uni en 15316-2!3!2008 (impianti di riscaldamento - sistemi distribuzione calore ambienti)

8/10/2019 UNI en 15316-2!3!2008 (Impianti Di Riscaldamento - Sistemi Distribuzione Calore Ambienti)

1/52


2/52

UNI Pagina IIUNI EN 15316-2-3:2008

Le norme UNI sono elaborate cercando di tenere conto dei punti di vista di tutte le partiinteressate e di conciliare ogni aspetto conflittuale, per rappresentare il reale statodellarte della materia ed il necessario grado di consenso.Chiunque ritenesse, a seguito dellapplicazione di questa norma, di poter fornire sug-gerimenti per un suo miglioramento o per un suo adeguamento ad uno stato dellartein evoluzione pregato di inviare i propri contributi allUNI, Ente Nazionale Italiano diUnificazione, che li terr in considerazione per leventuale revisione della norma stessa.

Le norme UNI sono revisionate, quando necessario, con la pubblicazione di nuove edizioni odi aggiornamenti. importante pertanto che gli utilizzatori delle stesse si accertino di essere in possessodellultima edizione e degli eventuali aggiornamenti.

Si invitano inoltre gli utilizzatori a verificare lesistenza di norme UNI corrispondenti allenorme EN o ISO ove citate nei riferimenti normativi.

PREMESSA NAZIONALE

La presente norma costituisce il recepimento, in lingua inglese, del-la norma europea EN 15316-2-3 (edizione luglio 2007), che assumecos lo status di norma nazionale italiana.

La presente norma stata elaborata sotto la competenza dellentefederato allUNI

CTI - Comitato Termotecnico Italiano

La presente norma stata ratificata dal Presidente dellUNI ed entrata a far parte del corpo normativo nazionale il 28 maggio 2008.


3/52


4/52

EN 15316-2-3:2007 (E)

2

Contents Page

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

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 Auxiliary energy demand....................................................................................................................126.1 General..................................................................................................................................................12

6.2 Design hydraulic power ......................................................................................................................126.3 Detailed calculation method...............................................................................................................136.3.1 Input/output data..................................................................................................................................136.3.2 Calculation method..............................................................................................................................146.3.3 Correction factors................................................................................................................................156.3.4 Expenditure energy factor ..................................................................................................................176.3.5 Intermittent operation..........................................................................................................................216.4 Deviations from the detailed calculation method.............................................................................236.5 Monthly auxiliary energy demand......................................................................................................236.6 Recoverable auxiliary energy.............................................................................................................24

7 System thermal loss of distribution systems...................................................................................247.1 General..................................................................................................................................................247.2 Detailed calculation method...............................................................................................................24

7.2.1 Input/output data..................................................................................................................................247.2.2 Calculation method..............................................................................................................................257.2.3 Thermal losses of accessories...........................................................................................................267.2.4 Recoverable and un-recoverable system thermal loss ...................................................................277.2.5 Total system thermal loss...................................................................................................................277.3 Calculation of linear thermal transmittance (W/mK):.......................................................................277.4 Calculation of mean part load of distribution per zone...................................................................28

8 Calculation of supply and return temperature depending on mean part load of distribution.....288.1 Temperature calculation of heat emitters .........................................................................................288.1.1 General..................................................................................................................................................288.1.2 Continuous control depending on outdoor temperature ................................................................298.1.3 Continuous control with thermostatic valves...................................................................................298.1.4 On-Off control with room thermostat ................................................................................................30

8.2 Effect of by-pass connections............................................................................................................308.3 Effect of mixing valves........................................................................................................................318.4 Parallel connection of distribution circuits.......................................................................................328.5 Primary circuits....................................................................................................................................33

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

UNI EN 15316-2-3:2008


5/52

EN 15316-2-3:2007 (E)

3

A.2 Tabulated calculation method for determination of annual auxiliary energy demand ................39A.2.1 Input/output data .................................................................................................................................39A.2.2 Calculation method, tabulated values...............................................................................................39A.2.3 Monthly auxiliary energy demand and recoverable auxiliary energy ............................................41A.3 Simplified calculation method for determination of annual system thermal loss........................41A.3.1 Input/output data .................................................................................................................................41

A.3.2 Calculation method .............................................................................................................................42A.3.3 Approximation of the length of pipes per zone in distribution systems.......................................42A.3.4 Default values of the outer total surface coefficient of heat transfer (convection and

radiation) ..............................................................................................................................................43

A.3.5 Approximation of -values ..............................................................................................................43A.3.6 Equivalent length of valves................................................................................................................44A.3.7 Default values for the exponent of the heat emission system .......................................................44A.4 Tabulated calculation method for determination of annual system thermal loss........................44A.4.1 Input/output data .................................................................................................................................44A.4.2 Calculation method, tabulated values...............................................................................................45A.5 Example................................................................................................................................................46

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

UNI EN 15316-2-3:2008


6/52

EN 15316-2-3:2007 (E)

4

Foreword

This document (EN 15316-2-3:2007) has been prepared by Technical Committee CEN/TC 228 Heatingsystems 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 identicaltext or by endorsement, at the latest by January 2008, and conflicting national standards shall be withdrawn atthe latest by January 2008.

This document has been prepared under a mandate given to CEN by the European Commission and theEuropean Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive2002/91/EC on the energy performance of buildings (EPBD). It forms part of a series of standards aimed atEuropean harmonisation of the methodology for calculation of the energy performance of buildings. Anoverview 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 awhole 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 thesystem requirements.

The requirements are mainly expressed as functional requirements, i.e. requirements dealing with the functionof 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 requirementsmight be used if fulfilment can be proved.

Heating systems differ among the member countries due to climate, traditions and national regulations. Insome 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 systemefficienciesconsists of the following parts:

Part 1: General

UNI EN 15316-2-3:2008


7/52


8/52

EN 15316-2-3:2007 (E)

6

Introduction

In a distribution system, energy is transported by a fluid from the heat generation to the heat emission. As thedistribution 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 iselectrical energy required by the circulation pumps. This leads to additional thermal and electrical energydemand.

