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NORMAEUROPEA
Pagina IUNI EN 15316-3-2:2008
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UNI EN 15316-3-2
MAGGIO 2008
Impianti di riscaldamento degli edificiMetodo per il calcolo dei
requisiti energetici e dei rendimenti dellimpiantoParte 3-2:
Impianti per la produzione di acqua calda sanitaria,
distribuzione
Heating systems in buildingsMethod for calculation of system
energy requirements and system efficienciesPart 3-2: Domestic hot
water systems, distribution
La norma fa parte di una serie di norme sul metodo di calcolo
deirequisiti energetici e dei rendimenti dellimpianto di
riscaldamentodegli edifici.La norma ha lo scopo di fornire i metodi
di calcolo per:- le perdite termiche dellimpianto di distribuzione
di acqua calda
sanitaria;- le perdite termiche dellimpianto di distribuzione di
acqua calda
sanitaria recuperabili per il riscaldamento degli ambienti;-
lenergia ausiliaria dellimpianto di distribuzione di acqua
calda
sanitaria.
TESTO INGLESE
La presente norma la versione ufficiale in lingua inglese
dellanorma europea EN 15316-3-2 (edizione ottobre 2007) e
tieneconto delle correzioni introdotte il 24 ottobre 2007.
ICS 91.140.10
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UNI Pagina IIUNI EN 15316-3-2:2008
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PREMESSA NAZIONALELa presente norma costituisce il recepimento,
in lingua inglese, del-la norma europea EN 15316-3-2 (edizione
ottobre 2007 con corre-zioni del 24 ottobre 2007), che assume cos
lo status di norma na-zionale italiana.
La presente norma stata elaborata sotto la competenza
dellentefederato allUNICTI - Comitato Termotecnico Italiano
La presente norma stata ratificata dal Presidente dellUNI ed
entrata a far parte del corpo normativo nazionale il 22 maggio
2008.
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EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORM
EN 15316-3-2
October 2007
ICS 91.140.10
English Version
Heating systems in buildings - Method for calculation of
systemenergy requirements and system efficiencies - Part 3-2:
Domestic hot water systems, distribution
Systmes de chauffage dans les btiments - Mthode decalcul des
besoins nergtiques et des rendements dessystmes - Partie 3-2 :
Systmes de production d'eau
chaude sanitaire, distribution
Heizungsanlagen in Gebuden - Verfahren zur Berechnungder
Energieanforderungen und Nutzungsgrade der Anlagen
- Teil 3-2: Trinkwassererwrmung, Verteilung
This European Standard was approved by CEN on 18 August
2007.
CEN members are bound to comply with the CEN/CENELEC Internal
Regulations which stipulate the conditions for giving this
EuropeanStandard the status of a national standard without any
alteration. Up-to-date lists and bibliographical references
concerning such nationalstandards 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
translationunder the responsibility of a CEN member into its own
language and notified to the CEN Management Centre has the same
status as theofficial 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 STANDARDIZATIONC O M I T E U R O P E N D
E N O R M A LI S A T I O NEUR OP IS C HES KOM ITEE FR NOR M UNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
2007 CEN All rights of exploitation in any form and by any means
reservedworldwide for CEN national Members.
Ref. No. EN 15316-3-2:2007: E
UNI EN 15316-3-2:2008
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rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
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EN 15316-3-2:2007 (E)
2
Contents Page
Foreword..............................................................................................................................................................4Introduction
.........................................................................................................................................................61
Scope
......................................................................................................................................................72
Normative references
............................................................................................................................73
Terms and definitions
...........................................................................................................................74
Symbols, units and indices
................................................................................................................105
Domestic hot water system
characteristics......................................................................................115.1
General..................................................................................................................................................115.2
Single zone and single
system...........................................................................................................125.3
Single zone and multiple systems
.....................................................................................................125.4
Multiple zones with single
system.....................................................................................................136
Distribution thermal losses
................................................................................................................136.1
Total distribution thermal losses
.......................................................................................................136.2
Thermal losses from individual distribution pipe
section...............................................................146.2.1
General..................................................................................................................................................146.2.2
Thermal losses from pipes based on dwelling area
........................................................................146.2.3
Thermal losses from pipes based on pipe lengths and number of
tappings per day..................156.2.4 Thermal losses from pipes
based on pipe lengths and distribution
efficiencies.........................156.2.5 Thermal losses from
pipes based on pipe lengths and tapping profiles
......................................166.2.6 Thermal losses from
pipes based on pipe lengths and average
temperature..............................166.2.7 Heat energy lost
due to wasted hot
water.........................................................................................166.2.8
Time
periods.........................................................................................................................................166.3
Thermal losses from circulation
loop................................................................................................166.3.1
General..................................................................................................................................................166.3.2
Thermal losses from circulation loop based on pipe length and a
fixed value of heat loss .......166.3.3 Thermal losses from
circulation loop based on a physical
approach...........................................176.3.4
Additional thermal losses from circulation loop during periods of
no circulation ......................176.3.5 Total thermal loss
from circulation loop
...........................................................................................176.4
Thermal losses due to accessories
...................................................................................................186.5
User outlets
..........................................................................................................................................187
Auxiliary
energy...................................................................................................................................187.1
Total auxiliary energy consumption
..................................................................................................187.2
Auxiliary energy consumption for ribbon heating
...........................................................................187.3
Auxiliary energy consumption for pumps
........................................................................................197.3.1
General..................................................................................................................................................197.3.2
Simplified
method................................................................................................................................197.3.3
Detailed calculation method
...............................................................................................................208
Recoverable, recovered and unrecoverable system losses
...........................................................20Annex
A (informative) Calculation of thermal losses from pipes based on
pipe lengths and the
number of tappings per day
...............................................................................................................22Annex
B (informative) Calculation of thermal losses from pipes based on
pipe lengths and
distribution efficiencies
......................................................................................................................24Annex
C (informative) Calculation of thermal losses from pipes based on
pipe lengths and
tapping profiles
....................................................................................................................................26Annex
D (informative) Calculation of thermal losses from circulation
loop...............................................28
UNI EN 15316-3-2:2008
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EN 15316-3-2:2007 (E)
3
D.1 Calculation of thermal losses based on pipe length
.......................................................................28D.2
Thermal losses based on a detailed calculation
method................................................................28D.2.1
General
.................................................................................................................................................28D.2.2
Determination of length of pipe
sections..........................................................................................28D.2.3
Determination of heat transfer coefficients
......................................................................................31D.2.4
Tabulated method for calculation of linear thermal
transmittance................................................33D.2.5
Determination of average ambient
temperature...............................................................................34D.2.6
Determination of average hot water temperature of pipe
section..................................................34Annex E
(informative) Calculation of thermal losses from user outlets
.....................................................35Annex F
(informative) Calculation of auxiliary energy requirement of a
circulation pump ......................36F.1 Simplified method for
calculation of auxiliary energy requirement of a circulation
pump.........36F.2 Detailed method for calculation of auxiliary
energy requirement of a circulation pump ............36F.2.1
Hydraulic energy requirement
...........................................................................................................36F.2.2
Hydraulic power required by the
pump.............................................................................................36F.2.3
Duration of the provision of domestic hot water
.............................................................................37F.2.4
Pump performance
coefficient...........................................................................................................38F.2.5
Intermittent pump
operation...............................................................................................................39F.2.6
Expenditure value coefficient
............................................................................................................39F.3
Auxiliary energy recoverable factor
..................................................................................................40Bibliography......................................................................................................................................................41
UNI EN 15316-3-2:2008
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EN 15316-3-2:2007 (E)
4
Foreword
This document (EN 15316-3-2:2007) 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 April 2008, and conflicting national
standards shall be withdrawn at the latest by April 2008.
