prEN 16905-5

Gas-fired endothermic engine driven heat pumps - Part 5: Calculation of seasonal performances in heating and cooling mode

This part of EN 16905 specifies the calculation of the seasonal performance factor for gas-fired endothermic engine driven heat pumps for heating and/or cooling mode including the engine heat recovery, to be used outdoors.
This document only applies to appliances with a maximum heat input (based on net calorific value) not exceeding 70 kW at standard rating conditions.
This document only applies to appliances under categories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P and II2Er3P according to EN 437.
This document only applies to appliances having:
a)   gas fired endothermic engines under the control of fully automatic control systems;
b)   closed system refrigerant circuits in which the refrigerant does not come into direct contact with the fluid to be cooled or heated;
c)   where the temperature of the heat transfer fluid of the heating system (heating water circuit) does not exceed 105 °C during normal operation;
d)   where the maximum operating pressure in the:
1)   heating water circuit (if installed) does not exceed 6 bar,
2)   domestic hot water circuit (if installed) does not exceed 10 bar.
This document applies to GEHP appliances only when used for space heating or space cooling or for refrigeration, with or without heat recovery.
This document is applicable to GEHP appliances that are intended to be type tested. Requirements for GEHP appliances that are not type tested would need to be subject to further consideration.

Gasbefeuerte endothermische Motor-Wärmepumpen - Teil 5: Berechnung der saisonalen Effizienzkennzahlen im Heiz- und Kühlmodus

Dieser Teil von EN 16905 legt die Berechnung des saisonalen Leistungsfaktors von gasbefeuerten endothermischen Motor-Wärmepumpen, die für den Heiz- und/oder Kühlbetrieb vorgesehen sind, einschließlich der Außen-Motor-Wärmerückgewinnung, fest.
Dieses Dokument gilt ausschließlich für Geräte mit einer Höchstwärmebelastung von 70 kW (bezogen auf den Heizwert [NCV; en: net calorific value]) bei Norm-Nennbedingungen.
Dieses Dokument gilt entsprechend EN 437 ausschließlich für Geräte der Kategorien I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P und II2Er3P.
Dieses Dokument gilt ausschließlich für Geräte mit:
a)   endothermischen Gasmotoren, die durch vollständig automatisierte Regelungen gesteuert werden;
b)   geschlossenen Kühlkreislaufsystemen, in denen das Kühlmittel nicht direkt mit der zu kühlenden oder zu erwärmenden Flüssigkeit in Berührung kommt;
c)   einer Temperatur des Wärmeübertragungsmediums im Heizsystem (Heizungswasserkreislauf), die im Normalbetrieb 105 °C nicht überschreitet;
d)   einem höchsten Betriebsdruck im:
1)   Heizungswasserkreislauf (falls installiert), der 6 bar nicht überschreitet,
2)   Trinkwasserkreislauf (falls installiert), der 10 bar nicht überschreitet.
Dieses Dokument gilt ausschließlich für GEHP-Geräte, die zur Raumheizung oder -kühlung oder zur Kälteerzeugung mit oder ohne Wärmerückgewinnung angewendet werden.
Dieses Dokument ist anwendbar für GEHP-Geräte, die einer Typprüfung zu unterziehen sind. Anforderungen an nicht typgeprüfte GEHP-Geräte wären ein Thema für weitere Überlegungen.

Pompes à chaleur à moteur endothermique alimenté au gaz - Partie 5 : Calcul des performances saisonnières en modes chauffage et refroidissement

La présente partie de l'EN 16905 décrit le calcul du facteur de performance saisonnière des pompes à chaleur à moteur endothermique alimenté au gaz pour le mode chauffage et/ou refroidissement, y compris la récupération de chaleur du moteur, qui doivent être utilisées en extérieur.
Le présent document ne s'applique qu'aux appareils dont le débit calorifique maximal (dérivé du pouvoir calorifique inférieur) ne dépasse pas 70 kW dans les conditions de performance nominale.
Le présent document se limite également aux appareils classés dans les catégories I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P et II2Er3P de l'EN 437.
Le présent document ne s'applique qu'aux appareils:
a)   équipés de moteurs endothermiques alimentés au gaz régulés par des systèmes de régulation entièrement automatisés;
b)   comportant des circuits fermés de réfrigérant dans lesquels le réfrigérant n'entre pas en contact direct avec le fluide à refroidir ou à chauffer;
c)   dans lesquels la température du fluide caloporteur du système de chauffage (circuit d'eau de chauffage) ne dépasse pas 105 °C dans les conditions normales de fonctionnement;
d)   dans lesquels la pression maximale de fonctionnement:
1)   ne dépasse pas 6 bar dans le circuit d'eau de chauffage (le cas échéant); et
2)   ne dépasse pas 10 bar dans le circuit d'eau chaude sanitaire (le cas échéant).
Le présent document s'applique aux appareils GEHP utilisés uniquement pour le chauffage de locaux, le refroidissement de locaux ou la réfrigération, avec ou sans récupération de chaleur.
Le présent document s'applique aux appareils GEHP destinés à être soumis à des essais de type. Les exigences relatives aux appareils GEHP non soumis à des essais de type pourraient être assujetties à des considérations supplémentaires.

