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NORMAEUROPEA

Pagina IUNI EN 15316-4-4:2008

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Ente Nazionale Italiano

di Unificazione

Via Sannio, 220137 Milano, Italia

UNI EN 15316-4-4

MAGGIO 2008

Impianti di riscaldamento degli edifici

Metodo per il calcolo dei requisiti energetici e deirendimenti dellimpiantoParte 4-4: Sistemi di generazione del calore, sistemi dicogenerazione negli edifici

Heating systems in buildingsMethod for calculation of system energy requirements and systemefficienciesPart 4-4: Heat generation systems, building-integrated cogeneration systems

La norma descrive un metodo di calcolo dei requisiti energetici,della produzione di elettricit e di energia termica, e delle perditerecuperabili delle unit di cogenerazione (riscaldamento e produ-zione acqua calda) in un edificio. Tali unit sono comunementericonosciute come unit di piccola e micro-cogenerazione, o microo piccoli CHP.

TESTO INGLESE

La presente norma la versione ufficiale in lingua inglese dellanorma europea EN 15316-4-4 (edizione luglio 2007).

ICS 91.140.10

L icenza d ' uso concessa a UNIV E RS ITA' CE NTRO A TE NE O DOC.P OLO MONTE DA GO pe r l ' abbonamento anno 200 8 .

L i cenzad ' uso in te rno su pos taz i one s ingo la. R ip roduz i one v ie tata. E ' p ro ib i t o qual s ias i u t i l izzo in re te (LAN, in te rne t , e t c . . . )

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UNI Pagina IIUNI EN 15316-4-4:2008

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 15316-4-4 (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 22 maggio 2008.



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EUROPEAN STANDARD

NORME EUROPENNE

EUROPISCHE NORM

EN 15316-4-4

July 2007

ICS 91.140.10

English Version

Heating systems in buildings - Method for calculation of systemenergy requirements and system efficiencies - Part 4-4: Heatgeneration systems, building-integrated cogeneration systems

Systmes de chauffage dans les btiments - Mthode de

calcul des besoins nergtiques et des rendements dessystmes - Partie 4-4: Systmes de gnration de chaleur,systmes de co-gnration intgrs au btiment

Heizsysteme in Gebuden - Verfahren zur Berechnung der

Energieanforderungen und Wirkungsgrade der Anlagen -Teil 4-4: Wrmeerzeugungssysteme, gebudeintegrierteKWK-Anlagen

This European Standard was approved by CEN on 21 June 2007.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this 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 STANDARDIZATION

C O M IT E U R O P E N D E N O R M A L IS A T IO N

EUROPISCHES KOMITEE FR NORMUNG

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 15316-4-4:2007: E

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Contents Page

Foreword..............................................................................................................................................................3

Introduction.........................................................................................................................................................5

1 Scope ......................................................................................................................................................6

2 Normative references............................................................................................................................6

3 Terms and definitions ...........................................................................................................................6

4 Symbols and abbreviations..................................................................................................................9

5 CHP system calculation ......................................................................................................................10

5.1 System boundaries..............................................................................................................................105.2 Auxiliary energy consumption...........................................................................................................105.3 Recoverable system thermal loss......................................................................................................105.4 Calculation period................................................................................................................................105.5 Available methodologies ....................................................................................................................105.6 Fractional contribution method..........................................................................................................115.6.1 Annual heat output of the cogeneration installation .......................................................................115.6.2 Annual fuel input for the cogeneration installation .........................................................................125.6.3 Annual system thermal loss of the cogeneration installation ........................................................125.6.4 Annual electricity output of the cogeneration installation..............................................................135.7 Annual load profile method................................................................................................................135.7.1 General approach ................................................................................................................................135.7.2 Determining the energy performance for full range of load conditions for the

cogeneration unit.................................................................................................................................13

5.7.3 Determining the annual load profile for the cogeneration unit.......................................................145.7.4 Annual heat output of the cogeneration installation .......................................................................155.7.5 Annual fuel input for the cogeneration installation .........................................................................165.7.6 Electricity output of the cogeneration installation...........................................................................165.7.7 Annual average thermal efficiency of the cogeneration installation..............................................165.7.8 Annual system thermal loss of the cogeneration installation ........................................................16