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:
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.
Heating systems also include the effect of attached systems such
as hot water production systems.
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.
UNI EN 15316-3-2:2008
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EN 15316-3-2:2007 (E)
5
EN 15316 Heating systems in buildings Method for calculation of
system energy requirements and system efficiencies consists of the
following parts:
Part 1: General
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
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
Part 4-6: Heat generation systems, photovoltaic systems
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 15316-3-2:2007 (E)
6
Introduction
This European Standard is one of a number of standards that
together describe methods for calculation of system energy
requirements and system efficiencies related to domestic hot water
systems. In particular this European Standard specifies methods for
calculation of the energy losses of the distribution system.
The user needs to refer to other European Standards or to
national documents for input data and detailed calculation
procedures not provided by this European Standard.
Only the calculation methods are normative. Values necessary to
complete the calculations should be given in a national annex.
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EN 15316-3-2:2007 (E)
7
1 Scope
This European Standard is part of a set of standards covering
methods for calculation of system energy requirements and system
efficiencies of heating systems in buildings. In particular this
European Standard is one of a number of standards dealing with
domestic hot water systems.
The scope of this specific part is to standardise the methods
for calculation of:
thermal losses from the domestic hot water distribution
system;
recoverable thermal losses for space heating from the domestic
hot water distribution system;
auxiliary energy of the domestic hot water distribution
system.
These values are input data for calculation of the overall
energy use according to prEN 15603 and EN 15316-1.
This European Standard specifies the:
inputs;
calculation methods;
outputs.
2 Normative references
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.
Not applicable
3 Terms and definitions
For the purposes of this document, the following terms and
definitions apply.
3.1auxiliary 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
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".
3.2buildingconstruction as a whole, including its envelope and
all technical building systems, for which energy is used to
condition the indoor climate, to provide domestic hot water and
illumination and other services related to the use of the
building
NOTE The term can refer to the building as a whole or to parts
thereof that have been designed or altered to be used
separately.
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EN 15316-3-2:2007 (E)
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3.3circulation loop part of the domestic hot water distribution
system where the water circulation is maintained by a pump
operating continuously or in cycles during a day
NOTE Where there is a circulation loop, there are heat losses
from the pipes during the whole period of water circulation and not
only related to hot water draw-offs.
3.4calculation period period of time over which the calculation
is performed
NOTE The calculation period can be divided into a number of
calculation steps.
3.5domestic hot water heating process of heat supply to raise
the temperature of the cold water to the intended delivery
temperature
3.6domestic hot water distribution system distribution pipes
installed between the heat generator or hot water storage vessel
(if present) and the user outlet or outlets. The domestic hot water
distribution system may include a circulation loop and individual
sections
3.7individual section of the domestic hot water distribution
system part of the domestic hot water distribution system where the
circulation of the domestic hot water is not maintained by a pump
but only due to the draw offs
NOTE The heat losses occur due to the energy used in heating up
the pipes and fittings of the distribution system.
3.8energy need for domestic hot water heat to be delivered to
the needed amount of domestic hot water to raise its temperature
from the cold network temperature to the prefixed delivery
temperature at the delivery point, not taking into account the
technical building thermal systems
3.9energy use for space heating or cooling or domestic hot water
energy input to the space heating or cooling system or the domestic
hot water system to satisfy the energy need for space heating or
cooling (including dehumidification) or domestic hot water,
respectively
NOTE If the technical building system serves several purposes
(e.g. space heating and domestic hot water), it can be difficult to
split the energy use into that used for each purpose. It can be
indicated as a combined quantity (e.g. energy need for space
heating and domestic hot water).
3.10heating or cooling season period of the year during which a
significant amount of energy for heating or cooling is needed
NOTE The season lengths are used to determine the operation
period of technical systems.
3.11heat 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)
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EN 15316-3-2:2007 (E)
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3.12recoverable system thermal loss part of a system thermal
loss which can be recovered to lower either the energy need for
heating or cooling or the energy use of the heating or cooling
system
NOTE This depends on the calculation approach chosen to
calculate the recovered gains and losses (holistic or simplified
approach).
3.13recovered 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
3.14ribbon heating also called trace heating. Electrical
resistance enveloping the pipes (one way) used to compensate the
heat loss of the pipes in order to maintain the domestic hot water
temperature in the distribution system at a required
temperature
3.15system boundary boundary that includes within it all areas
associated with the building (both inside and outside the building)
where energy is consumed or produced
NOTE Inside the system boundary the system losses are taken into
account explicitly, outside the system boundary they are taken into
account in the conversion factor.
3.16system thermal loss thermal loss from a technical building
system for heating, cooling, domestic hot water, humidification,
dehumidification, or ventilation or lighting that does not
contribute to the useful output of the system
NOTE 1 A system loss can become an internal heat gain for the
building, if it is recovered.
NOTE 2 Thermal energy recovered directly in the subsystem is not
considered as a system thermal loss but as heat recovery and
directly treated in the related system standard.
NOTE 3 Heat dissipated by the lighting system or by other
services (e.g. appliances of computer equipment) is not part of the
system thermal losses, but part of the internal heat gains.
3.17tapping program 24-hour cycle that defines a number of
domestic hot water draw-off requirements: succession of energy
needs corresponding to uses of domestic hot water during a day
3.18technical building system technical equipment for heating,
cooling, ventilation, domestic hot water, lighting and electricity
production composed of sub-systems
NOTE 1 A technical building system can refer to one or to
several building services (e.g. heating system, space heating and
domestic hot water system).
NOTE 2 Electricity production can include cogeneration and
photovoltaic systems.
3.19technical building sub-system part of a technical building
system that performs a specific function (e.g. heat generation,
heat distribution, heat emission)
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EN 15316-3-2:2007 (E)
10
3.20zone part of a building for which the energy need for
domestic hot water is to be calculated
4 Symbols, units and indices
For the purposes of this document, the following symbols and
units (Table 1) and indices (Table 2) apply.