Toplotna črpalka s plinsko gnanim motorjem z notranjim zgorevanjem - 5. del: Izračun sezonske zmogljivosti za ogrevanje in hlajenje

Ta del EN 16905 določa izračun sezonskega faktorja učinkovitosti za plinsko gnane endotermične motorne toplotne črpalke za način ogrevanja in/ali hlajenja, vključno z rekuperacijo toplote motorja, za uporabo na prostem.
Ta dokument se uporablja samo za naprave z največjim toplotnim vhodom (na osnovi spodnje kurilne vrednosti), ki ne presega 70 kW pri standardnih pogojih ocenjevanja.
Ta dokument se uporablja samo za naprave v kategorijah I2H, I2E, I2Er, I2R, I2E(S)B, I2L, I2LL, I2ELL, I2E(R)B, I2ESi, I2E(R), I3P, I3B, I3B/P, II2H3+, II2Er3+, II2H3B/P, II2L3B/P, II2E3B/P, II2ELL3B/P, II2L3P, II2H3P, II2E3P in II2Er3P v skladu z EN 437.
Ta dokument se uporablja samo za naprave, ki imajo:
a) plinsko gnane endotermične motorje pod nadzorom popolnoma avtomatskih kontrolnih sistemov;
b) zaprte hladilne kroge, v katerih hladilno sredstvo ne pride v neposreden stik s tekočino, ki se hladi ali ogreva;
c) kjer temperatura toplotnega prenosnega sredstva ogrevalnega sistema (ogrevalni vodni krog) med normalnim delovanjem ne presega 105 °C;
d) kjer največji obratovalni tlak v:
1) ogrevalnem vodnem krogu (če je nameščen) ne presega 6 barov,
2) krogu za sanitarno toplo vodo (če je nameščen) ne presega 10 barov.
Ta dokument se uporablja za GEHP naprave samo, kadar se uporabljajo za ogrevanje prostorov ali hlajenje prostorov ali za hlajenje, z ali brez rekuperacije toplote.
Ta dokument je veljaven za GEHP naprave, ki so namenjene tipnemu testiranju. Zahteve za GEHP naprave, ki niso tipno testirane, bi morale biti predmet nadaljnje obravnave.

General Information

• Status: Not Published
• Publication Date: 13-Dec-2026
• ICS: 27.080 - Heat pumps
• Technical Committee: CEN/TC 299 - Gas-fired sorption appliances and domestic gas-fired washing and drying appliances
• Drafting Committee: CEN/TC 299/WG 3 - Gas-fired endothermic engine heat pumps
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 23-Apr-2026
• Due Date: 26-Jul-2025
• Completion Date: 23-Apr-2026
• Directive: Harmonized Standard2016/2281 - Commission Regulation (EU) 2016/2281 of 30 November 2016 implementing Directive 2009/125/EC of the European Parliament and of the Council establishing a framework for the setting of ecodesign requirements for energy-related products, with regard to ecodesign requirements for air heating products, cooling products, high temperature process chillers and fan coil units
• Directive:

  ---

  Harmonized Standard811/2013 - Commission Delegated Regulation (EU) No 811/2013 of 18 February 2013 supplementing Directive 2010/30/EU of the European Parliament and of the Council with regard to the energy labelling of space heaters, combination heaters, packages of space heater, temperature control and solar device and packages of combination heater, temperature control and solar device
• Directive:

  ---

  Harmonized Standard813/2013 - Commission Regulation (EU) No 813/2013 of 2 August 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for space heaters and combination heaters
• Mandate: M/535 - [C(2016)2626) Standardisation request to the European standardisation organisations to draft harmonised European standards pursuant to Article 10(1) of Regulation (EU) No 1025/2012 of the European Parliament and of the Council in support of implementation of Commission Regulation (EU) No 813/2013 of 2 August 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to eco-design requirements for space heaters and combination heaters and Commission Delegated Regulation (EU) No 811/2013 of 18 February 2013 supplementing Directive 2010/30/EU of the European Parliament and of the Council with regard to the energy labelling of space heaters, combination heaters, packages of space heaters, temperature control and solar device and packages of combination heater, temperature control and solar device
• Mandate: M/560 - [C(2019) 1725 final] Ecodesign requirements for air heating products, cooling products, high temperature process chillers and fan coils in support of Commission Regulation (EU) 2016/2281
• Ref Project: oSIST prEN 16905-5:2026 - Gas-fired endothermic engine driven heat pumps - Part 5: Calculation of seasonal performances in heating and cooling mode

Relations

• Revises: EN 16905-5:2022 - Gas-fired endothermic engine driven heat pumps - Part 5: Calculation of seasonal performances in heating and cooling mode
• Effective Date: 31-Jul-2024

Overview

prEN 16905-5:2026 is a European Standard developed by CEN for the calculation of seasonal performance factors for gas-fired endothermic engine driven heat pumps (GEHPs) when operated in heating and/or cooling modes. This standard outlines methods for determining the energy efficiency of GEHP appliances, including consideration of engine heat recovery, under standard rating conditions for outdoor installation.

The standard applies exclusively to appliances with a maximum heat input of 70 kW (net calorific value) and specifies the requirements for type-tested GEHP systems. It includes detailed provisions for different types of installation and system layouts, ensuring that performance calculations across varied real-world applications are harmonized and transparent.

Key Topics

• Seasonal Performance Factor Calculation:
  prEN 16905-5 standardizes how to calculate the seasonal performance of GEHPs, accounting for heating, cooling, and potential engine heat recovery. These calculations are necessary for assessing annual energy efficiency and carbon footprint.

• Applicability and System Categories:
  The standard covers GEHP appliances with fully automatic control systems, closed-loop refrigerant circuits, and limits on system pressures and temperatures to ensure safe operation. It applies to a broad range of gas categories as defined in EN 437, including types I2H, I2E, I3P, and various II2/II3 combinations.