Annex A(informative) Share of preferential CHP systems...........................................................................18

Annex B(informative) Efficiency of building integrated cogeneration units..............................................19

Annex C(informative) Example: Annual load profile method ......................................................................20C.1 Cogeneration unit specifications (load-performance curve) ..........................................................20C.2 Building heat demand profile .............................................................................................................21C.3 Combining cogeneration unit specifications (load performance curve) and the annual

load profile............................................................................................................................................21C.4 Energy rating........................................................................................................................................22

Bibliography......................................................................................................................................................24

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Foreword

This document (EN 15316-4-4:2007) 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 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 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

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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 volumesystems

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 followingcountries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, CzechRepublic, 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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Introduction

This European Standard constitutes the specific part related to building-integrated cogeneration systems, ofthe set of EN 15316 standards on methods for calculation of system energy requirements and systemefficiencies of space heating systems and domestic hot water systems in buildings.

This European Standard specifies the structure for calculation of the system energy losses and the systemperformance of building-integrated cogeneration systems. The calculation method is used for the followingapplications:

judging compliance with regulations expressed in terms of energy targets;

optimisation of the energy performance of a planned heat generation system, by applying the method toseveral possible options;

assessing the effect of possible energy conservation measures on an existing heat generation system, bycalculating the energy use with and without the energy conservation measure.

The user needs to refer to other European Standards or to national documents for input data and detailedcalculation procedures not provided by this European Standard.

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1 Scope

This European Standard defines a method for calculation of the energy requirements, electricity production,thermal output and recoverable losses of building-integrated cogeneration units forming part of a heatgeneration system (space heating and domestic hot water) in a building. Such units are commonly known asmicro- or small scale cogeneration, or micro- or small scale CHP.

The calculation is based on the performance characteristics of the units, defined in product standards, and onother characteristics required to evaluate the performance of the units as included in the technical buildingsystem.

The test of building-integrated cogeneration units for heating systems may be worked out in a national annex.As soon as European test methods are available these should be used.

NOTE Primary energy savings and CO2savings, which can be achieved by cogeneration units compared to separateproduction of heat and consumption of electricity, are calculated according to prEN 15603. Indications about the savings

calculations are given in informative Annex C.

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.

prEN 156031), Energy performance of buildings Overall energy use, CO2emissions and definition of energy

ratings

3 Terms and definitions

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

3.1annual load profile methodcalculation method for an installation where the cogeneration unit is sized to run on different load rangesthroughout the year (e.g. the cogeneration unit operates as a boiler substitute and supplies the entire heatdemand of the building)

3.2annual electrical efficiencytotal annual electrical output of the cogeneration unit divided by the total annual fuel input

3.3annual heat efficiencytotal annual heat output of the cogeneration unit divided by the total annual fuel input

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

1)To be published.

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NOTE 1 This includes energy for fans, pumps, electronics etc. Electrical energy input to the 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".

3.5building-integrated cogenerationcogeneration unit installed to supply space heating, domestic hot water and possibly cooling within a building

NOTE It could operate as the only heating/cooling appliance of the building or in combination with other heatgenerators, such as boilers or electrical chillers. Unlike district heating systems, where heat and electricity are generatedat central plants and transmitted through networks to a number of remote buildings, a building-integrated cogeneration unitproduces heat for use within the building. The electricity produced by the integrated cogeneration unit may be used withinthe building or may be exported.

3.6cogeneration unitunit designed to provide thermal energy and electricity to a building using a cogeneration process

NOTE 1 The unit may include supplementary burners and thermal storage.

NOTE 2 The cogeneration units are also called CHP (Combined Heat and Power) plants or units.