Table 1 Symbols and units
Symbol Name of quantity Unit
A area m2
b location factor -
c specific heat capacity J/(kg K)
e system performance coefficient (expenditure factor) -
D diameter m
f conversion factor -
h height m
L length m
m mass kg
n number of operating times -
t time, period of time s
Q quantity of heat, energy J
thermal power W P electrical power W
heat loss coefficient W/mK
V volume m3
W auxiliary (electrical) energy J
energy loss factor -
efficiency - celsius temperature C heat conductivity W/mK
Table 2 Indices
amb ambient gen generation nom nominal
avg average hs heated space on circulation
B building hydr hydraulic off no circulation
col circulation loop (collective) in input to system out output
from system
dis distribution ind individual pmp pump
e external int internal rib trace heating
em emission ls losses tap deliveries
f floor nhs non heated space W domestic hot water
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rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
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, e tc . . . )
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EN 15316-3-2:2007 (E)
11
5 Domestic hot water system characteristics
5.1 General
The domestic hot water distribution system is given as one or
more pipes installed between the heat generator or hot water
storage vessel (if present) and the user outlet or outlets. The
domestic hot water distribution system may include a circulation
loop.
The most basic system, for which this method is applied,
consists of a single distribution pipe connecting a single heat
generator, or a storage vessel, and a user outlet (e.g. tap or
shower head). This is shown in Figure 1.
Key
1 generation
2 storage
3 distribution
4 emission
Figure 1 Basic domestic hot water system components
If the building is used for different applications or is divided
between different users, the method can be applied to the entire
building or to part of the building, as required. The calculation
method can also be applied to a building or to part of a building,
where there is more than one domestic hot water system installed.
For the
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EN 15316-3-2:2007 (E)
12
purposes of these calculations, the buildings are considered in
terms of the number of zones into which they are divided and the
number of domestic hot water systems within these zones.
A zone is defined as a building or part of a building, for which
the energy need for domestic hot water is to be calculated.
5.2 Single zone and single system
The simplest installation is a single system within a single
zone (see Figure 1).
5.3 Single zone and multiple systems
This installation corresponds to a zone in which the energy need
for domestic hot water is provided by means of more than one
domestic hot water generator. In a domestic building, this may be
one generator providing domestic hot water to a bathroom and
another generator providing domestic hot water to a kitchen (see
Figure 2). In non-domestic buildings, the installation depends on
the building sector.
Figure 2 Domestic hot water system, single zone and multiple
systems
Calculation of system losses shall be carried out separately for
each system. The total system loss for the zone is the sum of the
system losses of each system.
Each distribution system shall be kept separate in order to
define the heat load on the heat generator along with the
corresponding domestic hot water demand.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
13
5.4 Multiple zones with single system
This installation corresponds to a building split into a number
of separate zones, for which there is a common single domestic hot
water system, e.g. a block of flats with a central boiler (see
Figure 3).
Figure 3 Domestic hot water system, multiple zones and single
system
The total system loss is calculated for the system, and the
total thermal loss is the sum of thermal losses of each zone.
6 Distribution thermal losses
6.1 Total distribution thermal losses
For the calculations, the distribution system is considered
divided into two parts: a circulation loop, if present, and the
individual distribution pipes to the user outlet or outlets. The
thermal losses of each part are calculated separately.
The total thermal loss lsdisWQ ,, of the distribution system is
calculated by adding the thermal losses of each part as
follows:
collsdisWindlsdisWind
lsdisW QQQ ,,,,,,,, += (MJ/day) (1)
where
ind
indlsdisWQ ,,, is the sum of thermal loss from the individual
distribution pipes of the distribution system (no
circulation loop), MJ/day;
UNI EN 15316-3-2:2008
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p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
14
collsdisWQ ,,, is the thermal loss from the circulation loop of
the distribution system (collective part), if present, MJ/day.
6.2 Thermal losses from individual distribution pipe section
6.2.1 General
Where there is no circulation loop, thermal losses occur due to
the energy used for heating up the pipes and fittings of the
distribution system. This contributes also to a delay in reaching
the required minimum temperature of the domestic hot water at the
user outlet.
When the desired temperature is reached in the distribution
system, thermal losses from the distribution system occur during
the period of draw-off of domestic hot water.
The heat content within the distribution system, after a
draw-off of domestic hot water has been completed, is lost to the
surrounding environment, i.e. heat content of the hot water in the
distribution system and thermal capacity of the material of the
distribution system.
Insulation on the distribution pipes reduces the heat loss rate
during a hot water draw-off and thus reduces the total thermal
losses during a hot water demand period.
Further, insulation on the distribution pipes reduces the heat
loss rate regarding the heat content within the distribution
system, after a hot water draw-off has been completed. The effect
of the insulation in this respect depends on the time periods
between consecutive draw-offs. If the time period is sufficiently
long, pipe insulation does not affect the thermal loss of the heat
content and the hot water temperature drops to the ambient
temperature around the pipe. If the time period is short, pipe
insulation reduces the thermal loss of the heat content, as the hot
water temperature does not drop to the ambient temperature around
the pipe.
Thus, depending on the tapping pattern, the reduced thermal
losses and effect of insulation should be taken into account.
Different methods for calculation of thermal losses are
described in the following. The methods differ in the detail of the
calculations and the input data required. The method applied can be
chosen based on the data available and the objectives of the user.
The level of detail chosen should reflect the level of detail used
in defining the domestic hot water needs.
A national annex may specify which calculation method should be
used for different types of buildings. A national annex may also
specify which calculation method is applicable for the purpose of
energy labelling or any other specific use.
The calculations are based on daily domestic hot water
needs.
6.2.2 Thermal losses from pipes based on dwelling area
This method is a simplified method relating the thermal loss of
individual distribution pipes only to building floor area and,
thus, detailed knowledge of the domestic hot water distribution
system is not required for this method.
This method can only be applied in a limited number of
situations and is usually restricted to domestic buildings with a
domestic hot water distribution system that does not involve a
circulation loop.
If this method is applicable, details for the calculation and
limitations for its use shall be given in a national annex.
Although detailed knowledge of the domestic hot water distribution
system is not required, the pipe lengths shall be kept to a
minimum. The maximum acceptable distribution pipe length for this
method may be given in a national annex.
UNI EN 15316-3-2:2008
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rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
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, e tc . . . )
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EN 15316-3-2:2007 (E)
15
6.2.3 Thermal losses from pipes based on pipe lengths and number
of tappings per day
This method takes into account the thermal losses from the pipes
and the thermal losses from the water within the pipes. It is
necessary to know the pipe diameters and pipe lengths for each
individual section of the domestic hot water distribution
system.
This method is applicable only for domestic hot water
distribution pipes that are not part of a circulation loop.
The thermal loss is calculated by:
tapambnomdisWdisWww
indlsdisW nVcQ *)(**
1000*
,,,,,,
= (MJ/day) (2)
where
w is the specific mass of water (kg/m3);
wc is the specific heat capacity of water (kJ/kgK);
disWV , is the volume of water contained in the pipes (m3);
amb is the average ambient temperature around the pipes (C);
nomdisW ,, is the nominal hot water temperature in the pipes
(C);
tapn is the number of hot water draw-offs during a day.