• Rated Conditions and Limits:
  Only appliances where the heating circuit does not exceed 105°C (normal operation) and certain pressure limits are covered, thus excluding systems not conforming to these operational boundaries.

• Test Methods and Part-Load Conditions:
  Detailed guidance is provided on how to model and test GEHPs under real-world part-load conditions for both heating and cooling modes. These include specifications for air-to-air, water-to-air, brine-to-air, air-to-water, and water-to-water configurations.

• Technical Documentation and Harmonization:
  The standard links performance calculations with required technical documentation for compliance, supporting harmonization with key EU regulations such as the Ecodesign Directive and Energy Labelling Regulations.

Applications

• Regulatory Compliance and Market Access:
  Manufacturers can use prEN 16905-5 to demonstrate compliance with European efficiency requirements, including those from Ecodesign and energy labelling legislation. This is crucial for CE marking and market entry across the EU.

• Performance Benchmarking:
  Building owners, energy consultants, and specifiers benefit from standardized methodologies for comparing seasonal energy performance of GEHPs, supporting informed purchases and system design.

• Product Development and Innovation:
  By providing rigorous, harmonized calculation methods, the standard enables manufacturers to optimize designs for energy efficiency, supporting the development of high-performance heat pumps aligned with shifting environmental goals.

• Public and Commercial Buildings:
  GEHPs designed and tested to this standard are suited for space heating, space cooling, and refrigeration in a variety of settings, particularly where outdoor installation and high seasonal efficiency are priorities.

Related Standards

• EN 16905-1: Terms and definitions for gas-fired endothermic engine driven heat pumps
• EN 16905-4: Test methods for GEHP appliances
• EN 437: Specification of gas categories and pressures
• Commission Regulation (EU) No 813/2013: Ecodesign requirements for space heaters and combination heaters
• Commission Regulation (EU) No 2016/2281: Ecodesign requirements for air heating and cooling products
• Commission Regulation (EU) No 811/2013: Energy labelling for heating products

