Bsi bs en 15316 2 3 2007

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BRITISH STANDARD

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

The European Standard EN 15316-2-3:2007 has the status of a
British Standard

ICS 91.140.10

12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:

BS EN
15316-2-3:2007


BS EN 15316-2-3:2007

National foreword
This British Standard is the UK implementation of EN 15316-2-3:2007.
The UK participation in its preparation was entrusted to Technical Committee
RHE/24, Central heating installations.
A list of organizations represented on this committee can be obtained on

request to its secretary.
This publication does not purport to include all the necessary provisions of a
contract. Users are responsible for its correct application.

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Compliance with a British Standard cannot confer immunity from
legal obligations.

This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 31 August 2007

© BSI 2007

ISBN 978 0 580 56021 7

Amendments issued since publication
Amd. No.

Date

Comments


EUROPEAN STANDARD

EN 15316-2-3

NORME EUROPÉENNE
EUROPÄISCHE NORM

July 2007

ICS 91.140.10

English Version

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

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Systèmes de chauffage dans les bâtiments - Méthode de
calcul des besoins énergétiques et des rendements des
systèmes - Partie 2-3: Systèmes de distribution de
chauffage des locaux

Heizsysteme in Gebäuden - Verfahren zur Berechnung der
Energieanforderungen und Nutzungsgrade der Anlagen Teil 2-3: Wärmeverteilungssysteme

This European Standard was approved by CEN on 21 June 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the

official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36

© 2007 CEN

All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

B-1050 Brussels

Ref. No. EN 15316-2-3:2007: E


EN 15316-2-3:2007 (E)

Contents

Page

Foreword..............................................................................................................................................................4

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Introduction .........................................................................................................................................................6
1

Scope ......................................................................................................................................................7

2

Normative references ............................................................................................................................7

3

Terms and definitions ...........................................................................................................................7

4

Symbols, units and indices ..................................................................................................................9

5

Principle of the method and definitions ............................................................................................10

6
6.1
6.2
6.3
6.3.1
6.3.2
6.3.3
6.3.4

6.3.5
6.4
6.5
6.6

Auxiliary energy demand ....................................................................................................................12
General..................................................................................................................................................12
Design hydraulic power ......................................................................................................................12
Detailed calculation method ...............................................................................................................13
Input/output data..................................................................................................................................13
Calculation method..............................................................................................................................14
Correction factors................................................................................................................................15
Expenditure energy factor ..................................................................................................................17
Intermittent operation..........................................................................................................................21
Deviations from the detailed calculation method.............................................................................23
Monthly auxiliary energy demand......................................................................................................23
Recoverable auxiliary energy .............................................................................................................24

7
7.1
7.2
7.2.1
7.2.2
7.2.3
7.2.4
7.2.5
7.3
7.4

System thermal loss of distribution systems ...................................................................................24

General..................................................................................................................................................24
Detailed calculation method ...............................................................................................................24
Input/output data..................................................................................................................................24
Calculation method..............................................................................................................................25
Thermal losses of accessories...........................................................................................................26
Recoverable and un-recoverable system thermal loss ...................................................................27
Total system thermal loss...................................................................................................................27
Calculation of linear thermal transmittance (W/mK):.......................................................................27
Calculation of mean part load of distribution per zone ...................................................................28

8
8.1
8.1.1
8.1.2
8.1.3
8.1.4
8.2
8.3
8.4
8.5

Calculation of supply and return temperature depending on mean part load of distribution.....28
Temperature calculation of heat emitters .........................................................................................28
General..................................................................................................................................................28
Continuous control depending on outdoor temperature ................................................................29
Continuous control with thermostatic valves...................................................................................29
On-Off control with room thermostat ................................................................................................30
Effect of by-pass connections............................................................................................................30
Effect of mixing valves ........................................................................................................................31
Parallel connection of distribution circuits.......................................................................................32

Primary circuits....................................................................................................................................33

Annex A (informative) Preferred procedures .................................................................................................34
A.1
Simplified calculation method for determination of annual auxiliary energy demand ................34
A.1.1 Input/output data..................................................................................................................................34
A.1.2 Calculation method..............................................................................................................................35
A.1.3 Correction factors................................................................................................................................37
A.1.4 Expenditure energy factor ..................................................................................................................37
A.1.5 Intermittent operation..........................................................................................................................38
A.1.6 Monthly auxiliary energy demand and recoverable auxiliary energy ............................................38

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EN 15316-2-3:2007 (E)