Details on this method shall be given in a national annex. It is
possible to take into account other parameters, e.g. the thermal
capacity of the pipes. An example is described in Annex A.
It is possible also to include the thermal losses from the user
outlets in this method.
A reduction of thermal losses in case of short intervals between
the tapping cycles is not taken into account in this calculation
method. If this is to be considered, details shall be given in a
national annex, and for this purpose, the effect of pipe insulation
on thermal losses shall be taken into account. An example is
described in Annex A.
6.2.4 Thermal losses from pipes based on pipe lengths and
distribution efficiencies
This method is based on estimates of proportion of the heat
energy reaching the user outlets for different pipe lengths. A
distinction is made between supplies to kitchens and supplies to
bathrooms. Detailed knowledge of the domestic hot water
distribution system is not required for this method, however, an
approximation of the length and diameter of each of the delivery
pipes shall be made. The proportion of heat energy reaching the
user outlets is tabulated against pipe lengths and diameters.
This method is applicable only for domestic hot water
distribution pipes that are not part of a circulation loop.
If this method is applicable, details for the calculation and
suitable tabulated values shall be given in a national annex. A
table of default values is given in Annex B.
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
16
6.2.5 Thermal losses from pipes based on pipe lengths and
tapping profiles
This method is based on estimates of the thermal losses
expressed as a proportion of the domestic hot water energy demand
at the user outlets. Data on domestic hot water energy demand is
required for this method, but detailed knowledge of the domestic
hot water distribution system is not required, as long as
sufficient data is available to estimate the average pipe lengths.
Additionally, data is required on the location of the domestic hot
water distribution system, i.e. as to lengths of pipe sections
installed within the heated space and lengths of pipe sections
installed outside the heated space.
This method is described in Annex C. Details on this method,
including the equivalent energy loss factors, shall be given in a
national annex.
6.2.6 Thermal losses from pipes based on pipe lengths and
average temperature
This method is based on the same calculation principles as for
the thermal losses from a circulation loop based on a physical
approach (see 6.3.3). The only difference is the average
temperature of the domestic hot water taken into account, which is
normally lower for the individual section of the domestic hot water
distribution system than for the circulation loop.
Appropriate values shall be given in a national annex. An
example is given in D.2.
6.2.7 Heat energy lost due to wasted hot water
For most uses, a minimum domestic hot water temperature is
required at the user outlet, before it is considered useful. The
energy content of the water tapped, until the water at the user
outlet has reached the minimum required temperature, is wasted and
is considered as a thermal loss. These thermal losses may be
reduced if there is a high demand on the distribution system, i.e.
a large number of hot water draw-offs occur over a short time
period.
If the domestic hot water demand is defined in accordance with
EN 15316-3-1 on the basis of tapping programs, the conditions for
the minimum domestic hot water temperatures and flow rates are
given.
If the domestic hot water performance of the generator unit is
measured in accordance with EN 13203-2, the energy content of the
wasted domestic hot water is also measured.
If the domestic hot water performance of the generator is not
measured in accordance with EN 13203-2, the energy content of the
wasted domestic hot water may be calculated. A national annex
should give details on this method and the assumptions to be
made.
6.2.8 Time periods
The weekly, monthly or annual thermal losses are obtained by
multiplying the thermal loss per day by the appropriate number of
days.
6.3 Thermal losses from circulation loop
6.3.1 General
For a circulation loop, there are thermal losses from the pipes
during the whole period of water circulation, i.e. not restricted
to domestic hot water draw-offs.
6.3.2 Thermal losses from circulation loop based on pipe length
and a fixed value of heat loss
A fixed value of heat loss from the circulation loop may be
assumed. This method is applicable if exact design of the domestic
hot water distribution system is not available or the pipe
insulation thickness is not known. The value should be given in a
national annex. If a national annex is not provided or does not
include this value, a default value is given in D.1.
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, e tc . . . )
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EN 15316-3-2:2007 (E)
17
6.3.3 Thermal losses from circulation loop based on a physical
approach
The general determination of thermal losses of a circulation
loop comprising a number of pipe sections i isgiven by:
==i
WiambiavgdisWiWiWi
ioncollsdisWoncollsdisW tLUQQ *)(***10006.3
,,,,,,,,,,,,,,, (MJ/day) (3)
where
ioncollsdisWQ ,,,,, is the thermal losses of pipe section i
(during periods of circulation) (MJ/day);
iWU , is the linear thermal transmittance of pipe section i
(W/mK);
iWL , is the length of pipe section i (m);
iavgdisW ,,, is the average hot water temperature of pipe
section i (oC);
iamb, is the average ambient temperature around pipe section i
(oC);
Wt is the daily utilisation period at the corresponding
temperatures, iavgdisW ,,, (h/day).
The individual components of the equation are obtained from the
method given in D.2.
6.3.4 Additional thermal losses from circulation loop during
periods of no circulation
If the circulation loop is not operated continuously, the heat
energy within each pipe section of the circulation loop is lost to
the surrounding environment. This thermal loss is calculated
by:
==i
normiambiavgdisWidisWww
iioffcollsdisWoffcollsdisW nV
cQQ *)(**1000*
,,,,,,,,,,,,,,,
(MJ/day) (4)
where
w is the specific mass of water (kg/m3);
wc is the specific heat capacity of water (kJ/kgK);
idisWV ,, is the volume of water contained in pipe section i
(m3);
nnorm is the number of circulation pump operating cycles during
a day.
6.3.5 Total thermal loss from circulation loop
The total thermal loss from a circulation loop is the sum of
thermal losses during periods of circulation and thermal losses
during periods of no circulation:
offcollsdisWoncollsdisWcollsdisW QQQ ,,,,,,,,,,, += (MJ/day)
(5)
The weekly, monthly or annual thermal losses are obtained by
multiplying the thermal loss per day by the appropriate number of
days.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
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6.4 Thermal losses due to accessories
The thermal losses from the circulation loop and from individual
distribution pipes are increased by the thermal losses through
fittings, i.e. valves and flanges, as well as thermal losses
through pipe hangers.
These thermal losses are estimated by introducing an additional
equivalent pipe length. If these additional thermal losses are to
be included in the analysis, details shall be given in a national
annex.
6.5 User outlets
The domestic hot water is supplied to the user through a user
outlet, e.g. a tap, showerhead or similar device.
Depending on the design and the material of construction, the
user outlet absorbs heat energy during the supply of hot water and
causes a delay in reaching the required minimum hot water
temperature at the user outlet.
Depending on the characteristics of the user outlet, the user
needs more or less time to adjust the required temperature (e.g.
thermostatic user outlets). These delays increase thermal losses in
the domestic hot water distribution system.
The additional heat energy lost due to wasted hot water
(according to 6.2.7) may be combined with the thermal losses due to
user outlets and, thus, no additional calculation is required to
take user outlets into account.