By adhering to prEN 16905-5:2026, organizations ensure that their gas-fired endothermic engine driven heat pumps are assessed and classified according to the latest European requirements for seasonal energy performance, supporting efficiency, safety, and regulatory compliance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2026
Toplotna črpalka s plinsko gnanim motorjem z notranjim zgorevanjem - 5. del:
Izračun sezonske zmogljivosti za ogrevanje in hlajenje
Gas-fired endothermic engine driven heat pumps - Part 5: Calculation of seasonal
performances in heating and cooling mode
Gasbefeuerte endothermische Motor-Wärmepumpen - Teil 5: Berechnung der
saisonalen Effizienzkennzahlen im Heiz- und Kühlmodus
Pompes à chaleur à moteur endothermique alimenté au gaz - Partie 5 : Calcul des
performances saisonnières en modes chauffage et refroidissement
Ta slovenski standard je istoveten z: prEN 16905-5
ICS:
27.080 Toplotne črpalke Heat pumps
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2026
ICS 27.080 Will supersede EN 16905-5:2022
English Version
Gas-fired endothermic engine driven heat pumps - Part 5:
Calculation of seasonal performances in heating and
cooling mode
Pompes à chaleur à moteur endothermique alimenté Gasbefeuerte endothermische Motor-Wärmepumpen -
au gaz - Partie 5 : Calcul des performances saisonnières Teil 5: Berechnung der saisonalen Effizienzkennzahlen
en modes chauffage et refroidissement im Heiz- und Kühlmodus
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 299.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16905-5:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Part load conditions for space cooling . 8
4.1 General . 8
4.2 Air-to-air units . 8
4.3 Water-to-air and brine-to-air units . 9
4.4 Air-to-water and air-to-brine units . 9
4.5 Water-to-water and brine-to-water units . 10
5 Part load conditions for space heating . 12
5.1 General . 12
5.2 Air-to-air units . 12
5.3 Water(brine)-to-air units . 13
5.4 Air-to-water(brine) units . 14
5.4.1 General . 14
5.4.2 Low temperature application . 14
5.4.3 Intermediate temperature application . 15
5.4.4 Medium temperature application . 16
5.5 DX-to-water(brine), water-to-water(brine), brine-to-water(brine) units . 16
5.5.1 General . 16
5.5.2 Low temperature application . 17
5.5.3 Intermediate temperature application . 18
5.5.4 Medium temperature application . 19
6 Calculation methods for reference SPER . 19
c
6.1 General . 19
6.2 General formula for calculation of GUE and AEF . 20
c c
6.3 General formula for calculation of EHRE and AEHRF . 20
c c
6.4 General formula for calculation of reference SGUE . 20
c
6.5 Calculation of reference SEHRE . 21
c
6.6 Calculation of reference SGUE . 22
Tc
6.7 Calculation of reference SAEF . 22
c
6.8 Calculation of reference annual cooling demand (Q ) . 23
ref,c
6.9 Calculation of reference SAEF . 23
cON
6.10 Calculation of reference SAEHRF . 24
c
6.11 Calculation of reference total SAEF . 24
Tc
6.12 Procedures for the determination of GUE / AEF values . 24
cPL cPL
6.13 Procedures for the determination of EHRE / AEHRF values . 24
cPL cPL
6.14 Calculation of reference SPER . 25
c
6.15 Calculation of the annual primary energy consumption cooling Q . 25
CP
6.16 Calculation of the seasonal space cooling efficiency η . 25
s,c
7 Calculation methods for reference SPER . 26
h
7.1 General . 26
7.2 General formula for calculation of GUE and AEF . 26
h h
7.3 General formula for calculation of EHRE . 26
h
7.4 General formula for calculation of reference SGUE . 27
h
7.5 Calculation of reference SEHRE . 29
h
7.6 Calculation of reference SGUE . 30
Th
7.7 Calculation of reference SAEF . 30
h
7.8 Calculation of reference annual heating demand (Q ). 30
ref,h
7.9 Calculation of reference SAEF . 31
hON
7.10 Calculation of reference SAEHRFh . 31
7.11 Calculation of reference total SAEF . 32
Th
7.12 Procedures for the determination of GUE / AEF values . 32
hPL hPL
7.13 Procedures for the determination of EHRE / AEHRF values . 32
hPL hPL
7.14 Calculation of reference SPER . 32
h
7.15 Calculation of the annual primary energy consumption heating Q . 33
HP
7.16 Calculation of the seasonal space heating efficiency η . 33
sh
8 Technical documentation . 33
Annex A (normative) Determination of reference annual cooling/heating demands and
determination of hours for active mode, thermostat off, standby, off mode and crankcase
heater mode for reference SAEFc and SAEFh calculation . 35
A.1 Air-to-air, water-to-air and brine-to-air units . 35
A.1.1 Hours for active mode, thermostat-off and standby . 35
A.1.2 Hours for crankcase heater mode . 36
A.2 Air-to-water, air-to-brine, water-to-water, brine-to-water, DX –to-water and DX-to brine
units . 36
A.2.1 Hours for active mode, thermostat-off and standby . 36
A.2.2 Hours for crankcase heater mode . 37
Annex B (informative) Calculation example for reference SGUE , SAEF , SEHRE , SAEHRF , SGUE ,
c c c c Tc
SAEF and SPER . 38
Tc c
Annex C (informative) Calculation example for reference SGUE , SAEF , SEHRE , SAEHRF , SGUE ,
h h h h Tc
SAEF and SPER . 41
Th h
Annex D (informative) Template for technical documentation . 44
Annex E (normative) Rating of outdoor units of multi-split air conditioners and heat pumps . 49
E.1 General . 49
E.2 Terms and definitions . 49
E.3 Rating of outdoor units . 50
E.3.1 General . 50
E.3.2 Test procedure . 51
E.4 Calculation of the SPER based on the PER . 51
c c outdoor
E.5 Calculation of the SPER based on the SPER . 51
h h outdoor
Annex F (normative) Calculation procedure for determination of GUE , AEF and test procedure
TPL TPL
for units with fixed or variable capacity and Cd values . 52
F.1 Calculation procedure for determination of GUE values at part load conditions (cooling A to
D heating A to G) (GUE ) . 52
TPL
F.1.1 General . 52
F.1.2 For air-to-air, brine-to-air and water-to-air units . 52
F.1.3 For air-to-water, water-to-water and brine-to-water units . 53
F.2 Calculation procedure for determination of AEF values at part load conditions (cooling A to
D heating A to G) (AEFPL) . 54
F.2.1 General . 54
F.2.2 For air-to-air, brine-to-air and water-to-air units . 54
F.2.3 For air-to-water, water-to-water and brine-to-water units . 55
F.3 Test procedures for units with fixed capacity . 55
F.3.1 General . 55
F.3.2 Air-to-air and water-to-air units - Determination of the degradation coefficient Cd. 57
F.3.3 Air-to-water(brine) units and water(brine)-to-water(brine) and DX-to-water(brine) units -
Determination of the degradation coefficient Cd . 58
F.4 Test procedure for staged and variable capacity units . 59
F.4.1 General . 59
F.4.2 Settings for the required capacity ratio . 59
F.4.3 Compensation method . 59
Annex ZA (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) No 813/2013 OJ L 239/83 (6.9.2013) aimed to
be covered . 60
Annex ZB (informative) Relationship between this European Standard and the ecodesign
requirements of Commission Regulation (EU) No 2016/2281 OJ L 346/1 (30-11-2016) aimed
to be covered . 62
Annex ZC (informative) Relationship between this European Standard and the energy labelling
requirements of Commission Regulation (EU) No 811/2013 OJ L 239/1 (6.9.2013) aimed to
be covered . 64
Bibliography . 65

European foreword
This document (prEN 16905-5:2026) has been prepared by Technical Committee CEN/TC 299 “Gas-fired
sorption appliances, indirect fired sorption appliances, gas-fired endothermic engine heat pumps and
domestic gas-fired washing and drying appliances”, the secretariat of which is held by UNI.
This document is currently submitted to the CEN Enquiry.
This document supersedes EN 16905-5:2022.
5:2022:
Addition of Annex ZA, ZB and ZC in order to achieve harmonization to Commission Regulation (EU) No
813/2013, Commission Regulation (EU) 2016/2281 and Commission Delegated Regulation (EU) No
811/2013.
This document has been prepared under Standardization Requests addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, Annex ZB and Annex ZC which are
integral parts of this document.
EN 16905 comprises the following parts under the general title Gas‐fired endothermic engine driven heat
pumps:
— Part 1: Terms and definitions;
— Part 2: Safety;
— Part 3: Tests conditions;
— Part 4: Tests methods;
— Part 5: Calculation of seasonal performances in heating and cooling mode.