A.2
A.2.1
A.2.2
A.2.3
A.3
A.3.1
A.3.2
A.3.3
A.3.4
A.3.5
A.3.6
A.3.7
A.4

A.4.1
A.4.2
A.5

Tabulated calculation method for determination of annual auxiliary energy demand ................39
Input/output data .................................................................................................................................39
Calculation method, tabulated values...............................................................................................39
Monthly auxiliary energy demand and recoverable auxiliary energy ............................................41
Simplified calculation method for determination of annual system thermal loss........................41
Input/output data .................................................................................................................................41
Calculation method .............................................................................................................................42
Approximation of the length of pipes per zone in distribution systems .......................................42
Default values of the outer total surface coefficient of heat transfer (convection and
radiation) ..............................................................................................................................................43
Approximation of Ψ -values ..............................................................................................................43
Equivalent length of valves ................................................................................................................44
Default values for the exponent of the heat emission system .......................................................44
Tabulated calculation method for determination of annual system thermal loss ........................44
Input/output data .................................................................................................................................44
Calculation method, tabulated values...............................................................................................45
Example ................................................................................................................................................46

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Bibliography......................................................................................................................................................49

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EN 15316-2-3:2007 (E)

Foreword
This document (EN 15316-2-3:2007) has been prepared by Technical Committee CEN/TC 228 “Heating
systems in buildings”, the secretariat of which is held by DS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by January 2008, and conflicting national standards shall be withdrawn at
the latest by January 2008.

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This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive
2002/91/EC on the energy performance of buildings (EPBD). It forms part of a series of standards aimed at
European harmonisation of the methodology for calculation of the energy performance of buildings. An
overview of the whole set of standards is given in prCEN/TR 15615,.
The subjects covered by CEN/TC 228 are the following:

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design of heating systems (water based, electrical etc.);



installation of heating systems;



commissioning of heating systems;



instructions for operation, maintenance and use of heating systems;



methods for calculation of the design heat loss and heat loads;



methods for calculation of the energy performance of heating systems.

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Heating systems also include the effect of attached systems such as hot water production systems.

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All these standards are systems standards, i.e. they are based on requirements addressed to the system as a
whole and not dealing with requirements to the products within the system.
Where possible, reference is made to other European or International Standards, a.o. product standards.

However, use of products complying with relevant product standards is no guarantee of compliance with the
system requirements.
The requirements are mainly expressed as functional requirements, i.e. requirements dealing with the function
of the system and not specifying shape, material, dimensions or the like.
The guidelines describe ways to meet the requirements, but other ways to fulfil the functional requirements
might be used if fulfilment can be proved.
Heating systems differ among the member countries due to climate, traditions and national regulations. In
some cases requirements are given as classes so national or individual needs may be accommodated.
In cases where the standards contradict with national regulations, the latter should be followed.
EN 15316 Heating systems in buildings — Method for calculation of system energy requirements and system
efficiencies consists of the following parts:
Part 1: General

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EN 15316-2-3:2007 (E)

Part 2-1: Space heating emission systems
Part 2-3: Space heating distribution systems
Part 3-1: Domestic hot water systems, characterisation of needs (tapping requirements)
Part 3-2: Domestic hot water systems, distribution
Part 3-3: Domestic hot water systems, generation
Part 4-1: Space heating generation systems, combustion systems (boilers)
Part 4-2: Space heating generation systems, heat pump systems
Part 4-3: Heat generation systems, thermal solar systems

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Part 4-4: Heat generation systems, building-integrated cogeneration systems

Part 4-5: Space heating generation systems, the performance and quality of district heating and large volume
systems

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Part 4-6: Heat generation systems, photovoltaic systems

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

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.

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EN 15316-2-3:2007 (E)

Introduction
In a distribution system, energy is transported by a fluid from the heat generation to the heat emission. As the
distribution system is not adiabatic, part of the energy carried is emitted to the surrounding environment.
Energy is also required to distribute the heat carrier fluid within the distribution system. In most cases this is
electrical energy required by the circulation pumps. This leads to additional thermal and electrical energy
demand.
The thermal energy emitted by the distribution system and the electrical energy required for the distribution,
may partially be recovered as heat, if the distribution system is placed inside the heated envelope of the
building.

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This European Standard provides three methods of calculation.
The detailed calculation method describes the basics and the physical background of the general calculation
method. The required input data are part of the detailed project data assumed to be available (such as length
of pipes, type of insulation, manufacturer's data for the pumps etc.). The detailed calculation method provides
the most accurate energy demand and heat emission.

