EN ISO 12569:2017

SLOVENSKI STANDARD
01-februar-2018
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SIST EN ISO 12569:2013
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Thermal performance of buildings and materials - Determination of specific airflow rate in
buildings - Tracer gas dilution method (ISO 12569:2017)
Wärmetechnisches Verhalten von Gebäuden und Werkstoffen - Bestimmung des
spezifischen Luftvolumenstroms in Gebäuden - Indikatorgasverfahren (ISO 12569:2017)
Performance thermique des bâtiments et des matériaux - Détermination du débit d'air
spécifique dans les bâtiments - Méthode de dilution de gaz traceurs (ISO 12569:2017)
Ta slovenski standard je istoveten z: EN ISO 12569:2017
ICS:
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 12569
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2017
EUROPÄISCHE NORM
ICS 91.120.10 Supersedes EN ISO 12569:2012
English Version
Thermal performance of buildings and materials -
Determination of specific airflow rate in buildings - Tracer
gas dilution method (ISO 12569:2017)
Performance thermique des bâtiments et des Wärmetechnisches Verhalten von Gebäuden und
matériaux - Détermination du débit d'air spécifique Werkstoffen - Bestimmung des spezifischen
dans les bâtiments - Méthode de dilution de gaz Luftvolumenstroms in Gebäuden -
traceurs (ISO 12569:2017) Indikatorgasverfahren (ISO 12569:2017)
This European Standard was approved by CEN on 6 July 2017.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC 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
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12569:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 12569:2017) has been prepared by Technical Committee ISO/TC 163 "Thermal
performance and energy use in the built environment" in collaboration with Technical Committee
CEN/TC 89 “Thermal performance of buildings and building components” the secretariat of which is
held by SIS.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2018 and conflicting national standards shall be
withdrawn at the latest by March 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 12569:2012.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 12569:2017 has been approved by CEN as EN ISO 12569:2017 without any modification.
INTERNATIONAL ISO
STANDARD 12569
Third edition
2017-08
Thermal performance of buildings and
materials — Determination of specific
airflow rate in buildings — Tracer gas
dilution method
Performance thermique des bâtiments et des matériaux —
Détermination du débit d'air spécifique dans les bâtiments —
Méthode de dilution de gaz traceurs
Reference number
ISO 12569:2017(E)
©
ISO 2017
ISO 12569:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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.
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

ISO 12569:2017(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 1
4 Measurement method and its selection . 2
4.1 General . 2
4.2 Concentration decay method . 4
4.2.1 Principle . 4
4.2.2 Two-point decay method . 5
4.2.3 Multipoint decay method . 6
4.2.4 Step-down exhaust concentration method . 6
4.2.5 Pulse method . 7
4.3 Continuous dose method . 8
4.3.1 Principle . 8
4.3.2 Average inverse concentration method . 8
4.3.3 Average concentration method . 9
4.3.4 Stationary concentration method .10
4.4 Constant concentration method .10
4.5 Type of tracer gas.10
4.6 Measurement apparatus .11
4.6.1 General.11
4.6.2 Tracer gas dosing device .13
4.6.3 Tracer gas sampling apparatus .14
4.6.4 Gas analyser .14
5 Procedure.14
5.1 Building preparations .14
5.2 Ancillary measurements .14
5.3 Concentration decay method .15
5.3.1 Calculation of two-point and multi-point methods .15
5.3.2 Procedure of two-point and multi-point methods .16
5.3.3 Calculation of step-down exhaust concentration method and pulse method .17
5.3.4 Procedure of the step-down exhaust concentration method and pulse method .18
5.4 Continuous dose methods .21
5.4.1 Calculation of average of inverse concentration method.21
5.4.2 Procedure of average of inverse concentration method .22
5.4.3 Calculation of average concentration method .23
5.4.4 Procedure of average concentration method .24
5.4.5 Calculation of stationary concentration method .25
5.4.6 Procedure of stationary concentration method.25
5.5 Constant concentration method .27
5.5.1 Calculation of constant concentration method .27
5.5.2 Procedure of constant concentration method .27
6 Accuracy .28
6.1 General .28
6.2 Tracer gas dose procedure and room concentration distribution .29
6.3 Tracer gas sampling and storage method .29
6.4 Tracer gas concentration measuring instruments .29
6.4.1 General.29
6.4.2 Resolution .29
6.4.3 Tracer gas analyser drift.29
6.4.4 Accuracy of tracer gas analyser .29
ISO 12569:2017(E)
6.4.5 Calibration of tracer gas analyser .30
6.4.6 Standard gas concentration .30
6.5 Changes in outside wind and outdoor air temperature and schedule of air
conditioning system .30
7 Test report .30
7.1 General .30
7.2 Details necessary to identify the simulation tested .31
7.3 Details of heating and ventilation systems .31
7.4 Test conditions and apparatus .31
7.5 Collected data and results .31
7.6 Date of the test .32
Annex A (normative) Confidence intervals .33
Annex B (normative) Method to estimate ventilation rate Q and effective mixed zone
v
[3][4]
volume V simultaneously .36
emz
Annex C (informative) Considerations when measuring the ventilation rate of large spaces .41
Annex D (informative) Effects of internal and external temperature difference, temperature
change, and outdoor air concentration change during the measurement period .42
Annex E (informative) Estimation error minimizing method in two-point and multi-point
decay methods .46
Annex F (informative) Propagation of error analysis .51
Bibliography .53
iv © ISO 2017 – All rights reserved

