ISO 5222-1:2025

International
Standard
ISO 5222-1
Second edition
Heat recovery ventilators and
2025-10
energy recovery ventilators —
Testing and calculating methods for
performance factor —
Part 1:
Sensible heating recovery seasonal
performance factors of heat
recovery ventilators (HRVs)
Ventilateurs récupérateurs de chaleur et ventilateurs
récupérateurs d'énergie — Méthodes d'essai et de calcul des
facteurs de performances —
Partie 1: Facteurs de performances saisonnières de la
récupération de chaleur sensible des ventilateurs récupérateurs
de chaleur (HRV)
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 2
5 Tests . 3
5.1 General requirements .3
5.2 Test conditions .3
5.3 Test methods .3
5.3.1 General .3
5.3.2 Energy saving stage limit temperature .4
5.3.3 Sensible heating recovery performance test . .4
5.3.4 Determination of bypass outdoor temperature .4
5.3.5 Measurement of power input of heat recovery ventilator with bypass ventilation
function.4
5.3.6 Determination of the frosting temperature by test .5
6 Calculations . 6
6.1 Gross sensible heating recovery effectiveness (ε ) .6
sh
6.2 Calculation of seasonal performance factor of sensible heating recovery (F ) .6
sh
6.2.1 Reference outdoor air heating load and sensible heating recovery capacity .6
6.2.2 The characteristics of sensible heating recovery capacity against outdoor
temperature .7
6.2.3 Power input characteristics of sensible heating recovery against outdoor
temperature .7
6.2.4 Outdoor temperature bin distribution for heating .8
6.2.5 Calculation of seasonal sensible heating recovery capacity (E ) .8
sh
6.2.6 Calculation of seasonal sensible heating recovery power input (P ) .9
in,E
6.2.7 Calculation of seasonal performance factor for sensible heating recovery (F ) .9
sh
7 Test report . 9
Annex A (informative) The schematic diagram of heat recovery ventilators (HRVs) heating (H)
operation . 10
Annex B (informative) The default outdoor temperature bin distribution for heating .13
Annex C (normative) Method of determination of the temperature T . 14
F,0
Annex D (informative) Calculating method for seasonal performance factor when setting a
specific application heating load .15
Annex E (normative) Calculation of the bypass outdoor temperature . 17
Annex F (informative) Report template .18
Bibliography .21

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 86, Refrigeration and air-conditioning,
Subcommittee SC 6, Testing and rating of air-conditioners and heat pumps.
This second edition cancels and replaces the first edition (ISO 5222-1:2023), which has been technically
revised. The main changes are as follows:
— terms and definitions have been revised to align with ISO 5222-2 and ISO 5222-3;
— symbols have been revised in accordance with the ISO/IEC Directives, Part 2;
— names of stages have been revised to align with ISO 5222-2 and ISO 5222-3;
— 6.2 sensible heating coefficient of energy and 3.3 coefficient of energy have been deleted;
— errors in 6.2.3 have been corrected;
— a note has been added to 6.2.5 for clarification;
— Figure A.1 has been revised to align with ISO 5222-2 and ISO 5222-3.
A list of all parts in the ISO 5222 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 5222-1:2025(en)
Heat recovery ventilators and energy recovery ventilators —
Testing and calculating methods for performance factor —
Part 1:
Sensible heating recovery seasonal performance factors of
heat recovery ventilators (HRVs)
1 Scope
This document specifies the testing and calculating methods for sensible heating recovery seasonal
performance factor of heat recovery ventilators (HRVs) covered by ISO 16494-1.
This document also specifies the test conditions and the corresponding test procedures for determining the
sensible heating recovery seasonal performance factor of HRVs. It is intended for use only for marking and
comparison purposes.
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.
ISO 16494-1:2022/Amd 1:2023, Heat recovery ventilators and energy recovery ventilators — Method of test for
performance — Part 1: Development of metrics for evaluation of energy related performance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16494-1 and the following 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/
3.1
heat recovery
transfer of sensible energy from exhaust air to supply air in heat recovery ventilators
while heating
3.2
bypass ventilation function
function for reducing power input of the fans while the heat energy recovered is less than the additional
energy input due to overcoming the resistance of recovery heat exchanger during its operation time
Note 1 to entry: The bypass ventilation function makes either the supply air or exhaust air or both airflows go through
the bypass passage with energy saving control.

3.3
gross effectiveness
measured effectiveness, not adjusted for leakage, motor heat gain or heat transfer
through the unit casing
Note 1 to entry: The sensible heating gross effectiveness of heat recovery ventilators, at equal airflow, is described in
ISO 16494-1:2022, 9.5.
3.4
bypass outdoor temperature
T
b
outdoor temperature in heating conditions, at which the power reduction to heat recovery ventilators
(HRVs) by operating in bypass mode is equal to the saving of power input to the heating system due to the
heat recovered by HRVs
3.5
seasonal performance factor of sensible heating recovery
F
sh
ratio of seasonal amount of sensible heat recovered together with power value of moving air to the whole
power input of heat recovery ventilators, under the rating conditions and seasonal outdoor temperature
bins selected from this standard
3.6
building heating balance temperature
T
BHB
outdoor air temperature at which building internal heat gain, solar radiation, and so on, equals to heat loss
through the building envelope
4 Symbols and abbreviated terms
Symbol Description Unit
c specific heat of leaving supply air (SA) kJ/(kg· °C)
p
E capacity of seasonal sensible heating recovery Wh
sh
F seasonal performance factor of sensible heating re
...