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 thebuilding.

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 lengthof pipes, type of insulation, manufacturer's data for the pumps etc.). The detailed calculation method providesthe most accurate energy demand and heat emission.

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

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

Other influences, which are not reflected by the tabulated values, shall be calculated by the simplified or thedetailed calculation method. The energy demand determined from the tabulated calculation method isgenerally higher than the calculated energy demand by the simplified calculation method. Use of this methodis possible with a minimum of input data.

The general calculation method for the electrical energy demand of pumps consists of two parts. The first partis calculation of the hydraulic demand of the distribution system, and the second part is calculation of theexpenditure energy factor of the pump. Here, it is possible to combine the detailed and the simplifiedcalculation method. For example, calculation of pressure loss and flow may be done by the detailedcalculation 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 beapplied through a.o. relevant boundary conditions of each country, thus facilitating easy calculations and quickresults. In national annexes, it is only allowed to change the boundary conditions and other assumptions. Thecalculation 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 todetermine.

UNI EN 15316-2-3:2008


9/52

EN 15316-2-3:2007 (E)

7

1 Scope

This European Standard provides a methodology to calculate/estimate the system thermal loss of water baseddistribution systems for heating and the auxiliary energy demand, as well as the recoverable part of each. Theactual 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 thisEuropean Standard by different calculation methods, i.e. a detailed calculation method, a simplified calculationmethod and a method based on tabulated values. The general method of calculation can be applied for anytime-step (hour, day, month or year).

Pipework lengths for the heating of decentralised, non-domestic ventilation systems equipment are to becalculated in the same way as for water based heating systems. For centralised, non-domestic ventilationsystems 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 thesame calculation methods as shown in this European Standard. Specifically, determination of auxiliary energy demand isbased on the same assumptions for efficiency of pumps, because the efficiency curve applied is an approximation forinline and external motors. It needs to be decided by the standardisation group of CEN, whether or not the extension forcooling 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 Normative references

The following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies. For undated references, the latest edition of the referenceddocument (including any amendments) applies.

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

3 Terms and definitions

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

3.1technical building systemtechnical equipment for heating, cooling, ventilation, domestic hot water, lighting and electricity productioncomposed by sub-systems

NOTE 1 A technical building system can refer to one or to several building services (e.g. heating system, heating anddomestic hot water system).

NOTE 2 Electricity production can include cogeneration and photovoltaic systems.

3.2technical building sub-systempart of a technical building system that performs a specific function (e.g. heat generation, heat distribution,heat emission)

3.3space heatingprocess of heat supply for thermal comfort

3.4auxiliary energyelectrical energy used by technical building systems for heating, cooling, ventilation and/or domestic hot waterto support energy transformation to satisfy energy needs

UNI EN 15316-2-3:2008


10/52

EN 15316-2-3:2007 (E)

8

NOTE 1 This includes energy for fans, pumps, electronics etc. Electrical energy input to a ventilation system for airtransport 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".

3.5heat recoveryheat generated by a technical building system or linked to a building use (e.g. domestic hot water) which isutilised 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)

3.6system thermal lossthermal 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

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

3.7

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

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

3.9calculation stepdiscrete time interval for the calculation of the energy needs and uses for heating, cooling, humidification anddehumidification

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

3.10calculation periodperiod of time over which the calculation is performed

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

3.11heating or cooling seasonperiod 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.

UNI EN 15316-2-3:2008


11/52

EN 15316-2-3:2007 (E)

9

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

zhA , Heated floor in the zone [m]

c Specific heat capacity [J/kg K]

dise Expenditure energy factor for operation of circulation pump [-]

Sf Correction factor for supply flow temperature control [-]

NETf Correction factor for hydraulic networks (layout) [-]

desSf , Correction factor for heating surface design [-]

HBf Correction factor for hydraulic balance [-]

PMGf , Correction factor for generators with integrated pump management [-]

PLf Correction factor for partial load characteristics [-]

Cf Correction factor for control of the pump [-]

PSPf Correction factor for selection of design point [-]

f Correction factor for differential temperature dimensioning [-]

qf& Correction factor for surface related heating load [-]

f Correction factor for efficiency [-]

levh Floor height [m]

LL Building length [m]

maxL Maximum length of pipe [m]

WL Building width [m]

byk Ratio of flow over the heat emitter to flow in the ring [-]

n Exponent of the heat emission system [-]

levN Number of floors [-]

desp Differential pressure at design point [kPa]

HSp Differential pressure of heating surfaces [kPa]

CVp Differential pressure of control valves for heating surfaces [kPa]

ZVp Differential pressure of zone valves [kPa]

Gp Differential pressure of heat supply [kPa]

FHp Differential pressure of floor heating systems [kPa]

ADDp Differential pressure of additional resistances [kPa]

deshydrP , Hydraulic power at design point [W]

pmpelP , Actual power input [W]

refpmpelP ,, Reference power input [W]

H Design heating load [kW]

rblauxdisHQ ,,, Recoverable auxiliary energy for space heating [kWh/time step]

rvdauxdisHQ ,,, Recovered auxiliary energy in the distribution system [kWh/time step]

UNI EN 15316-2-3:2008


12/52

EN 15316-2-3:2007 (E)

10

anlsdisHQ ,,, Annual system thermal loss of the distribution system [kWh/year]

anrbllsdisHQ ,,,, Recoverable system thermal losses for space heating [kWh/year]

annrbllsdisHQ ,,,, Unrecoverable system thermal losses [kWh/year]

R Pressure loss in pipes [kPa/m]

anopt , Heating hours per year [h/year] Linear thermal transmittance [W/mK]

desV& Flow at design point [m/h]

minV& Minimum volume flow [m/h]

anauxdisHW ,,, Annual auxiliary energy demand [kWh/year]

mauxdisHW ,,, Monthly auxiliary energy demand [kWh/month]

anhydrdisHW ,,, Annual hydraulic energy demand [kWh/year]

compf Resistance ratio of components [-]

k Time factor [-]

bk Boost mode time factor [-]

rk Regular mode time factor [-]

setbk Set back mode time factor [-]

desdis, Design heating system temperature difference [K]

P Efficiency of pump at design point [-]

dis Mean part load of the distribution [-]

Specific density [kg/m]

i Surrounding temperature [C]

m Mean medium temperature [C]

u Temperature in unheated space [C]

s Supply temperature [C]

r Return temperature [C]

dess , Design supply temperature [C]

desr, Design return temperature [C]

5 Principle of the method and definitions

The method allows the calculation of the system thermal loss and the auxiliary energy demand of water baseddistribution 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 andgeneration. A simple heating system has no buffer-storage, no distributor/collector, and only one pump isapplied. 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 commonprimary heating circuit or individual primary heating circuits (in Figure 1, only one primary heating circuit isshown).

