliary energy for central hot water heating pipe system
Auxiliary energy expenditure for circulation
The auxiliary energy expenditure required to operate heating circulation pumps is calculated on the basis of
the hydraulic requirement of the distribution system and an expenditure factor describing the operation of the
pump.
45

DIN V 18599-5:2007-02
where
46
Qh, d, aux Wh,
d, hydr ⋅ eh,
d, aux
Q h,d,aux
W h,d,hydr
e h,d,aux
= (40)
is the auxiliary energy expenditure (in the respective month), in kWh;
is the hydraulic energy requirement (in the respective month), in kWh;
is the expenditure factor for operation of the heat pump.
For intermittent operation the auxiliary energy shall be obtained from equation (47).
Hydraulic energy requirement
The hydraulic energy requirement of heating distribution is obtained from the hydraulic power at the design
point (P hydr ) together with the mean distribution part load (β h,d and t h ). The correction factors f Sch and f Abgl
take into account the principal parameters governing the system design.
Integrated pump management reduces the running time of the heat circulation pump. This is taken into
account by introducing the factor f d,PM in equation (41).
where
Phydr
Wh, d, hydr = ⋅ β h, d ⋅ ( th
⋅ fd,
PM)
⋅ fSch
⋅ fAbgl
(41)
1 000
P hydr
β h,d
t h
f Sch
f Abgl
f d,PM
is the hydraulic power of the pump at the design point, in W;
is the mean distribution part load;
is the number of heating hours in the respective month (see 4.1), in h;
is the correction factor to account for the hydraulic circuit;
is the correction factor to account for the hydraulic balance;
is the correction factor for heat generators with integrated pump management.
⎯ For heat generators without integrated pump management, the factor f d,PM = 1.
⎯ For heat generators with integrated pump management and boiler temperature control with external
sensors, the factor f d,PM = 0,75.
⎯ For heat generators with integrated pump management and boiler temperature control with internal
sensors, the factor f d,PM = 0,45.
Hydraulic power of the pump at the design point
The hydraulic power of the pump at the design point is given by
P = 0,
2778
⋅ ∆ p ⋅V&
hydr (42)

where
V & is the volume flow at the design point, in m 3 /h;
∆p is the pressure drop at the design point, in kPa.
DIN V 18599-5:2007-02
The volume flow at the design point is obtained from the design heat load Q max
& (see 4.1) and the design
temperature difference ∆ϑ HK in the heating circuit.
where
h,
max
=
1, 15 ⋅ ∆ϑHK
Q&
V
& (43)
∆ϑ HK
is the temperature difference at the design point (see 5.2), in K.
The pressure drop at the design point is given by the resistance of the piping (with individual resistances) and
the components providing additional resistances.
where
∆ (44)
p = 0, 13 ⋅ Lmax
+ 2 + ∆pFBH
+ ∆pWE
L max
∆p FBH
∆p WE
is the maximum length of the piping, in m;
is the pressure drop of the underfloor heating = 25 kPa (if present);
is the pressure drop of the heat generator, in kPa.
If no product data are available, then for heat generators with a water content of < 0,15 l/kW at
Qh, max
& < 35 kW ∆pWE = 20 ⋅ ,
2
V& in kPa and at Qh, max
& ≥ 35 kW ∆pWE = 80 kPa, while for heat generators with
a water content of > 0,15 l/kW ∆p WE = 1 kPa shall be used.
The maximum pipe length for a rectangular building can be estimated from the external dimensions of the
building or zone according to DIN V 18599-2.
where
⎛ BG
⎞
L max = 2 ⋅ ⎜ LG
+ + nG
⋅ hG
+ ld
⎟
(45)
⎝ 2
⎠
L G is the largest extended length of the building (see 4.1), in m;
B G is the largest extended width of the building (see 4.1), in m;
n G is the number of heated storeys (see 4.1);
h G is the average height of a storey (see 4.1), in m;
l d = 10 (an allowance for connections in the case of two-pipe heating systems), in m;
h,
47

DIN V 18599-5:2007-02
48
l d
= L + B (an allowance for connections in the case of one-pipe heating systems), in m.
The boundary conditions specified in 6.2 shall apply when calculating the piping section lengths to be
assumed.
Correction factors for:
Type of system (hydraulic circuit) f Sch
⎯ two pipe systems: f Sch = 1;
⎯ one-pipe systems: f Sch = 8,6 ⋅ m + 0,7
where
m is the proportional radiator mass flow, in %.
Hydraulic balance f Abgl
⎯ For hydraulically balanced heating distribution: f Abgl = 1.
⎯ For heating distribution that is not hydraulically balanced: f Abgl = 1,1.
Expenditure factor
To assess the performance of the heat pump, an expenditure factor e h,d,aux is calculated using equation (46).
The expenditure factor takes account of the principal parameters governing the annual electrical expenditure
of the pump, which can be derived from the size and efficiency of the pump as well as its part load and control
performance. When calculating on a monthly basis, it is assumed for simplification that a monthly value for
e h,d,aux can be calculated using the monthly value β h,d .
where
−1
( CP1
+ CP2
⋅ h, d )
e (46)
h, d, aux = fe
⋅
β
C P1 , C P2 are constants from Table 17;
f e
where
is the efficiency factor, calculated as follows:
⎛
0,
5 ⎞
⎜ ⎛ ⎞ ⎟
f ⎜ 200 ⎟
e = ⎜1
, 25 +
⋅ b
P
⎟
⎜
⎜ ⎟
⎟
⎝
⎝ hydr ⎠
⎠
for an unidentified pump
PPumpe
f e =
Phydr
for an identified pump
b is the over-dimensioning factor, determined as follows:
⎯ for pumps designed to meet the demand, b = 1;
⎯ for pumps which are not designed to meet the demand, b = 2.

DIN V 18599-5:2007-02
For existing pumps, the power stated on the rating plate can be taken as an approximate value for P Pumpe .
Table 17 — Constants C P1 ,and C P2 for calculation of the expenditure factor of heat pumps
Pump control C P1 C P2
Uncontrolled 0,25 0,75
∆pconst 0,75 0,25
∆p variable 0,90 0,10
Intermittent operation
The pump operates in the intermittent mode if it is operated outside the usage time at limited power or is
switched off. In these cases the electrical energy expenditure of the heating circulation pumps is determined
as follows:
Q
where
h, d, aux
Q h,d,aux
W h,d,hydr
e h,d,aux
t h,rL
f P,A
t h
h
( t − t )
1,
03 ⋅ th,
rL + fP,
A ⋅ h h, rL
= Wh,
d, hydr ⋅ eh,
d, aux ⋅
(47)
t
is the electrical energy use (in the respective month), in kWh;
is the hydraulic energy requirement (in the respective month), in kWh;
is the expenditure factor for heat pump operation;
is the monthly design running time (see 5.4.1), in h;
is the correction factor to account for pump set-back/switch-off;
is the number of heating hours in the respective month (see 4.1), in h.
The correction factor to account for set-back or switch-off of the pump is given by the following:
⎯ for set-back operation:
0 ≤ f P,A ≤ 1; default value 0,6;
⎯ for switch-off:
f P,A = 0.
Deviations in the calculation procedure
In certain applications, deviations in the calculation procedure shall be taken into account.
⎯ One-pipe heating
The total mass flow and accordingly the throughflow at the pump are approximately constant. The pump
operates at the design point throughout the year. For the mean hydraulic part load β h,d = 1 applies.
49

DIN V 18599-5:2007-02
⎯ Overflow valves
Overflow valves are used to ensure minimum water circulation flow at the heat generator or to limit the
pressure drop at the connected load. The function of the overflow valve results from the interaction of the
system pressure loss, pump performance curve and response pressure of the valve. The effects on the
mean hydraulic requirement can be estimated with the aid of equation (48).
where
50
(β' h,d from the definition of the mean part load)
& min
V ( − h, ′ d)
V&
h, d = βh,
′ d + 1 β ⋅
β (48)
V & is the design volume flow, in m 3 /h;
Vmin & is the minimum volume flow, in m3 /h.
The minimum volume flow shall depend on the requirements of the heat generator or on the load circuit
overpressure safeguard.
6.3 Storage
Heat loss
If the heating circuit is provided with a storage tank (to minimize the cyclical behaviour of the heat generator or
to store solar energy, for instance) the storage losses shall be calculated according to equation (49).
where
( ϑh,
s − ϑi
)
Qh, s = f Verbindung ⋅ ⋅ dh,
mth ⋅ qB,
S
45
Q h,s
ϑ h,s
ϑ i
d h,mth
q B,S
is the heat loss of the storage tank (in the respective month) (see 4.2), in kWh;
is the mean temperature of the storage tank (see clause 5), in °C;
is the average ambient temperature (see 4.1 or Table 15), in °C;
is the number of heating days (in the respective month) (see 4.1);
is the stand-by heat loss, in kWh/d.
As long as the storage tank is located in the same space as the heat generator, the heat loss from the pipe
between heat generator and storage tank shall be taken to be f Verbindung = 1,2. For another configuration (e.g.
if they are located in separate rooms) the pipe losses shall be calculated according to 6.2.
The factor 1,2 takes blanket account of the additional thermal losses that occur through the piping extending
from the heat generator to the storage tank. The stand-by heat loss q B,S of the buffer storage tank shall be
measured according to DIN V 4753-8 (with a mean temperature difference between the storage water and the
installation space of 45 K). The monthly heat loss Q h,s from the buffer storage tank can then be determined on
the basis of the stand-by heat loss thus measured, the location of the storage tank, and the mean heating
circuit temperature.
(49)

DIN V 18599-5:2007-02
Electric central storage heaters shall be calculated in the same way as buffer storage tanks. The stand-by
losses from one or more storage heaters shall be determined on the basis of those actually in use. No default
values are specified for the storage losses. The distribution and control and emission losses are calculated as
for central water heating systems.
If the storage tank is located in a zone, the loss corresponds to the uncontrolled heat gain:
where
Q I,h,s = Q h,s
Q I,h,s
Q h,s
is the uncontrolled loss to the zone from the storage tank (in the respective month), in kWh;
is the loss from the storage tank (in the respective month), in kWh.
Boundary conditions for the default values
If the stand-by heat loss q B,S of the storage tank is not known (i.e. it has not been measured as specified in
DIN V 4753-8), it can, for simplification, be determined using equation (51) for calculation of the thermal
losses due to storage.
where
q B,S = 0,4 + 0,14 · V 0,5
q B,S is the stand-by heat loss, in kWh/d;
V is the nominal capacity of the storage tank, in l.
For operation in combination with a heat pump, the nominal capacity of the storage tank required for
determining the stand-by heat loss qB,S can be estimated as V = 9,5 · QN & . The volume of a storage tank that
is operated in combination with a biomass combustion system can be taken to be V = 50 · QN & , with a mean
temperature ϑh,s of 85 °C.
If the volume of the buffer storage tank exceeds 1 500 l, then the storage function shall comprise a number of
individual storage tanks. In this case it shall be assumed that there is at least one storage tank with a capacity
of 1 500 l and that there is just one other storage tank that provides the remaining volume. In this case, the
storage losses shall be added together.
Auxiliary energy for charging a buffer storage tank
If a separate circulation pump is required for operation of the buffer storage tank, then the auxiliary energy
shall be determined using equation (52).
where
Qh,
s, aux
PPumpe
⋅ tP
= (52)
1 000
Q h,s,aux is the auxiliary energy of the pump (in the respective month) (see 4.2.4), in kWh;
P Pumpe is the rated power consumption of the pump (from design data or equation (53)), in W;
t P
is the operating period of the pump (in the respective month), in h.
(50)
(51)
51

DIN V 18599-5:2007-02
The auxiliary energy for operation of a buffer storage tank can be calculated if the pump power is known. This
value can be specified, for example on the basis of a particular pump selected. The operating period of the
buffer storage tank pump is given by t P = β h,s · 24 · d h,mth , if it is operated at the same time as the heat
generator.
Boundary conditions for the default values
If the pump power is not known it can be roughly calculated using equation (53). It shall also be assumed that
the pump is in operation at the same time as the heat generator.
where
52
P Pumpe = 40 + 0,03 ⋅ L G ⋅ B G ⋅ n G
P Pumpe is the rated power consumption of the pump, in W;
L G
B G
n G
6.4 Heat generator
is the largest extended length of the building (see 4.1), in m;
is the largest extended width of the building (see 4.1), in m;
is the number of heated storeys (see 4.1).
If there is additional requirement for heat generation alone from another part of the DIN V 18599 series of
prestandards (e.g. for HVAC systems according to DIN V 18599-7) this is also to be taken into account. If the
desired temperature is higher than that of conventional heating systems, this is also to be taken into account.
If, on the other hand, heat is supplied to the heating system from other parts of the DIN V 18599 series (e.g.
from an extract air heat pump, see DIN V 18599-6 or DIN V 18599-7), then this is also to be taken into
account when calculating the heat generation requirement (see also DIN V 18599-1).
The remaining energy need met by the additional heat generator (e.g. a boiler), is given by:
where
Q * h,outg = Q h,outg – Q h,sol – Q rv,h,outg
Q * h,outg
Q h,outg
is the remaining generator heat output (in the respective month), in kWh;
is the generator heat output to the heating distribution (in the respective month) (see 4.2), in
kWh;
Q rv,h,outg is the generator heat output of the residential ventilation system for space heating (in the
respective month) (see 4.1), in kWh;
Q h,sol
is the energy contribution of the solar system for space heating (in the respective month), in
kWh.
In the ensuing calculations Q * h,outg shall be used instead of Q h,outg .
If several heat generators are used, they shall be calculated in the sequence in which they are used for
energy generation.
(53)
(54)

DIN V 18599-5:2007-02
If the same heat generator is used for space heating and domestic hot water, then in the ensuing calculations
the time the generator is being operated for domestic hot water heating purposes according to DIN V 18599-8
shall be deducted from the heating time.
The maximum required heat generator output of a building or building zone for space heating, domestic hot
water heating, residential ventilation and HVAC is the sum of all loads that are required in parallel or of the
largest load in prioritized operation:
Q&
= ⎜
⎛
⎟
⎞
N , max max
⎝∑Q&
N,
gl,
Q&
Vorrang
(55)
⎠
The following clauses deal with the space heating system. Unless otherwise described, calculations for the
other subsystems shall be by analogy.
6.4.1 Solar systems supporting domestic hot water heating and space heating systems (combination
systems)
Calculation of the contribution of solar systems in meeting the energy need (combination systems) shall be
according to recognized technical rules or shall make use of documented results from recognized simulation
programmes.
If the solar system is combined with a bivalent space heating system (e.g. using a heat pump with an electric
heating rod), this shall be taken into account when considering the heat pump or heating rod (the proportion of
the space heating supplied by the base load heat generator then refers to the energy need for heating less the
heat provided by solar energy).
6.4.1.1 Satisfaction of energy need by solar combination systems
The total solar energy contribution of the combination system is calculated as follows:
where
Q K,sol = Q w,sol + Q h,sol
Q w,sol
Q h,sol
is the energy contribution of the solar system for domestic water heating (in the respective
month), in kWh;
is the energy contribution of the solar system for space heating (in the respective month), in
kWh.
The energy contribution of the combination system for domestic water heating is calculated as specified in
DIN V 18599-8 as follows:
where
Q w,sol = Q K,sol · f K,w
f K,w
is the fraction of energy provided by the combination system for domestic water heating (see
equation (64)).
The energy contribution of the combination system for space heating is given by
Q h,sol = Q K,sol · (1,0 – f K,w ) (58)
(56)
(57)
53