3.7cogenerationsimultaneous generation in one process of thermal energy and electrical and/or mechanical energy

3.8design heat loaddesired heat flow necessary to achieve the specified design conditions

3.9

dumped heatwasted heat, which exceeds the current heat demand of the building and cannot be stored or used

3.10electricity from cogenerationelectricity generated in a process linked to the production of useful heat

3.11full loadoperation state of the technical system (e.g. cogeneration unit) where the actual load requirement is equal tothe nominal (maximal) output capacity of the device

3.12

fractional contribution methodcalculation method for an installation where the CHP unit is sized to run at full load most of the time, thus theheat output of the CHP unit supplies the base load of the installation (fractional contribution of the heatdemand)

3.13gross calorific valuequantity of heat released by a unit quantity of fuel, when it is burned completely with oxygen at a constantpressure equal to 101 320 Pa, and when the products of combustion are returned to ambient temperature

NOTE 1 This quantity includes the latent heat of condensation of any water vapour contained in the fuel and of thewater vapour formed by the combustion of any hydrogen contained in the fuel.

NOTE 2 According to ISO 13602-2, the gross calorific value is preferred to the net calorific value.

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NOTE 3 The net calorific value does not take into account the latent heat of condensation.

3.14heat-led installations

unit controlled by the heat demand with no dumped heat

NOTE This does not mean that the unit provides the whole heat demand.

3.15net power productionelectrical total power production minus all auxiliary energy consumption

3.16part loadoperation state of the technical system (e.g. cogeneration unit) where the actual load requirement is lowerthan the nominal (maximal) output capacity of the device

3.17peak boilerboiler used to supplement the heat output provided by the cogeneration unit for peak heat loads

3.18plant size ratiomaximum rate of heat output of the cogeneration unit divided by the sum of the design heat load and anyadditional daily heat load (averaged over the day)

3.19power bonus methodall energy inputs are related to the thermal output and the electricity produced is counted as a bonus

3.20

preferential generation appliancesappliance in a multi-plant generation system (e.g. cogeneration units) which are operating in priority

3.21recoverable 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

3.22thermal efficiency of a cogenerationheat output of the cogeneration divided by the fuel input

NOTE 1 Efficiency can be based on annual load conditions or part-load conditions.

NOTE 2 The energy input and all system losses are related to the thermal output. The electricity is counted as a bonus(power bonus method).

3.23useful heatheat produced in a cogeneration process to satisfy the demand for heating or cooling

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4 Symbols and abbreviations

For the purposes of this document, the following symbols and units (Table 1) and indices (Table 2) apply.

Table 1 Symbols and units

Symbol Quantity Unit

E energy in general, including primary energy, energy carriers(except quantity of heat, mechanical work and auxiliary(electrical) energy)

Ja b

ndays number of days -

P power in general including electrical power W

Q quantity of heat Ja

W auxiliary (electrical) energy, mechanical work Ja

X fraction %

fraction -

efficiency factor -

Celsius temperature Ca Hours (h) may be used as the unit for time instead of seconds for all quantities involving time (i.e. for

time periods as well as for air change rates), but in that case the unit for energy is Wh instead of Jb The unit depends on the type of energy carrier and the way its amount is expressed.

Table 2 Indices

an annual gen generation out output

avg time-average H heating pr produced

C cooling HW heating anddomestic hot water

pref preferential

chp combined heat and power in input rbl recoverable

day daily ls losses T thermal

dis distribution max maximum W domestic hot water

el electricity npref non preferential

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5 CHP system calculation

5.1 System boundaries

The system boundary for the cogeneration sub-system comprises only the cogeneration unit.

The cogeneration unit may be of any type, possibly including a supplementary burner and thermal store,provided it has been tested as a whole to provide the energy performance information needed. The generatedheat is used for heating, domestic hot water and eventually an absorption chiller.

Electrical connection components are only taken into account if they are part of the unit and tested together.

Peak boilers of conventional design are used when the heat output of the CHP plant is insufficient to meet theinstantaneous heat demand. Peak boilers are not included in the cogeneration sub-system boundaries.

5.2 Auxiliary energy consumption

Auxiliary energy consumption is taken into account by applying only the net power production i.e. the totalpower production minus all auxiliary energy consumption, e.g. for pumps inside the system boundaries.