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

UNI EN 15316-2-3:2008


13/52

EN 15316-2-3:2007 (E)

11

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

Key

1 next heating circuit2 pump

3 room4 emission5 buffer-storage6 pump7 generator8 generation9 distribution10 primary heating circuits11 secondary heating circuits

Figure 1 Scheme distribution and definitions of heating circuits

UNI EN 15316-2-3:2008


14/52

EN 15316-2-3:2007 (E)

12

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

6 Auxiliary energy demand

6.1 General

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

The hydraulic power at the design point can be calculated from physical basics. However, for calculation ofthe hydraulic power during operation, this can only be achieved by a simulation. Therefore, for the detailedcalculation method in this standard, correction factors are applied, which represent the most importantinfluences 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 theefficiency 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 detailedcalculation method in this European Standard, correction factors are applied, which represent the mostimportant influences on expenditure energy, such as efficiency, part load, design point selection and control.

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

6.2 Design hydraulic power

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

desdesdeshydr VpP &= 2778,0, [W] (1)

where

desV& is the flow at design point [m/h];

desp is the differential pressure at design point [kPa].

The flow is calculated from the heat load outemH ,, of the zone (the design heat load shall be according to

EN 12831) and the design temperature difference desdis, of the heating system:

desdis

outemH

desc

V,

.,3600

=& [m/h] (2)

where

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

is the density [kg/m];

UNI EN 15316-2-3:2008


15/52

EN 15316-2-3:2007 (E)

13

desdis, is the design temperature difference [K].

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

ADDGZVCVHScompdes pppppLRfp ++++++= max1 [kPa] (3)

where

compf is the resistance ratio of components [-];

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

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

HSp is the differential pressure of heating surface [kPa];

CVp is the differential pressure of control valve for heating surface [kPa];

ZVp is the differential pressure of zone valves [kPa];

Gp is the differential pressure of heat supply [kPa];

ADDp is the differential pressure of additional resistances [kPa].

6.3 Detailed calculation method

6.3.1 Input/output data

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

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

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

outemH ,, design heat load of the zone according to EN 12831;

desdis,

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

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

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

dis mean part load of the distribution [-];

anopt , heating hours per year [h/year];

UNI EN 15316-2-3:2008


16/52

EN 15316-2-3:2007 (E)

14

Sf correction factor for supply flow temperature control [-];

NETf correction factor for hydraulic networks [-];

SDf correction factor for heating surface dimensioning [-];

HBf correction factor for hydraulic balance [-];

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

- by calculation according to 6.3.4;

f correction factor for efficiency [-];

PLf correction factor for part load [-];

PSP

f correction factor for design point selection [-];

Cf 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:

anauxdisHW ,,, annual auxiliary energy demand [kWh/year];

mauxdisHW ,,, monthly auxiliary energy demand [kWh/month];

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

rblauxdisHQ ,,, 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:

disanhydrdisHanauxdisH eWW = ,,,,,, [kWh/year] (4)

where

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

UNI EN 15316-2-3:2008


17/52

EN 15316-2-3:2007 (E)

15

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

dise 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 ( deshydrP , ), the mean part load of the distribution ( dis ) and the heating hours in the

time step ( anopt , ):

PMGHBSDNETSanopdis

deshydr

anhydrdisH ffffftP

W ,,,

,,,1000

= [kWh/year] (5)

where

deshydrP , is the hydraulic power at design point [W];

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

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

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

NETf is the correction factor for hydraulic networks [-];

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

HBf is the correction factor for hydraulic balance [-];

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

The correction factors, Sf , NETf and SDf include the most important parameters related to dimensioning of

the heating system. The factor HBf takes into account the hydraulic balance of the distribution system. The

correction factor PMGf , for generators with integrated pump management, takes into account the reduction of

operation time in relation to the heating time.

6.3.3 Correction factors

6.3.3.1 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 Correction factor for supply flow temperature control Sf

1=Sf for systems with outdoor temperature compensation;

UNI EN 15316-2-3:2008


18/52

EN 15316-2-3:2007 (E)

16

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

temperature) or very much higher flow temperature than necessary.

Key

1 correction factor Sf [-]

2 ground plan AN [m]3 flow temperature characteristics

Figure 2 Correction factor Sf for constant flow temperature and very much higher flow temperature

6.3.3.3 Correction factor for hydraulic networks NETf

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

NETf see Table 2 for other types of layout.

Table 2 Correction factor NETf for hydraulic network

Network designOne family

houseDwellings

2 pipe system

Ring line 1,0 1,0

Ascending pipe 0,93 0,92

Star-shaped 0,98 0,98

UNI EN 15316-2-3:2008


19/52

EN 15316-2-3:2007 (E)

17

The star-shaped network design is also valid for floor heating systems.

For one-pipe heating systems, the correction factor NETf is given by:

7,06,8 += byNET kf [-] (6)

where

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

6.3.3.4 Correction factor for heating surface dimensioning SDf

1=SDf for dimensioning according to design heat load;

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

6.3.3.5 Correction factor for hydraulic balance HBf

See A.1.3.

6.3.3.6 Correction factor for generators with integrated pump management PMGf ,

See A.1.3.

6.3.4 Expenditure energy factor

6.3.4.1 General

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

CPSPPLdis ffffe = [-] (7)

where

f is the correction factor for efficiency [-];

PLf is the correction factor for part load [-];

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

Cf is the correction factor for control [-].