DIN V 18599-5:2007-02
6.4.1.2 Energy contribution of solar combination systems
Combination systems dealt with in this document consist of a combination storage tank or a solar buffer
storage tank and a domestic hot water storage tank (dual storage system). The hot water storage tank uses
the same configuration as for small solar systems used for hot water heating. When a combination storage
tank is used, domestic hot water heating is either according to the instantaneous principle or by means of a
small tank that is located within the combination storage tank (“tank in tank” principle). The solar buffer
storage tank or the solar part of the combination storage tank is used for storage of the energy supplied by the
solar system.
The procedure outlined is only suitable for calculating combination systems that do not have significant annual
variations in heat storage.
Required parameters
To determine the energy contribution of the combination system the following parameters need to be known:
⎯ total annual heat required for domestic hot water Q w,outg,a , obtained from the sum of the monthly values
(see 4.2), in kWh;
⎯ collector (product data determined according to DIN EN 12975-2; see DIN V 18599-8 for default values
(including those for old systems)):
54
⎯ Ac the aperture area of the collector, in m 2 ;
⎯ η 0
⎯ k 1
⎯ k 2
the conversion factor;
is a heat loss coefficient, in W/(m 2 · K);
is a heat loss coefficient, in W/(m 2 · K 2 );
⎯ IAM (50°) is the incidence angle modifier to account for Θ = 50° incident radiation;
⎯ c is the effective heat capacity, in kJ/(m 2 · K).
⎯ inclination and alignment of the collector field (see DIN V 18599-8 for default values, including those for
old systems):
⎯ inclination angle β (β = 0° horizontal);
⎯ angle of deviation from the southerly alignment γ (γ = –90° east).
For residential buildings the default value for the collector area for combination systems is twice the surface
area for hot water systems (see DIN V 18599-8). Default values for the aperture area of collectors on nonresidential
buildings are not specified for combination systems; in this case, project values shall be used.
⎯ storage tank (product data, determined according to DIN V 4753-8 or DIN V ENV 12977-3; see 6.3 for
default values, including those for old systems):
⎯ V sto
⎯ (UA) s
⎯ (UA) * s
is the total storage volume, in l;
is the heat loss rate of the storage tank, in W/K;
is the specific heat loss rate, in W/(K · l).
⎯ total annual heat required for space heating Q h,outg,a obtained from the sum of the monthly values (see
4.2.1), in kWh; total heat load for domestic hot water and space heating: Q W,ges = Q w,outg + Q h,outg;

⎯ solar load ratio, in m 2 /kWh:
DIN V 18599-5:2007-02
Ac
slr = (59)
QW,
ges
⎯ temperature level in the space heating circuit ϑ h (see 5.2), in °C;
⎯ storage tank (product data, determined according to DIN V 4753-8 or DIN V ENV 12977-3; see
DIN V 18599-8 for default values, including those for old systems).
For conversion of the values of thermal loss, the following equation can be used:
where
1 000 ⋅ 24 h
( UA ) s = qB,
S ⋅
(60)
45 K
(UA) s
q B,S
is the heat loss rate of the storage tank, in W/K;
is the stand-by heat loss, in kWh/d.
If the combination system consists of a domestic hot water storage tank and a solar buffer storage tank, then
the total specific heat loss rate of the storage tanks is given by
where
*
( UA)
s
(UA) * s
(UA) s,dhw
(UA) s,sol
V dhw,sto
V sto
( UA)
s, dhw + ( UA)
s,
sol
Vdhw,
sto + Vsto
= (61)
is the total specific heat loss rate, in W/(K ⋅ l);
is the heat loss rate of the domestic hot water storage tank, in W/K;
is the heat loss rate of the solar buffer storage tank or the combination storage tank, in W/K;
is the total volume of the domestic hot water storage, in l;
is the total storage volume, in l.
If the combination system consists of a combination storage tank, the total specific heat loss rate of the
combination storage tank is given by
* ( UA)
s
( UA ) s = (62)
Vsto
⎯ volume of the solar buffer storage tank of the reference system:
where
V sol,ref = Ac ⋅ 70 l/m 2 (63)
V sol,ref
is the volume of the solar buffer storage tank of the reference system, in l;
55

DIN V 18599-5:2007-02
56
Ac is the aperture area of the collector, in m 2 ;
70 is a factor, in l/m 2 .
⎯ ratio f K,w of the domestic water thermal load to the total thermal load:
f
K,w
Qw,
outg Qw,
outg
= =
(64)
Q Q + Q
W, ges
h, outg
w, outg
6.4.1.3 Calculation procedure for combination systems
The monthly energy contribution of the solar system is calculated using equation (65) by distributing the
annual input over the individual months:
where
QK, sol = fM
⋅ QK,
sol, a
(65)
Q K,sol,a is the annual energy contribution of the solar system, in kWh;
Q K,sol
f M
is the energy contribution of the solar system in the respective month, in kWh;
is the factor accounting for the contribution made in the respective month in relation to the
annual contribution from Table 18.
Table 18 — Distribution of annual solar contribution over months
Month
January 0,057
February 0,055
March 0,117
April 0,134
May 0,109
June 0,081
July 0,087
August 0,073
September 0,098
October 0,097
November 0,069
December 0,023
The annual energy contribution of the combination system is calculated using the following equation:
where
Q K,sol,a = Q sys ⋅ f NA ⋅ f slr ⋅ f s,loss ⋅ f h,T
f M
(66)

Q K,sol,a is the annual energy contribution of the combination system, in kWh;
Q sys
f NA
f slr
f s,loss
f h,T
DIN V 18599-5:2007-02
is the annual energy contribution of the combination system for reference conditions, in kWh;
is the correction factor to account for inclination and alignment (horizontal and azimuthal
angles);
is the correction factor to account for the solar load ratio;
is the correction factor to account for the heat loss rate of the storage tank or tanks;
is the correction factor to account for the temperature level of the space heating.
6.4.1.3.1 Determination of the annual energy contribution of the combination system, in relation to a
reference system (Q sys )
Q sys , in kWh per year, is calculated using the following equation:
( ⋅ η − 16,
3 ⋅ k − 504 ⋅ k + 133 ⋅IAM
(50°
) − 0,
590 ⋅ c − 23,
) Ac
Qsys = 199 0 1 2
5 ⋅
(67)
The collector parameters shall be used in the units of measurement specified in 6.4.1.2.
6.4.1.3.2 Determination of the correction factor to take into account inclination and alignment (f NA )
The correction factor to account for inclination and alignment of the collector field f NA can be taken from
Table 19.
Inclination
Table 19 — Correction factor for inclination and alignment
Angle of deviation from a southerly alignment
East: γ = –90° West: γ = +90°
–90° –60° –40° –20° 0° 20° 40° 60° 90°
0° 0,66 0,66 0,66 0,66 0,66 0,66 0,66 0,66 0,66
15° 0,66 0,73 0,76 0,79 0,81 0,80 0,78 0,75 0,68
30° 0,65 0,78 0,85 0,90 0,93 0,92 0,88 0,82 0,70
45° 0,64 0,81 0,90 0,97 1,00 0,98 0,94 0,86 0,70
60° 0,62 0,80 0,91 0,99 1,02 1,01 0,95 0,86 0,68
75° 0,56 0,76 0,87 0,95 0,99 0,98 0,92 0,82 0,64
90° 0,49 0,67 0,76 0,83 0,86 0,86 0,82 0,75 0,57
6.4.1.3.3 Determination of the correction factor to take into account the solar load ratio (f slr )
The correction factor to account for the solar load ratio f slr can be taken as a function of f K,w and slr from
Table 20.
slr shall be obtained by means of equation (59) and f K,w by means of equation (64).
57

DIN V 18599-5:2007-02
58
slr
m 2 /kWh
Table 20 — Correction factor for the solar load ratio (f slr )
f K,w = 0,1 f K,w = 0,2 f K,w = 0,3 f K,w = 0,5
0,000 25 1,569 1,751 1,957 2,213
0,000 5 1,312 1,466 1,634 1,852
0,000 75 1,162 1,300 1,446 1,642
0,001 1,056 1,182 1,312 1,492
0,001 25 0,973 1,091 1,208 1,376
0,001 5 0,906 1,016 1,124 1,281
0,001 75 0,849 0,953 1,052 1,021
0,002 0,799 0,898 0,990 1,132
0,002 5 0,717 0,807 0,886 1,016
0,003 0,649 0,732 0,801 0,921
0,003 5 0,592 0,669 0,730 0,841
0,004 0,543 0,614 0,667 0,771
0,004 5 0,499 0,566 0,613 0,710
0,005 0,460 0,522 0,564 0,655
6.4.1.3.4 Determination of the correction factor to take into account the magnitude of the heat loss
rate of the storage tank or tanks (f s,loss )
The specific heat loss rate of the actual system in its entirety shall be related to the specific heat loss rate of
the reference system:
R
where
s, loss
(UA) * s
w, out
0,
101 87 ⋅ Q
*
s
( UA)
= (68)
0,
044 7 ⋅ Q + 0,14 V
w, out
+ V
sol, ref
sol, ref
is the total specific heat loss rate, in W/( K· l);
V sol,ref is the volume of the solar buffer storage tank of the reference system (see equation (63)), in l;
Q w,outg is the total annual heat demand for domestic hot water, in kWh.
The correction factor to account for the heat loss rate of the storage tank or tanks (f s,loss ) can be determined
as a function of R s,loss from Table 21.
Table 21 — Correction factor for the heat loss rate of the storage tank or tanks (f s,loss )
R s,loss 0,25 0,50 0,75 1,00 1,50 2,0 2,5 3,0 3,5 4,0
f s,loss 1,053 1,035 1,018 1,000 0,965 0,930 0,895 0,860 0,825 0,790

Regression equation:
DIN V 18599-5:2007-02
f s,loss = 1,07 – 0,07 · R s,loss (69)
6.4.1.3.5 Determination of the correction factor to take into account the temperature level (at the
design point) of the space heating (f h,T )
The correction factor to account for the temperature level of the space heating (f h,T ) can be taken as a
function of slr and ϑ h from Table 22.
NOTE See equation (59) for calculation of slr.
ϑ h
°C
Table 22 — Correction factor for the temperature level of the space heating f h,T
slr
m 2 /kWh
0,000 35 0,000 6 0,001 0,004 0,006
20 1,034 1,050 1,076 1,090 1,104
30 1,017 1,025 1,038 1,045 1,052
40 1,000 1,000 1,000 1,000 1,000
50 0,983 0,975 0,962 0,955 0,948
60 0,966 0,950 0,924 0,910 0,896
70 0,949 0,925 0,886 0,865 0,844
80 0,932 0,900 0,848 0,820 0,792
6.4.1.3.6 Energy fraction from the combination system used for domestic water heating (f K,w )
The energy fraction from the combination system that is used for domestic water heating can be taken as a
function of f K,w and slr from Table 23.
NOTE See equation (59) for calculation of slr and equation (64) for calculation of f K,w .
59

DIN V 18599-5:2007-02
60
Table 23 — Energy fraction from the combination system for domestic water heating
slr
m 2 /kWh
f K,w = 0,1 f K,w = 0,2 f K,w = 0,3 f K,w = 0,5
0,000 25 0,539 0,781 0,908 0,953
0,000 5 0,390 0,602 0,732 0,859
0,000 75 0,323 0,518 0,645 0,803
0,001 0,283 0,465 0,589 0,764
0,001 25 0,255 0,428 0,550 0,734
0,001 5 0,234 0,399 0,519 0,709
0,001 75 0,218 0,377 0,495 0,688
0,002 0,205 0,359 0,475 0,670
0,002 5 0,184 0,330 0,443 0,640
0,003 0,169 0,308 0,418 0,615
0,003 5 0,158 0,291 0,399 0,594
0,004 0,148 0,277 0,382 0,576
0,004 5 0,140 0,265 0,369 0,560
0,005 0,133 0,255 0,357 0,545
6.4.1.4 Calculation procedure for large combination systems
The energy contribution from large combination systems is dependent on a large number of operating
parameters. This is particularly the case if long-term heat storage is integrated into these systems. Calculation
of the energy contribution of large combination systems with long-term heat storage is not possible with the
calculation method specified in this document.
The energy contribution of large combination systems that make only a relatively small contribution to meeting
the space heating load (i.e. fK,w > 0,75), and which are operated at low solar load ratios (i.e.
slr < 0,001 5 m2 /kWh), can be approximated using the method described in this document for large solar
systems used for domestic water heating.
For solar systems for which no calculation procedure is described in this document, the energy contribution
can be determined with the aid of simulation programmes used in planning design.
6.4.1.5 Auxiliary energy for operation of the solar pump
After determining the solar system parameters, the surface area-related auxiliary energy of the solar pump
shall be calculated using equation (70).
Q
where
h, g, aux
PP,
sol ⋅ tP,
sol
= (70)
1 000
Q h,g,aux is the surface area-related auxiliary energy of the solar pump (in the respective month), in kWh;

P P,sol
t P,sol
is the rated power consumption of the solar pump, in W;
is the operating period of the solar pump for heating (in the respective month), in h.
Boundary conditions for the default values
DIN V 18599-5:2007-02
If the above parameters are not known due to the absence of design calculations, the auxiliary energy of the
solar pump can be approximated using the following boundary conditions:
Auxiliary energy of the solar pump: Q h,g,aux = 0,05 · Q h,sol , in kWh per month.
6.4.2 Heat pump
In the calculation procedure described below the following physical factors which have an effect on the annual
performance factor and the energy consumption of the heat pump are taken into account:
⎯ type of heat pump (air-to-water, brine-to-water, water-to-water, air to air);
⎯ system configuration (domestic water heating and operating mode);
⎯ generator heat output to the heating system and domestic hot water system;
⎯ effects of fluctuations of the source and sink temperatures on the power and coefficient of performance
(COP) of the heat pump;
⎯ effects of part load operation (cycle losses);
⎯ auxiliary energy required for operation of the heat pump, that is not taken into account under test rig
conditions;
⎯ system losses due to installed storage tanks.
On the basis of these input data the following output data are calculated:
⎯ energy in the form of electric power or fuel Q h,f , required to provide the generator heat output;
⎯ total thermal losses of the heat pump Q h,g ;
⎯ auxiliary energy Q h,g,aux required for operation of the heat pump;
⎯ total recoverable thermal losses of the heat pump k rd,g · Q h,g,aux .
The output data (along with the data of all other heat generators) are then used in the energy balance
described in DIN V 18599-1. For greater clarity, the balances for electrically driven and combustion enginedriven
heat pumps are presented in Annex A.
Heat pumps with combustion drive can recover part of the drive losses by means of a downstream heat
exchanger. Q rd,mot,g is a characteristic of the heat pump that depends on the efficiency and design of the
system for the recovery of heat from the cooling system and exhaust gas.
If no product data are available, p rd,mot = 0,4 can be taken as a default value for heat pumps driven by a gas
engine with appropriate cooling of the engine. For all other heat pumps p rd,mot = 0 in the absence of product
data.
61