Introduction
This document specifies the calculation of seasonal performances in heating and cooling mode of air
conditioners and heat pumps using either air, water or brine as heat transfer media, with gas-fired
endothermic engine driven compressors when used for space heating, cooling and refrigeration,
hereafter referred to as “GEHP appliance”.
Single split and multisplit systems are covered by this document.
The GEHP appliances can have one or more primary or secondary functions.
The GEHP appliances having their condenser cooled by air and by the evaporation of external additional
water are not covered by this document.
(EU) 2016/426 relating to appliances burning gaseous fuels and repealing Directive 2009/142/EC (see
EN 16905-4:2026, Annex ZA).
EN 16905-1:2023, EN 16905-3:2024, EN 16905-4:2026 and prEN 16905-5:2026 are linked to the Energy
Related Products Directive (2009/125/EC) in terms of tests conditions, tests methods and seasonal
performances calculation methods under Mandate M/535; (see EN 16905-3:2024, Annex ZA, EN 16905-
4:2026, Annex ZA, prEN 16905-5:2026, Annex ZA, Annex ZB and Annex ZC).
These documents will be reviewed whenever new mandates could apply.

1 Scope
This part of EN 16905 specifies the calculation of the seasonal performance factor for gas-fired
endothermic engine driven heat pumps for heating and/or cooling mode including the engine heat
recovery, to be used outdoors.
This document only applies to appliances with a maximum heat input (based on net calorific value) not
exceeding 70 kW at standard rating conditions.
This document only applies to appliances under categories I , I , I , I , I , I , I , I , I , I ,
2H 2E 2Er 2R 2E(S)B 2L 2LL 2ELL 2E(R)B 2ESi
I , I , I , I , II , II , II , II , II , II , II , II , II and II according to
2E(R) 3P 3B 3B/P 2H3+ 2Er3+ 2H3B/P 2L3B/P 2E3B/P 2ELL3B/P 2L3P 2H3P 2E3P 2Er3P
EN 437.
This document only applies to appliances having:
a) gas fired endothermic engines under the control of fully automatic control systems;
b) closed system refrigerant circuits in which the refrigerant does not come into direct contact with the
fluid to be cooled or heated;
c) where the temperature of the heat transfer fluid of the heating system (heating water circuit) does
not exceed 105 °C during normal operation;
d) where the maximum operating pressure in the:
1) heating water circuit (if installed) does not exceed 6 bar,
2) domestic hot water circuit (if installed) does not exceed 10 bar.
This document applies to GEHP appliances only when used for space heating or space cooling or for
refrigeration, with or without heat recovery.
This document is applicable to GEHP appliances that are intended to be type tested. Requirements for
GEHP appliances that are not type tested would need to be subject to further consideration.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 16905-1:2023, Gas‐fired endothermic engine driven heat pumps — Part 1: Terms and definitions
EN 16905-4:2026, Gas‐fired endothermic engine driven heat pumps — Part 4: Test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 16905-1:2023 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Part load conditions for space cooling
4.1 General
For the purpose of calculation of application SGUE , SAEF , SEHRE , SAEHRF , SGUE , SAEF and reference
c c c c Tc Tc
SGUE , SAEF , SEHRE , SAEHRF , SGUE , SAEF as explained in Clauses 6 and 7, the part load ratios
c c c c Tc Tc
mentioned below shall be based on the part load ratio formulas with at least two decimal digits. For the
purpose of SGUE , SAEF , SEHRE , SAEHRF , SGUE , SAEF the different conditions shall be defined by a
c c c c Tc Tc
reference design temperature T equal to 35 °C.
designc
The calculation of SGUE , SAEF , SEHRE , SAEHRF , SGUE , SAEF and reference SGUE , SAEF , SEHRE ,
c c c c Tc Tc c c c
SAEHRFc, SGUETc, SAEFTc is determined via linear interpolation of the respective part load values at the
reference part load conditions mentioned below (A, B, C, D).
4.2 Air-to-air units
For outdoor air-to-recycled air units, the part load conditions for determining the declared capacity (DC)
and the declared GUE , AEF , EHRE , AEHRF , GUE , AEF shall be given in Table 1.
c c c c Tc Tc
Table 1 — Part load conditions for outdoor air-to- recycled air units
Outdoor heat Indoor heat
exchanger exchanger
Part load
Formula
ratio
Air dry bulb Air dry (wet) bulb