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For the simplified calculation method, some assumptions are made for the most relevant cases, reducing the
required input data (e.g. the lengths of pipes are calculated by approximations depending on the outer
dimensions of the building and efficiency of pumps is approximated). This method may be applied if only few
data are available (in general at an early stage of design). With the simplified calculation method, the
calculated energy demand is generally higher than the calculated energy demand by the detailed calculation
method. The assumptions made for the simplified method depend on national design, and therefore this
method is part of informative Annex A.

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The tabulated calculation method is based on the simplified calculation method, with some further
assumptions being made. Only input data for the most important influences are required with this method. The
further assumptions made for this method depend on national design as well, and therefore the tabulated
method is also part of informative Annex A.

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Other influences, which are not reflected by the tabulated values, shall be calculated by the simplified or the
detailed calculation method. The energy demand determined from the tabulated calculation method is
generally higher than the calculated energy demand by the simplified calculation method. Use of this method
is possible with a minimum of input data.
The general calculation method for the electrical energy demand of pumps consists of two parts. The first part
is calculation of the hydraulic demand of the distribution system, and the second part is calculation of the
expenditure energy factor of the pump. Here, it is possible to combine the detailed and the simplified
calculation method. For example, calculation of pressure loss and flow may be done by the detailed
calculation method and calculation of the expenditure energy factor may be done by the simplified calculation
method (when the data of the building are available and the data of the pump are not available) or vice versa.
In national annexes, the simplified calculation method as well as the tabulated calculation method could be
applied through a.o. relevant boundary conditions of each country, thus facilitating easy calculations and quick
results. In national annexes, it is only allowed to change the boundary conditions and other assumptions. The
calculation methods as described are to be applied.
The recoverable part of the auxiliary energy demand is given as a fixed ratio and is therefore also easy to
determine.

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EN 15316-2-3:2007 (E)

1

Scope

This European Standard provides a methodology to calculate/estimate the system thermal loss of water based

distribution systems for heating and the auxiliary energy demand, as well as the recoverable part of each. The
actual recovered energy depends on the gain to loss ratio. Different levels of accuracy, corresponding to the
needs of the user and the input data available at each design stage of the project, are provided in this
European Standard by different calculation methods, i.e. a detailed calculation method, a simplified calculation
method and a method based on tabulated values. The general method of calculation can be applied for any
time-step (hour, day, month or year).

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Pipework lengths for the heating of decentralised, non-domestic ventilation systems equipment are to be
calculated in the same way as for water based heating systems. For centralised, non-domestic ventilation
systems equipment, the length is to be specified in accordance with its location.
NOTE
It is possible to calculate the system thermal loss and auxiliary energy demand for cooling systems with the
same calculation methods as shown in this European Standard. Specifically, determination of auxiliary energy demand is
based on the same assumptions for efficiency of pumps, because the efficiency curve applied is an approximation for
inline and external motors. It needs to be decided by the standardisation group of CEN, whether or not the extension for
cooling systems should be made in this European Standard. This is also valid for distribution systems in HVAC (in ducts)
and also for special liquids.

2

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Normative references

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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.

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EN 12831, Heating systems in buildings — Method for calculation of the design heat load

3

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Terms and definitions

For the purposes of this document, the following terms and definitions apply.

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3.1
technical building system

technical equipment for heating, cooling, ventilation, domestic hot water, lighting and electricity production
composed by sub-systems
NOTE 1
A technical building system can refer to one or to several building services (e.g. heating system, heating and
domestic hot water system).
NOTE 2

Electricity production can include cogeneration and photovoltaic systems.

3.2
technical building sub-system
part of a technical building system that performs a specific function (e.g. heat generation, heat distribution,
heat emission)
3.3
space heating
process of heat supply for thermal comfort
3.4
auxiliary energy
electrical energy used by technical building systems for heating, cooling, ventilation and/or domestic hot water
to support energy transformation to satisfy energy needs

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EN 15316-2-3:2007 (E)

NOTE 1
This includes energy for fans, pumps, electronics etc. Electrical energy input to a ventilation system for air
transport and heat recovery is not considered as auxiliary energy, but as energy use for ventilation.
NOTE 2

In EN ISO 9488, the energy used for pumps and valves is called "parasitic energy".