DIN V 18599-5:2007-02
where
62
Qrd,
mot, g
p rd, mot = (71)
Q
p rd,mot
h, f
is the fraction of recovered fuel input given to the generator;
Q rd,mot,g is the recovered energy from the engine (in the respective month), in kWh;
Q h,f
is the energy use for the generator (in the respective month) (see 4.2 and Annex A), in kWh.
6.4.2.1 Principles of the calculation
The calculation can be carried out using the following monthly procedure or using a recognized calculation
programme. If no calculation procedure is described in this document, the energy contribution can be
determined with the aid of simulation programmes used in planning design.
The energy performance of a heat pump largely depends on the conditions under which it is used, in particular
on the temperature of the heat source and heat sink. The temperature of the heat source (e.g. outdoor air) can
vary greatly within any single month. The assessment of the energy efficiency of the heat pumps is therefore
not performed in a single step for each month but takes into account the frequency distribution of the
temperature of the heat source for the respective month.
For heat pumps with outdoor air as their heat source the calculation procedure is therefore based on an
assessment of the distribution of the outdoor air temperature. The frequency with which a particular outdoor
air temperature occurs in a month is given in intervals of 1 K.
As measurements of the heat output and the coefficient of performance of a heat pump are generally only
available for certain temperature combinations, the frequency distribution of the outdoor air temperature is
divided into temperature classes (bins). Each bin is limited by an upper temperature ϑupper and a lower
temperatureϑlower . The design operating conditions of the heat pump in each bin are characterized by the
operating points at the midpoint of each bin.
The operating points are selected such as to reproduce the test conditions specified in DIN EN 14511 (all
parts). The temperature limits between two bins are selected to be approximately at the midpoint between two
operating points, and are to be rounded to whole numbers.
For each bin the heat output of the pump and the coefficient of performance are assessed on the basis of the
test rig measurements according to DIN EN 14511 (all parts). The coefficient of performance and the heat
output of the pump at each testing point are adjusted to take account of
⎯ the source temperature;
⎯ the temperatures in the distribution piping;
⎯ the heat pump load.
The difference between the required generator heat output and the heat supplied by the heat pump may need
to be provided by a second generator. The losses associated with heat pump operation are calculated for
each bin.
The overall results for a calculation period (month) are obtained from the results for each bin, the individual
bins being weighted.

DIN V 18599-5:2007-02
Figure 5 — Distribution of cumulated bin hours for the outdoor air temperature
Generator heat output in the bins
The generator heat output in a month is distributed over the individual bins, i, using a weighting factor, w i ,
obtained from equation (72).
Qh, outg, i Qh,
outg ⋅ wi
= (72)
The weighting factors are calculated by means of equation (73).
where
HDHϑ
− HDH
upper ϑlower
wi
= (73)
HDH
w i
HDH t
HDH ϑupper
HDH ϑlower
t
is the weighting factor of bin i;
is the total number of heating degree hours up to the upper ambient temperature limit for
space heating, in Kh;
are the heating degree hours up to the temperature at the upper limit of bin i, in Kh;
are the heating degree hours up to the temperature at the lower limit of bin i, in Kh.
63

DIN V 18599-5:2007-02
The default values given below can be used if the upper ambient temperature limit for space heating is not
known:
⎯ 10 °C for passive energy houses;
⎯ 12 °C for buildings meeting the requirements of EnEV 2002/2004 for buildings with normal indoor
temperatures;
⎯ 15 °C for all other buildings.
The heating degree hours up to a temperature ϑ x are determined by means of equation (74):
where
64
ϑx
∑ ϑ
ϑ = ϑmin
( ) = n ⋅ ( ϑ − ϑ)
HDH ϑ i
(74)
ϑ min
ϑ x
n ϑ
ϑ i
x
is the minimum outdoor temperature from the relevant set of climatic data, in °C;
is the heating degree hours temperature limit (this shall not be higher than the upper ambient
temperature limit for space heating), in °C;
is the hours frequency of the temperature ϑ x , in h;
is the indoor set-point temperature, in °C.
For simplification, i shall be taken to be 20 °C.
The hours frequency of the outdoor temperature for the location of Würzburg is given in Table 24. For other
locations, the corresponding test reference years can be used.
The following procedure shall be used for heat pumps with other heat sources:
For constant source temperatures:
⎯ Ground as source: The 0 °C bin has a weighting of 1.
⎯ Groundwater as source: The 10 °C bin has a weighting of 1.
⎯ Extract air as source: The 20 °C bin has a weighting of 1.
NOTE Extract air heat pumps for residential buildings are dealt with in DIN V 18599-6. In that standard, the generator
heat output, Q rv,h,outg , is calculated for the ensuing calculations in DIN V 18599-5 without an additional calculation for the
heat pump being required.
Extract air with heat recovery as source: The drop in temperature due to heat recovery is taken into account.
For units in which the heat recovery is positioned upstream of the exhaust air heat pump, the exhaust air
temperature is calculated for each month for the bin in question from the heat recovery efficiency and the
design temperature of the room (exhaust air efficiency from DIN EN 308 without deductions or heat recovery
according to Deutsches Institut für Bautechnik (DIBt) less 12 %).
The heat exchanger efficiency determined according to recognized technical rules characterizes the
temperature increase of the supply air in relation to the maximum possible temperature increase. Besides the
operating characteristics of the heat exchanger (WÜT), the heat dissipated by electrical components (e.g.
fans, controls) also affects the heat exchanger efficiency. Leakage losses shall be within the maximum

DIN V 18599-5:2007-02
permissible limits and the thermal losses via the surface of equipment are also to be taken into account. In
addition, the performance of ventilation units operating during periods of frost shall be considered unless the
ventilation system is fitted with a ground heat exchanger for preheating the air, which according to recognized
technical rules ensures a frost-free (and hygienic) supply air flow. If the heat exchanger efficiency does not
take the above into account, and if the supply and extract air volume flows cannot be adjusted with suitable
components so as to ensure a permanent volume flow balance, the heat exchanger efficiency shall be
reduced by 9 %.
Exhaust air efficiency measurements from DIN EN 308 are used without deductions.
where
Fortluft, mth
ex −
( ϑex
− ϑe
) η WÜT, mth
ϑ = ϑ
⋅
(75)
ϑ Fortuft
ϑ ex
ϑ e
η WÜT,mth
Default values:
is the temperature of the exhaust air, in °C;
is the temperature of the air extracted from the space (see 4.1 and Table 15), in °C;
is the outdoor air temperature (see 4.1), in °C;
is the heat exchanger efficiency with regard to heat recovery (in the respective month),
in °C.
Heat exchanger efficiency without a ground-supply air heat exchanger: η WÜT,mth = 0,60
Heat supply efficiency with a ground-supply air heat exchanger: η WÜT,mth = 0,67
The weighting factors for the bins are calculated using equation (73).
NOTE Extract air heat pumps for residential buildings are dealt with in DIN V 18599-6. In that standard, the generator
heat output, Qrv,h,outg , is determined for the ensuing calculations in DIN V 18599-5 without an additional calculation for the
heat pump being required.
6.4.2.2 Outdoor air as heat source; average climatic data for Germany
The hours frequency of the outdoor temperatures for average climatic conditions in Germany is given in
Table 24, taking the town of Würzburg as an example. For other locations the corresponding test reference
years can be used.
The sum of hours in the individual bins, distributed according to the testing points from DIN EN 14511 (all
parts) are given in Table 25.
65

DIN V 18599-5:2007-02
66
Outdoor
temp.
°C
January
hours
February
hours
Table 24 — Hours frequency of outdoor temperature (reference location: Würzburg)
March
hours
April
hours
May
hours
June
hours
July
hours
August
hours
September
hours
October
hours
November
hours
December
hours
–15 0 0 0 0 0 0 0 0 0 0 0 0 0
–14 0 1 0 0 0 0 0 0 0 0 0 0 1
–13 2 3 0 0 0 0 0 0 0 0 0 0 5
–12 2 6 0 0 0 0 0 0 0 0 0 0 8
–11 6 1 0 0 0 0 0 0 0 0 0 3 10
–10 2 5 0 0 0 0 0 0 0 0 0 5 12
–9 14 7 0 0 0 0 0 0 0 0 0 5 26
–8 11 7 1 0 0 0 0 0 0 0 1 4 24
–7 11 4 2 0 0 0 0 0 0 0 9 14 40
–6 4 5 4 0 0 0 0 0 0 0 5 15 33
–5 3 13 1 0 0 0 0 0 0 0 13 8 38
–4 3 8 4 0 0 0 0 0 0 0 8 12 35
–3 14 10 3 0 0 0 0 0 0 0 6 8 41
–2 31 25 8 0 0 0 0 0 0 0 6 30 100
–1 46 51 6 0 0 0 0 0 0 0 13 54 170
0 101 98 16 0 0 0 0 0 0 6 52 68 341
1 164 87 32 13 2 0 0 0 0 6 57 99 460
2 112 89 61 12 10 0 0 0 0 2 40 100 426
3 80 69 78 30 14 0 0 0 0 14 35 103 423
4 37 54 66 47 11 0 0 0 0 35 75 37 362
5 46 36 70 59 18 0 0 0 4 58 54 30 375
Annual
hours

Outdoor
temp.
°C
January
hours
February
hours
March
hours
April
hours
May
hours
Table 24 (continued)
June
hours
July
hours
August
hours
September
hours
October
hours
November
hours
DIN V 18599-5:2007-02
December
hours
6 23 27 71 79 31 0 0 0 3 57 44 38 373
7 7 17 75 64 41 2 0 0 2 47 90 37 382
8 12 19 57 65 26 2 1 0 6 44 79 10 321
9 4 8 49 66 36 6 3 2 8 55 49 9 295
10 1 7 42 49 29 7 1 4 17 71 30 19 277
11 4 4 25 52 31 37 4 8 41 86 21 12 325
12 3 4 23 45 48 36 14 18 55 79 20 16 361
13 1 1 11 43 50 51 33 29 100 57 5 5 386
14 0 3 8 37 49 73 35 47 92 49 2 3 398
15 0 3 8 27 65 86 69 54 75 31 2 0 420
16 0 0 5 14 55 64 79 64 52 19 2 0 354
17 0 0 12 6 51 59 83 72 64 9 2 0 358
18 0 0 2 4 30 54 81 80 62 4 0 0 317
19 0 0 1 2 27 47 71 71 45 7 0 0 271
20 0 0 3 1 25 27 61 64 25 3 0 0 209
21 0 0 0 1 19 34 41 42 21 2 0 0 160
22 0 0 0 4 21 35 34 52 15 2 0 0 163
23 0 0 0 0 13 39 31 43 13 1 0 0 140
24 0 0 0 0 15 19 22 25 7 0 0 0 88
25 0 0 0 0 11 14 21 27 4 0 0 0 77
26 0 0 0 0 5 11 16 22 3 0 0 0 57
Annual
hours
67

DIN V 18599-5:2007-02
68
Outdoor
temp.
°C
January
hours
February
hours
March
hours
April
hours
May
hours
Table 24 (continued)
June
hours
July
hours
August
hours
September
hours
October
hours
November
hours
December
hours
27 0 0 0 0 11 7 16 11 3 0 0 0 48
28 0 0 0 0 0 5 12 2 3 0 0 0 22
29 0 0 0 0 0 1 8 2 0 0 0 0 11
30 0 0 0 0 0 4 7 1 0 0 0 0 12
31 0 0 0 0 0 0 1 3 0 0 0 0 4
32 0 0 0 0 0 0 0 1 0 0 0 0 1
33 0 0 0 0 0 0 0 0 0 0 0 0 0
Annual
hours

DIN V 18599-5:2007-02
Table 25 — Monthly hours sum in the individual bins, distributed according to the testing points from
DIN EN 14511 (all parts)
Bin w-7 w2 w7 w10 w20
Testing point –7 2 7 10 20
Temperature
limits
°C
–15 to –2 –2 to 4 4 to 8 8 to 15 15 to 32
Monthly
sum
January hours 103 540 88 13 0 744
February hours 95 448 99 30 0 672
March hours 23 259 273 166 23 744
April hours 0 102 267 319 32 720
May hours 0 37 116 308 283 744
June hours 0 0 4 296 420 720
July hours 0 0 1 159 584 744
August hours 0 0 0 162 582 744
September hours 0 0 15 388 317 720
October hours 0 63 206 428 47 744
November hours 48 272 267 129 4 720
December hours 104 461 115 64 0 744
Year hours 373 2182 1451 2462 2292 8760
6.4.2.3 Energy need for domestic hot water
Domestic hot water is calculated in DIN V 18599-8.
Heat pumps with simultaneous space heating and domestic hot water heating operation shall have
coefficients of performance for domestic water heating, space heating and combined operation. The energy
need for space heating and domestic hot water shall be distributed over the bins according to running times.
The limit of the running time in combined operation is defined by the minimum running time for hot water and
space heating. The residual energy for space heating or hot water shall be calculated using the coefficient of
performance of the relevant operating mode.
6.4.2.4 Calculation of the fraction of heating energy to be provided by the second generator (backup
heating)
Operation of the second generator (back-up heating) is dependent on the system design criteria and can be
characterized in terms of the operating mode (alternate, parallel, or partly parallel operation) and the
respective temperatures, the switch-off temperature for the heat pump and switch-on temperature for the
second generator at the balance point. Using these temperatures the energy requirement of the heat pump
and back-up heating operation can be calculated.
6.4.2.4.1 Alternate operation
In alternate operation the heat pump supplies the entire heat down to a specified outdoor temperature (cut-out
limit). If the temperature falls below the cut-out limit the heat pump switches off and the second generator
69

DIN V 18599-5:2007-02
satisfies the full heating energy requirement. The weighting factor of the bin in which the cut-out limit falls shall
be recalculated with HDH(ϑ ltc ) = HDH(ϑ lower ).
Figure 6 shows the cumulative frequency of the outdoor air temperature in bins with the ranges covered by the
heat pump (areas A 11 and A 12 ) and second generator (area A 2 ).
where
70
Figure 6 — Bin hours and energy fractions of the heat pump and the second generator (back-up
heating) in alternate operation
pbu,
h
P bu,h
( ϑ )
= (76)
HDH ltc
HDH t
is the energy fraction of the second generator (back-up heating);
HDH(ϑltc ) are the cumulated heating degree hours of the second generator (back-up heating) up to
the low temperature cut-out limit ϑltc , in Kh;
HDH t
ϑ bp
is the total number of heating degree hours, in Kh;
is the balance point temperature, in °C.