temperature temperatures
% °C °C
A (35–16)/(T -16) 100,00 35 27(19)
designc
B (30–16)/(T -16) 73,68 30 27(19)
designc
C (25–16)/(Tdesignc-16) 47,37 25 27(19)
D (20–16)/(T -16) 21,05 20 27(19)
designc
4.3 Water-to-air and brine-to-air units
For water-to-air and brine-to-air units, the part load conditions for determining the declared capacity
(DC) and the declared GUE , AEF , EHRE , AEHRF , GUE , AEF shall be given in Table 2.
c c c c Tc Tc
Table 2 — Part load conditions for water-to-air and brine-to-air units
Indoor heat
Outdoor heat exchanger
exchanger
Cooling
tower or Ground
Part
Dry cooler
water(brine) coupled
Formula load
application Air dry (wet)
loop application
ratio
Inlet/outlet bulb
application Inlet/outlet
water temperature
Inlet/outlet water(brine)
temperatures
water(brine) temperatures
temperatures
% °C °C °C °C
A (35–16)/(T -16) 100,00 30/35 10/15 50/55 27(19)
designc
a a a
B (30–16)/(T -16) 73,68 26/ 10/ 45/ 27(19)
designc
a a a
C (25–16)/(T -16) 47,37 22/ 10/ 40/ 27(19)
designc
a a a
D (20–16)/(T -16) 21,05 18/ 10/ 35/ 27(19)
designc
If a cooling tower and a water-to-air unit are sold as a matched assembly, they shall be tested as an air-
to-air unit.
a
With the flow rate as determined during “A” test for units with a fixed flow rate or a fixed water temperature
difference of 5 °K for units with a variable flow rate. If for any of the test conditions the resulting flow rate is below
the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the inlet temperature for this
test condition.
4.4 Air-to-water and air-to-brine units
For each application, units either allowing or not allowing a variation of the outlet water/brine
temperature with the outdoor temperature are considered. The part load conditions for determining the
declared capacity (DC) and the declared GUE , AEF , EHRE , AEHRF , GUE , AEF shall be given in Table 3.
c c c c Tc Tc
The variable outlet temperature (T ) shall only be applied when the control provides a regulation
outlet,average
of outlet water temperature that considers the outdoor temperature.
For the determination of water (brine) temperature for fixed capacity units with variable outlet
temperature refer to EN 16905-4:2026.
For units with variable outlet that have to cycle on/off to reach the required part load ratio, the inlet and
outlet temperatures of the indoor heat exchanger shall be determined according to EN 16905-4:2026,
Annex H.
Table 3 — Part load conditions of air-to-water and air-to-brine units
Outdoor heat
Indoor heat exchanger
exchanger
Part Outdoor air Fan coil application
Cooling floor
Formula load dry bulb Inlet/outlet water(brine)
application
ratio temperature temperatures
Inlet/outlet
water(brine)
Fixed Variable
temperatures
b
outlet outlet
% °C °C °C °C
A (35–16)/(T -16) 100,00 35 12/7 12/7 23/18
designc
a a a
B (30–16)/(T -16) 73,68 30 /7 /8,5 /18
designc
a a
/7 /10 a
C (25–16)/(T -16) 47,37 25 /18
designc
a a a
D (20–16)/(T -16) 21,05 20 /7 /11,5 /18
designc
a
With the flow rate as determined during “A” test for units with a fixed flow rate or with a fixed water
temperature difference 5 K for units with a variable flow rate. If for any of the test conditions the resulting flow
rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the outlet
temperature for this test condition.
b
If the variable outlet temperature is above the maximum of the operating range of the unit, this maximum
should be considered.
4.5 Water-to-water and brine-to-water units
For each application, units either allowing or not allowing a variation of the outlet water/brine
temperature with the outdoor temperature are considered. The part load conditions for determining the
declared capacity (DC) and the declared GUE , AEF , EHRE , AEHRF , GUE , AEF shall be given in Table 4.
c c c c Tc Tc
The variable outlet temperature (T ) shall only be applied when the control provides a regulation
outlet,average
of outlet water temperature that considers the outdoor temperature.
For the determination of water (brine) temperature for fixed capacity units with variable outlet
temperature refer to EN 16905-4:2026.
For units with variable outlet that have to cycle on/off to reach the required part load ratio, the inlet and
outlet temperatures of the indoor heat exchanger shall be determined according to EN 16905-4:2026,
Annex H.
Table 4 — Part load conditions of water-to-water, water-to-brine, brine-to-water, brine-to-brine and DX-to-water units
Outdoor heat exchanger Indoor heat exchanger
Cooling tower or Fan coil application
Ground coupled Dry cooler
water(brine) loop Inlet/outlet water Cooling floor
DX
application application
application temperatures application
Inlet/outlet Inlet/outlet
Bath
Inlet/outlet Inlet/outlet water
water(brine) water(brine)
temperature
Variable
water(brine) temperatures
Fixed outlet
temperatures temperatures
b
outlet
temperatures
% °C °C °C °C °C °C
(35–16) /
A 100,00 30/35 10/15 50/55 30 12/7 12/7 23/18
(Tdesignc-16)
(30–16) /
a a a a a a
B 73,68 26/ 10/ 45/ 30 /7 /8,5 /18
(Tdesignc-16)
(25–16) /
a a a a a a
C 47,37 22/ 10/ 40/ 30 /7 /10 /18
(T -16)
designc
(20–16) /
a a a a a a
D 21,05 18/ 10/ 35/ 30 /7 /11,5 /18
(T -16)
designc
If a cooling tower and water-to-water unit are sold as a matched assembly, they shall be tested as an air-to-water unit.
a
With the flow rate as determined during “A” test for units with a fixed flow rate or with a fixed water temperature difference of 5 K for units with a variable flow rate. If for any
of the test conditions the resulting flow rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the outlet temperature for this test
condition.
b
If the variable outlet temperature is above the maximum of the operating range of the unit, this maximum should be considered.