With these four correction factors, the expenditure energy factor take into account the most importantinfluences on the energy demand, representing the design, the efficiency of the pump, the part load and thecontrol.

The physical relations are shown in Figure 3.

UNI EN 15316-2-3:2008


20/52

EN 15316-2-3:2007 (E)

18

Key

1 pressure head H [m] 2 power P1 [W]

3 flow rate [m/h] 4 H0,max

5 Hpmp 6 Hdes

7 HPL 8 Phydr,des

9 PPL 10 Pel,pmp

11 Pel,pmp,max 12 PPL,C

13 Pel,pmp,ref

14 PLV& 15 V&

16

PL

CPL

PLP

Pf ,= 17

refpumpel

pumpel

PSPP

Pf

,,

,=

18

deshydr

refpumpel

P

Pf

,

,,= 19

pumpeldis

PLPL

P

Pf

,=

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

UNI EN 15316-2-3:2008


21/52

EN 15316-2-3:2007 (E)

19

6.3.4.2 Correction factor for efficiency f

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

deshydr

refpmpel

P

P

f ,

,,

= [-] (8)

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

+=

5,0

,

,,,

20025,1

deshydr

deshydrrefpmpelP

PP [W] (9)

6.3.4.3 Correction factor for part load PLf

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 thepipe system, and thus on the hydraulic energy demand, is taken into account by the mean part load of the

distribution 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 thedistribution.

Key

1 correction factor fPL[-]2 mean part load of distribution dis3 mean part load ratio (PLR)

Figure 4 Correction factor for part load of the pump

UNI EN 15316-2-3:2008


22/52


23/52

EN 15316-2-3:2007 (E)

21

The constant differential pressure control of the pump, keeps the differential pressure of the pump constant atthe design value within the whole flow area. The variable differential pressure control varies the differentialpressure 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 ipvar is

valid.

6.3.5 Intermittent operation

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

set back mode;

boost period;

regular mode.

Key

1 room temperature2 time3 set back4 boost5 regular mode6 set back

Figure 6 Intermittent operation, phases

UNI EN 15316-2-3:2008


24/52

EN 15316-2-3:2007 (E)

22

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

boostanauxdisHsetbanauxdisHreganauxdisHimanauxdisH WWWW ,,,,,,,,,,,,,,,, ++= [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, rk :

disanhydrdisHrreganauxdisH eWkW = ,,,,,,, [kWh/year] (12)

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 - 0,,,, =setbanauxdisHW ;

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

max,,,, 3,0 pmpelsetbpmpel PP = [W] (13)

and the auxiliary energy demand is determined by multiplication with a time factor for the proportional time

of set back operation, setbk :

anop

setbpmpel

setbsetbanauxdisH tP

kW ,,,

,,,,1000

= [kWh/year] (14)

set back of supply temperature. If thermostatic valves in this mode are not set back, the flowcompensates the lower supply temperature and the auxiliary energy demand is not reduced. For this typeof set back operation, the auxiliary energy demand is calculated as for the regular mode operation. The

correction factor for control to be applied is 1=Cf in case of room temperature control with constantvalue (no changes between regular mode and set back mode). In case of room temperature control withset back, Cf depends on the type of pump control (see Figure 5).

For the boost mode operation, the power boostpmpelP ,, is equal to the power despmpelP ,, 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, bk :

anop

boostpmpel

bboostanauxdisH tP

kW ,,,

,,,,1000

= [kWh/year] (15)

The time factors can be calculated according to ratios of time periods.

The regular mode time factor, rk , expresses the number of hours of regular mode operation ropt , per total

number of hours per time period Pt (period could be day, week, month or year):

P

rop

rt

tk

,= [-] (16)

UNI EN 15316-2-3:2008


25/52

EN 15316-2-3:2007 (E)

23

The boost mode time factor, bk , expresses the number of hours of boost mode operation per total number of

hours per time period Pt . 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:

P

boostop

b t

t

k

,

= [-] (17)

The set back mode time factor, setbk , expresses the number of hours of set back mode operation per total

number of hours per time period Pt and is determined from rk and bk :

brsetb kkk =1 [-] (18)

6.4 Deviations from the detailed calculation method

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

One-pipe heating systemsThe 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 1=dis

Overflow valvesOverflow valves are used to ensure a minimum flow at the heat generator or a maximum differentialpressure at the heat emitter. The function of the overflow valve is given by the interaction between thepressure loss of the system, the characteristics of the pump and the set point of the overflow valve. Theinfluence on hydraulic energy demand can be estimated by applying a corrected mean part load of

distribution, dis :

( )des

disdisdisVV&

&

min1 += [-] (19)

where

dis is the mean part load of distribution;

desV& is the design volume flow [m/h];

minV& is the minimum volume flow [m/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 anauxdisHW ,,, is determined. Where necessary, the monthly auxiliary energy demand

is calculated by:

anopandis

mopmdis

anauxdisHmauxdisHt

tWW

,,

,,

,,,,,,

=

[kWh/month] (20)

UNI EN 15316-2-3:2008


26/52

EN 15316-2-3:2007 (E)

24

where

mdis , is the mean part load of distribution for the month;

andis , is the mean part load of distribution for the year;

mopt , is the heating hours per month;

anopt , is the heating hours per year.

Calculation of dis is given in 7.4.

6.6 Recoverable auxiliary energy

For pumps operated in heating circuits, part of the auxiliary energy demand is converted to thermal energy.One part of the thermal energy is recovered in the distribution system, as heat transferred to the water, and

another part of the thermal energy is recoverable for space heating, as heat transferred to the surrounding air.

Recovered auxiliary energy in the distribution system:

anauxdisHrblauxrvdauxdisH WfQ ,,,,,,, = [kWh/year] (21)

Recoverable energy for space heating:

anauxdisHrblauxrblauxdisH WfQ ,,,,,,, )1( = [kWh/year] (22)

where rblauxf , is the factor for recoverable auxiliary energy. Values of rblauxf , are given in A.1.3.4.