6.4.2.4.2 Parallel operation
DIN V 18599-5:2007-02
In parallel operation, the heat pump alone supplies the necessary heat down to a specified outdoor
temperature (balance point temperature). At temperatures below the balance point temperature the second
generator switches on. Both heat generators work in parallel. The second generator supplies only the part that
the heat pump cannot supply because of its heat output limitation.
Figure 7 shows the cumulative frequency of the outdoor air temperature in bins with the ranges covered by the
heat pump (areas A 11 , A 12 and A 13 ) and second generator (area A 2 ).
where
Figure 7 — Bin hours and energy fractions of the heat pump and the second generator (back-up
heating) in parallel operation
pbu,
h
p bu,h
ϑ bp
ϑ i
n hours
HDH(
ϑbp ) − ( ϑ ) ⋅ nhours
( ϑbp
)
= (77)
i − ϑbp
HDH t
is the energy fraction of the second generator (back-up heating);
is the balance point temperature, in °C;
is the ambient temperature (see 4.1 or Table 15), in °C;
are the cumulated hours to the balance point of the second generator (back-up heating), in
h;
HDH(ϑbp ) are the cumulated heating degree hours of the second generator (back-up heating) up to
the balance point temperature ϑbp , in Kh;
71

DIN V 18599-5:2007-02
72
HDH t
is the total number of heating degree hours, in Kh.
6.4.2.4.3 Partly parallel operation
In partly parallel operation the heat pump alone supplies the necessary heat down to a specified outdoor
temperature (balance point temperature). At temperatures below the balance point temperature the second
generator switches on. Both heat generators work in parallel. The second generator supplies only the heat
that the heat pump cannot supply because of its heat output limitation. When the lower cut-out limit of the heat
pump is reached, the heat pump switches off and the second generator alone supplies the heat required. The
weighting factor of the bin in which the cut-out limit falls shall be recalculated with HDH(ϑ ltc ) = HDH(ϑ lower ).
Figure 8 shows the cumulative frequency of the outdoor air temperature in bins with the ranges covered by the
heat pump (areas A 11 and A 12 ) and second generator (area A 2 ).
where
Figure 8 — Bin hours and energy fractions of the heat pump and the second generator
(back-up heating) in partly parallel operation
A HDH ( ϑbp ) − (( ϑ
1
i − ϑbp
) ⋅ ( nhours
( ϑbp
) − nhours
( ϑltc
))
pbu,
h = =
A2
HDH t
p bu,h
ϑ bp
ϑ i
is the energy fraction of the second generator (back-up heating);
is the balance point temperature, in °C;
is the ambient temperature (see 4.1 or Table 15), in °C;
(78)

ϑ ltc
n hours
is the cut-out limit (switch-off temperature) for the heat pump, in °C;
DIN V 18599-5:2007-02
are the cumulated hours to the balance point of the second generator (back-up heating), in
h;
HDH(ϑbp ) are the cumulated heating degree hours of the second generator (back-up heating) up to
the balance point temperature ϑ bp , in Kh;
HDH t
is the total number of heating degree hours, in Kh.
The energy supplied by the heat pump and the second generator in bivalent partly parallel operation shall be
determined using equation (78).
6.4.2.5 Heat output and coefficient of performance of the heat pump at full load (steady-state
operation)
6.4.2.5.1 Electrically driven heat pumps
6.4.2.5.1.1 Correction for source temperature
The heat output and the coefficient of performance of heat pumps shall be taken from the test rig
measurements according to DIN EN 14511 (all parts) for the respective bin. All testing points shall be taken
into account.
Data not supplied by testing laboratories can be supplemented by product data from DIN EN 14511 (all parts).
Default values are given in Annex A and can be used if no other data are available. These however only
reproduce the performance of a typical commercial heat pump and there is no longer a reference to a specific
unit. For monovalent heat pump operation it shall be assumed that the power of the heat pump under design
conditions for the space heating mode is equal to the maximum heat load according to Annex B of
DIN V 18599-2.
If the source temperature in a particular bin does not correspond to the testing point used it shall be corrected
by interpolation or extrapolation as specified below. If interpolation is not possible owing to a lack of data, the
correction for the source and sink temperatures is carried out applying the exergetic efficiency approach
described in Annex A.
Outdoor air as source
Correction is not usually required as the bin distribution corresponds to the testing points. However, if a
correction is necessary, intermediate values shall be determined by linear interpolation or extrapolation
between the testing points.
Exhaust air as source
The coefficient of performance is corrected as specified in Annex A (exergetic efficiency) in order to align it
with the indoor temperature of the building, if no further testing points are available for interpolation.
Ground and groundwater as source
The mean source temperature is determined from the average monthly outdoor temperature.
The general correlation is shown in Table 26. The values for average climatic conditions in Germany are given
in Table 27. The data for the source temperatures are either obtained from test records or use default values.
Intermediate values are determined by linear interpolation or extrapolation between testing points.
73

DIN V 18599-5:2007-02
74
Table 26 — Mean source temperature for ground and groundwater as a function of the average
outdoor temperature
Average outdoor temperature
°C
Mean brine temperature
°C
Mean groundwater temperature
°C
20 4,5 12,0
10 3,0 10,7
7 2,6 10,2
5 2,3 10,0
2 1,8 9,6
0 1,5 9,3
–2 1,2 9,0
–5 0,8 8,6
–7 0,5 8,4
–10 0 8,0
Table 27 — Mean source temperature for ground and groundwater as a function of the average
monthly outdoor temperature
Average outdoor
temperature
°C
Mean brine temperature
°C
Mean groundwater
temperature
°C
January –1,3 1,3 9,1
February 0,6 1,6 9,4
March 4,1 2,1 9,9
April 9,5 2,9 10,6
May 12,9 3,4 11,0
June 15,7 3,9 11,4
July 18 4,2 11,7
August 18,3 4,2 11,8
September 14,4 3,7 11,2
October 9,1 2,9 10,5
November 4,7 2,2 9,9
December 1,3 1,7 9,5
6.4.2.5.1.2 Correction for the distribution temperature
Water based heating distribution
Two corrections are to be made as a function of the temperature of the distribution.

DIN V 18599-5:2007-02
The coefficient of performance of the heat pump is first corrected as a function of the mean monthly supply
temperature (see 5.2, equation (13)). The testing points are then linearly interpolated or extrapolated to the
mean supply temperature of the distribution for each bin.
In addition, a second correction is necessary if the heat pump is operated with a temperature difference
between the heating circuit flow and return temperatures that deviates from the temperature difference in the
test rig measurements according to DIN EN 14511 (all parts). This effect is accounted for by the correction
factor from Table 28.
COP T = COP · f ∆ϑ
where
COP T
is the corrected coefficient of performance of the heat pump;
COP is the coefficient of performance from test rig measurements according to DIN EN 14511 (all
parts); the default values given in Annex A are used if no product data are available;
f ∆ϑ
∆ϑ M
∆ϑ B
is the correction factor from Table 28;
is the temperature difference from test rig measurements according to DIN EN 14511 (all parts),
in K; the default value is 10 K if no boundary conditions for the test are known;
is the temperature difference when the heat pump is in operation, in K.
In space heating mode, ∆ϑ B = ∆ϑ HK (from equation (12)).
Table 28 — Correction factors f ∆ϑ to account for deviations in temperature differences in heat pump
measurement and operation
T. d. in
operation
∆ϑ B
Temperature difference in the test rig measurements
∆ϑ M
K
3 4 5 6 7 8 9 10 11 12 13 14 15
3 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928 0,918 0,908 0,898 0,887 0,877
4 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928 0,918 0,908 0,898 0,887
5 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928 0,918 0,908 0,898
6 1,031 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928 0,918 0,908
7 1,041 1,031 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928 0,918
8 1,051 1,041 1,031 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939 0,928
9 1,061 1,051 1,041 1,031 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949 0,939
10 1,072 1,061 1,051 1,041 1,031 1,020 1,010 1,000 0,990 0,980 0,969 0,959 0,949
(79)
75

DIN V 18599-5:2007-02
Direct output to room air
If the heat output is directly to the room air (e.g. via condensation of the refrigerant in an air heat exchanger),
then the indoor set-point temperature shall be used as the distribution temperature. If the temperature does
not correspond to test rig measurements, the value shall be extrapolated where there are a number of testing
points, but if there is only one testing point, the result shall be corrected applying the exergetic efficiency
approach (see Annex A).
6.4.2.5.2 Non-electrically driven heat pumps with combustion drive
Heat pumps with combustion drive include engine-driven heat pumps and sorption heat pumps.
The calculation shall be carried out on the basis of test measurements from a recognized testing laboratory.
If no product data are available, the values specified in Annex A shall be used in the calculations.
6.4.2.6 Coefficient of performance in part load operation
6.4.2.6.1 Principle
Since heat pumps provided with fixed-speed compressors operate at part load operation by cycling between
on and off status, losses due to cycling of the compressor occur which reduce the coefficient of performance
of the heat pump.
Variable capacity units controlled stepwise (i.e. cascading) or continuously, are more efficient at part load
operation.
For the calculation, the coefficients of performance and heat outputs at part load operation are required for the
operating point of each bin. At least one coefficient of performance at 50 % load measured as described in
DIN CEN/TS 14825 is required.
The coefficient of performance at part load operation is given by the following relationship:
where
76
COPpl COPfl
⋅ fpl
COP pl
COP fl
f pl
= (80)
is the coefficient of performance at part load operation;
is the coefficient of performance at full load operation;
is the correction factor to account for part load operation.
The correction factor f pl takes account of the thermal inertia of the distribution system and heat pump as well
as the running time of the heat pump. The running time of the heat pump is accounted for by the load factor
FC.
The load factor can be calculated using the following equation
tON,
g, i
FC = (81)
ti

where
FC is the load factor;
t on,g,i
t i
is the running time of the heat pump in bin i (in the respective month), in h;
DIN V 18599-5:2007-02
is the total time in bin i (in the respective month), in h (if outdoor air is the heat source, see
Table 25).
For electrically operated heat pumps f pl is given in Annex A for radiators, convectors, and surface heating.
For absorption heat pumps f pl is given (as c dt ) in Annex A.
6.4.2.6.2 Running time of the heat pump
The running time of the heat pump depends on the heat output of the pump under the operating conditions
(heat source temperature and heating water supply and return temperatures) and the required generator heat
output. The running time in each bin is calculated as follows:
where
h, outg,
i
ON, g, i =
0, 001⋅
Φg,
i
Q
t (82)
t ON,g,i
is the running time of the heat pump in bin i (in the respective month), in h;
Q h,outg,i is the generator heat output in bin i (in the respective month) (see equation 72), in kWh;
Φ g,i
is the heat output of the heat pump in bin i, in W.
The heat output of the heat pump shall be taken from the test records. If no product data are available, it shall
be assumed in the case of monovalent operation that the heat output of the heat pump under design
conditions is equal to the maximum heat load required by the zone being served according to Annex B of
DIN V 18599-2. For bivalent operation, the maximum heat output of the heat pump is to be taken from the
project documents. The heat output in each bin shall be determined using the relative heat output given in A.3.
The following boundary condition applies:
where
∑
T−
≥ t M, ON tON,
g, i
(83)
bins
t ON,g,i
is the maximum possible running time of the heat pump (in the respective month), in h.
The maximum possible running time of the heat pump is given in Table 25. Equation (83) limits the running
time proportionately in the respective bins.
Since the running time of the heat pump depends on the heat demand, the operating mode of the heat pump
is to be taken into account.
If the mean monthly supply temperature of the distribution is higher than the maximum supply temperature of
the heat pump, then the supply temperature of this bin shall be determined and the running time of the heat
pump for this bin shall be limited.
77

DIN V 18599-5:2007-02
Where heat pumps are used for both space heating and domestic hot water heating, the maximum possible
running time for space heating can also be limited by the sum of the running times. The running time for
domestic hot water heating shall be determined as specified in DIN V 18599-8.
If the running time is greater than the maximum possible running time obtained from equation (83), the
running times for space heating and domestic hot water heating are reduced by the same number of hours
unless the heat pump control system foresees other provisions.
The heat output of the heat pump is limited to the actual running time.
where
78
Q 0, 001
Φ
(84)
h, outg, i,WP = ⋅ tON,
g, i,WP ⋅
g, i
Q h,outg,i,WP is the generator heat output of the heat pump in bin i (in the respective month), in kWh;
t ON,g,i,WP
Φ g,i
is the actual running time of the heat pump in bin i (in the respective month), in h;
is the heat output of the heat pump in bin i, in W.
6.4.2.7 Generator thermal losses
Hot water buffer storage tank
Any external buffer storage tank that may be installed is dealt with in 6.3.
If the buffer storage tank is part of the heat pump, the losses are calculated using equation (49) and are
distributed over individual bins as follows:
where
t
Q i
h, g, s, i Qh,
s ⋅
th
= (85)
Q h,g,s,i is the heat loss of the storage tank to the surrounding environment in bin i (in the respective
month), in kWh;
Q h,s
t i
t h
is the heat loss of the buffer storage tank (in the respective month), in kWh; the default value
given in 6.3 shall be used if no product data are available;
is the time in bin i (in the respective month), in h;
is the number of heating hours in the respective month (see 4.1), in h.
Further generator thermal losses
For electrically driven heat pumps no further losses are considered, i.e. Q h,g,WP = 0. For heat pumps with
combustion drive the data shall be used from test rig results or manufacturers’ data.
where
Q h, g, i Qh,
g, s, i + Qh,
g, WP, i
Q h,g,i
= (86)
is the generator heat loss in bin i (in the respective month), in kWh.