If the thermal losses from user outlets are to be considered
separately, the need for this calculation shall be indicated in a
national annex. The basis of the calculation method is given in
Annex E. These thermal losses are dependent on the number of hot
water draw-offs. This dependence shall be detailed in the national
annex.
Default values for the thermal losses from different types of
user outlets may be used in place of a calculation. If default
values are applicable, these shall be given in a national
annex.
7 Auxiliary energy
7.1 Total auxiliary energy consumption
For the domestic hot water distribution system, auxiliary energy
may be used for ribbon heating and for pumps, and the total
auxiliary energy consumption is determined by:
pmpdisWribdisWauxdisW WWW ,,,,,, += (MJ//day) (6)
where
ribdisWW ,, is the auxiliary energy consumption for the ribbon
heater (MJ/day);
pmpdisWW ,, is the auxiliary energy consumption for pumps
(MJ/day).
7.2 Auxiliary energy consumption for ribbon heating
Where ribbon heating or trace heating is applied to reduce the
heat losses, it is assumed that the auxiliary energy consumption
for the ribbon heater is equal to what the heat losses from the
pipe would have been without the heater.
The ribbon heater does not contribute to the generation of hot
water. The heat losses compensated by the ribbon heater shall not
be added to the heat losses of other individual parts of the
domestic hot water
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
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EN 15316-3-2:2007 (E)
19
distribution system, used to determine the heat demand and the
load on the heat generator. The ribbon heater is supplied by
electricity and should thus be considered as part of the auxiliary
energy requirements.
The auxiliary energy consumption for the ribbon heater is
calculated by:
WambavgdisWdisWribWribdisW tULW *)(***10006.3
,,,,,, = (MJ/day) (7)
where
ribWL , is the length of pipe section heated by trace heating
(m);
disWU , is the linear thermal transmittance of pipe section
(W/mK);
avgdisW ,, is the average hot water temperature of pipe section
(oC);
amb is the average ambient temperature around pipe section
(oC);
Wt is the duration of the provision of hot water (h/day).
It is assumed that the ribbon heater operates during the same
time periods as the domestic hot water heating programme setting,
if this is not continuous.
The weekly, monthly or annual auxiliary energy consumptions are
obtained by multiplying the auxiliary energy consumption per day by
the appropriate number of days.
7.3 Auxiliary energy consumption for pumps
7.3.1 General
Electrical energy is required for the pump to overcome the
hydraulic losses within the domestic hot water distribution system.
A simplified method or a detailed calculation method may be applied
to estimate the auxiliary energy consumption for pumps in domestic
hot water distribution systems.
The proportion of the auxiliary energy consumption for a pump,
which is transferred as heat to the circulating water, should be
given in a national annex. If a national annex is not provided or
does not include this value, the default value given in Annex F may
be applied. For the purpose of the calculations, the auxiliary
energy recovered as heat to the circulating water is subtracted
from the total thermal losses of the circulation loop.
7.3.2 Simplified method
The auxiliary energy consumption for the pump may be estimated
from the pump power rating as follows:
pmppmppmpdisW tPW **6.3,, = (MJ/day) (8)
where
Ppmp is the power rating of the pump (kW);
tpmp is the pump running time (h/day).
Values for tpmp should be given in a national annex. If a
national annex is not provided or does not include this value, a
default value is given in F.1.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
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The weekly, monthly or annual auxiliary energy consumptions are
obtained by multiplying the auxiliary energy consumption per day by
the appropriate number of days.
7.3.3 Detailed calculation method
If the design of the domestic hot water distribution system is
available, a detailed calculation method can be applied. The
auxiliary energy consumption for the pump can be calculated from
the hydraulic energy requirement and the performance of the
pump.
The general calculation of the auxiliary energy consumption for
the circulation pump is:
pmpdisWhydrdisWpmpdisW eWW ,,,,,, *= (MJ/day) (9)
where
hydrdisWW ,, is the hydraulic energy requirement (MJ/day);
pmpdisWe ,, is the performance coefficient for circulation pump
(-).
Details of the method are given in F.2.
The weekly, monthly or annual auxiliary energy consumptions are
obtained by multiplying the auxiliary energy consumption per day by
the appropriate number of days.
8 Recoverable, recovered and unrecoverable system losses
The calculated system losses are not all necessarily lost. Some
of the system losses are recoverable for space heating and a
proportion of these may actually be recovered and contribute to the
space heating.
The recoverable system losses are expressed as a fraction of the
distribution thermal losses and a fraction of the distribution
auxiliary energy consumption:
rblauxdisWauxdisWrbllsdisWlsdisWrbllsdisW fWfQQ ,,,,,,,,,,,,, **
+= (MJ/day) (9)
where
rbllsdisWf ,,, is the fraction of distribution thermal losses
recoverable for space heating;
rblauxdisWf ,,, is the fraction of distribution auxiliary energy
consumption recoverable for space heating.
The fractions depend on e.g. location of the pipes, location of
the pump, duration of the heating season. If the pipes are
installed in the heated space of the building, the thermal losses
may be recoverable. However, recoverable losses can only be
considered during periods of the year where there is a significant
space heating demand.
The proportion of the total recoverable system losses that can
be recovered is determined according to other standards (e.g. EN
ISO 13790 and prEN 15603) for which the total recoverable system
losses are provided as an input.
The fractions shall be specified in a national annex. If a
national annex is not provided or does not include these values, it
is considered that no system losses are recoverable for the space
heating. ( rbllsdisWQ ,,, = 0).
Under some circumstances, the recoverable system losses may add
to the cooling load required in a building.
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rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
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In some situations, the system losses may be reduced by an
energy gain from the building to the cold water supply or by heat
recovery from the wastewater. These energy transfers may be
ignored, unless otherwise required by a national annex.
Some of the auxiliary energy may be recovered as heat in the
domestic hot water system, see 7.3.1.
UNI EN 15316-3-2:2008
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, e tc . . . )
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EN 15316-3-2:2007 (E)
22
Annex A(informative)
Calculation of thermal losses from pipes based on pipe lengths
and the number of tappings per day
This calculation method takes into account the thermal losses
from the pipes and the thermal losses from the water within the
pipes. It is necessary to know the pipe diameters and pipe lengths
for each individual section of the domestic hot water distribution
system.
This annex is only applicable for domestic hot water
distribution pipes that are not part of a circulation loop.
For every pipe section i, the maximum thermal losses are given
by:
tapiambinomdisWidisppidisWww
iindlsdisW nmcVc
Q *}{*}1000
***{ ,,,,
,,,,,,,,
+= (MJ/day) (A.1)
where
w is the specific mass of water (kg/m3);
wc is the specific heat capacity of water (kJ/kgK);
idisWV ,, is the volume of water contained in pipe section i
(m3);
pc is the specific heat capacity of pipe material (kJ/kgK);
idispm ,, is the mass of pipe section i (kg);
inomdisW ,,, is the nominal hot water temperature in pipe
section i (C);
iamb, is the average ambient temperature around pipe section i
(C);
tapn number of tappings per day using pipe section i.