7 System thermal loss of distribution systems

7.1 General

The system thermal loss of a distribution system depends on the mean temperature of the supply and returnand the temperature of the surroundings. Also the kind of insulation has an important influence on the systemthermal loss.

7.2 Detailed calculation method

7.2.1 Input/output data

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

L length of pipes in the zone;

linear thermal transmittance in W/mK for each pipe in the zone;

m mean medium temperature in the zone in C;

UNI EN 15316-2-3:2008


27/52

EN 15316-2-3:2007 (E)

25

i surrounding temperature in the zone (unheated and heated space) in C;

opt heating hours in the time step in h/(time step).

Number of valves and hangers taken into account

The output data of the detailed calculation method are:

anlsdisHQ ,,, annual system thermal loss of the distribution system in the zone [kWh/year];

rbllsdisHQ ,,, recoverable system thermal loss for space heating in the zone [kWh/timestep];

nrbllsdisHQ ,,, unrecoverable system thermal loss in the zone [kWh/timestep].

7.2.2 Calculation method

The thermal losses for all of the pipes j in a time step is given by:

( ) anopjjimjL

j

anlsdisH tLQ ,,,,,, = [kWh/year] (23)

where

is the linear thermal transmittance in W/mK;

m is the mean medium temperature in C;

i is the surrounding temperature in C;

L is the length of the pipe;

j is the index for pipes with the same boundary conditions;

anopt , is the heating hours in the time step in h/year.

For parts of the distribution system with the same linear thermal transmittance, the same mean mediumtemperature and the same surrounding temperature, the thermal losses are given by a shorter term:

=j

anopjjanlsdisHanlsdisH tLqQ ,,,,,,,, & [kWh/year] (24)

where janlsdisHq ,,,,& is the thermal loss per length of pipe depending on , m and i

The mean medium temperature of heating circuits, with outdoor temperature compensation of the supplytemperature, depends on the mean part load of distribution and the temperature difference between meanemission system design temperature and room temperature. Calculation of the mean medium temperature isgiven in Clause 8.

Therefore, the thermal losses per length in a space with surrounding temperature i , depends on the mean

part load of distribution and is given by:

UNI EN 15316-2-3:2008


28/52


29/52

EN 15316-2-3:2007 (E)

27

7.2.4 Recoverable and un-recoverable system thermal loss

In heated rooms, the thermal losses of the pipes may be re covered for space heating and is thus recoverable.In unheated rooms, the thermal losses of pipes are not recoverable.

Given the sum of pipe length jrblL , in heated spaces, the recoverable system thermal loss for space heating

of the time step, anrbllsdisHQ ,,,, , is calculated by:

=j

anopjrbljanlsdisHanrbllsdisH tLqQ ,,,,,,,,,, & [kWh/year] (31)

Given the sum of pipe length jlsL , in uncontrolled or unheated spaces, the unrecoverable system thermal loss

of the time step, annrbllsdisHQ ,,,, , is calculated by:

=j

anopjlsjanulsdisHannrbllsdisH tLqQ ,,,,,,,,,,, & [kWh/year] (32)

7.2.5 Total system thermal loss

The total system thermal loss is given by:

annrbllsdisHanrbllsdisHanlsdisH QQQ ,,,,,,,,,,, += [kWh/year] (33)

7.3 Calculation of linear thermal transmittance (W/mK):

The linear thermal transmittance for insulated pipes in air with a total heat transfer coefficient includingconvection and radiation at the outside is given by:

+

=

aai

a

D dhdd 1ln

21

[W/(mK)] (34)

where

ai dd , is the inner diameter (without insulation), outer diameter of the pipe (with insulation) (m);

ah is the outer total surface coefficient of heat transfer (convection and radiation) (W/mK);

D is the thermal conductivity of the insulation (material) (W/mK).

For embedded pipes, the linear thermal transmittance is given by:

+

=

aEi

a

D

em

d

z

d

d 4ln

1ln

1

2

1

[W/(mK] (35)

where

z is the depth of pipe from surface;

E is the thermal conductivity of the embedded material (W/mK).

UNI EN 15316-2-3:2008


30/52

EN 15316-2-3:2007 (E)

28

For non-insulated pipes, the linear thermal transmittance is given by:

apaip

ap

P

non

dhd

d

,,

, 1ln

2

1

+

=

[W/mK] (36)

where

apip dd ,,, is the inner diameter, outer diameter of the pipe (m);

P is the thermal conductivity of the pipe (material) (W/mK).

As an approximation, the linear thermal transmittance for non-insulated pipes is given by:

apanon dh ,= [W/mK] (37)

For heating systems, the inner total heat transfer coefficient needs not to be taken into account.

NOTE Additional information can be found in ISO 12241. Default values of outer total surface coefficients of heattransfer are given in A.3.4.

7.4 Calculation of mean part load of distribution per zone

The mean part load of distribution is given by:

opem

outdisH

dist

Q

= ,, [-] (38)

where

outdisHQ ,, is the heat output of the distribution system per calculation interval;

em is the nominal power of the installed heat emitters per zone

or design heat load per zone at design stage;

opt are the heating hours in the zone per calculation interval.

8 Calculation of supply and return temperature depending on mean part load ofdistribution

8.1 Temperature calculation of heat emitters

8.1.1 General

There are three basic cases for the temperature calculation of heat emitters:

1. Continuous control depending on outdoor temperature (constant flow rate, variable temperature).

2. Continuous control with thermostatic valves (set flow temperature, variable flow rate).

3. On-Off operation (typical: room thermostat control).

UNI EN 15316-2-3:2008


31/52

EN 15316-2-3:2007 (E)

29

8.1.2 Continuous control depending on outdoor temperature

For emission subsystems with constant flow rate and supply temperature control depending on the outdoor

temperature, the supply temperature s and the return temperature r , as well as the mean emission system

temperature m , are given as functions of the mean part load of distribution in each zone:

( ) indisdesdism +=1

[C] (39)

( ) indisidessdiss +=1

, )( [C] (40)

( ) indisidesrdisr +=1

, )( [C] (41)

where

dis is the part load of the distribution system in the zone;

des is the temperature difference in C between mean emission system design temperature and room

temperature

i

desrdess

des

+

=2

,, [K] (42)

n is the exponent of the emission system;

dess , is the design supply temperature in C;

desr, is the design return temperature in C;

i is the room temperature in C.