6.4.2.8 Calculation of total energy consumption
6.4.2.8.1 Electrically driven heat pumps
Auxiliary energy consumption of the heat pump in the space heating mode
DIN V 18599-5:2007-02
The electrical energy consumption is calculated by adding together the electrical energy consumption in the
individual bins as follows:
Q
+
where
h, f,
1
nbin
∑
i = 1
Q h,f,1
=
Q
nbin
∑
i = 1
Q
h, outg, WP, i
h, outg, combi,
i
+ Q
+ Q
h, g, i
h, g,
i
− p
COP
− ( 1−
p
h, combi
combi,
i
COP
h, combi
sin,
i
⋅ k
rd, g
) ⋅ k
⋅Q
rd, g
⋅Q
h, g, aux, i
h, g, aux,
i
is the delivered energy required for operation of the heat pump in the space heating mode
(in the respective month), in kWh;
Q h,outg,WP,i is the generator heat output in bin i (in the respective month) which is met by the heat pump
in single (space heating) mode (see 6.4), in kWh;
Q h,outg,combi,i is the generator heat output in bin i (in the respective month) which is met by the heat pump
in combined space heating and domestic hot water heating mode (see 6.4), in kWh;
Q h,g,i
k rd,g
Q h,g,aux,i
COP sin,i
is the generator heat loss in bin i (in the respective month), in kWh;
is the fraction of auxiliary energy recovered as thermal energy (k rd,g = 0);
is the auxiliary energy for operation of the heat pump in the space heating mode in bin i (in
the respective month), in kWh;
is the coefficient of performance of the heat pump in single (space heating) mode in bin i;
NOTE This corresponds to the coefficient of performance under average operating conditions.
COP combi,i
is the coefficient of performance of the heat pump in combined space heating and domestic
hot water heating mode in bin i;
NOTE This corresponds to the coefficient of performance under average operating conditions.
p h,combi
n bin
is the fraction of combined space heating and domestic water heating (simultaneous
operation);
is the number of bins.
6.4.2.8.2 Heat pumps with combustion drive
The fuel input energy of the heat pump is calculated by adding the values in the individual bins by means of
equation (88).
(87)
79

DIN V 18599-5:2007-02
80
nbin
h, f,
1 = ∑
i = 1
Q
where
Q h,f,1
Q h,outg,i
k rd,g
Q h,g,aux,i
COP i
Q
h, outg,
i
− k
rd, g
COP
i
⋅Q
h, g, aux, i
⋅ f
Hs/Hi
is the delivered energy (gas) of the heat pump (in the respective month), in kWh;
is the generator heat output for the heating system in bin i, in kWh;
is the fraction of auxiliary energy recovered as thermal energy (k rd,g = 0);
is the auxiliary energy of the heat pump in the space heating mode in bin i (in the respective
month), in kWh;
is the coefficient of performance of the heat pump in the space heating mode in bin i;
NOTE This corresponds to the coefficient of performance under average operating conditions.
f Hs/Hi
n bin
6.4.2.9 Auxiliary energy
where
w, g, aux
is the ratio of gross calorific value to net calorific value ratio of the fuel used;
is the number of bins.
( prim, aux + sek, aux ) ⋅ 0, 001 tON,
g, aux
Q = Φ Φ
⋅
(89)
Q h,g,aux
Φ prim,aux
Φ sek,aux
t ON,g,aux
is the total auxiliary energy use (in the respective month), in kWh;
is the power requirement of the primary circuit, in W;
is the power requirement of the secondary circuit, in W;
is the running time of the auxiliary component (in the respective month), in h.
If the power consumption of the auxiliary component is not known, it is calculated according to equation (90).
Φ
where
prim/sek, aux
Φ prim,aux
Φ sek,aux
∆p
⋅ V
=
η ⋅ 3 600
&
aux
is the power requirement of the primary circuit, in W;
is the power requirement of the secondary circuit, in W;
∆p is the pressure drop in the primary or secondary circuit respectively, in Pa;
V & is the volume flow, in m 3 /h;
(88)
(90)

DIN V 18599-5:2007-02
NOTE This value can be taken from test rig measurements as specified in DIN EN 14511 (all parts) or from
product data.
η aux
is the efficiency of the circulation pump.
NOTE The efficiency of the circulation pumps is specified in DIN EN 14511 (all parts) as η aux = 0,3.
6.4.2.9.1 Primary circuit (heat source)
For the heat pump the drive energy of the source pump is taken into account in the generator subsystem.
The sum of the running times of the heat pump over all bins t on,g,i is to be assumed for the running time of
auxiliary components t ON,aux .
Air-to-water heat pump
As air-to-water heat pumps are tested as a unit, the auxiliary energy for the fan in the source circuit is already
taken into account when measuring according to DIN EN 14511 (all parts).
Brine-to-water and water-to-water heat pump
In the case of brine-to-water and water-to-water heat pumps, the auxiliary energy to compensate for the
internal pressure drop in the evaporator is taken into account in the coefficient of performance in the test rig
measurement according to DIN EN 14511 (all parts). The missing source pump auxiliary energy required to
compensate for the pressure drop in the heat source system is to be taken into account using equation (90). If
no values are available, a pressure loss of 40 kPa is used and the volume flow is determined using the
nominal power of the heat pump at a temperature difference of 3 K.
6.4.2.9.2 Secondary circuit
The secondary auxiliary energy shall only be taken into account in the case of heat pumps with integrated
buffer storage tanks or a hydraulic diverter. The secondary pressure loss of the heat pump has already been
included in the determination of the coefficient of performance according to DIN EN 14511 (all parts). ∆p we
shall thus be set at zero in equation (44).
If there is a hydraulic decoupling between the heat pump and the distribution system (e.g. by means of a
parallel buffer storage tank), the additional storage tank charge pump is also assigned to the generator
subsystem (heat pump). In this case the energy to compensate for the external pressure drop is to be taken
into account. If no values are available a pressure loss of 10 kPa is used.
The sum of the running times of the heat pump in all bins t on,g,i shall be assumed as the running time of
auxiliary components t ON,aux .
6.4.2.10 Energy consumption of the second generator (back-up heating system)
Q
where
⎛
max ⎜ Q −
⋅
⎜ h, outg,i Qh,
outg,i, WP;
pbu,h
Q
⎝ i
h, outg,bu = ∑ h, outg,i
Q h,outg,bu
⎞
⎟
⎟
⎠
is the generator heat output in bin i (in the respective month), provided by the second
generator (back-up heating) (see 6.4), in kWh;
Q h,outg,i,WP is the generator heat output of the heat pump in bin i (in the respective month), in kWh;
(91)
81

DIN V 18599-5:2007-02
82
Q h,outg,i
P bu,h
is the energy need of the distribution system in bin i (in the respective month), in kWh;
is the energy fraction of the second generator (back-up heating).
6.4.2.11 Total energy consumption
The total electrical energy consumption (electrical or fuel input energy) is the sum of the input energy of the
heat pump and the second generator:
where
Q h, f Qh,
f,1 + Qh,
f, bu
Q h,f
Q h,f,1
Q h,f,bu
= (92)
is the total energy use (electric power or gas) for space heating (heat pump and back-up heating
in the case of electric power) (in the respective month), in kWh;
is the energy use of the heat pump in the space heating mode (in the respective month), in kWh;
is the energy use of the second generator (back-up heating) in the space heating mode (in the
respective month), in kWh.
6.4.2.12 Regenerative energy contribution
The regenerative energy used for the heat supply can be calculated as
where
Q h, in Qh,
outg − Qh,
f + Qh,
g
Q h,in
= (93)
is the ambient heat for the heating system (in the respective month), in kWh;
Q h,outg is the generator heat output to the heating system (in the respective month), in kWh (see 6.4);
Q h,f
Q h,g
is the energy use of the heat pump in the space heating mode (in the respective month) (see
6.4.2), in kWh;
are the generation thermal losses of the heating system to the installation space (in the
respective month) (see 6.4.2), in kWh.
6.4.2.13 Performance factor to account for the generator subsystem
For information purposes, the annual performance factor can be calculated on the basis of the sum of the
monthly energy need for heating and the energy expenditure:
∑
∑Qh,
f
h, outg
Monate
SPF g, t, a =
(94)
+ Q
Monate
Q
h, aux, g
The monthly performance factor can be calculated (also for information purposes) as:
SPF
g, t
Qh,
outg
= (95)
Q + Q
h, f
h, aux, g

where
SPF g,t,a
SPF g,t
Q h,outg
Q h,f
is the annual performance factor of the heat pump;
is the monthly performance factor of the heat pump;
DIN V 18599-5:2007-02
is the generator heat output for the heating system (in the respective month), in kWh (see 6.4);
is the energy use for the heating system (in the respective month), in kWh.
6.4.3 Conventional boilers
Determination of heat generation losses: heating Q h,g
The boiler output shall be designed to give the following part load levels: β h,i ≤ 1.
If there is only one boiler, the value of β is calculated as follows:
where
β = Q&
/ Q&
(96)
β h
h
d, in
N
is the part load level;
Qd, in
& is the mean heat output to the heat distribution, in kW;
QN & is the boiler rated output, in kW.
6.4.3.1 Multiple boiler systems
A differentiation shall be made between the two following modes of operation of multiple boiler systems.
Parallel operation (without priority switching)
All boilers are in operation at the same time to meet the heat demand. The part load level of the individual
boiler then corresponds to the ratio of the total mean heat output to the total rated output of the boilers.
where
( & ∑ N, )
β h, i = Q&
d, in / Q j
(97)
β h,i
is the part load level;
Qd, in
& is the mean heat output, in kW;
QN, j
& is the total rated output of the boilers, in kW.
83

DIN V 18599-5:2007-02
Series operation (with priority switching)
The boiler rated outputs are added step-by-step in the sequence each individual boiler i switches on in
accordance with the controller setting. The boiler is at full load (100 %) as long as after each step the sum of
these boiler outputs remains less than the energy requirement.
Only when the sum of these boiler outputs, added step-by-step, exceeds the requirement does the boiler
whose rated output was the last to be added operate in the part load regime. The part load β h,n for this nth
boiler is calculated as follows:
If ∑ < Q&
d, in Q&
N, n :
where
84
h, n
( Qd,
in − Q&
) / Q&
N, n
& ∑ N, n−1
β =
(98)
β h,n
is the part load level of the boiler;
Qd, in
& is the mean heat output to the heat distribution, in kW;
QN, n
&
is the rated output of the boiler, in kW.
The stand-by period for heat generation d H,g,i for a single boiler system, for all boilers in the case of parallel
operation, or for the lead boiler in the case of sequenced control corresponds to d h,mth (the number of heating
days in the respective month, in d (see 5.4.1)); that of the following boilers (only if there is water-side
separation from the boiler circuit when inoperative) is d h,mth · β h,n . This procedure shall be used by analogy for
hot water production according to DIN V 18599-8 if a multiple boiler system is used.
6.4.3.2 Fuel-fired systems (boilers)
In this clause the subscript i is used for calculations with more than one boiler.
The heat loss Q h,g and auxiliary energy Q h,g,aux of a boiler are calculated on the basis of the rated heat output
QN & , the efficiencies ηK100% , ηK pl% (ηK30% ) according to Directive 92/42/EEC (Boiler Efficiency Directive), the
stand-by thermal loss qB,70 and the electric power Paux of the auxiliary units of a boiler. These values shall
either be determined from measurements as product data from DIN EN 304, DIN EN 303-5, DIN EN 297 or
DIN EN 656, or else default values can be used if no measured values are available. In addition the
efficiencies are adjusted to the boiler temperature at the operating point.
If additional heat is provided by a solar system from 6.4.1 or from other sources from DIN V 18599-6 or
DIN V 18599-7, then Qh,outg shall be replaced by Q *
h,outg from equation (54). In each case the maximum
required operating temperature shall be used as the basis during the operating time:
HK, m
( ϑ , ϑ , )
ϑ = max ϑ
(99)
HK, m
h*
r, Nutz
When determining the operating time it is important whether the running times of the different processes occur
in the same period or in different periods. In the following equations the times shall be combined with the
associated temperatures. For simplicity, only normal heating operation is dealt with.
The total generation loss of the heating system Q h,g , referred to the gross calorific value (Hs) is calculated as
Q h,g = Σ(Q h,g,v,i · d h,rB ) (100)

where
Q h,g
DIN V 18599-5:2007-02
is the total generation loss of the heating system (in the respective month) (see 4.2.2), in kWh;
Q h,g,v,i is the boiler heat loss, in kWh/d;
d h,rB
is the design number of operating days (in the respective month), in d (see 5.4.1).
The daily generation losses of the boiler Q h,g,v, are determined as a function of the mean boiler part load β h
and the load regimes on which testing of the generator is based, with part loads β K,pl (equal to 0,3 in the case
of oil and gas boilers, and between 0,3 and 0,5 in the case of automatic feed biomass combustion systems)
and β K,100% (equal to 1,0):
If 0 < β h,i ≤ β K,pl , then
where
Qh,g,v,i = ((βh,i /βK,pl ) · ( Q& V,g,pl – Q& B,h ) + Q& B,h ) · (th,rL,T – tw,100% ) (101)
β h,i
is the part load level of the boiler;
Q & V,g,pl is the thermal power loss of the boiler at part load, in kW;
Q & B,h
t h,rL,T
is the thermal power loss of the boiler in stand-by mode, in kW;
is the daily design running time (see 5.4.1), in h;
t w,100% is the daily running time of the boiler for domestic water heating (see 4.1), in h.
If β K,pl < β h < 1,0, then
where
Qh,g,v,i = ((βh,i – βK,pl )/(1 – βK,pl ) · ( Q& V,g,100% – Q& V,g,pl ) + ( Q& V,g,pl ) · (th,RL,T – tw,100% ) (102)
Q & V,g,100%
is the thermal power loss of the boiler at rated output, in kW.
Mean heat output of the generation process
If the generator only has to meet the heat requirements of the space heating system or the heat requirements
of the space heating system combined with domestic hot water heating, then the mean heat output is
calculated according to equation (103).
Q& d,in = Qh,outg /(dh,rB · (th,rL,T – tw,100% )) (103)
As soon as there is no heating requirement in the particular month and thus d h,rB = 0, then Q & d,in also
becomes zero.
If the generator has to meet further heating requirements (e.g. for air conditioning) in addition to space heating
and domestic hot water heating, then the mean heat output is calculated according to equation (104).
85

DIN V 18599-5:2007-02
where
86
Q & d,in = ΣQ h,outg /(t Betrieb,K – t w,100% ) · d Nutz,mth
ΣQ h,outg
t Betrieb,K
is the total heat output from 4.2.1, taking account of 6.4;
(104)
is the monthly operating time of the generator, taking account of all heat loads to be
supplied from 4.2.1.
Calculation of the daily power loss Q & V,g,100% , Q& V,g,pl% , Q& B,h :
Thermal power loss of the boiler at stand-by Q & B,h :
where
Q & B,h = q B,ϑ · ( Q& N /η k,100% ) · f Hs/Hi
q B,ϑ
Q & N
is the stand-by loss at the mean boiler temperature;
is the boiler rated output, in kW;
η k,100% is the boiler efficiency at full load;
f Hs/Hi
is the ratio of gross calorific value to net calorific value of the fuel used (see 4.1).
The stand-by loss q B,ϑ of the boiler at the mean boiler temperature is calculated as follows:
where
(105)
q B,ϑ = q B,70 · (ϑ HK,m – ϑ i )/(70 – 20) (106)
q B,70
ϑ HK,m
ϑ i
is the stand-by loss;
is the mean boiler temperature (see 5.4), in °C;
is the ambient temperature (see 4.1 or Table 15), in °C.
If the mean operating temperatures ϑHK,m of boilers (or, in the case of condensing units, the mean return
temperatures ϑRL,m ) deviate from the test temperatures given in Table 29, the efficiencies shall be adjusted to
take the change in temperature conditions into account. The test temperatures ϑg,test are given in Table 29.