A reduction of thermal losses in case of short intervals between
the tapping cycles is not taken into account in this calculation
method.
Thermal losses due to energy content of wasted hot water at the
user outlets, while the desired domestic hot water temperature has
not been reached, are not included in this calculation method.
If the thermal losses from user outlets, i.e. materials of
shower heads or taps, are to be included, a further contribution is
added to Equation (A.1) taking into account the mass and specific
heat capacity of the user outlet material.
Influence of pipe insulation in case of short tapping
intervals
In case of short tapping intervals, the effect of pipe
insulation on thermal losses should be taken into account. The
following calculation method can be applied.
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
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p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
23
For every pipe section i, the thermal losses for each tapping,
which is followed by a short interval ttap, are given by:
}{*}1000
***{ ,,,,
,,,,,,,,, iWinomdisW
idisppidisWwwtapiindlsdisW
mcVcQ
+= [MJ] (A.2)
and }1000)*(*)***{(/)**(,,,,,,,,,,,,,,*)(
iambinomdisWidisppidisWwwtapii mcVctLqiambinomdisWiambiW e
++= (C) (A.3)
where
iW , is the final hot water temperature in pipe section i before
the next tapping (C);
qi is the density of heat flow rate of pipe section i (W/m);
Li is the length of pipe section i (m);
ttap is the time interval before the next tapping (s).
The density of heat flow rate is given by:
)(* ,,,, iambinomdisWRi Uq = (W/m) (A.4)
where
UR is the linear thermal transmittance (W/mK) according to
Equation (D.1).
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
24
Annex B(informative)
Calculation of thermal losses from pipes based on pipe lengths
and distribution efficiencies
This method is only applicable for domestic buildings and
domestic hot water distribution pipes that are not part of a
circulation loop. It is based on estimates of the proportion of the
heat energy reaching the user outlets for different pipe lengths. A
distinction is made between supplies to kitchens and supplies to
bathrooms.
It is necessary initially to determine the length of the
delivery pipes from the heat generator (or hot water storage
vessel) or from the circulation loop to the kitchen and to the
bathroom: kitchenL and bathroomL .
The proportion of heat energy reaching the user outlet is termed
kitchenpipe, and bathroompipe, , respectively.
Values for these parameters are to be obtained from tables.
Default values are given in Table B.1.
The combined efficiency of the domestic hot water delivery pipes
is calculated by:
+
=
bathroompipe
bathroom
kitchenpipe
kitchenpipe ff
,,
1
(B.1)
where
kitchenf is the fraction of domestic hot water demand in the
kitchen;
bathroomf is the fraction of domestic hot water demand in the
bathroom.
Default values for kitchenf and bathroomf are:
2,0=kitchenf and 8,0=bathroomf .
The total thermal loss from the domestic hot water delivery
pipes is calculated by:
pipe
pipeWindlsdisW QQ
),,,
1(*
= (MJ/day) (B.2)
where
indlsdisWQ ,,, is the thermal loss of delivery pipes
(MJ/day);
WQ is the energy need for domestic hot water (see EN 15316-3-1)
(MJ/day).
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
25
Table B.1 Proportion of heat energy reaching user outlets Length
of delivery pipe [m] 2
> 2 to 4
> 4 to 6
> 6 to 8
> 8 to 10
> 10 to 12
> 12 to 14 > 14
Kitchen kitchenpipe,
dint < 8 mm for 2/3 of the pipe length
1,00 0,86 0,75 0,67 0,60 0,55 0,50 0,46
dint < 10 mm for 2/3 of the pipe length
1,00 0,79 0,65 0,55 0,48 0,43 0,38 0,35
Other pipes 1,00 0,69 0,53 0,43 0,36 0,31 0,27 0,24
Bathroom bathroompipe,
All pipes 1,00 0,95 0,90 0,86 0,82 0,78 0,75 0,72
where dint is the internal pipe diameter of the delivery
pipe.
NOTE These values are determined by assuming: - an average of 2
tappings of 1 litre in the kitchen and one tapping of 8 litres in
the bathroom for every 10 litres of tappings; - complete loss of
the heat energy of the water content in the pipes; - additional
loss of the heat energy of the water content in the pipes and
start/stop losses, at a rate of 0,7 of the loss of the heat energy
of the water content in the pipes.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
26
Annex C(informative)
Calculation of thermal losses from pipes based on pipe lengths
and tapping profiles
This method is based on estimates of the thermal losses
expressed as a proportion of the for domestic hot water energy
demand at the user outlets. Data on domestic hot water energy
demand is required for this method. If thermal losses from user
outlets are taken into account, these losses should be added to the
energy demand for domestic hot water.
The energy demand for domestic hot water is based on the
European domestic hot water tapping programs. Although these are
not identical to the domestic hot water energy usage for all
potential buildings and usage types, they do provide a
representative mixture of small and large hot water draw-offs for
different total energy requirements.
The thermal loss indlsdisWQ ,,, is expressed as:
WdisWindlsdisW QQ *,,,, = (MJ/day) (C.1)
where
disW , is the energy loss factor as proportion of the domestic
hot water energy requirement;
WQ is the energy requirement for domestic hot water (see EN
15316-3-1) (MJ/day).
Three values of disW , are required based on the three domestic
hot water tapping programs:
1,,disW is the energy loss factor for domestic hot water tapping
program 1, with 1,WQ equivalent to 7,560 MJ/day (2,100
kWh/day);
2,,disW is the energy loss factor for domestic hot water tapping
program 2, with 2,WQ equivalent to 21,042 MJ/day (5,845
kWh/day),
3,,disW is the energy loss factor for domestic hot water tapping
program 3, with 3,WQ equivalent to 41,958 MJ/day (11,655
kWh/day)
and
1,1,,1,,,, * WdisWindlsdisW QQ = (MJ/day);
2,2,,2,,,, * WdisWindlsdisW QQ = (MJ/day);
3,3,,3,,,, * WdisWindlsdisW QQ = (MJ/day).
The three energy loss factors are given by:
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
27
avgnhsdisWavghsdisWdisW LL ,,,,,,1,, *008,0)6(*005,009,0 ++=
avgnhsdisWavghsdisWdisW LL ,,,,,,2,, *008,0)6(*005,010,0 ++=
avgnhsdisWavghsdisWdisW LL ,,,,,,3,, *008,0)6(*005,005,0 ++=
where
avghsdisWL ,,, is the average length of distribution pipe within
heated space;
avgnhsdisWL ,,, is the average length of distribution pipe in
non-heated space (if appropriate).
For a specific level of the energy requirement for domestic hot
water WQ , the energy loss factor can be determined by
interpolation as follows:
If 2,WW QQ < ( ) ( )[ ]1,2,2,2,,, /*01,0 WWWWdisWdisW QQQQ =
If 2,WW QQ > ( ) ( )[ ]2,3,2,2,,, /*05,0 WWWWdisWdisW QQQQ = Two
higher European tapping cycles have been developed for larger
energy requirements for domestic hot water. These may also be
applied if the actual domestic hot water energy requirement is
higher than 3,WQ .