Formula
Part load ratio
5 Part load conditions for space heating
5.1 General
For the purpose of calculation of SGUE , SAEF , SEHRE , SAEHRF SGUE , SAEF , and reference SGUE ,
h h h h Th Th h
SAEF , SEHRE , SAEHRF SGUE , SAEF , as explained in Clauses 6 and 7, the part load ratios mentioned
h h h Th Th
below shall be based on the part load ratio formulas with at least two decimal digits.
The calculation of SGUE , SAEF , SEHRE , SAEHRF , SGUE , SAEF and reference SGUE , SAEF , SEHRE ,
h h h h Th Th h h h
SAEHRF , SGUE , SAEF is determined via linear interpolation of the respective part load values at the
h Th Th
reference part load conditions mentioned below (A, B, C, D). For the purpose of reference SGUE , SAEF ,
h h
SEHRE , SAEHRF , SGUE , SAEF there are three reference conditions: average(A), warmer (W) and
h h Th Th
colder (C).
The relevant T values are defined as follows:
designh
— Average dry bulb temperature conditions at −10 °C outdoor temperature and 20 °C
climate indoor temperature;
— Colder dry bulb temperature conditions at −22 °C outdoor temperature and 20 °C
climate indoor temperature
— Warmer dry bulb temperature conditions at +2 °C outdoor temperature and 20 °C
climate indoor temperature
For outdoor air dry bulb temperatures higher or equal to −10 °C the wet bulb temperature equals the dry
bulb temperature minus 1 K. For dry bulb temperatures below −10 °C, the wet bulb temperature is not
defined.
For heat pumps, the relevant T is defined as follows:
biv
— for the average heating season, the dry bulb temperature is +2 °C or lower;
— for the colder heating season, the dry bulb temperature is −7 °C or lower;
— for the warmer heating season, the dry bulb temperature is +7 °C or lower.
For heat pumps, the relevant TOL is defined as follows:
— for the average heating season, the dry bulb temperature is −7 °C or lower;
— for the colder heating season, the dry bulb temperature is −15 °C or lower;
— for the warmer heating season, the dry bulb temperature is +2 °C or lower.
If the declared TOL is lower than the T of the considered climate, then the outdoor dry bulb
designh
temperature is equal to T for the part load condition E in Table 5, Tables 7 to 10.
designh
In case of colder climate and if TOL is below −20 °C, an additional part load condition G at −15 °C shall
apply for air-to-air and air-to-water heat pumps.
5.2 Air-to-air units
The part load conditions for determining the reference SGUE (Formula (16)), SAEF (Formula (20)),
h h
SEHRE (Formula (18)), SAEHRF (Formula (23)), SGUE (Formula (19)), SAEF (Formula (24)), shall be
h h Th Th
given in Table 5.
Table 5 — Part load conditions for air-to-recycled air units for the reference heating seasons
Part load ratio
Outdoor heat Indoor heat
exchanger exchanger
in %
Air dry (wet)
Air dry bulb
Formula Average Warmer Colder bulb
temperature
temperature
°C °C
A (−7–16)/(T -16) 88,46 n/a 60,53 −7(−8) 20
designh
B (+2–16)/(T -16) 53,85 100,00 36,84 2(1) 20
designh
C (+7–16)/(T -16) 34,62 64,29 23,68 7(6) 20
designh
D (+12–16)/(T -16) 15,38 28,57 10,53 12(11) 20
designh
E (TOL-16)/(T -16) TOL 20
designh
F (T -16)/(T -16) T 20
biv designh biv
G (−15 - 16) / (Tdesignh-16) n/a n/a 81,58 −15 20

5.3 Water(brine)-to-air units
The part load conditions for determining the reference SGUEh (Formula (16)), SAEFh (Formula (20)),
(Formula (18)), SAEHRF (Formula (23)), SGUE (Formula (19)), SAEF (Formula (24)), shall be
SEHREh h Th Th
given in Table 6.
Table 6 — Part load conditions for water(brine)-to-air for the reference heating seasons
Part load ratio Outdoor heat
exchanger
Indoor heat
in %
exchanger
inlet/outlet
temperature
Formula Average Warmer Colder
Water
Water Brine Dry bulb
loop
°C °C °C °C
a a a
A (−7–16)/(T -16) 88,46 n/a 60,53 10/ 0/ 20/ 20
designh
a a a
B (+2–16)/(T -16) 53,85 100,00 36,84 10/ 0/ 20/ 20
designh
a a a
C (+7–16)/(T -16) 34,62 64,29 23,68 10/ 0/ 20/ 20
designh
a a a
D (+12–16)/(T -16) 15,38 28,57 10,53 10/ 0/ 20/ 20
designh
(T -16)/(T
designh designh
a a a
E 100,00 100,00 100,00 10/ 0/ 20/ 20
−16)
a a a
F (T -16)/(T -16) 10/ 0/ 20/ 20
biv designh
a
With the flow rate as determined at the standard rating conditions for units with a fixed flow rate or with a
fixed water temperature difference of 3 K for units with a variable flow rate. If for any of the test conditions the
resulting flow rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with
the inlet temperature for this test condition.

