ISO 5222-2:2025

International
Standard
ISO 5222-2
First edition
Heat recovery ventilators and
2025-02
energy recovery ventilators —
Testing and calculating methods for
seasonal performance factor —
Part 2:
Sensible cooling recovery seasonal
performance factors of heat
recovery ventilators (HRV)
Ventilateurs récupérateurs de chaleur et ventilateurs
récupérateurs d'énergie — Méthodes d'essai et de calcul des
facteurs de performances saisonnières —
Partie 2: Facteurs de performances saisonnières de la
récupération de froid 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 .4
5.3.1 General .4
5.3.2 Energy saving stage limit temperature .4
5.3.3 Sensible cooling recovery performance test .4
5.3.4 The 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 Measurement of power input of heat recovery ventilator with no bypass
ventilation function .5
6 Calculations . 5
6.1 Gross sensible cooling recovery effectiveness (ε ) .5
sc
6.2 Calculation of seasonal performance factor of sensible cooling recovery (F ) .5
sc
6.2.1 Reference outdoor air cooling load and sensible cooling recovery capacity .5
6.2.2 The characteristics of sensible cooling recovery capacity against outdoor
temperature .6
6.2.3 Power input characteristics of sensible cooling recovery against outdoor
temperature .7
6.2.4 Outdoor temperature bin distribution for cooling .7
6.2.5 Calculation of seasonal sensible cooling recovery capacity (E ) .7
sc
6.2.6 Calculation of seasonal sensible cooling recovery power input (P ) .8
in,E
6.2.7 Calculation of seasonal performance factor for sensible cooling recovery (F ) .8
sc
7 Test report . 8
Annex A (Informative) The schematic diagram of HRVs cooling (C) operation .10
Annex B (informative) The default outdoor temperature bin distribution for cooling.12
Annex C (informative) Calculating method for seasonal performance factor when setting a
specific application cooling load .13
Annex D (normative) The calculation of bypass outdoor temperature .15
Annex E (informative) Report template .16
Bibliography .18

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, SC 6,
Testing and rating of air-conditioners and heat pumps.
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 5222-2:2025(en)
Heat recovery ventilators and energy recovery ventilators —
Testing and calculating methods for seasonal performance
factor —
Part 2:
Sensible cooling recovery seasonal performance factors of
heat recovery ventilators (HRV)
1 Scope
This document specifies the testing and calculating methods for sensible cooling recovery seasonal
performance factor of heat recovery ventilators (HRV) covered by ISO 16494-1.
This document also specifies the test conditions and the corresponding test procedures for determining the
sensible cooling recovery seasonal performance factor of HRVs. The rating conditions are those specified in
Annex B and in ISO 16494-1. The procedures of this document can be used for other temperature conditions.
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, Heat recovery ventilators and energy recovery ventilators — Method of test for performance
— Part 1: Development of metrics for evaluation of energy related performance
ISO 16494-1:2022/Amd 1:2023, Heat recovery ventilators and energy recovery ventilators — Method of test for
performance: Part1: Development of metrics for evaluation of energy related performance — Amendment 1
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
sensible cooling heat recovery
transfer of sensible energy from exhaust air to supply air in the HRVs while cooling
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 the supply air and/or exhaust air go through the heat recovery
exchanger by bypass way with energy saving control.