3.5
heat recovery
heat generated by a technical building system or linked to a building use (e.g. domestic hot water) which is
utilised directly in the related system to lower the heat input and which would otherwise be wasted (e.g.
preheating of the combustion air by flue gas heat exchanger)
3.6
system thermal loss
thermal loss from a technical building system for heating, cooling, domestic hot water, humidification,
dehumidification, ventilation or lighting that does not contribute to the useful output of the system

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

3.7
recoverable system thermal loss
part of a system thermal loss which can be recovered to lower either the energy need for heating or cooling or
the energy use of the heating or cooling system

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3.8
recovered system thermal loss
part of the recoverable system thermal loss which has been recovered to lower either the energy need for
heating or cooling or the energy use of the heating or cooling system

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3.9
calculation step
discrete time interval for the calculation of the energy needs and uses for heating, cooling, humidification and
dehumidification

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NOTE
Typical discrete time intervals are one hour, one month or one heating and/or cooling season, operating
modes and bins.

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3.10
calculation period
period of time over which the calculation is performed
NOTE

The calculation period can be divided into a number of calculation steps.

3.11
heating or cooling season
period of the year during which a significant amount of energy for heating or cooling is needed
NOTE

8

The season lengths are used to determine the operation period of technical systems.


EN 15316-2-3:2007 (E)

4

Symbols, units and indices

For the purposes of this document, the symbols, units and indices given in Table 1 apply.
Table 1 — Symbols, units and indices

Ah , z
c
edis

Heated floor in the zone
Specific heat capacity
Expenditure energy factor for operation of circulation pump

fS
f NET
f S , des

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f HB
f G , PM
f PL
fC
f PSP
fϑ
f q&

[-]

Correction factor for hydraulic networks (layout)

[-]

Correction factor for heating surface design

[-]

Correction factor for hydraulic balance

[-]

Correction factor for generators with integrated pump management

[-]

Correction factor for partial load characteristics

[-]

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Correction factor for control of the pump

w.

Correction factor for selection of design point

Correction factor for differential temperature dimensioning

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bz

Correction factor for surface related heating load
Correction factor for efficiency

hlev

LL
Lmax

Floor height

∆p des

[J/kg K]
[-]

Correction factor for supply flow temperature control

fη

LW
k by
n
N lev

[m²]

Building length

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[-]
[-]
[-]

[-]
[-]
[m]
[m]

Maximum length of pipe

[m]

Building width

[m]

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Ratio of flow over the heat emitter to flow in the ring

[-]

Exponent of the heat emission system

[-]

Number of floors

[-]

标准

Differential pressure at design point

[kPa]

∆p HS
∆pCV

Differential pressure of heating surfaces

[kPa]

Differential pressure of control valves for heating surfaces

[kPa]

∆p ZV
∆p G

Differential pressure of zone valves

[kPa]

Differential pressure of heat supply

[kPa]

∆pFH
∆p ADD
Phydr , des

Differential pressure of floor heating systems

[kPa]

Differential pressure of additional resistances

[kPa]

Hydraulic power at design point

[W]

Pel , pmp

Actual power input

[W]

Pel , pmp , ref

Reference power input

[W]

ΦH
QH ,dis ,aux ,rbl

Design heating load
Recoverable auxiliary energy for space heating

[kWh/time step]

Q H ,dis ,aux ,rvd

Recovered auxiliary energy in the distribution system

[kWh/time step]

[kW]

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EN 15316-2-3:2007 (E)

QH ,dis ,ls ,an

Annual system thermal loss of the distribution system

[kWh/year]

QH ,dis ,ls ,rbl ,an

Recoverable system thermal losses for space heating

[kWh/year]

Q H ,dis ,ls ,nrbl ,an Unrecoverable system thermal losses
Pressure loss in pipes

R
top , an
Heating hours per year

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[kPa/m]
[h/year]

Ψ
V&des
V&

Linear thermal transmittance

WH , dis , aux , an

Annual auxiliary energy demand

WH , dis , aux , m

Monthly auxiliary energy demand

[kWh/month]

WH , dis , hydr , an

Annual hydraulic energy demand

[kWh/year]

min

[W/mK]

Flow at design point

[m³/h]

Minimum volume flow

[m³/h]
[kWh/year]

f comp

Resistance ratio of components

[-]

k
kb

Time factor

[-]

Boost mode time factor

[-]

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kr
k setb

Regular mode time factor

∆ϑdis, des

Design heating system temperature difference

ηP

Efficiency of pump at design point

β dis

w.