Wchp,gen,aux= 0

NOTE This value is input data for calculations according to prEN 15603.

5.3 Recoverable system thermal loss

No losses are recoverable for space heating needs.

Qchp,gen,ls,rbl= 0

NOTE This value is input data for calculations according to prEN 15603.

5.4 Calculation period

System thermal losses should be calculated separately for each calculation period. The average values shallbe consistent with the selected time intervals. This may be done in one of the following two different ways:

by using annual data for the system operation period and performing the calculations using annualaverage values;

by dividing the year into a number of calculation periods (e.g. months, weeks), performing the calculations

for each period using period-dependent values and sum up the results for all the periods over the year.

If there is seasonal heating in the building, the year should at least be divided into two calculation periods, i.e.the time of the heating season and the time of the rest of the year.

5.5 Available methodologies

NOTE 1 The performance of a cogeneration unit (thermal efficiency, electrical output) varies strongly with the part-load.

The operation mode depends on boiler/CHP/buffer tank combinations, regulatory frameworks etc.

Two operation modes may be distinguished:

cogeneration unit is sized to run at full load most of the time, thus the heat output of the CHP unit supplies

the base load of the installation;

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cogeneration unit is sized to run on different load ranges (e.g. the cogeneration unit operates as a boilersubstitute and supplies the entire heat demand of the building).

NOTE 2 For such installations, the load varies over a large range throughout the year and operation at low load

influences strongly the annual energy performance of the cogeneration unit.

In this European Standard, two calculation methods corresponding to the two operation modes are given:

"fractional contribution method", for a CHP unit running at full load most of the time and supplying thebase load of the installation (fractional contribution of the heat demand);

"annual load profile method", for a CHP unit running on different part loads (e.g. operating as a boilersubstitute).

NOTE 3 In principle, the annual load profile method could also be applied for cogeneration units operated to supply thebase load of the installation. However, the fractional contribution method is easier to use and has a sufficient accuracy forthe considered case.

NOTE 4 The cogeneration unit can be sized to supply the base electricity demand and supplies thus only part of theheat demand. In this European Standard, only heat which is not dumped heat is accepted. This case can be taken intoaccount by the annual load profile method. It is only a question of sizing.

All methods used to calculate part load and annual performance of CHP systems should be validated. At leastthe following influence factors should be taken into account:

water temperature (return/flow);

start/stop effects;

part load operation;

air inlet temperature.

5.6 Fractional contribution method

5.6.1 Annual heat output of the cogeneration installation

The annual heat output of the cogeneration installation excludes any dumped heat and is limited by themaximum heat demand within the building(s).

The annual heat output of the cogeneration installation Qchp,gen,outshall be determined by:

chpingenCingenCchpindisHWindisHWoutgenchp XQXQQ ,,,,,,,,,,,, += (1)

where

QHW,dis,in is the heat input to the space heating and domestic hot water distribution sub-system according to prEN 15603;

QC,gen,in is the heat input to the cooling generation system according to prEN 15603;

XHW,dis,in,chp is the share of the heat input to the space heating and domestic hot waterdistribution sub-system covered by the cogeneration installation;

XC,gen,in,chp is the share of the heat input to the cooling generation system covered by thecogeneration installation.

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If cogeneration is combined with other space heating/cooling/ domestic hot water appliances, the relativeshare of space heating, cooling and domestic hot water provided by the cogeneration installation has to bedetermined.

For space heating/cooling/domestic hot water systems in existing buildings, the share of cogeneration couldbe determined on the basis of operational records.

In the case of new installations, the shares of cogeneration could be estimated on the basis of the designspecifications and the control strategies of all relevant components of the space heating/cooling/domestic hotwater systems. Detailed methods for determining the relative share of space heating, cooling and domestichot water provided by the cogeneration installation should be specified in national annexes to this EuropeanStandard.

One possible calculation method is given in Annex A.

5.6.2 Annual fuel input for the cogeneration installation

The annual fuel input for the cogeneration installation Echp,gen,inis calculated by:

anchpT

outgenchp

ingenchp

QE

,,

,,

,,

= (2)

where

Qchp,gen,out is the annual thermal output of the cogeneration (e.g. heating, domestic hotwater);

T,chp,an is the annual heat efficiency of the cogeneration.