NOTE Default values for the exponent of the heat emission system are given in A.3.7.

8.1.3 Continuous control with thermostatic valves

For emission subsystems with continuous control with thermostatic valves (constant or set flow temperature,

variable flow rate), the average temperature of the emitters m is given by:

( ) indisdesdism +=1

[C] (43)

where

i is the part load of the distribution system in the zone;

des is the temperature difference in C between mean emission system design temperature and room

temperature

i

desrdess

des

+

=2

,, [K] (44)

UNI EN 15316-2-3:2008


32/52

EN 15316-2-3:2007 (E)

30

n is the exponent of the emission system.

The flow temperature s is the design or set value.

The return temperature is given by:

( )ismr ;2max = [C] (45)

8.1.4 On-Off control with room thermostat

In this case, the operating conditions are the same as the design conditions, that is:

desss , = [C] (46)

desrr , = [C] (47)

NOTE The design condition may vary according to the calculation interval.

8.2 Effect of by-pass connections

If there is a by-pass control, the return temperature of the distribution circuit r is generally higher than that ofthe heat emitter and is given by:

.

86,0

V

outfr

= [C] (48)

where

V&

is the distribution circuit flow rate, either the design value or the set value;

f is the distribution circuit supply temperature, which is the same as that of the mains and the same as

the heat emitter supply (flow) temperature.

Examples of such circuits are given in Figure 7.

UNI EN 15316-2-3:2008


33/52

EN 15316-2-3:2007 (E)

31

Key

1 emitter

2 balancing valve

3 three-way control valve

Figure 7 Sample by-pass type distribution circuits

8.3 Effect of mixing valves

With a mixing valve circuit, return temperature of the distribution circuit r is the same as the heat emitterreturn temperature:

remr , = [C] (49)

The distribution circuit supply temperature f is the same as that of the mains and is higher than or equal to

the heat emitter supply (flow) temperature.

The distribution circuit flow V& (supplied from the mains) is given by:

rf

inV

=

86,0. [kg/h] (50)

Examples of such circuits are given in Figure 8.

UNI EN 15316-2-3:2008


34/52

EN 15316-2-3:2007 (E)

32

Key

1 emitter

2 balancing valve

3 three-way control valve

4 control valve

Figure 8 Sample mixing type distribution circuits

8.4 Parallel connection of distribution circuits

If there are several distribution circuits i connected together, the resulting flow rate and return temperature arecalculated as follows.

The flow temperature is the same for all distribution circuits:

fdisifdis ,,, = [C] (51)

The total flow rate disV& is the sum of the flow rates of the distribution circuits:

=i

idisdis VV ,&& [m/h] (52)

The resulting return temperature totrdis ,, is given by:

dis

outdis

fdistotrdis

V.

,

,,,

86,0= [C] (53)

UNI EN 15316-2-3:2008


35/52


36/52

EN 15316-2-3:2007 (E)

34

Annex A(informative)

Preferred procedures

A.1 Simplified calculation method for determination of annual auxiliary energydemand

A.1.1 Input/output data

For the simplified calculation method, some assumptions are made for the most relevant cases, reducing therequired input data (e.g. the lengths of pipes are calculated by approximations depending on the outerdimensions of the building and efficiency of pumps is approximated). This method may be applied if only fewdata are available (in general at an early stage of design). The assumptions made in A.1.2 through A.1.5 may

be changed on a national level in a national annex, but the calculation method as given by A.1.2.1, A.1.2.3,A.1.5 and A.1.6 is to be applied.

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

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

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

outemH ,, design heat load according to EN 12831 of the zone;

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

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

- by simplified calculation according to A.1.2.2;

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

dis mean part load of distribution [-];

anopt , heating hours per year [h/year];

NET

f correction factor for hydraulic networks [-];

HBf correction factor for hydraulic balance [-];

PMGf , correction factor for generators with integrated pump management [-];

rblauxf , factor for recoverable auxiliary energy [-];

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

- by simplified calculation according to A.1.4.

UNI EN 15316-2-3:2008


37/52

EN 15316-2-3:2007 (E)

35

Type of pump control

Design temperature level

Heat emitter type

Intermittent operation

The output data of the simplified calculation method are:

anauxdisHW ,,, annual auxiliary energy demand [kWh/year];

mauxdisHW ,,, monthly auxiliary energy demand [kWh/month];

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

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

A.1.2 Calculation method

A.1.2.1 Hydraulic energy demand

For given values of correction factors (and assuming )0,1= SDS ff , the hydraulic energy demand can be

expressed as a function of heating hours per time step and the mean part load of distribution:

PMGHBNETanopdis

deshydr

anhydrdisH ffftP

W ,,,

,,,1000

= (A.1)

Correction factors are given in A.1.3. The correction factor for hydraulic networks NETf is only necessary to

distinguish between one-pipe and two-pipe heating systems.

A.1.2.2 Differential pressure at the design point

An approximation for the differential pressure at the design point can be made with a fixed pressure loss perlength of heating circuit (100 Pa/m) and an additional pressure loss ratio for components of 0,3. Variables fordetermining the differential pressure at the design point are thus only the maximum length of the heatingcircuit in the zone and the pressure losses of the heat emission system and the heat generation system:

GFHdes ppLp +++= 213,0 max (kPa) (A.2)

where

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

FHp is the additional pressure loss for floor heating systems [kPa];

Gp is the pressure loss of heat generators [kPa].

This approximation is applicable for the primary heating circuit as well as for the secondary heating circuit.

UNI EN 15316-2-3:2008


38/52

EN 15316-2-3:2007 (E)

36

If the manufacturer's data for FHp and/or Gp is not available, the following default values can be applied:

FHp = 25 kPa including valves and distributor;

Gp see Table A.1.