Set back mode time factor

Specific density

θi
θm
θu
θs

θr
θ s , des

Surrounding temperature

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Mean medium temperature

x
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bz

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Mean part load of the distribution

ρ

θ r , des
5

[kWh/year]

[-]
[-]

[K]
[-]
[-]
[kg/m³]
[°C]
[°C]

Temperature in unheated space

[°C]

Supply temperature

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[°C]

Return temperature

[°C]

Design supply temperature

[°C]

Design return temperature

[°C]

Principle of the method and definitions

The method allows the calculation of the system thermal loss and the auxiliary energy demand of water based
distribution systems for heating circuits (primary and secondary), as well as the recoverable system thermal
losses and the recoverable auxiliary energy.
As shown in Figure 1, a heating system can be divided in three parts – emission and control, distribution and
generation. A simple heating system has no buffer-storage, no distributor/collector, and only one pump is
applied. Larger heating systems comprise more than one secondary heating circuit with different emitters.
Often, such larger heating systems comprise also more than one heat generator with either one common
primary heating circuit or individual primary heating circuits (in Figure 1, only one primary heating circuit is
shown).
The subdivision of the heating system into primary and secondary circuits is given by any hydraulic separator,
which can be a buffer-storage with a large volume or a hydraulic separator with a small volume. Anyhow, the

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EN 15316-2-3:2007 (E)

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calculation method is valid for a closed heating circuit, and therefore the equations have to be applied for each
circuit taking into account the corresponding values.

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Key
1
2
3
4
5
6
7
8
9
10
11

next heating circuit
pump

room
emission
buffer-storage
pump
generator
generation
distribution
primary heating circuits
secondary heating circuits
Figure 1 — Scheme distribution and definitions of heating circuits

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EN 15316-2-3:2007 (E)

Controls in distribution systems are thermostatic valves at the emitter which throttles the flow or room
thermostats which shut on/off the pump. Only if the flow is throttled the control of the pump (speed control) is
valid.

6

Auxiliary energy demand

6.1 General
The auxiliary energy demand of hydraulic networks depends on the distributed flow, the pressure drop and the
operation condition of the circulation pump. While the design flow and pressure drop is important for
determining the pump size, the part load factor determines the energy demand in a time step.

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The hydraulic power at the design point can be calculated from physical basics. However, for calculation of
the hydraulic power during operation, this can only be achieved by a simulation. Therefore, for the detailed
calculation method in this standard, correction factors are applied, which represent the most important
influences on auxiliary energy demand, such as part load, controls, design criteria.
The general calculation approach is to separate the hydraulic demand, which depends on the design of the
network, and the expenditure energy for operation of the circulation pump, which takes into account the
efficiency of the pump in general. However, for calculation of the expenditure energy during operation,
knowledge of the efficiency of the pump at each operation point is required, Therefore, for the detailed
calculation method in this European Standard, correction factors are applied, which represent the most
important influences on expenditure energy, such as efficiency, part load, design point selection and control.

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All the calculations are made for a zone of the building with the affiliated area, length, width, floor height and
number of floors.

6.2 Design hydraulic power

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For all the calculations, the hydraulic power and the differential pressure of the distribution system at the
design point are important. The hydraulic power is given by:

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Phydr , des = 0,2778 ⋅ ∆pdes ⋅ V&des

where

[W]

(1)

标准

is the flow at design point [m³/h];
V&des
∆pdes is the differential pressure at design point [kPa].
The flow is calculated from the heat load Φ H , em , out of the zone (the design heat load shall be according to
EN 12831) and the design temperature difference

∆ϑdis, des of the heating system:

3600 ⋅ Φ H , em.out
V&des =

c ⋅ ρ ⋅ ∆ϑdis , des
where

c

is the specific heat capacity [kJ/kg K];

ρ

is the density [kg/m³];

12

[m³/h]

(2)


EN 15316-2-3:2007 (E)

∆ϑdis, des

is the design temperature difference [K].

The differential pressure for a zone at the design point is determined by the resistance in the pipes (including
components) and the additional resistances (the most important are listed below):

∆pdes = (1 + f comp ) ⋅ R ⋅ Lmax + ∆pHS + ∆pCV + ∆pZV + ∆pG + ∆p ADD [kPa]

(3)

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where

f comp

is the resistance ratio of components [-];

R

is the pressure loss per m [kPa/m];

Lmax

is the maximum pipe length of the heating circuit [m];

∆pHS is the differential pressure of heating surface [kPa];
∆pCV is the differential pressure of control valve for heating surface [kPa];
∆pZV is the differential pressure of zone valves [kPa];
∆pG

is the differential pressure of heat supply [kPa];

f
z
b

m
o

c

.
w
x

.
w
ww

∆p ADD is the differential pressure of additional resistances [kPa].
6.3 Detailed calculation method
6.3.1

网
享
分

Input/output data

标准

The input data for the detailed calculation method are listed below. These are all part of the detailed project
data.