Boiler type
Table 29 — Boiler temperatures
ϑ g,test 100 (full load)
°C
Gas/oil
DIN V 18599-5:2007-02
ϑ g,test,pl (part load)
°C
Standard 70 50
Low temperature 70 40
Condensing 70 30 a
Biomass
Standard 70 70
a Directive 92/42/EEC specifies a return temperature of 30 °C when testing condensing boilers.
The boiler efficiencies determined under test conditions (ϑg,test100 ; ϑg,test,pl ) shall be corrected to take into
account the actual operating temperature (ϑ HK,m or ϑRL,m ) as follows:
η k,100%,Betrieb = η k,100% + G · (ϑ g,Test 100 – ϑ HK,m ) (107)
η k,pl,Betrieb = η k,pl + H · (ϑ g , Test,pl – ϑ HK,m ) (108)
If a number of heating circuits with differing temperatures are connected, then the highest value shall be used
for ϑ HK,m or ϑ RL,m , as appropriate (see clause 5).
For condensing boilers operated at part load, the mean return temperature ϑRL,m is substituted for the mean
boiler temperature ϑHK,m in equation (108).
Table 30 — Temperature correction factors
Boiler type Factor G Factor H
Standard boiler 0 0,000 4
Low temperature boiler 0,000 4 0,000 4
Condensing boiler, gaseous fuels 0,002 0,002
Condensing boiler, liquid fuels 0,000 4 0,001
Standard biomass boiler 0 0,000 4
Thermal power loss at part load:
Q & V,g,pl = (f Hs/Hi – η k,pl,Betrieb )/η k,pl,Betrieb · β K,pl · Q& N
Thermal power loss at full load:
Q & V,g,100% = (f Hs/Hi – η k,100%,Betrieb )/η k,100%,Betrieb · Q& N
(109)
(110)
87

DIN V 18599-5:2007-02
Calculation of the recoverable thermal losses
Uncontrolled heat gains from generators installed within the heated zone caused by losses via the envelope
(q s,ϑ ) of the generator can be taken into account as follows:
atmospheric gas boiler:
88
q s,ϑ = 0,5 · q B,ϑ
all other boilers:
q s,ϑ = 0,75 · q B,ϑ
Thus the total radiation losses Q I,h,g in the calculation period are calculated as follows:
Q I,h,g = q s,ϑ � · Q & N /η k,100% · (t h,rL,T – t w , 100% ) · d h,rB
Auxiliary energy Q h,g,aux
The auxiliary energy for space heat generation Q h,g,aux is calculated using the auxiliary power P aux of the
boiler (measured at full load, at part load and in stand-by mode) on the basis of a volume flow at a difference
of 20 K between the supply and return temperatures, and the mean boiler part load β h,i . In set-back mode, the
heat generator runs at a reduced temperature and with a reduced running time. These effects are taken into
account via the design running time, as is any possible period of operational shut down.
where
(111)
(112)
(113)
Q h,g,aux = Σ(P h,g,aux,i · (t h,rL -t w , 100% · d mth · d Nutz,a /365) + P aux,SB · (24 · d mth – t h,rL ) (114)
Q h,g,aux
P aux,SB
th,rL
d mth
If 0 < β h,i ≤ β K,pl ,
where
is the auxiliary energy for space heat generation (see 4.2.3), in kWh;
is the auxiliary power consumption of the boiler at stand-by, in kW;
is the monthly design running time (see 5.4.1), in h;
is the number of days (in the respective month) (see 4.1).
P h,g,aux,i = (β h,i /β K,pl ) · (P aux,pl,i – P aux,SB ) + P aux,SB
P h,g,aux,i
P aux,pl
If βK,pl�� < βh,i < 1,0:
is the auxiliary power consumption of the boiler when in operation, in kW;
is the auxiliary power consumption of the boiler at part load, in kW.
P h,g,aux,i = (β h,i – β K,pl )/(1 – β K,pl ) · (P aux,100 – P aux,pl ) + P aux,pl
(115)
(116)

where
P aux,100 is the auxiliary power consumption of the boiler at full load, in kW.
DIN V 18599-5:2007-02
When determining the auxiliary power consumption for automatic feed biomass central boilers a distinction is
to be made between systems with and without a buffer storage tank. For systems with buffer storage tanks,
correction of the value P aux,pl is not required.
For systems without buffer storage tanks, P aux,pl shall be adjusted to P aux,pl,bio,korr to take into account the
higher ignition power requirement as a function of the relationship between the boiler part load βK,pl forming
the basis of the part load measurement, and the mean boiler load βh,i in the calculation period.
f β,Bio = β K,pl /β h,i
For 1 < f β,Bio < 3 the following applies:
P aux,pl,bio,korr. = P aux,pl · f β,Bio
If f β,Bio ≥ 3 the following applies:
(117)
(118)
P aux,pl,bio,korr. = P aux,pl · 3 (119)
This corrected value P aux,pl,bio,korr. is introduced into equations (115) and (116) instead of P aux,pl .
Boundary conditions in the absence of data
If no product data are available, the following values can be used in the ensuing calculations:
boiler efficiencies at full load and where βK,pl = 0,3 (up to a boiler output of 400 kW, however if this is higher,
the efficiency at a rated output Q& N of 400 kW shall be used):
ηk,100% = (A + B · log ( Q& N ))/100 (120)
ηk,pl = (C + D · log ( Q& N ))/100 (121)
89

DIN V 18599-5:2007-02
Change-fuel boilers
90
Boiler type
Solid fuel boilers (fossil fuel)
Atmospheric gas boiler
Heating boiler with forced draught burner
Burner replacement (only heating boiler
with forced draught burner)
Biomass boiler
Table 31 — Efficiency factors
Year of
construction
Factor A Factor B Factor C Factor D
before 1978 77,0 2,0 70,0 3,0
1978 to 1987 79,0 2,0 74,0 3,0
before 1978 78,0 2,0 72,0 3,0
1978 to 1994 80,0 2,0 75,0 3,0
after 1994 81,0 2,0 77,0 3,0
Standard boilers:
before 1978 79,5 2,0 76,0 3,0
1978 to 1994 82,5 2,0 78,0 3,0
after 1994 85,0 2,0 81,5 3,0
before 1978 80,0 2,0 75,0 3,0
1978 to 1986 82,0 2,0 77,5 3,0
1987 to 1994 84,0 2,0 80,0 3,0
after 1994 85,0 2,0 81,5 3,0
before 1978 82,5 2,0 78,0 3,0
1978 to 1994 84,0 2,0 80,0 3,0
Class 3 from 1994 67 6 68 7
Class 2 from 1994 57 6 58 7
Class 1 from 1994 47 6 48 7
Atmospheric gas boiler
Gas-fired central heating boilers
(11 kW, 18 kW and 24 kW)
Heating boiler with forced draught burner
Low temperature boilers:
1978 to 1994 85,5 1,5 86,0 1,5
after 1994 88,5 1,5 89,0 1,5
before 1987 η 100% = 86 % η pl = 84 %
1987 to 1992 η 100% = 88 % η pl = 84 %
before 1987 84,0 1,5 82,0 1,5
1987 to 1994 86,0 1,5 86,0 1,5
after 1994 88,5 1,5 89,0 1,5
Burner replacement (only heating boiler before 1987 86,0 1,5 85,0 1,5
with forced draught burner) 1987 to 1994 86,0 1,5 86,0 1,5
Condensing boilers
before 1987 89,0 1,0 95,0 1,0
1987 to 1994 91,0 1,0 97,5 1,0
after 1994 92,0 1,0 98,0 1,0
Condensing boiler, improved a from 1999 94,0 1,0 103 1,0
a If default values for “improved” condensing boilers are used in the calculation, the efficiency given in the product data of the
installed boiler shall be at least the efficiency specified above.

DIN V 18599-5:2007-02
If the flue gas loss of existing boilers is known, then while retaining the boundary conditions the boiler
efficiency can also be approximated to η K = 100 – q A – q St , with η K,100% = η K .
The radiation loss q St of the boiler as a function of its rated heat output Q & N
in kW is given by:
qSt = (K · ( QN & ) L )/100 (122)
Change-fuel boilers
Solid fuel boilers
Atmospheric gas boiler
Boiler type
Table 32 — Radiation loss factors
Year of
construction
(where
differentiation is
required)
Factor K Factor L
before 1978 13,5 –0,3
1978 to 1987 11,5 –0,3
before 1978 13,0 –0,3
from 1978 11,0 –0,3
Standard boilers:
before 1978 12,0 –0,35
from 1978 9,0 –0,45
Heating boiler with forced draught burner before 1978 12,0 –0,4
(oil/gas) from 1978 9,0 –0,37
Low temperature boilers:
Atmospheric gas boiler – 9,0 –0,45
Gas-fired central heating boilers
(11 kW, 18 kW and 24 kW combination boilers)
Heating boiler with forced draught burner
(oil/gas)
– 9,0 –0,6
– 7,0 –0,4
Condensing boilers (oil/gas) – 5,5 –0,4
The stand-by thermal loss q B,70 of the boiler as a function of its rated heat output Q & N
in kW is given by:
q B,70 = (E ⋅ ( Q & N )F )/100 (123)
91

DIN V 18599-5:2007-02
92
Table 33 — Stand-by heat factors
Boiler type Year of construction Factor E Factor F
Change-fuel boilers before 1987 12,5 –0,28
Solid fuel boiler
Atmospheric gas boiler
Heating boiler with forced draught burner
(oil/gas)
before 1978 12,5 –0,28
1978 to 1994 10,5 –0,28
after 1994 8,0 –0,28
Standard boilers:
before 1978 8,0 –0,27
1978 to 1994 7,0 –0,3
after 1994 8,5 –0,4
before 1978 9,0 –0,28
1978 to 1994 7,5 –0,31
after 1994 8,5 –0,4
Biomass boiler after 1994 14 –0,28
Atmospheric gas boiler
Gas-fired central heating boiler
(11 kW, 18 kW and 24 kW combination
boiler)
Low temperature boilers:
up to 1994 6,0 –0,32
after 1994 4,5 –0,4
up to 1994
q B,70°C = 0,022
Combination boiler KSp b after 1994 q B,70°C = 0,022
Combination boiler DL a after 1994 q B,70°C = 0,012
Heating boiler with forced draught burner
up to 1994 7,0 –0,37
(oil/gas) after 1994 4,25 –0,4
Condensing boilers (oil/gas)
Combination boiler KSp b (11 kW, 18 kW and
24 kW)
Combination boiler DL a (11 kW, 18 kW and
24 kW)
up to 1994 7,0 –0,37
after 1994 4,0 –0,4
after 1994
after 1994
q B,70°C = 0,022
q B,70°C = 0,012
a DL: Boiler with integrated domestic hot water heating working on the instantaneous principle with a heat exchanger (V < 2 l).
b KSp: Boiler with integrated domestic hot water heating working on the instantaneous principle with only a small hot water storage
tank (2 < V < 10 l).
The auxiliary power consumption Paux of the boiler as a function of the rated heat output Q& N in kW is as
follows:
P aux,x = (G + H · ( Q & N )n )/1 000 (124)

Boiler type
Table 34 — Auxiliary energy factors
Auxiliary power
consumption
DIN V 18599-5:2007-02
Factor
G
Factor
H
Factor
n
From 1994
Boiler with forced draught burner P aux,100 0 45 0,48
Boiler with atmospheric burner up to 250 kW
Boiler with atmospheric burner from 250 kW
Auto feed pellet central boiler a , with buffer storage tank
Auto feed wood chip central boiler a , with buffer storage
tank
All other boilers
P aux,pl 0 15 0,48
P aux,SB 15 0 0
P aux,100 40 0,35 1
P aux,pl 20 0,1 1
P aux,SB 15 0 0
P aux,100 80 0,7 1
P aux,pl 40 0,2 1
P aux,SB 15 0 0
P aux,100 40 2 1
P aux,pl 40 1,8 1
P aux,SB 15 0 0
P aux,100 60 2,6 1
P aux,pl 70 2,2 1
P aux,SB 15 0 0
P aux,100 0 45 0,48
P aux,pl 0 15 0,48
Change-fuel boilers P aux,SB 20 b 0 0
Solid fuel boilers
Standard boilers
Atmospheric gas boiler
Heating boiler with forced draught burner (oil/gas)
P aux,100 0 0 0
P aux,pl 0 0 0
P aux,SB 15 b 0 0
P aux,100 40 0,148 1
P aux,pl 40 0,148 1
P aux,SB 15 b 0 0
P aux,100 0 45 0,48
P aux,pl 0 15 0,48
P aux,SB 15 b 0 0
93

DIN V 18599-5:2007-02
Low temperature boilers
Atmospheric gas boiler
94
Boiler type
Gas fired central heating boiler
Heating boiler with forced draught burner (oil/gas)
Condensing boilers (oil/gas)
Table 34 (continued)
Auxiliary power
consumption
a Paux,100 and P aux,pl are 40 % higher if combined with a forced draught burner.
b If electrically-operated boiler control is used, otherwise Paux,SB = 0.
6.4.3.3 Hand stocked biomass combustion systems
Factor
G
Factor
H
P aux,100 40 0,148 1
P aux,pl 40 0,148 1
P aux,SB 15 b 0 0
Factor
n
P aux,100 0 45 0,48
P aux,pl 0 15 0,48
P aux,SB 15 b 0 0
P aux,100 0 45 0,48
P aux,pl 0 15 0,48
P aux,SB 15 b 0 0
P aux,100 0 45 0,48
P aux,pl 0 15 0,48
P aux,SB 15 b 0 0
The following assumptions apply to a hand stocked biomass combustion system if this is the only base load
heat generator used for heating (i.e. without another base load heat generator, such as a gas or oil boiler or a
heat pump). Furthermore, if heat generators are located within the heated zone, input of combustion air shall
be directly from outdoors (operation independent of room air; this also includes ingress of outdoor air for any
draught regulator that may be present).
Furthermore, the assumptions apply to operation of combustion systems located inside the apartment or
building they heat, i.e. such that the biomass heat generator loss (indirect loss) is principally to a heat carrier
circuit (e.g. a pump hot water heating circuit or the supply air ductwork of a residential ventilation system) by
means of which the heat is transported to spaces located a greater distance away. Heat generators whose
minimum heat output to the heat carrier circuit is greater than 20 % of the nominal heat load required by the
building shall be operated together with a buffer storage tank.
The generation heat losses Q h,g and the auxiliary energy of a biomass combustion system are calculated by
means of equations (125) to (129). The parameters required for the calculations shall be determined either as
specified in DIN EN 13240, DIN 18892, DIN EN 13229 and DIN EN 303-5, or using other recognized test
methods appropriate to the generator; if values are not available from measurements, the values in Table 34
shall be used. For biomass combustion systems that are designed to give off heat to the space in which they
are installed (direct heat output to spaces within the heated zone) and that are operated with the purpose of
heating these spaces, this direct loss is also taken into account in the following calculation.