Condition
Condition
5.4 Air-to-water(brine) units
5.4.1 General
The part load conditions for determining the reference SGUE (Formula (16)), SAEF (Formula (20)),
h h
SEHRE (Formula (18)), SAEHRF (Formula (23)), SGUE (Formula (19)), SAEF (Formula (24)), shall be
h h Th Th
given in Table 7, Table 8 and Table 9.
The variable outlet temperature (T ) shall only be applied when the control provides an outdoor
outlet, average
air temperature dependant modification of the outlet temperature.
For the determination of water (brine) temperature for fixed capacity units with variable outlet
temperature refer to EN 16905-4:2026.
For units with variable outlet that have to cycle on/off to reach the required part load ratio the inlet and
outlet temperatures of the indoor heat exchanger shall be determined according to EN 16905-4:2026.
5.4.2 Low temperature application
Table 7 — Part load conditions for air-to-water(brine) units in low temperature application for
the reference heating seasons
Outdoor heat
Indoor heat exchanger
exchanger
Part load ratio
in %
Dry (wet) bulb Fixed
d
Variable outlet
temperature outlet
°C °C °C
All
Formula Average Warmer Colder Outdoor air Average Warmer Colder
climates
(−7–16)/
a a a
A 88,46 n/a 60,53 −7(−8) /35 /34 n/a /30
(Tdesignh-16)
(+2–16)/
a a a a
B 53,85 100,00 36,84 2(1) /35 /30 /35 /27
(Tdesignh-16)
(+7–16)/
a a a a
C 34,62 64,29 23,68 7(6) /35 /27 /31 /25
(Tdesignh-16)
(+12–16)/
a a a a
D 15,38 28,57 10,53 12(11) /35 /24 /26 /24
(Tdesignh-16)
a a b a b a b
E (TOL-16)/(Tdesignh-16) TOL /35 / / /
a a c a c a c
F (T -16)/(T -16) T /35 / / /
bivalent designh biv
(−15-16)/
a a
G n/a n/a 81,58 −15 /35 n/a n/a /32
(T −16)
designh
a
With the flow rate as determined at the standard rating conditions at 30/35 conditions for units with fixed flow rate, and
with a fixed water temperature difference of 5 K for units with a variable flow rate. If for any of the test conditions the resulting
flow rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the outlet temperature
for this test condition.
b
Variable outlet shall be calculated by interpolation from Tdesignh and the temperature which is closest to the TOL.
c
Variable outlet shall be calculated by interpolation between the upper and lower temperatures which are closest to the
bivalent temperature.
d
If the variable outlet temperature is below the minimum of the operation range of the unit, this minimum should be
considered.
Condition
5.4.3 Intermediate temperature application
Table 8 — Part load conditions for air-to-water(brine) units in intermediate temperature
application for the reference heating seasons
Outdoor heat
Indoor heat exchanger
exchanger
Part load ratio
in %
Dry (wet) bulb Fixed
d
Variable outlet
temperature outlet
°C °C °C
All
Formula Average Warmer Colder Outdoor air Average Warmer Colder
climates
(−7–16)/
a a a
A 88,46 n/a 60,53 −7(−8) /45 /43 n/a /38
(Tdesignh-16)
(+2–16)/
a a a a
B 53,85 100,00 36,84 2(1) /45 /37 /45 /33
(Tdesignh-16)
(+7–16)/
a a a a
C 34,62 64,29 23,68 7(6) /45 /33 /39 /30
(Tdesignh-16)
(+12–16)/
a a a a
D 15,38 28,57 10,53 12(11) /45 /28 /31 /26
(Tdesignh-16)
a a b a b a b
E (TOL-16)/(T -16) TOL /45 / / /
designh
a a c a c a c
F (T -16)/(T -16) T /45 / / /
bivalent designh biv
(−15-16) /
a a
G n/a n/a 81,58 −15 /45 n/a n/a /41
(T −16)
designh
a
With the flow rate as determined at the standard rating conditions at 30/35 conditions for units with fixed flow rate, and
with a fixed water temperature difference of 5 K for units with a variable flow rate. If for any of the test conditions the resulting
flow rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the outlet temperature
for this test condition.
b
Variable outlet shall be calculated by interpolation from Tdesignh and the temperature which is closest to the TOL.
c
Variable outlet shall be calculated by interpolation between the upper and lower temperatures which are closest to the
bivalent temperature.
d
If the variable outlet temperature is below the minimum of the operation range of the unit, this minimum should be
considered.
Condition
5.4.4 Medium temperature application
Table 9 — Part load conditions for air-to-water(brine) units in medium temperature application
for the reference heating seasons
Outdoor heat
Indoor heat exchanger
exchanger
Part load ratio
in %
Dry (wet) bulb Fixed
d
Variable outlet
temperature outlet
°C °C °C
All
Formula Average Warmer Colder Outdoor air Average Warmer Colder
climates
(−7–16)/
a a a
A 88,46 n/a 60,53 −7(−8) /55 /52 n/a /44
(Tdesignh-16)
(+2–16)/
a a a a
B 53,85 100,00 36,84 2(1) /55 /42 /55 /37
(Tdesignh-16)
(+7–16)/
a a a a
C 34,62 64,29 23,68 7(6) /55 /36 /46 /32
(Tdesignh-16)
(+12–16)/
a a a a
D 15,38 28,57 10,53 12(11) /55 /30 /34 /28
(Tdesignh-16)
a a b a b a b
E (TOL-16)/(Tdesignh-16) TOL /55 / / /
a a c a c a c
F (T -16)/(T -16) T /55 / / /
bivalent designh biv
(−15-16)/
a a
G n/a n/a 81,58 −15 /55 n/a n/a /49
(T −16)
designh
a
With the flow rate as determined at the standard rating conditions at 30/35 conditions for units with fixed flow rate, and
with a fixed water temperature difference of 5 K for units with a variable flow rate. If for any of the test conditions the resulting
flow rate is below the minimum flow rate then this minimum flow rate is used as a fixed flow rate with the outlet temperature
for this test condition.
b
Variable outlet shall be calculated by interpolation from Tdesignh and the temperature which is closest to the TOL.
c
Variable outlet shall be calculated by interpolation between the upper and lower temperatures which are closest to the
bivalent temperature.
d
If the variable outlet temperature is below the minimum of the operation range of the unit, this minimum should be
considered.
5.5 DX-to-water(brine), water-to-water(brine), brine-to-water(brine) units
5.5.1 General
The part load conditions for determining the reference SGUE (Formula (16)), SAEF (Formula (20)),
h h
SEHRE (Formula (18)), SAEHRF (Formula (23)), SGUE (Formula (19)), SAEF (Formula (24)), shall be
h h Th Th
given in Table 10, Table 11 and Table 12.
The variable outlet temperature (T ) shall only be applied when the control provides an outdoor
outlet, average
air temperature dependant modification of the outlet temperature.
For the determination of water (brine) temperature for fixed capacity units with variable outlet
temperature refer to EN 16905-4:2026.
For units with variable outlet that have to cycle on/off to reach th
...