Table A.1 Pressure loss of heat generators

Type of heat generator Gp [kPa]

Generator with water content > 0,3 l/kW 1

kWoutemH 35max,,,


39/52

EN 15316-2-3:2007 (E)

37

A.1.3 Correction factors

A.1.3.1 Correction factor for hydraulic networks NETf

1=NETf for two-pipe heating systems;

7,06,8 += byNET kf for one-pipe heating systems, where byk is the ratio of flow over the heat emitter to flow

in the ring [-].

A.1.3.2 Correction factor for hydraulic balance HBf

1=HBf for hydraulic balanced systems;

15,1=HBf for hydraulic non-balanced systems.

A.1.3.3 Correction factor for generators with integrated pump management PMGf ,

1, =PMGf for outdoor temperature controlled standard generator (OTC);

75,0, =PMGf for outdoor temperature controlled wall hanging generator (OTC);

45,0, =PMGf for room temperature controlled wall hanging generator (RTC).

A.1.3.4 Recoverable auxiliary energy rblauxf ,

75,0, =rblauxf for non-insulated pump;

90,0, =rblauxf for insulated pump.

A.1.4 Expenditure energy factor

For the simplified calculation method, the expenditure energy factor is calculated similarly as for the detailedcalculation method, according to Equation (7) in 6.3.4.1, with the following additional assumptions:

correction factor for control, Cf , is determined from Figure 5 with 11,1,

max,, =pmpel

pmpel

P

P;

correction factor for design point selection 5,1=PSPf (see Figure 3);

efficiency factor PSPe fff = ;

approximation of the efficiency curve of the pump.

Thus, the expenditure energy factor is simplified to:

)( 1

21

+= disPPedis CCfe (A.4)

where

21, PP CC are constants, according to Table A.2 [-];

UNI EN 15316-2-3:2008


40/52


41/52


42/52

EN 15316-2-3:2007 (E)

40

number of floors in the zone: )/(, WLzhlev LLAN = ;

floor height levh = 3 m.

Table A.3 Annual auxiliary energy demand, tabulated calculation method

Annual auxiliary energy demand, anauxdisHW ,,, [kWh/year]

( anopt , = 5 000 heating hours)

Generators with standard water volume Generators with small water volume

Two-pipe-system with radiatorsType of pump control:

Two-pipe-system with radiatorsType of pump control:Ah,z[m]

pump not controlled dpconst dpvariabel pump not controlled dpconst dpvariabel

100 99 64 53 105 68 57

150 126 82 68 151 98 82

200 151 98 82 206 134 112

300 196 127 106 349 226 189

400 238 154 129 544 352 294500 278 180 150 799 517 432

600 316 205 171 915 592 495

700 354 229 192 1 021 661 553

800 391 253 211 1 125 728 609

900 427 276 231 1 226 794 664

1 000 463 299 250 1 326 858 718

Two-pipe-system with floor-heatingType of pump control:

Two-pipe-system with floor-heatingType of pump control:Ah,z[m]

pump not controlled dpconst dpvariabel pump not controlled dpconst dpvariabel

100 193 125 105 198 128 107

150 246 159 133 263 170 142

200 294 190 159 333 215 180300 379 245 205 497 322 269

400 458 296 248 709 459 384

500 532 344 288 979 634 530

600 602 390 326 1 122 726 607

700 671 434 363 1 254 812 679

800 738 477 399 1 384 895 749

900 803 520 435 1 510 977 817

1 000 867 561 469 1 635 1 058 885

One-pipe-system with radiatorsType of pump control:

One-pipe-system with radiatorsType of pump control:Ah,z[m]

pump not controlled pump not controlled

100109 115

150 141 164

200 170 222

300 224 369

400 274 568

500 323 827

600 370 950

700 417 1 063

800 463 1 174

900 509 1 283

1 000 554 1 390

UNI EN 15316-2-3:2008


43/52

EN 15316-2-3:2007 (E)

41

For a different number of heating hours per year than given in Table A.3, the annual auxiliary energy demand

anauxdisHW ,,, is determined from the tabulated values in Table A.3 by multiplication with a factor5000

,anoptf = ,

where anopt , is the number of heating hours per year (h/year).

To take into account intermittent heating, the annual auxiliary energy demand anauxdisHW ,,, is determined from

the tabulated values in Table A.3 by multiplication with a factor imf as follows:

Regular mode 06:00 22:00 h every day and set back mode for the remaining time: 87,0=imf ;

If the pump is turned off during the set back mode: 69,0=imf

Regular mode 06:00 22:00 h on Monday Friday and set back mode for the remaining time: 87,0=imf ;

If the pump is turned off during the set back mode: 60,0=imf

A.2.3 Monthly auxiliary energy demand and recoverable auxiliary energy

For the tabulated calculation method, the monthly auxiliary energy demand is calculated according to 6.5.

For the tabulated calculation method, the recovered auxiliary energy in the distribution system is given by:

anauxdisHrvdauxdisH WQ ,,,,,, 75,0 = [kWh] (A.8)

and the recoverable auxiliary energy for space heating is given by:

anauxdisHrblauxdisH WQ ,,,,,, 25,0 = [kWh] (A.9)

A.3 Simplified calculation method for determination of annual system thermal loss


For the simplified calculation method, some assumptions are made for the most relevant cases, reducing therequired input data (e.g. the lengths of pipes are calculated by approximations depending on the outerdimensions of the building). This method may be applied if only few data are available (in general at an earlystage of design). The assumptions made in A.3.3 through A.3.7 may be changed on a national level in anational annex, but the calculation method as given by A.3.2 is to be applied.

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

LL length of the zone [m];

WL width of the zone [m];

levh height of the floor in the zone [m];

levN number of floors in the zone [-];

UNI EN 15316-2-3:2008


44/52

EN 15316-2-3:2007 (E)

42

tabulated U-Values per length for each part of the distribution system in the zone [W/mK];

m mean medium temperature in the zone [C];

a surrounding temperature in the zone (unheated and heated space) [C];

opt heating hours in the time step [h/time step];

Number of valves and hangers taken into account

The output data of the simplified calculation method are:

anlsdisHQ ,,, annual system thermal loss of the distribution system in the zone [kWh/year];

anrbllsdisHQ ,,,, recoverable system thermal loss for space heating in the zone [kWh/year];

annrbllsdisHQ ,,,, unrecoverable system thermal loss in the zone [kWh/year].