Phydr , des

hydraulic power at the design point for the zone [in W]
-

by calculation according to Equations (1) and (2)

Φ H , em , out design heat load of the zone according to EN 12831;

∆ϑdis, des

design temperature difference for the distribution system in the zone [K];

Lmax

maximum pipe length of the heating circuit in the zone [m];

∆p

differential pressure of the circuit in the zone [kPa];

β dis

mean part load of the distribution [-];

top , an

heating hours per year [h/year];

13


EN 15316-2-3:2007 (E)

fS

correction factor for supply flow temperature control [-];

f NET

correction factor for hydraulic networks [-];

f SD

correction factor for heating surface dimensioning [-];

f HB

correction factor for hydraulic balance [-];

edis

expenditure energy factor for operation of the circulation pump [-]

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-

by calculation according to 6.3.4;

fη

correction factor for efficiency [-];

f PL

correction factor for part load [-];

f PSP

correction factor for design point selection [-];

fC

correction factor for control of the pump [-].

Type of pump control
Design temperature level
Heat emitter type
Intermittent operation
The output data of the detailed calculation method are:

WH , dis , aux , an

annual auxiliary energy demand [kWh/year];

WH , dis , aux , m

monthly auxiliary energy demand [kWh/month];

Q H ,dis ,aux ,rvd

recovered auxiliary energy in the distribution system [kWh/time step];

QH ,dis ,aux ,rbl

recoverable auxiliary energy for space heating [kWh/time step].

6.3.2

Calculation method

The annual auxiliary energy demand for circulation pumps for water based heating systems is calculated by:

WH , dis , aux , an = WH , dis , hydr , an ⋅ edis
where

WH , dis , aux , an

14

is the annual auxiliary energy demand [kWh/year];

[kWh/year]

(4)


EN 15316-2-3:2007 (E)

WH , dis , hydr , an

is the annual hydraulic energy demand [kWh/year];

edis

is the expenditure energy factor for operation of circulation pump [-].

The hydraulic energy demand for the circulation pumps in heating systems, is determined from the hydraulic
power at the design point ( Phydr , des ), the mean part load of the distribution ( β dis ) and the heating hours in the
time step ( top , an ):

WH , dis , hydr , an =

Phydr , des
1000

⋅ β dis ⋅ top , an ⋅ f S ⋅ f NET ⋅ f SD ⋅ f HB ⋅ f G , PM

[kWh/year]

(5)

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where

Phydr , des

is the hydraulic power at design point [W];

β dis

is the mean part load of the distribution [-];

top , an

are the heating hours per year [h/year];

fS

is the correction factor for supply flow temperature control [-];

f NET

is the correction factor for hydraulic networks [-];

f SD

is the correction factor for heating surface dimensioning [-];

f HB

is the correction factor for hydraulic balance [-];

f G , PM

is the correction factor for generators with integrated pump management [-].

The correction factors,

f S , f NET and f SD include the most important parameters related to dimensioning of

the heating system. The factor

f HB takes into account the hydraulic balance of the distribution system. The

correction factor f G , PM for generators with integrated pump management, takes into account the reduction of
operation time in relation to the heating time.
6.3.3
6.3.3.1

Correction factors
General

The correction factors are based on a wide range of simulations of different networks. Some of the correction
factors can not be changed without changing the method. Correction factors, which are based on
assumptions, may be changed on a national level in a national annex (see A.1.3).
6.3.3.2

fS = 1

Correction factor for supply flow temperature control

fS

for systems with outdoor temperature compensation;

15


EN 15316-2-3:2007 (E)

fS

see Figure 2, for systems without outdoor temperature compensation (i.e. constant flow

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temperature) or very much higher flow temperature than necessary.

Key

f S [-]

1

correction factor

2
3

ground plan AN [m²]
flow temperature characteristics

Figure 2 — Correction factor
6.3.3.3

f S for constant flow temperature and very much higher flow temperature

Correction factor for hydraulic networks

f NET

f NET = 1 for a two-pipe ring line horizontal layout (on each floor);

f NET
see Table 2 for other types of layout.
Table 2 — Correction factor
Network design
2 – pipe system
Ring line
Ascending – pipe
Star-shaped

16

f NET for hydraulic network
One family
house

Dwellings

1,0
0,93
0,98

1,0
0,92
0,98


EN 15316-2-3:2007 (E)

The star-shaped network design is also valid for floor heating systems.
For one-pipe heating systems, the correction factor

f NET is given by:

f NET = 8,6 ⋅ k by + 0,7

[-]

(6)

where

k by

is the ratio of flow over the heat emitter to flow in the ring [-].