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
28
Annex D (informative)
Calculation of thermal losses from circulation loop
D.1 Calculation of thermal losses based on pipe length
If a national annex is not provided or does not include a value
for the thermal losses from the pipes of the circulation loop, a
default value of 40W/m of pipe length may be applied.
D.2 Thermal losses based on a detailed calculation method
D.2.1 General
The variables required for calculation of the thermal losses
from the pipes of the circulation loop can be obtained by the
following.
D.2.2 Determination of length of pipe sections
For carrying out the calculations, the domestic hot water
distribution system may be considered as comprising up to three
different pipe sections. In general, these sections can be
described as:
horizontal distribution from the heat generator to the main
supply pipes (section LV);
main supply pipes (section LS);
individual branching pipes to the user outlets (section
LSL).
In specific installations, all three sections may not be
present.
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
29
Figure D.1 Location of pipes
The pipes of section LV (see Figure D.1) may be situated within
an unheated space, such as a cellar or an attic, or they may be
situated within a thermal skin of the building or the floor.
The pipes of section LS may be vertical or horizontal or a
combination of both. They are normally situated within the thermal
skin of the building.
Pipes of sections LV and LS may constitute part of a circulation
loop. These are treated separately. Pipes of section LSL are not
part of a circulation loop.
For new buildings with an already designed domestic hot water
system, as well as for new domestic hot water systems installed in
existing buildings, calculations of thermal losses should be based
on actual pipe lengths within each pipe section according to the
design or actual installation.
For new buildings in the early stage of design, where the exact
design of the domestic hot water system is still not available,
representative values of pipe lengths can be applied. These values
are related to the effective floor area of the building, and
default values given in Table D.1 may be applied. These default
values are based on an average floor area of 80 m2 and an average
pipe spur length of 6 m.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
30
Table D.1 Default values for calculation of thermal losses from
circulation loop and distribution pipes
Parameters Symbol Unit Section LV Section LS Section LSLAmbient
temperature outside the heating period
nhpamb, C 22 C
Ambient temperature amb
C13 C in an unheated space and 20 C in a heated space
20 C in a heated space
Length of circulation loop L m 2LB+ 0,012 5LBBB
0,075LBBBnfhf
Length of main distribution pipe L m LB+ 0,062 5LBBB
0,038LBBBnfhf
Length of individual branching pipe, only for transfer into
adjacent rooms with a common installation wall
L m 0,05LBBBnf
Length of individual branching pipe, for all other cases
L m 0,075LBBBnf
where
BL is the largest extended length of the building (m);
BB is the largest extended width of the building (m);
fn is the number of heated storeys;
fh is the height of the storeys (m).
The length of the individual pipes is to be determined directly.
If no detailed pipe network plan is available, the length can be
determined from Table D.2 according to the number of tap points per
individual branching pipe. The assumption is made that the
individual branching pipes are all situated within the heated
space.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
31
Table D.2 Default values for calculation of thermal losses from
individual pipes
Parameter Symbol Unit Section LSL
Average ambient temperatureavgamb, C 20
Pipe length for one tap in a room, e.g. from under-sink heater
to tap
L m
80
1 NA
Pipe length for more than one tap in a room, e.g. in a
bathroom
L m
80
3 NA
Pipe length for more than one tap in an adjacent room with a
common installation wall
L m
80
4 NA
Pipe length for supply central within the home unit
L m
80
6 NA
where AN is the floor area in m2.
Decentralised domestic hot water systems provide individual
rooms with hot water and do therefore not include a common
distribution system or circulation loops. In this case, the only
thermal losses from the distribution system are those associated
with the individual distribution pipes. The heat generator may
supply a single user outlet or a number of user outlets. In either
case, the heat generator is installed within the heated space of
the building and hence there are no distribution pipes situated in
an unheated space. For calculation of the thermal losses from these
pipes, the actual length of the pipes should be used. If details of
the piping are not available, representative values for the pipe
lengths can be used. These values are related to the floor area of
the building and may be given in a national annex. If a national
annex is not provided or does not include these values, default
values given in Table D.2 may be applied.
D.2.3 Determination of heat transfer coefficients
D.2.3.1 General
The heat transfer coefficient for any pipe section depends on
the diameter of the pipe, the location of the pipe (whether within
the heated space or not), the type and thickness of any insulation
and the age of the installation.
Local or national requirements may define the level of pipe
insulation to be used, and thus determine the heat transfer
coefficients. Values for insulated pipes may therefore be given in
a national annex. If a national annex is not provided or does not
include these values, default values given in Table D.3 may be
applied.
D.2.3.2 Non-insulated pipes exposed
The thermal losses from a non-insulated pipe consist of losses
through both convection and radiation. The heat transfer from the
hot water to the pipe wall and the conduction within the pipe wall
(for metal pipes) can be ignored. Where these pipes are exposed,
the resulting heat loss coefficients are given in Table D.3.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
32
D.2.3.3 Non-insulated pipes beneath plaster
For non-insulated pipes installed beneath plaster, a distinction
is made between:
pipes in a non-insulated outer wall of an older building;
pipes in an external wall insulated on the outside in an older
or new building;
pipes in a single layer external wall in a new building.
The resulting heat loss coefficients are given in Table D.3.
D.2.3.4 Insulated pipes
The linear thermal transmittance can be calculated by:
e
e
insul DDD
U
*1*
*21
int
+
= (W/mK) (D.1)
where
insul is the heat conductivity of the insulation (W/mK);
eD is the external diameter of insulated pipe (including
insulation) (m);
intD is the internal pipe diameter (m);
is the heat transfer coefficient (W/m2K)
for insulated pipes = 8 W/m2K;
for non-insulated pipes = 14 W/m2K.
If information is not available for calculation of the heat loss
coefficients, the values given in Table D.3 may be applied.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
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EN 15316-3-2:2007 (E)
33
Table D.3 Typical values of linear thermal transmittance of
pipes for new and existing buildings
U[W/mK]
Age/class of building Section Lv Section LS Section LSL
From 1995 assumed that insulation thickness is approximately
equal to the pipe external diameter
0,2 0,3 0,3
1980 to 1995 assumed that insulation thickness is approximately
equal to half of the pipe external diameter
0,3 0,4 0,4
Up to 1980 0,4 0,4 0,4
Non-insulated pipes exposed
A 200 m 1,0 1,0 1,0
200 m < A 500 m 2,0 2,0 2,0
A > 500 m 3,0 3,0 3,0
Non-insulated pipes installed in external walls total/usable
a
External wall non-insulated 1,35 / 0,80
External wall with external insulation 1,00 / 0,90
External wall without insulation but characterized by a low
thermal transmittance (U = 0,4 W/mK)
0,75 / 0,55
a (total = total thermal losses of the pipe, usable =
recoverable thermal losses).