DIN V 18599-5:2007-02
The generation losses Q h,g of a hand stocked biomass combustion system are calculated according to
equation (125) as a function of the efficiency in steady-state operation (η Betrieb ) and the efficiency during a
base cycle (η GZ ), weighted by the quantities of heat that are supplied in the two phases of operation (f Q,GZ ).
Furthermore the effect of over-heating the installation space if generators are located inside the heated zone
is taken into account, in the event that the quantity of heat these give off directly into the space is excessive in
proportion to the size of the space (f ce ).
where
Q h,g = ((f Q,GZ · f Hs/Hi /η GZ + (1 – f Q,GZ + f ce ) · f Hs/Hi /η Betrieb ) – 1) · Q h,outg
Q h,outg is the heat to be provided by the generator (in the respective month)) (see 6.4), in kWh;
f Q,GZ
η GZ
f ce
f Hs/Hi
is the heat fraction of a base cycle according to equation (126);
(125)
is the efficiency of the biomass combustion system in a base cycle according to product data or
Table 35;
is the over-heating factor from equation (129);
is the ratio of gross calorific value to net calorific value according to 4.1;
η Betrieb is the efficiency of the biomass combustion system in steady-state operation according to
product data or Table 35.
In the above, the base cycle is the phase of operation of a biomass combustion system, beginning with the
start-up of combustion at room temperature, firing until steady-state operation is attained, and the subsequent
cooling of the boiler down to room temperature.
The heat fraction of the base cycle is calculated using equation (126). If the generator does not heat domestic
hot water while in the space heating mode, then Q w,outg shall be set at 0.
where
fQ,
GZ
f Q,GZ
x Z
Q N,GZ
xZ
⋅ QN,
GZ
Qh,
outg + Qw,
outg
dh,
rB
= (126)
is the heat fraction of the base cycle with f Q,GZ ≤ 1;
is the number of cycles per day from equation (127), in d –1 ;
is the total heat supplied by the heat generator during a base cycle according to product data or
Table 35, in kWh;
Q h,outg is the monthly heat to be supplied by the heat generator for space heating, in kWh (see 6.4);
d h,rB
is the monthly design number of operating days (see 5.4.1);
Q w,outg is the monthly heat to be supplied by the heat generator for domestic hot water, in kWh.
95

DIN V 18599-5:2007-02
When calculating the number of cycles it is assumed that these are essentially defined by the properties of the
heating circuit. (Any direct loss to the installation space is not taken into account when determining the
number of cycles.) Furthermore it is assumed that modulating generators are operated such that their heat
output is adjusted to suit demand (provided the demand is greater than the minimum heat output; in equation
(127) it is assumed that the mean output is equal to 1,2 times the minimum output). The number of cycles per
day is obtained by means of equations (127) and (128) as follows:
96
x
where
x Z
Z
z HK,m
1,
2 ⋅ 20 971⋅
z
=
( V + V
S, HK
HK, m
HK
⋅Q&
N, min
⋅(
1−
f
) ⋅(
ϑ −ϑ
h, S, max
Q&
) ⋅ f
)
HK, m
is the number of cycles per day, in 1/d with: x Z ≥ 1;
Q&
(127)
is the mean proportion of the heat output emitted to the heating circuit, according to product
data or Table 35;
QN, min
& is the minimum output of the heat generator according to product data or Table 35, in kW;
Q& f is the performance factor from equation (128);
V S,HK
V HK
ϑ h,s,n,max
ϑ HK,m
is the volume of heating circuit water in the storage tank according to product data or in
addition to 6.3, in l;
is the volume of the water in the distribution from project data or Table 35, in l;
is the maximum operating temperature of the buffer storage tank according to product data
or Table 35, in °C;
is the mean heating circuit temperature, in °C.
In the case of buffer storage tanks in which a separate domestic water storage tank is integrated (combination
storage tank) and which can exchange heat readily with the heating circuit water, the effective volume of the
heating circuit water in the storage tank can be increased by half the volume of domestic hot water. Otherwise
calculations shall only use the water that is actually transported by the heating circuit (in a storage tank this is
the volume of the zone through which the water flows).
In equation (128) a performance factor is introduced to describe the ratio of the maximum required heat output
on an average day (for space heating and for domestic hot water heating) to the heat output of the biomass
boiler delivered to the heating circuit.
f
where
Q&
Qw,
outg
Q&
d, in +
24 ⋅ dh,
rB ⋅ zHK,
m
= (128)
Q&
N, min
Q& f is the performance factor with fQ < 1;
z HK,m
is the mean proportion of heat output delivered to the heat distribution, according to product data
or Table 35;

Qd, in
& is the mean heat loss to the heat distribution of the building, in kW;
Q w,outg is the monthly heat supplied by the generator for domestic hot water, in kWh;
d h,rB
is the monthly design number of operating days (see 5.4.1);
DIN V 18599-5:2007-02
QN, min
& is the minimum long-term power output capacity of the generator according to product data or
Table 35, in kW.
If a central biomass combustion system is located inside the heated zone and its design is such that it delivers
more heat directly to the installation space than the latter needs for heating purposes, then for simplification
25 % of this heat is taken to be a thermal loss. This thermal loss is taken into account by the over-heating
factor f CE :
f
where
CE
f CE
Q CE
0,
25 ⋅ Q
=
Q + Q
h, outg
CE
w, outg
=
Q
0,
25 ⋅ Q
+ Q
h, outg
h
w, outg
⎛ Q&
⋅ ⎜
⎝
is the over-heating factor, with f CE ≥ 0;
N, max
⋅(
1−
z
Q&
h, max
HK, m
is the non-usable, direct heat loss from the generator;
)
−
L
Q h,outg is the monthly heat supplied by the generator for space heating, in kWh (see 6.4);
Q w,outg is the monthly heat supplied by the generator for domestic hot water, in kWh;
Q h,b
is the annual energy need for heating the building, in kWh (see 4.1);
QN, max
& is the maximum output capacity of the generator according to product data or Table 35, in kW;
z HK,m
G
A
⋅ B
Auf
G
⋅ n
G
⎞
⎟
⎠
(129)
is the mean proportion of heat output delivered to the heat distribution, according to product data
or Table 35;
Qh, max
& is the maximum heat load required by the building (see 4.1), in kW;
A Auf
L G
B G
n G
is the floor area of the installation space in which the biomass boiler is located, in m 2 ;
is the largest extended length of the building (see 4.1), in m;
is the largest extended width of the building (see 4.1), in m;
is the number of heated storeys (see 4.1).
The area of the installation space can also comprise the area taken up by adjacent spaces if these can be
heated regularly thanks to the ingress of warm air from the installation space or adjacent spaces, provided this
air has been directly heated in the biomass boiler and its ingress can be controlled.
97

DIN V 18599-5:2007-02
The auxiliary energy of a biomass boiler that is fitted with electrically operated components such as a
controller, combustion air fan, integrated storage charging pump, or heating rod for automatic ignition, is given
by equation (130). If the biomass combustion system has a permanently fitted circulation pump, this shall be
operated during testing such that there is an external pressure drop in the water-side section of 10 kPa, and
the temperature difference between the supply and return temperatures at the maximum heat output of the
boiler is less than 15 K.
where
98
Q = x ⋅ Q ⋅ d + ( Q + Q − x ⋅ Q ⋅ d ) ⋅ f
(130)
h, g, aux
Z
aux, GZ
h, rB
h, outg
w, outg
Z
N, GZ
h, mth
el, Betrieb
Q h,g,aux is the monthly auxiliary energy of the biomass boiler in the heating season, in kWh;
x Z
is the number of cycles per day;
Q aux,GZ is the auxiliary energy required during a base cycle according to product data or Table 35, in
kWh;
Q h,outg is the monthly heat to be supplied by the boiler for space heating (see 6.4), in kWh;
Q w,outg is the monthly heat to be supplied by the heat generator for domestic hot water, in kWh;
f el,Betrieb is the relative power consumption in steady-state operation;
Q N,GZ
d h,rB
is the usable heat supplied by the heat generator during a base cycle according to product data
or Table 35, in kWh;
is the monthly design number of operating days (see 5.4.1).
Boundary conditions in the absence of product data
If the product data are not known (in full or in part), then for simplification the generator expenditure factor and
the auxiliary energy of a biomass boiler can be calculated using the default values given in Table 35. The
rated output of the boiler ( Q & N,max ) that is required for this purpose can be estimated from 5.3 if no data are
available from the manufacturer.

Table 35 — Default values
Parameter Meaning Unit
DIN V 18599-5:2007-02
Log wood firing
Direct and indirect loss
η Betrieb Efficiency in steady-state operation – 0,70
η GZ Efficiency in the base cycle – 0,85 · η Betrieb
QN,GZ Heat delivered by the boiler during a base cycle kWh N, max ⋅1,5
h
z HK,m Fraction of heat output to the heat distribution – 0,4
QN, max
&
Maximum power output capacity in operation
according to DIN V 18599-2
Q &
1,3 Q& ⋅
kW h, max
QN, min
& Minimum power output capacity in operation kW , 9 ⋅ N, max
0 Q &
QN, m
& Mean power output capacity in operation kW N, max
ϑ h,s,max Maximum storage charging temperature K 85
V HK Water volume of the heating circuit l 0,8 (l/m 2 ) · L G · B G · n G
Qaux,GZ Auxiliary energy for the base cycle kWh 0,05a or , 02 + 0,
02 ⋅ b
N, max
f el,Betrieb
Relative auxiliary power consumption in steady-state
operation
a Equipment with controller only.
b Equipment with fan/ignition source.
Q &
0 Q &
W 0,001a or 0, 011 QN, max
& ⋅
The values for the auxiliary energy do not include the auxiliary energy of any storage charging pump that may
be present. This shall be taken into account separately when dealing with the storage system.
If for determination of the over-heating factor f CE the ratio of the area of the installation space to the net floor
area of the storey is not known, this can be assumed to be 0,2.
6.4.3.4 Decentralized fuel-fired systems
In the case of decentralized fuel fired systems the energy for net (usable) heat, control and emission,
distribution and generation is brought together into one quantity which is then used in the subsequent balance
calculation as described in 4.2. It thus corresponds directly to the energy use of the heat generator.
6.4.3.4.1 Gas space heaters
Chimney-dependent units
up to 1985 Q h,f = 1,40 · Q h,b in kWh in the respective month
after 1985 Q h,f = 1,34 · Q h,b in kWh in the respective month
Outside wall units
up to 1985 Q h,f = 1,47 · Q h,b in kWh in the respective month
b
99

DIN V 18599-5:2007-02
after 1985 Q h,f = 1,40 · Q h,b in kWh in the respective month
6.4.3.4.2 Oil-fired stand-alone stoves with vaporization burner
up to 1985 Q h,f = 1,40 · Q h,b in kWh in the respective month
after 1985 Q h,f = 1,34 · Q h,b in kWh in the respective month
6.4.3.4.3 Tiled stove (“Kachelofen”)
100
Q h,f = 1,55 · Q h,b
6.4.3.4.4 Coal-fired iron stove
Q h,f = 1,60 · Q h,b
6.4.3.4.5 Heating of large indoor spaces
in kWh in the respective month
in kWh in the respective month
Radiant tube heater (Type C), decentralized convection air heaters (Type C)
The heat generation loss for radiant tube heaters and decentralized convection air heaters is given by:
Q h,g = f · Q h,outg in kWh in the respective month (131)
In the above, the following efficiency factors shall be applied (see Table 36).
Nominal heat output
kW
Table 36 — Efficiency factor
Factor f
> 4 to 25 0,111
> 25 to 50 0,099
> 50 0,087
It shall be assumed that these heaters are installed in the space they are intended to heat and are
independent of room air, and that they are connected to concentric air piping / a flue.
Luminous radiant heaters (Type A)
The heating system generally comprises a number of luminous radiant heaters. The heat generation loss for
luminous radiant heater systems is given by:
where
Q h,g = V Abluft,spez · c p,Abluft · (ϑ Abluft – ϑ Außen ) · t h,rL
V Abluft,spez is the specific combustion air demand = 10 m 3 /(h · kW heat load);
c p,Abluft is the specific heat capacity = 0,361 Wh/(m 3 · K);
ϑ Abluft is the extract air temperature = 18 °C;
(132)

ϑ e
t h,rL
is the average monthly outdoor air temperature (see 4.1), in °C;
is the monthly design running time (see 5.4.1), in h.
DIN V 18599-5:2007-02
It is assumed that these heat generators are installed in the space they are intended to heat and that they are
fitted with an indirect flue system conforming to DIN EN 13410.
Auxiliary energy for luminous radiant heaters
The auxiliary energy for wall or ceiling fans in relation to the energy need for heating the large indoor space,
heated by a luminous radiant heater, is as follows:
Q h,g,aux = 0,000 6 · Q h,b in kWh in the respective month (133)
6.4.4 Electric heaters
6.4.4.1 Decentralized electric heaters
Decentralized electrical systems are taken into account in the emission subsystem.
6.4.4.2 Central electric heaters
In the case of central electric heating, the following loss shall be assumed:
⎯ storage with separate generation Q h,s + Q h,g = 0,11 · Q h,outg in kWh in the respective month;
⎯ storage with integrated generation Q h,s + Q h,g = 0,09 · Q h,outg in kWh in the respective month
where
Q h,outg is the generator heat output (in the respective month) (see 6.4.1), in kWh.
6.4.5 District heating and local heating
The heat loss Q h,g of the dwelling substations is given by:
with
and
Q h,g = H DS ⋅ (ϑ DS – ϑ i ) (134)
H DS = B DS ⋅ Φ DS 1/3 ΦDS in kW, H DS in kWh/K · a (135)
ϑ DS = D DS ⋅ ϑ prim,DS + (1 – D DS ) ⋅ϑ sek,DS
For ϑprim,DS and ϑsek,DS the mean temperatures on the primary and secondary sides of the dwelling
substation shall be used respectively, ϑsek,DS being equal to ϑHK,m .
The equations are numerical value equations. The rated output Φ DS (equal to N
Q & ) of the dwelling substation
in kW and the numerical values from Tables 37 and 38 are used, thus giving the thermal losses Q h,g,DS in
kWh per year.
(136)
101

DIN V 18599-5:2007-02
102
Table 37 — D DS as a function of the primary temperature and type of dwelling substation
Type of dwelling substation
(Design) primary temperature)
ϑ prim,DS
°C
Hot water, low temperature 105 0,6
Hot water, high temperature 150 0,4
Low pressure steam 110 0,5
High pressure steam 180 0,4
Table 38 — Coefficient B DS as a function of the class of insulation and type of dwelling substation
Type of
station
D DS
Class of insulation of components of the dwelling
substation according to DIN EN 12828
Insulation of the secondary side 4 3 2 1
Insulation of the primary side 5 4 3 2
Hot water, low temperature 3,5 4,0 4,4 4,9
Hot water, high temperature 3,1 3,5 3,9 4,3
Low pressure steam 2,8 3,2 3,5 3,9
High pressure steam 2,6 3,0 3,3 3,7
In principle it is possible to consider the system on a monthly basis. As this is generally too complex, it is
recommended that a year be selected as the calculation period, and that in the ensuing calculations the
unmodified thermal losses in the course of the year should be taken into account. In some cases it may be
useful to calculate separate values for summer and winter.
The auxiliary energy of the dwelling substation is neglected. If the supply temperature for the heating system
of the building is controlled by a central control system, a value of Q h,g,aux = 10 kWh in the respective month is
assumed.
6.4.6 Decentralized CHP
Decentralized heat and power generation is dealt with in DIN V 18599-9.