6.3.3.4

Correction factor for heating surface dimensioning

f SD = 1

f SD

for dimensioning according to design heat load;

f SD = 0,96 in case of additional over-sizing of the heating surfaces.

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6.3.3.5

Correction factor for hydraulic balance

f HB

See A.1.3.
Correction factor for generators with integrated pump management f G , PM

6.3.3.6
See A.1.3.
6.3.4
6.3.4.1

Expenditure energy factor
General

For assessment of partial load conditions and control performance of the circulation pump, the expenditure
energy factor is determined by:

edis = fη ⋅ f PL ⋅ f PSP ⋅ f C

[-]

(7)

where

fη

is the correction factor for efficiency [-];

f PL

is the correction factor for part load [-];

f PSP

is the correction factor for design point selection [-];

fC

is the correction factor for control [-].

With these four correction factors, the expenditure energy factor take into account the most important
influences on the energy demand, representing the design, the efficiency of the pump, the part load and the
control.
The physical relations are shown in Figure 3.

17


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EN 15316-2-3:2007 (E)

Key
1

pressure head H [m]

2

power P1 [W]

3

flow rate [m³/h]

4

H0,max

5
7

Hpmp
HPL

6

Hdes

8

Phydr,des

9

PPL

10 Pel,pmp

11 Pel,pmp,max

12 PPL,C

13 Pel,pmp,ref
14

15 V&

V&PL

16

f PL =

18

fη =

PPL,C
PPL

Pel , pump , ref
Phydr , des

17

f PSP =

19

f PL =

Pel , pump
Pel , pump ,ref

PPL
β dis ⋅ Pel , pump

Figure 3 — Expenditure energy factor - physical interpretation of the correction factors

18


EN 15316-2-3:2007 (E)

6.3.4.2

Correction factor for efficiency f η

The correction factor for efficiency is given by the relation between the reference power input at the design
point and the hydraulic power at the design point:

fη =

Pel , pmp , ref
Phydr , des

[-]

(8)

The reference power input is calculated by means of the hydraulic characteristics of the pump:

Pel , pmp , ref

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6.3.4.3

0, 5

 200  


= Phydr , des ⋅ 1,25 + 

P
 
 hydr , des  


Correction factor for part load

[W]

(9)

f PL

The correction factor for part load takes into account the reduction of pump efficiency by partial load. It also
takes into account the hydraulic characteristics of non-controlled pumps. The impact of the partial load on the
pipe system, and thus on the hydraulic energy demand, is taken into account by the mean part load of the
distribution β dis , according to 6.3.2.
Figure 4 shows the correction factor for part load of the pump, depending on the mean part load of the
distribution.

Key
1
2
3

correction factor fPL [-]
mean part load of distribution ßdis
mean part load ratio (PLR)
Figure 4 — Correction factor for part load of the pump

19


EN 15316-2-3:2007 (E)

6.3.4.4

Correction factor for design point selection

f PSP

f PSP is given by the relation between the actual power input of

The correction factor for design point selection

the pump and the reference power input at the design point:

f PSP =

Pel , pmp
Pel , pmp , ref

[-]

where

Pel , pmp

is the actual power input of pump at design point [W];

Pel , pmp , ref

is the reference power input of pump at design point [W].

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6.3.4.5

fC = 1
fC

Correction factor for control of the pump

fC

for non-controlled pumps;
see Figure 5 for controlled pumps.

Key
1
2
3

correction factor for control of the pump fC [-]
Pel,pmp,max / Pel,pmp
∆pconst - control

4

∆p var i - control

5

pump control
Figure 5 — Correction factor for control of the pump

20

(10)

EN 15316-2-3:2007 (E)

The constant differential pressure control of the pump, keeps the differential pressure of the pump constant at
the design value within the whole flow area. The variable differential pressure control varies the differential
pressure of the pump from the design value at design flow to often half of the design value at zero flow.
If a wall hanging generator, with integrated pump management, has a modulation control of the pump
depending on the temperature difference between supply and return, then the correction factor for ∆p var i is
valid.
6.3.5

Intermittent operation

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For intermittent operation, there are three different phases (see Figure 6):


set back mode;



boost period;



regular mode.