All energy inputs are related to the thermal output. The electricity is counted as a bonus (power bonusmethod).

The heat efficiency of the cogeneration installation should be based on operational data or certified values fortype-tested cogeneration units. Typical values should be given in national annexes to this European Standard.If the heat efficiency of a cogeneration unit is not known, indicative efficiency values given in informativeAnnex B may be used.

5.6.3 Annual system thermal loss of the cogeneration installation

The annual system thermal loss of the cogeneration Qchp,gen,lsis calculated by:

)11

(,,

,,,, =

anchpT

outgenchplsgenchp QQ

(3)

All sub-system losses are related to the thermal output. The electricity is counted as a bonus (power bonusmethod).

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5.6.4 Annual electricity output of the cogeneration installation

The annual electricity generated by the cogeneration unit Eel,chp,outis calculated by:

anchpelingenchpoutchpel EE ,,,,,, = (4)

where

el,chp,an is the annual electrical efficiency of the cogeneration.

The electrical efficiency of the cogeneration installation should be based on operational data or certifiedvalues for type-tested cogeneration units. Typical values should be given in national annexes to this standard.If the electrical efficiency of a cogeneration unit is not known, indicative efficiency values given in informativeAnnex B may be used.

5.7 Annual load profile method

5.7.1 General approach

NOTE This method develops the annual energy performance of the cogeneration installation from knowledge of theperformance of the cogeneration at operating conditions (e.g. part-load, water temperature, ambient temperature) and theannual load profile of the cogeneration. This method is well suited for cogeneration installations where the load varies overa large range throughout the year, and operation at low load influences strongly the annual energy performance (e.g. forcogeneration installations which supply the entire heat demand of the building, the cogeneration unit operates as a boilersubstitute).

For this method, the thermal and electrical energy performance of the cogeneration unit over the full loadrange shall be known. For preference, this should be ascertained by suitable laboratory tests under a numberof different part-load conditions.

The plant size ratio of the cogeneration unit, taking account of the demand for heat in the building, shall bedetermined. An annual load profile is developed from relevant regional climate data (such as degree-days) inconjunction with the plant size ratio.

Annual energy input and output, and average annual efficiency, are subsequently calculated by summing upthe performance at different part-load levels. It is assumed, that the cogeneration unit is heat-led andcontrolled in such a way, that there is no dumped heat.

Total annual quantities for fuel input, heat output, system thermal loss and net electrical output are recordedas the output from this method. If the cogeneration unit is inadequately sized for the heat demand of thebuilding, the heat deficit (to be produced by another heat generator) is also calculated.

Combining these quantities for calculation of primary energy and CO2emissions is carried out according toprEN 15603.

5.7.2 Determining the energy performance for full range of load conditions for the cogeneration unit

Knowledge of the energy performance of the installed cogeneration unit under different part-load conditions isobtained from either laboratory test results or other relevant data.

This information is used to establish the load-performance curves for thermal efficiency and electrical output ofthe cogeneration unit. An example of load performance curves is illustrated in Figure 1.

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Key

R Results from laboratory test procedure

X Thermal efficiency

Y Proportion of full-load

Z Electrical output (kWh)

Figure 1 Load-performance curves for thermal efficiency and electrical output(example only)

The load performance curves for thermal efficiency and net electrical output may be representative for eachcogeneration technology or for each cogeneration unit. The intervals defining the performance curve shall givereliable information over the whole part load range. These intervals are defined in the relevant productstandards.

NOTE 1 If product information based on product standards is not available, the load-performance curve for thermalefficiency should be given with values at 10 % intervals over the load range 0 to 100 % recorded as T,chp,0 to T,chp,100.From the load-performance curve for net electrical output, values at 10 % intervals over the load range 0 to 100 % should

be recorded as Eel,chp,out,0to Eel,chp,out,100(kWh/day).