A.1 Electrically driven heat pumps
Annex A
(normative)
Energy use to meet the heating need
DIN V 18599-5:2007-02
Figure A.1 — Energy balance of the generator subsystem (electrically driven heat pump)
The energy balance for the generator subsystem in respect of thermal losses is as follows:
where
Q = Q + Q − k ⋅ Q − Q
(A.1)
h, f
Q h,f
h, outg
h, g
rd, g
h, g, aux
h, in
is the delivered energy for the heat generator (heat pump) (in the respective month), in kWh;
Q h,outg is the generator heat output to the heat distribution system (in the respective month) (see 6.4.1),
in kWh;
Q h,g
k rd,g
are the losses of the generator subsystem (in the respective month), in kWh;
is the recovered energy fraction of the auxiliary systems;
Q h,g,aux is the auxiliary input energy for operation of the generator (in the respective month), in kWh;
Q h,in
is the ambient heat (in the respective month), in kWh;
103

DIN V 18599-5:2007-02
The fractions of recovered energy of the auxiliary system are not taken into account, hence k rd,g = 0.
The energy for operation of the heat pump Q h,f shall be taken from the test rig measurements according to
DIN EN 14511 (all parts). Taken into account are the auxiliary energy for source and sink pumps (primary and
secondary sides), to compensate for the internal pressure drop in the heat pump evaporator (heat source) and
condenser (heating) as well as the auxiliary energy for control, for defrosting, and any back-up heating
equipment that may be installed (e.g. oil sump heating).
A.2 Heat pumps with combustion drive
104
Figure A.2 — Energy balance of the generator subsystem (heat pump with combustion drive)
For heat pumps with combustion drive, the energy balance for the generator subsystem in respect of thermal
losses is as follows:
Q
where
h, f
Q h,f
Qh,
out, g + Qh,
g − krd,
g ⋅ Qh,
g, aux − Qh,
in
= (A.2)
1+ p
rd, mot
is the delivered energy for the heat generator (heat pump) (in the respective month), in kWh;
Q h,outg is the generator heat output to the heat distribution system (in the respective month) (see 6.4), in
kWh;
Q h,g
k rd,g
are the losses of the generator subsystem (in the respective month), in kWh;
is the fraction of recovered heating energy of the auxiliary systems;

DIN V 18599-5:2007-02
Q h,g,aux is the auxiliary input energy for operation of the generator (in the respective month), in kWh;
Q h,in
p rd,mot
is the ambient heat (in the respective month), in kWh;
is the recovered input fuel supplied to the generator.
Auxiliary energy recovered as thermal energy is not taken into account (k rd,g = 0).
A.3 Default values for heat pump calculations
A.3.1 Default power values and coefficients of performance for electrically driven heat
pumps
Table A.1 — Air-to-water heat pumps with a supply temperature of 35 °C
Supply temperature 35 °C
Outdoor temperature –7 °C 2 °C 7 °C 15 °C 20 °C
Relative heat output 0,72 0,88 1,04 1,25 1,36
Coefficient of performance (COP) today 2,7 3,1 3,7 4,3 4,9
Coefficient of performance (COP) from 1979 2,4 2,8 3,3 3,6 4,4
to 1994
Coefficient of performance (COP) before
1979
2,2 2,5 3,0 3,2 4,0
Table A.2 — Air-to-water heat pumps with a supply temperature of 50 °C
Supply temperature 50 °C
Outdoor temperature –7 °C 2 °C 7 °C 15 °C 20 °C
Relative heat output 0,68 0,84 1,00 1,24 1,29
Coefficient of performance (COP) today 2,0 2,3 2,8 3,3 3,5
Coefficient of performance (COP) from 1979 1,8 2,1 2,5 3,0 3,2
to 1994
Coefficient of performance (COP) before
1979
1,6 1,9 2,3 2,7 2,8
Table A.3 — Brine-to-water heat pumps with supply temperatures of 35 °C and 50 °C
Supply temperature 35 °C 50 °C
Primary temperature –5 °C 0 °C 5 °C –5 °C 0 °C 5 °C
Relative heat output 0,88 1,00 1,12 0,85 0,98 1,09
Coefficient of performance (COP) today 3,7 4,3 4,9 2,6 3,0 3,4
Coefficient of performance (COP) from 1979 to
1994
3,0 3,5 4,0 2,1 2,4 2,8
Coefficient of performance (COP) before 1979 2,7 3,1 3,5 1,9 2,2 2,5
105

DIN V 18599-5:2007-02
106
Table A.4 — Water-to-water heat pumps with supply temperatures of 35°C and 50 °C
Supply temperature 35 °C 50 °C
Primary temperature 10 °C 15 °C 10 °C 15 °C
Relative heat output 1,07 1,20 1,00 1,13
Coefficient of performance (COP) today 5,5 6,0 3,8 4,1
Coefficient of performance (COP) from 1979 to
1994
4,6 5,0 3,2 3,4
Coefficient of performance (COP) before 1979 3,9 4,3 2,7 2,9
A.4 Default power values and coefficients of performance for combustion enginedriven
heat pumps
A.4.1 Air-to-water heat pumps
Combustion engine-driven air-to-water heat pumps
Figure A.3 — Heat output of combustion engine-driven air-to-water heat pumps at various source and
sink temperatures

A.4.2 Combustion engine-driven air-to-water heat pumps
DIN V 18599-5:2007-02
Figure A.4 — Standard coefficients of performance for combustion engine-driven air-to-water heat
pumps at various source and sink temperatures
A.4.3 Air-to-air heat pumps
Combustion engine-driven air-gas heat pumps
Figure A.5 — Heat output of combustion engine-driven air-to-air heat pumps
107

DIN V 18599-5:2007-02
Combustion engine-driven air-to-air heat pumps
Figure A.6 — Standard coefficient of performance of combustion engine-driven air-to-air heat pumps
A.4.4 Absorption heat pumps
A.4.4.1 Heat output
Default power values and coefficients of performance for NH 3 /H 2 O heat pumps
Water-to-water direct-fired NH 3 /H 2 O absorption heat pumps
108
Figure A.7 — Heat output of water-to-water NH 3 /H 2 O absorption heat pumps at various source and
sink temperatures

A.4.4.2 Default power values and coefficients of performance for H 2 O/LiBr heat pumps
Water-to-water direct-fired H 2 O/LiBr absorption heat pumps
DIN V 18599-5:2007-02
Figure A.8 — Heat output of water-to-water H 2 O/LiBr absorption heat pumps at various source and
sink temperatures
109

DIN V 18599-5:2007-02
A.5 Correction factor for part load operation
A.5.1 Electrically driven heat pumps
Performance factors of electrically driven heat pumps are greatly dependent on the part load behaviour. The
part load behaviour is affected by the equivalent performance of the heat distribution system and the volume
of hot water per kW heat output. Buffer storage tanks are counted as part of the volume of hot water of the
heat distribution system.
The load factor is determined according to equation (81).
Table A.5 — Correction factor for part load operation of electrically driven heat pumps with radiators
Type of heat
distribution
system
Convectors/
radiators
110
Equivalent
water
content
Load factor
%
l/kW 10 20 30 40 50 60 70 80 90 99
5 58,8 58,8 58,8 58,8 58,8 71,4 80,0 85,7 92,3 99,5
10 80,1 80,1 80,1 80,1 80,1 84,8 89,1 92,2 95,5 99,6
15 85,9 85,9 85,9 85,9 85,9 91,7 94,4 96,0 97,5 99,7
20 89,1 89,1 89,1 89,1 89,1 93,8 95,8 97,1 98,3 99,8
Table A.6 — Correction factor for part load operation of electrically driven heat pumps with surface
heating systems
Type of heat
distribution
system
Surface
heating
Property
light
heavy
Spacing
of the
pipes
Intermediate values are to be interpolated.
Load factor
%
cm 10 20 30 40 50 60 70 80 90 99
30 95,3 95,4 95,5 95,7 95,9 96,1 96,2 96,9 98,1 99,9
20 97,1 97,2 97,2 97,3 97,4 97,4 97,6 97,9 98,4 99,9
10 98,6 98,6 98,6 98,6 98,6 96,6 98,7 98,9 99,1 99,9
30 96,1 96,1 96,1 96,3 96,4 96,5 96,8 97,3 98,2 99,9
20 97,8 97,8 97,9 98,0 98,1 98,1 98,2 98,4 98,8 99,9
10 99,1 99,1 99,1 99,1 99,1 99,1 99,2 99,2 99,4 99,9

A.5.2 Absorption heat pumps with modulation burner
DIN V 18599-5:2007-02
Table A.7 — Correction factor for part load operation of absorption heat pumps
Load factor
%
10 20 30 40 50 60 70 80 90 100
C dt 71,5 81,4 88,3 93,3 96,8 99,2 99,9 99,9 99,9 99,9
A.6 Calculation procedure for source and sink temperature corrections with a set
exergetic efficiency
This procedure is based on the principle that the thermodynamic quality of the process remains constant over
the whole of the operating range. The thermodynamic quality of a process can be expressed in terms of the
exergetic or Carnot efficiency as the ratio between the real coefficient of performance of the process and the
ideal Carnot coefficient of performance. The exergetic efficiency can thus be calculated by means of the
following equation:
where
COP
η =
(A.3)
ex
COPc
η ex
is the exergetic or Carnot efficiency;
COP is the coefficient of performance;
COP c
is the Carnot coefficient of performance.
The Carnot coefficient of performance (COP c ) is determined using equation (A.4).
where
T Θsi
+ 273,
15
COP c =
=
(A.4)
T
Θ −Θ
COP c
T hot
T cold
Θ si
Θ so
hot
hot − Tcold
si
is the Carnot coefficient of performance;
so
is the temperature on the hot side of the process, in K;
is the temperature on the cold side of the process, in K;
is the sink temperature, in °C;
is the source temperature, in °C.
Both the source and sink temperatures can be taken into account by this relationship.
The effective coefficient of performance (COP eff ) at varying source temperatures is calculated using equation
(A.5).
111

DIN V 18599-5:2007-02
where
112
COPc,
eff
COPeff = COPstandard
⋅
(A.5)
COP
COP eff
COP standard
COP c,eff
COP c,standard
c,
standard
is the coefficient of performance at effective source temperatures;
is the coefficient of performance under standard conditions;
is the Carnot coefficient of performance at effective source temperatures;
is the Carnot coefficient of performance under standard conditions.
A correction factor to account for the effect of the temperature on the coefficient of performance or the
auxiliary energy consumption to compensate for storage losses can be calculated as follows:
where
COPc,
eff Tsi,
out, eff ⋅ ( Θ si, out, standard − Θ so, in, standard )
f T =
=
(A.6)
COP
T
⋅ ( Θ − Θ )
f T
COP eff
COP standard
T si,out,eff
T si,out,standard
Θ so,in,eff
Θ so,in,standard
c,
standard
si, out, standard
si, out, eff
so, in, eff
is the correction factor to account for the deviation of the temperature from the default
value;
is the coefficient of performance at effective source temperatures;
is the coefficient of performance under standard conditions;
is the effective outlet temperature on the sink side, in K;
is the outlet temperature on the sink side under standard conditions, in K;
is the effective outlet temperature on the source side, in °C;
is the inlet temperature on the source side under standard conditions, in °C.
The coefficient of performance under the effective temperature conditions and the losses P es can be corrected
by the coefficient of performance under standard conditions COP w,t using the temperature correction factor f t .
The sink temperature (and with it the coefficient of performance) varies during the operating period. The
coefficient of performance is corrected according to equation (A.7).
where
Θhw
Θ si + 273,
15
∫
dΘ
si
( Θ si − Θ so )
Θcw
COP c =
(A.7)
( Θhw
− Θcw
)
COP c
Θ cw
Θ hw
Θ si
Θ so
is the Carnot coefficient of performance;
is the cold water inlet temperature, in °C;
is the domestic hot water temperature used, in °C;
is the sink temperature of the heat pump, in °C;
is the source temperature of the heat pump, in °C.

The integral can be solved analytically, hence equation (A.8):.
where
DIN V 18599-5:2007-02
( Θso
+ 273,
15)
⎛Θ
− ⎞
= +
⋅ ⎜ hw Θ so
COP c 1
ln
⎟
( − ⎜
⎟
(A.8)
Θhw
Θcw
) ⎝ Θcw
− Θ so ⎠
COP c
Θ cw
Θ hw
Θ si
Θ so
is the Carnot coefficient of performance;
is the cold water inlet temperature, in °C;
is the domestic hot water temperature used, in °C;
is the sink temperature of the heat pump, in °C;
is the source temperature of the heat pump, in °C;
A.7 VRF systems: relative heat output performance
Table A.8 — Relative heat output performance
Outdoor temperature °C –7 2 7 10
COP a 2,79 3,09 3,65 3,85
Relative heat output at
Load ratio 100 % 0,81 0,96 1,00 1,00
Load ratio 90 % 0,89 1,00 1,00 1,00
Load ratio 80 % 0,97 1,00 1,00 1,00
Load ratio less than 75 % 1,00 1,00 1,00 1,00
a COP for a room temperature of 20 °C and load ratios between 10 % and 100 % (without defrosting).
113

DIN V 18599-5:2007-02
114
Figure A.9 — VRF systems: COP heating for load ratios between 10 % and 100 %
Figure A.10 — VRF systems: relative heat output performance

DIN V 18599-5:2007-02
Figure A.11 — VRF systems: relative COP heating for load ratios between 10 % and 100 %
115

DIN V 18599-5:2007-02
B.1 General information
116
Annex B
(informative)
Dimensioning of buildings
The dimensioning of buildings is described in terms of the length, the width, and also the number and height of
the storeys. Where buildings are not rectangular in shape, an arrangement of dimensioning parameters is
shown here as an example.
The individual dimensions summate to give the total building length L G and building width B G .
∑
LG = Li
and
i
Figure B.1 shows four examples of building geometry.
∑ Li
Bi
BG
i
LG
⋅
= (B.1)
a) EXAMPLE 1
Figure B.1 — Building geometry

) EXAMPLE 2
c) EXAMPLE 3
Figure B.1 (continued)
DIN V 18599-5:2007-02
117

DIN V 18599-5:2007-02
118
Alternatively, mean values can be used, as in d):
d) EXAMPLE 4
Figure B.1 (concluded)
B
G
=
∑
i
i
B
i

Bibliography
DIN V 18599-5:2007-02
[1] DIN 4753-4, Water heaters and water heating installations for drinking water and service water —
Part 4: Corrosion protection on the water side by means of hot-setting, duroplastic coating materials —
Requirements and testing
[2] DIN EN 215, Thermostatic heat radiator valves — Requirements and test methods
[3] DIN EN 832, Thermal performance of buildings — Calculation of energy use for heating - Residential
buildings
[4] DIN EN 12831, Heating systems in buildings — Method for calculation of the design heat load
[5] E DIN EN ISO 13789, Thermal performance of buildings — Transmission heat loss coefficient —
Calculation method
[6] VDI 2067, Economic efficiency of building installations
119