Key
1
2

3
4
5
6

room temperature
time
set back
boost
regular mode
set back
Figure 6 — Intermittent operation, phases

21


EN 15316-2-3:2007 (E)

The annual auxiliary energy demand for intermittent operation is given by the sum of auxiliary energy demand
for each phase:

WH ,dis ,aux ,an ,im = WH ,dis ,aux ,an ,reg + WH ,dis ,aux ,an ,setb + WH ,dis ,aux ,an ,boost

[kWh/year]

(11)

For the regular mode operation, the auxiliary energy demand is determined from Equation (4) in 6.3.2 and by
multiplication with a time factor for the proportional time of regular mode operation, kr :

WH , dis , aux , an , reg = k r ⋅ WH , dis , hydr , an ⋅ edis

[kWh/year]

(12)

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For the set back operation, it is necessary to distinguish between:


turn off mode, for which the auxiliary energy demand of the pump is zero - WH , dis , aux , an , setb = 0 ;



set back of supply temperature and minimum speed of the pump. When the pump is operated at
minimum speed, the power is assumed to be constant as follows:

Pel , pmp , setb = 0,3 ⋅ Pel , pmp , max

[W]

(13)

and the auxiliary energy demand is determined by multiplication with a time factor for the proportional time
of set back operation, k setb :

WH , dis , aux , an, setb = ksetb ⋅


Pel , pmp , setb
1000

⋅ top , an

[kWh/year]

(14)

set back of supply temperature. If thermostatic valves in this mode are not set back, the flow
compensates the lower supply temperature and the auxiliary energy demand is not reduced. For this type
of set back operation, the auxiliary energy demand is calculated as for the regular mode operation. The
correction factor for control to be applied is f C = 1 in case of room temperature control with constant
value (no changes between regular mode and set back mode). In case of room temperature control with
set back, f C depends on the type of pump control (see Figure 5).

For the boost mode operation, the power

Pel , pmp,boost is equal to the power Pel , pmp , des at the design point. The

auxiliary energy demand for the boost mode operation is determined by multiplication with a time factor for the
proportional time of boost mode operation, kb :

WH ,dis ,aux ,an ,boost = k b ⋅

Pel , pmp ,boost
1000

⋅ top ,an

[kWh/year]

(15)

The time factors can be calculated according to ratios of time periods.
The regular mode time factor,

kr , expresses the number of hours of regular mode operation top , r per total

number of hours per time period

kr =

22

top , r
tP

t P (period could be day, week, month or year):
[-]

(16)


EN 15316-2-3:2007 (E)

The boost mode time factor,

kb , expresses the number of hours of boost mode operation per total number of

hours per time period t P . The number of hours of boost mode operation is typically one or two hours per day,
as an average over the year, and may be calculated in accordance with EN ISO 13790:

kb =

top ,boost
tP

[-]

(17)

The set back mode time factor,

k setb , expresses the number of hours of set back mode operation per total

number of hours per time period

t P and is determined from kr and kb :

k setb = 1 − kr − kb

[-]

(18)

6.4 Deviations from the detailed calculation method

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For some applications, deviations from the detailed calculation method are taken into account:


One-pipe heating systems
The total flow in the heating circuit and in the pump is constant. The pump is always working at the design
point. The mean part load of distribution is β dis = 1



Overflow valves
Overflow valves are used to ensure a minimum flow at the heat generator or a maximum differential
pressure at the heat emitter. The function of the overflow valve is given by the interaction between the
pressure loss of the system, the characteristics of the pump and the set point of the overflow valve. The
influence on hydraulic energy demand can be estimated by applying a corrected mean part load of
′ :
distribution, β dis

V&

′ = β dis + (1 − β dis ) ⋅ min
β dis
V&des

[-]

(19)

where

β dis

is the mean part load of distribution;

V&des

is the design volume flow [m³/h];

V&min

is the minimum volume flow [m³/h].

The minimum volume flow takes into account the requirements of the heat generator or the maximum
pressure loss of the heat emitter.

6.5 Monthly auxiliary energy demand
In the detailed calculation method, as well as in the simplified and tabulated calculation methods, the annual
auxiliary energy demand WH , dis , aux , an is determined. Where necessary, the monthly auxiliary energy demand
is calculated by:

WH , dis , aux , m = WH , dis , aux , an ⋅

β dis , m ⋅ top , m
β dis , an ⋅ top , an

[kWh/month]

(20)

23