3.3
sensible cooling gross effectiveness
ε
sc
measured effectiveness, not adjusted for leakage, motor heat gain, or heat transfer through the unit casing
Note 1 to entry: The sensible cooling gross effectiveness of an HRV, at equal airflow, is described in ISO 16494-1:2022 9.5.
3.4
net supply airflow
Q
m2, net
portion of the leaving supply airflow that originated as enter in supply airflow
Note 1 to entry: The net supply airflow is expressed in kg/s.
Note 2 to entry: The formulae for determining net supply air flow are given in ISO 16494-1:2022, 9.4.1 (ducted units)
and 9.4.2 (unducted units).
3.5
bypass outdoor temperature
T
b
outdoor temperature in cooling conditions, at which the electricity power reduction for the HRVs by
operating in bypass mode is equal to the saving of electricity power input to the cooling system due to the
heat recovered by the HRVs
3.6
seasonal performance factor of sensible cooling recovery
F
sc
ratio of seasonal amount of sensible cooling recovered together with power value of moving air to the whole
electricity input of HRVs, under the rating conditions and seasonal outdoor temperature bins selected from
this document
3.7
building cooling balance temperature
T
BCB
outdoor air temperature at which building heat gain 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 cooling recovery Wh
sc
F Seasonal performance factor of sensible cooling recovery Wh/Wh
sc
L Reference outdoor air sensible cooling load at outdoor air bin tempera- W
sc,t,j
ture t
j
n Bin hours which the outdoor air bin temperature occurs h
j
n Number of temperature bins -
P Power input to ventilator at outdoor air bin temperature t W
in,t,j j
P Power input to the HRVs to operate the fans at outdoor air bin tempera- W
in,no,t,j
ture t for all stages, for HRVs without bypass ventilation function
j
P Power input to the HRVs at outdoor air bin temperature t for bin temper- W
in,by,t,j j
ature in C or C , for HRVs with bypass ventilation function
stage1 stage2
P Power value of moving air at outdoor air bin temperature t J/s or W
vma,t,j j
P Electricity power input of seasonal sensible cooling recovery Wh
in,E
Q Net supply mass flow rate kg/s
m2,net
Q Ventilation air cooling load with recovery W
vwr
Q Ventilation air cooling load without recovery W
v
Symbol Description Unit
Q Cooling load generated from internal gain and solar gain etc W
ig
Q Cooling amount saved by recovery function W
s
t The outdoor air bin temperature at bin number j °C
j
T Outdoor air temperature when HRVs operates under air bypass ventila- °C
b
tion function
T Outdoor air temperature at which building heat gain equals to heat loss °C
BCB
through the building envelope
T The dry bulb temperature of entering exhaust air (RA) under ISO 16494- °C
1:2022 standard testing conditions (T1/T2/T3/T4/T8)
T Lowest outdoor temperature during cooling season °C
oac
ε Gross sensible cooling effectiveness of HRVs %
sc
ϕ Sensible cooling recovery capacity of the HRVs at outdoor air bin temper- W
sc,t,j
ature t
j
5 Tests
5.1 General requirements
The test conditions used, the accuracy and uncertainties of the instruments used shall conform to 5.2 and
ISO 16494-1.
5.2 Test conditions
For ε , E and F , there are five standard test conditions T1/T2/T3/T4/T8 corresponding to
sc sc sc
ISO 16494-1:2022, Table 1. The HRVs shall be tested at one of the five test conditions, which shall be selected
to most closely represent the outdoor temperature bin distribution in the region as described in Annex B
and Annex C.
Outdoor temperature bin distribution and bin hours differ from region to region. If the bin hours are set to a
certain value for a certain region, the integrated value of cooling load and electric energy consumption can
be determined.
Table 1 shows the requirements for the default values and the reference outdoor temperature bin distribution
for testing and calculation. If a different outdoor temperature bin distribution is to be set, refer to the setting
method as described in Annex C.
Table 1 — Conditions of performance test (cooling)
Outdoor air temperature Indoor air temperature Application tempera-
(°C) (°C) ture bin type for calcu-
lation
Dry bulb Wet bulb Dry bulb Wet bulb
T1 35 23 21 15
T2 35 24 24 17
T3 35 31 27 20 In Annex B or C
T4 35 24 27 19
T8 35 24 25 18
NOTE Allowable variation of readings is given in ISO 16494-1:2022, Table F.2.

5.3 Test methods
5.3.1 General
For higher seasonal energy performance, HRVs can be designed with an air flow bypass ventilation
function integrating fan speed control or airflow dampers adjustment, which can change the fan power
input according to different outdoor temperature conditions, while maintaining necessary aerodynamic
performance.
5.3.2 Energy saving stage limit temperature
To assess the energy saving ability of HRVs, the operation stages under the application temperature bin are
showed in Annex A using a schematic diagram.
5.3.3 Sensible cooling recovery performance test
5.3.3.1 Standard condition performance tests
Sensible cooling recovery performance, efficiency as well as airflow and static pressure shall be measured
corresponding to the selected standard cooling performance tests conditions in Table 1, conducted in
accordance with ISO 16494-1.
5.3.3.2 Determination of performance at application climate
The sensible cooling recovery performance under certain climate temperature bins shall also be determined
by calculation using the temperature bins see Annex B and Annex C.
5.3.4 The determination of bypass outdoor temperature
The manufacturer shall specify the value of bypass outdoor temperature, the laboratory shall verify whether
the tested unit has this function and what is the action temperature by test. If the manufacturer does not
specify it, the laboratory shall calculate the bypass outdoor temperature as per Annex D and set it as T .
b
5.3.5 Measurement of power input of heat recovery ventilator with bypass ventilation function
5.3.5.1 The manufacturer may provide information on how to set the bypass ventilation function if
requested by the testing laboratories.
NOTE 1 Due to the additional air resistance of heat recovery exchanger, when the heat energy recovered is less than
the additional energy input due to overcoming the resistance of recovery heat exchanger during its operation time,
the equipment can provide the bypass ventilation function to reduce the additional energy consumption, when only
ventilation is necessary.
NOTE 2 When the bypass ventilation function is active, there can be several means to reduce the additional energy
consumption, for example, with fan speed control or valve control in the fan’s inlet or outlet, etc., to keep the same
airflow rate and pressure as the rating performance condition.
5.3.5.2 The tests shall be conducted at the required control set which allows steady state operation of the
equipment under the given test conditions.
5.3.5.3 Test of unit with bypass ventilation function and fan speed control:
a) Set up the bypass ventilation function according to the manufacturer’s instructions.
b) Adjust the test auxiliary device to keep the average pressure value at air outlet and inlet of unit in
Figure A.1 of ISO 16494-1:2022/Amd 1:2023 within 5 % of the tested unit’s nominal value and the air
flow rate larger or equal to its nominal value.

c) According to ISO 16494-1:2022, measure and record the data of the air flow rate, pressure and electricity
power input.
d) Determine and record the outdoor temperature at which the bypass ventilation function acts, either by
the manufacturer’s statement, or by measurement. The power input value measured when the bypass
ventilation function is activated is recorded as the bypass ventilation function power input, used to
calculate F corresponding to each outdoor bin temperature in the ventilation period.
sc
5.3.5.4 Test of unit with bypass ventilation function and with electric driving air damper automatically,
but without fan speed c
...