NOTE 2 It would be preferable if the thermal efficiency of the cogeneration unit is also given as a function of thetemperature of the heat output. For some cogeneration unit parts, the output temperature could be very low (example:intercooler out= 35 C). If the heat emission system of the building installation is not adapted accordingly, the heat outputof the cogeneration unit can not be totally used.

5.7.3 Determining the annual load profile for the cogeneration unit

The annual load profile for the cogeneration unit is determined by taking account of e.g. the regional climate,design heat load, plant size ratio, control strategies (operation modes).

An example of an annual load profile for a cogeneration unit with sufficient power to provide the entire heatdemand of the building is given in Figure 2.

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NOTE 1 For a cogeneration unit with insufficient power to provide the entire heat demand of the building, the annualload profile comprises a larger proportion of the time at full load.

Key

X Days per year

H Heat load through year (10% brands)

Y Proportion of full load

Figure 2 Annual load profile of the cogeneration unit (example only)

NOTE 2 From the annual load profile, the number of days at 10 % intervals over the load range 0 to 100 % should berecorded as ndays0to ndays100. Observe that:

ndaysi= 365.i

The annual load profile and the values obtained from the load-performance curves are subsequentlycombined in order to determine:

total heat output,

total fuel input,

total net electricity generated,

during one year.

5.7.4 Annual heat output of the cogeneration installation

The annual heat output of the cogeneration unit Qchp,gen,outis calculated by:

i

i

ioutgenchpoutgenchp ndaysQQ = ,,,,, (5)

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where

i is the part-load index;

Qchp,gen,out,i is the thermal output per day of cogeneration unit at load i;ndaysi is the number of days per year for which part-load i applies.

5.7.5 Annual fuel input for the cogeneration installation

The annual fuel input for the cogeneration unit Echp,gen,inis calculated by:

i

i ichpT

ioutgenchp

ingenchp ndaysQ

E =,,

,,,

,,

(6)

where


T,chp,i is the thermal efficiency of cogeneration unit at part-load i;

ndaysi is the number of days per year for which part-load i applies.

5.7.6 Electricity output of the cogeneration installation

The annual net electricity generated by the cogeneration unit Eel,chp,outis calculated by:

i

i

ioutchpeloutchpel ndaysEE = ,,,,, (7)

where


Eel,chp,out,i is the net electrical output per day of cogeneration unit at part-load i;

ndaysi is the number of days per year for which part-load i applies.

5.7.7 Annual average thermal efficiency of the cogeneration installation

The annual average thermal efficiency of the cogeneration installation T,chp,an,avg, defined as the total heatoutput of the cogeneration installation divided by the total fuel input during one year, is calculated by:

ingenchp

outgenchp

avganchpTE

Q

,,

,,

,,, = (8)

5.7.8 Annual system thermal loss of the cogeneration installation

The annual system thermal loss of the cogeneration installation Qchp,gen,lsis calculated by:

outgenchpingenchplsgenchp QEQ ,,,,,, = (9)

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All system losses are related to the thermal output. The electricity is counted as a bonus (power bonusmethod).

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Annex A(informative)

Share of preferential CHP systems

The part of heat generated by preferential operated cogeneration units in the heat supply to the building is afunction of the plant size ratio T (Table A.1).

Table A.1 Share of heat generated by preferential operatedcogeneration units as a function of plant size ratio T

T XT,chp

From 0,1 to 0,2 0,4

From 0,2 to 0,8 0,6

This example shows that if the plant size ratio is between 10 % and 20 %, then the cogeneration unit supplies40 % of the annual heat demand to the building.

If the cogeneration unit has a much higher plant size ratio (e.g. 80 %), then the supplied heat to the building isonly increased to 60 %.

NOTE XT,chp depends on the operation mode of the cogeneration unit, the technology etc. In the example given inTable A.1, the CHP is heat led and the CHP is the preferential generation appliance. The example in Table A.1 is given

only to illustrate the calculation method. It is strongly recommended to determine XT,chp in a detailed manner in a nationalannex.