A.3.2 Calculation method

The annual system thermal loss is determined from the calculation method given in 7.2.2 (for the detailedcalculation method), which is simplified through the assumptions and approximations given in the following.

The recoverable and (unrecoverable) system thermal losses are determined according to 7.2.4.

A.3.3 Approximation of the length of pipes per zone in distribution systems

For the simplified calculation method, approximations of the length of the pipes in a building or a zone (see

Figure A.1) are made, based on the length (LL) and width (LW) of the building or zone, the floor height (h lev)and the number of floors (Nlev), see Table A.4 and Table A.5.

LV Pipe length between generator and vertical shafts.These (horizontal) pipes could be in unheated spaces(basement, attic) or in heated spaces.

LS Pipe length in shafts (e.g. vertical). These pipes areeither in heated spaces, in outside-walls or in theinside of the building. The heating medium is alwayscirculating.

LA Connection pipes. These pipes are flow controlled by

the emission system in heated spaces.

Figure A.1 Type of pipes in a distribution system

UNI EN 15316-2-3:2008


45/52

EN 15316-2-3:2007 (E)

43

Table A.4 Approximation of pipe lengths (two-pipe heating systems)

Values Result Unit Part V

(from the generatorto the shafts)

Part S

(vertical shafts)

Part A

(connectionpipes)

Meansurroundingtemperature

C 13 respectively 20 20 20

Pipe length incase of shafts inoutside walls

Li m 2.LL+

0,01625.LL

.LW

20,025

.LL

.LW

.hlev

.Nlev 0,55

.LL

.LW

.Nlev

Pipe length incase of shaftsinside thebuilding

Li m 2.LL+

0,0325.LL

.LW+ 6

0,025.LL

.LW

.hlev

.Nlev 0,55

.LL

.LW

.Nlev

Table A.5 Approximation of pipe length (one-pipe heating systems)

Values Result Unit Part V

(from the generatorto the shafts)

Part S

(vertical shafts)

Part A

(connectionpipes)

Pipe length incase of shaftsinside of thebuilding

L m 2.LL+

0,0325.LL

.LW+ 6

0,025.LL

.LW

.hlev

.Nlev

+ 2.(LL + LW)

.Nlev

0,1.LL

.LW

.Nlev

A.3.4 Default values of the outer total surface coefficient of heat transfer (convection andradiation)

ah outer total surface coefficient of heat transfer (convection and radiation) (W/mK)

value for insulated pipes = 8 W/m2K

value for un-insulated pipes = 14 W/m2K

A.3.5 Approximation of -values

For the simplified calculation method, approximations of the -values are made for the different types of

pipes (see Table A.6). These should be constant values.

UNI EN 15316-2-3:2008


46/52

EN 15316-2-3:2007 (E)

44

Table A.6 Default values of linear thermal transmittance [W/mK]for new and existing buildings

Age or class of building Distribution part

Part V Part S Pars A

From 1995 assumed that insulation

thickness is approximately equal to pipeexternal diameter

0,2 0,3 0,3

1980 to 1995 - assumed that insulationthickness is approximately equal to half ofpipe external diameter

0,3 0,4 0,4

Up to 1980 0,4 0,4 0,4

Non-insulated pipes

A200 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

Pipes laid in external walls total /recoverable

a

External wall non-insulated 1,35 / 0,80External wall external insulated 1,00 / 0,90

External wall without insulationbut low thermal transmittance (U=0,4 W/mK)

0,75 / 0,55

a (total = total thermal loss of the pipe, recoverable = recoverable thermal loss of

the pipe).

A.3.6 Equivalent length of valves

Table A.7 provides the equivalent length of valves, including flanges, depending on the kind of insulation.

Table A.7 Equivalent length of valves

Valves including flanges

Equivalent length in m

(diameter d 100 mm)

Equivalent length in m

(diameter d > 100 mm)

not insulated 4,0 6,0

insulated 1,5 2,5

A.3.7 Default values for the exponent of the heat emission system

Radiators: n = 1,33.

Floor heating systems n = 1,1.

A.4 Tabulated calculation method for determination of annual system thermal loss


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

UNI EN 15316-2-3:2008


47/52


48/52


49/52


50/52

EN 15316-2-3:2007 (E)

48

System thermal loss:

Given:

-values: in heated spaces: 0,255 W/mK, in unheated spaces: 0,200 W/mK;

with the outer dimensions of the building:

Lv = 28,6 m;

Ls = 12 m;

La = 88 m;

mean temperature of the distribution: m = 35,06 C;

heating hours: anopt , = 5 000 h/year;

temperature in heated space = 20 C and temperature in unheated space = 13 C.

Calculations:

nrbllsdisHq ,,,& = 4,413 W/m, rbllsdisHq ,,,& = 3,841 W/m

Lu = Lv = 28,6 m, Lh = Ls + La = 100 m

annrbllsdisHQ ,,,, = 631 kWh/year, anrbllsdisHQ ,,,, = 1 921 kWh/year

Annual system thermal loss:

anlsdisHQ ,,, = 2 552 kWh/year

Recoverable system thermal loss:

anrbllsdisHQ ,,,, = 1 921 kWh/year

UNI EN 15316-2-3:2008


51/52

EN 15316-2-3:2007 (E)

49

Bibliography

[1] prCEN/TR 156151), Explanation of the general relationship between various CEN standards and the

Energy Performance of Buildings Directive (EPBD) ("Umbrella document")

[2] EN ISO 9488, Solar energy Vocabulary (ISO 9488:1999)

[3] ISO 12241, Thermal insulation for building equipment and industrial installations Calculation rules

[4] EN ISO 13790, Thermal performance of buildings Calculation of energy use for space heating (ISO13790:2004)

1)To be published.

UNI EN 15316-2-3:2008


52/52

uni en 15316-2!3!2008 (impianti di riscaldamento - sistemi distribuzione calore ambienti)

Documents