D.2.4 Tabulated method for calculation of linear thermal
transmittance
An alternative simplified method for calculation of the linear
thermal transmittance may be applied. The simplified equation for
the linear thermal transmittance is:
UdisWRUdisWdisW BdAU ,,,,, * += (W/mK) (D.2)
where
UdisWA ,, and UdisWB ,, are coefficients depending on the pipe
insulation class and dR is given in metres.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
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, e tc . . . )
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EN 15316-3-2:2007 (E)
34
The coefficients UdisWA ,, and UdisWB ,, may be given in a
national annex. If a national annex is not provided or does not
include these values, default values given in Table D.4 may be
applied.
Table D.4 Parameters for calculation of the linear thermal
transmittance of pipes
Type of pipe insulation dR min (m)
dR max (m)
AW,dis,U(W/m2K)
BW,dis,U(W/mK)
Class 2 0,010 0,300 2,60 0,200
Class 3 0,010 0,300 2,00 0,180
Class 4 0,010 0,300 1,50 0,160
Class 5 0,010 0,300 1,10 0,140
Class 6 0,010 0,300 0,80 0,120
D.2.5 Determination of average ambient temperature
The average ambient temperature is solely dependent on the
location of the pipe.
)(* int,int edisWamb b = (oC) (D.3)where
int is the internal temperature (oC);
e mean outside temperature (oC);
disWb , location factor (-).
Values for the location factor are given in Table D.5.
Table D.5 Location factor corresponding to the location of the
pipes Location of the circulation loop
disWb ,Outside the building 1
Outside the heated space, horizontal circulation 0.8
Within the heated space 0
Other (e.g. embedded pipe) to be calculated and
substantiated
D.2.6 Determination of average hot water temperature of pipe
section
The average domestic hot water temperature within a pipe section
may be given in a national annex. If a national annex is not
provided or does not include this value, the default average
temperature of the water is:
32 oC in an individual spur;
60 oC in a circulation loop.
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
35
Annex E(informative)
Calculation of thermal losses from user outlets
If thermal losses associated with the thermal capacity of the
user outlets are to be taken into account, the effect of different
outlet types may be calculated from the following procedure.
The thermal losses due to the user outlets are:
tapememWlsemW nnQ **,,, = (MJ/day) (E.1) where
emW , is the heat loss of the specific type of user outlet
(MJ/tapping cycle);
emn is the number of user outlets of the specific type in the
building;
tapn is the number of tapping cycles per day.
If this calculation is considered necessary, values for emW ,
and tapn are provided in a national annex.
emW , depends on the domestic hot water temperature, the cold
water inlet temperature and the water flow rate, and should be
determined based on the values in Table E.1.
Table E.1 Basic conditions for determination of emW ,Domestic
hot water temperature 60 C
Cold water inlet temperature 10 C
Water flow rate 12 l/min
The number of tapping cycles during the day, tapn , depends on
the type of activity.
UNI EN 15316-3-2:2008
L icenza d 'uso concessa a UNIVERSITA ' CENTRO ATENEO DOC.POLO
MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
rno su pos taz i one s ingo la . R ip roduz i one v ie ta ta . E '
p ro ib i to qua l s ias i u t i l izzo in re te (LAN, in te rne t
, e tc . . . )
-
EN 15316-3-2:2007 (E)
36
Annex F(informative)
Calculation of auxiliary energy requirement of a circulation
pump
F.1 Simplified method for calculation of auxiliary energy
requirement of a circulation pump
For the simplified calculation method for estimating the
auxiliary pump energy, the default value tpmp = 24 h/day may be
applied (this is the worst case situation, assuming the pump
operates continuously through the day).
F.2 Detailed method for calculation of auxiliary energy
requirement of a circulation pump
F.2.1 Hydraulic energy requirement
The hydraulic energy depends on the hydraulic resistance of the
system and the pump running time:
WhydrhydrdisW tPW **6,3,, = (MJ/day) (F.1)
where
hydrP is the hydraulic power required by the pump (kW);
Wt is the duration of the provision of domestic hot water
(h/day).
F.2.2 Hydraulic power required by the pump
The hydraulic power required by the circulation pump to overcome
the hydraulic resistance of the system is:
= VpPhydr **36001
(kW) (F.2)
where
V is the volume flow rate (m/h);
p is the differential pressure across the pump (kPa).
The volume flow rate depends on the thermal output of the heat
generator, outgenWQ ,, (kW), and the maximum temperature
difference, genW , (oC), across the heat generator:
genW
outgenWQV,
,,
*15,1 =
(m/h) (F.3)
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
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, e tc . . . )
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EN 15316-3-2:2007 (E)
37
The differential pressure across the circulation pump depends on
the resistance of the pipes and fittings in the circulation system
as follows:
genWfittingsWcoldisW ppLp ,,,,*1,0 ++= (kPa) (F.4) where
coldisWL ,, is the maximum pipe length (m);
fittingsWp , is the differential pressure across fittings, such
as back-flow preventer and thermostatic valve (kPa);
genWp , differential pressure across heat generator (kPa).
If no product data are available, the following default values
may be applied:
for storage tanks 1 kPa;
for continuous-flow systems 15 kPa.
The maximum pipe length for the circulation loop can for a
rectangular building approximately be determined from the external
dimensions of the building/zone:
( )ffBcoldisW hnLL *5,2*2,, ++= (m) (F.5) where
BL is the largest extended length of the building (m);
fn is the number of heated storeys;
fh is the average height of a storey (m).
F.2.3 Duration of the provision of domestic hot water
The running time of the circulation loop Wt is determined for
apartment blocks by:
ffBB ****32,05007,0
110
hnBL
tW+
+= (h/day) (F.6)
and Wt is limited to 24 h/day
where
BL is the largest extended length of the building (m),
BB is the largest extended width of the building (m);
fn is the number of heated storeys;
UNI EN 15316-3-2:2008
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MONTE DAGO per l ' abbonamento anno 2008 .L i cenza d 'uso in te
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EN 15316-3-2:2007 (E)
38
fh is the average height of a storey (m).
For non-residential buildings, Wt is to be set equal to the
daily utilisation time period (h/day).
F.2.4 Pump performance coefficient
The performance coefficient effpmpe , for operation of the
circulation pump is:
94,0, **
= Dpmpeffeffpmp Cfe (-) (F.7) where
efff is the efficiency factor;
pmpC is the pump control factor according to Table F.1;
D is the load factor. If power rating of the circulation pump is
given, the efficiency factor efff is calculated by:
hydr
pmpeff P
Pf = (-) (F.8)
where Ppmp is the power rating of the circulation pump (kW).
If power rating of the circulation pump is not available, the
efficiency factor, efff , is given by:
04,0*015,0*5,1
74,0 +=
hydreff P
bf (-) (F.9)
where b = 1 for new buildings and b = 2 for existing
buildings.
Table F.1 Pump control factor Cpmp
Pump control Fixed speed constp varp
Cpmp 0,97 0,66 0,52
The load factor, D , is the ratio o