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Annex C(informative)

Example: Annual load profile method

C.1 Cogeneration unit specifications (load-performance curve)

In this example, the cogeneration unit specifications at full load are:

PT,chp,out,100= 17,36 kW;

Pel,chp,out,100= 4,62 kW.

Heat and electricity output at full load are calculated from these specifications as:

Qchp,gen,out,100= 17,36 24 = 417 kWh = 1 500 MJ/day;

Eel,chp,out,100= 4,6 24 = 110 kWh = 397,5 MJ/day.

Performance of the cogeneration unit, under part-load conditions at 10 % intervals, has been determined inlaboratory tests, and the results are given in Table C.1.

NOTE It may be acceptable to interpolate some of the values, rather than measure performance at every 10 %interval, provided the characteristics of the unit are well understood and it is known there are no discontinuities of value orgradient in the load-performance curves. Discontinuities are likely to occur in multi-stage plant; for example in units thathave supplementary burners, or a limited modulation range, or generator cut-off at low thermal output.

Table C.1 records results for a whole day in every case, so the unit does not necessarily have to perform at auniform rate throughout the day. The thermal efficiency at each part-load condition is calculated as the heatoutput divided by the fuel input.

Table C.1 Results from performance tests of the cogeneration unit

C1 C2 C3 C4 C5

Part-loadi

Heat output

Qchp,gen,out,i

Fuel input

Echp,gen,in,i

Net electrical output

Eel,chp,out,i

Thermal efficiency

T,chp,i

Test procedure Test procedure Test procedure (C2/C3)x100

% MJ/day MJ/day MJ/day %

0 0 0 0 010 150 375 0 40

20 300 545 0 55

30 450 750 72,5 60

40 600 952 144,5 63

50 750 1 136 217,0 66

60 900 1 323 289,0 68

70 1 050 1 500 325,0 70

80 1 200 1 667 361,5 72

90 1 350 1 824 379,5 74

100 1 500 2 000 397,5 75

From Table C.1 a load-performance curve can be drawn, as shown in Figure 1.

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C.2 Building heat demand profile

The heat input to the building thermal distribution systems is determined for every day of a typical year, takinginto account those services, for which the cogeneration unit should contribute (e.g. space heating, domestic

hot water). The heat demand for space heating is based on a.o. the heat transfers and knowledge of climateconditions (e.g. degree-days).

The daily heat demand values (in MJ) are divided into ranges, corresponding to 10 % part-load intervals. Thenumber of days of each month relevant to every part-load interval of daily heat demand is recorded as shownin Table C.2.

Table C.2 Building heat demand profile (days in typical year)

Daily building heat demand (in MJ) divided into 10% part-load intervals iand approximate load of the cogeneration unit (%)

less

than75 MJ

75 to

225 MJ

225 to

375 MJ

375 to

525 MJ

525 to

675 MJ

675 to

825 MJ

8 25 to

975 MJ

975 to

1 125MJ

1 125to

1275MJ

1 275to

1425MJ

1 425

MJ ormore

< 5 %5 %-15 %

15 %-25 %

25 %-35 %

35 %-45 %

45 %-55 %

55 %-65 %

65 %-75 %

75 %-85 %

85 %-95 %

> 95 %

MonthDays/month

0 % 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90 % 100 %

Jan 31 2 4 5 6 6 5 3

Feb 28 1 3 4 5 5 5 3 2

Mar 31 1 3 6 7 4 4 4 2

Apr 30 1 5 6 5 5 4 3 1

May 31 3 6 7 6 3 2 2 2

Jun 30 4 6 7 9 4

Jul 31 10 13 8

Aug 31 18 8 5

Sep 30 8 4 4 4 3 3 2 1 1

Oct 31 3 4 6 4 4 4 3 2 1

Nov 30 2 3 3 3 5 5 4 3 2

Dec 31 1 1 2 3 5 5 5 4 4 1

TOTAL 365 40 40 40 40 40 40 37 34 30 18 6

The annual load profile consists of the number of days (ndays) at each part-load condition for thecogeneration unit. It can also be plotted as a histogram, as shown in Figure 2.

C.3 Combining cogeneration unit specifications (load performance curve) and theannual load profile

The load performance curve and the annual load profile for the cogeneration unit are combined in Table C.3 toproduce the annual energy totals, using equations from 5.7.

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Table C.3 Annual energy calculations

C1 C2 C3 C4 C5 C6 C7 C8i ndaysi

days

Qchp,gen,out,i

MJ/d

(Qchp,gen,out,i* ndaysi)

MJ/year

T,chp,i

%

Echp,gen,in,i

MJ/year

Eel,chp,out,i

MJ/day

(Eel,chp,out,i* ndaysi)

MJ/year

Table C2/total Table C1/C2 C2xC3 Table C2/C5 C4/C5 Table C1/C4 C2xC7

0 40 0 0 0 0 0 010 40 150 6 000 40 % 15 000 0 020 40 300 12 000 55 % 21 818 0 030 40 450 18 000 60 % 30 000 72,5 2 90040 40 600 24 000 63 % 38 093 144,5 5 78050 40 750 30 000 66 % 45 452 217,0 8 68060 37 900 33 300 68 % 48 970 289,0 10 69370 34 1 050 35 700 70 % 51 000 325,0 11 05080 30 1 200 36 000 72 % 50 000 361,5 10 84590 18 1 350 24 300 74 % 32 836 379,5 6 831

100 6 1 500 9 000 75 % 12 000 397,5 2 385365 228 300 345 169 59 164

The results from the annual energy calculations are:

Qchp,gen,out = 228 300 MJ;

Eel,chp,out = 59 164 MJ;

Echp,gen,in = 345 169 MJ.

The annual average thermal efficiency of the cogeneration installation T,chp,an,avg defined as the total heat

output of the cogeneration installation divided by the total fuel input during one year, is calculated by:

T,chp,an,avg= Qchp,gen,out/ Echp,gen,in

T,chp,an,avg= 228 300 / 345 169 = 0,66 = 66 %

The annual system thermal loss of the cogeneration installation Qchp,gen,lsis calculated by:

outgenchpingenchplsgenchp QEQ ,,,,,, =

228300345169,,

=

lsgenchp

Q = 116 869

C.4 Energy rating

The benefit of the cogeneration unit is shown by the energy rating of the installation according to prEN 15603.

In this example, it is assumed that the whole electricity produced by the cogeneration unit is exported.

The primary energy rating of the cogeneration installation according to prEN 15603 is given in Table C.4.

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Table C.4 Primary energy rating of the installation with a cogeneration unit

Building thermalneeds

MJ/year

Technical building systemperformance

MJ/year

Energy delivered

MJ/year

Energy rating

MJ/year

228 300 57 705(345 169 228 300 59 164)

Fuel input 345 169(gas)

517 753(rating factor 1,5)

Energy exportedMJ/year

Electricity 59 164 177 492(rating factor 3,0)

340 261(517 753 177 492)

The primary energy rating without the cogeneration unit would be as given in Table C.5. It is assumed that theannual average efficiency of the heat generator is 90 %.

Table C.5 Primary energy rating of the installation without a cogeneration unit

Building thermalneeds

MJ/year

Technical building systemperformance

MJ/year

Energy delivered

MJ/year

Energy rating

MJ/year

228 300 25 366

(253 666 228 300 0)

Fuel input 253 666

(gas)

380 500

(rating factor 1.5)

Energy exportedMJ/year

Electricity 0 0

380 500(380 500 0)

As a result, the installation equipped with a cogeneration unit has lower primary energy consumption than aninstallation with a heat generator with an annual average efficiency of 90 %.

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Bibliography

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

[2] prCEN/TR 156153), Explanation of the general relationship between various CEN standards and the

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

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

[4] ISO 13602-2, Technical energy systems Methods for analysis Part 2: Weighting and aggregation ofenergywares

3)To be published.

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Riproduzione vietata - Legge 22 aprile 1941 N 633 e successivi aggiornamenti.UNI

Ente Nazionale Italiano

di Unificazione

Via Sannio 2



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UNI EN 15316-4-4_2008