ISO 12569:2017(E)
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment, Subcommittee SC 1, Test and measurement methods.
This third edition cancels and replaces the second edition (ISO 12569:2012), which has been technically
revised.
ISO 12569:2017(E)
Introduction
The aim of ventilation is to maintain a proper hygienic status of the room by introducing outdoor air
and diluting contaminants, heat, moisture or odour generated in the room, and evacuating them. In
terms of energy savings, it is also important to keep the ventilation at the required rate, in order to
reduce heat loss and heat gain under air conditioning as much as possible. Measurement of airflow rates
is often necessary, for example, to check if the performance of a ventilation system is as intended, to
assess the source strength of contaminants, to ensure that contaminants are properly eliminated, etc.
The methods described here can be used to measure the ventilation rate or the specific airflow rate.
vi © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 12569:2017(E)
Thermal performance of buildings and materials —
Determination of specific airflow rate in buildings —
Tracer gas dilution method
1 Scope
This document establishes methods to obtain the ventilation rate or specific airflow rate in a building
space (which is considered to be a single zone) using a tracer gas.
The measurement methods apply for spaces where the combined conditions concerning the uniformity
of tracer gas concentration, measurement of the exhaust gas concentration, effective mixed zone and/or
fluctuation of ventilation are satisfied.
This document provides three measurement methods using a tracer gas: concentration decay method,
continuous dose method, and constant concentration method.
NOTE Specific measurement conditions are given in Table 1.
2 Normative references
There are no normative references in this document.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
single zone
V
space which only exchanges air with the outside
3.2
effective mixed zone
V
emz
space within a single zone (3.1), excluding sealed furniture or storage space, in which tracer gas (3.6)
supplied to the zone is regarded as uniformly distributed
Note 1 to entry: Measured in cubic metres.
Note 2 to entry: Forced mixing of air in the zone is often needed to keep uniform tracer gas concentration.
3.3
ventilation rate
Q
v
total volume of air passing through the zone to the outside per unit of time
3 3
Note 1 to entry: Measured in m /s or m /h.
ISO 12569:2017(E)
3.4
specific airflow rate
N
ratio of the ventilation rate (3.3) of a zone to the volume of the effective mixed zone (3.2), per second or
per hour
3.5
building envelope
boundary or barrier separating the interior volume of a building from the outside environment
3.6
tracer gas
gas that can be mixed with air and measured in very small concentration in order to study airflow rate
3.7
concentration decay method
method by which the specific airflow rate (3.4) is obtained from the decaying curve of concentration
observed after the end of the injection of tracer gas (3.6)
3.8
continuous dose method
method by which the ventilation rate (3.3) is obtained from the concentration resulting from continuous
generation or injection of the tracer gas (3.6)
3.9
constant concentration method
method by which the ventilation rate (3.3) is obtained from the injection rate of tracer gas (3.6) dosed
for constant concentration in the space
4 Measurement method and its selection
4.1 General
Selection of a measurement method and data processing depends on the building structure, ventilation
system and measurement instrument employed. One of the three measurement methods (concentration
decay method, continuous dose method and constant concentration method) is used to estimate the
ventilation rate or specific airflow rate. The concentration decay method has a limited measurement
time of up to several hours while the continuous dose and constant concentration methods can provide
a longer measurement time up to several weeks. The guideline of selection of the method and what is
measured by the method is listed in Table 1.
In order to improve the accuracy of deriving the ventilation rate or specific airflow rate, it is sometimes
necessary to devise measures that approximate prerequisite conditions demanded of measurement
methods. In particular, if a measurement method were used that requires uniformity of concentration
in the effective mixed zone, it would be preferable to forcibly mix the internal air. In general, forced
mixing of internal air has little effect on ventilation rate or specific airflow rate, but there is a risk that
forced mixing affects the measured ventilation rate if natural ventilation due to temperature differences
predominates and the temperature within the room is distributed significantly, or if airflow emitted
from a fan for the purpose of mixing air directly impinges on the leakage areas in buildings. In such
instances, a mixing system needs to be improved or it would be recommended to select a measurement
method that could ensure uniformity of concentration without mixing.
In Table 1, specifications for the various applications are described as follows.
— “Room concentration can be maintained uniform at initial stage only” means making the
concentration in the effective mixed zone uniform by a method such as forced mixing when
supplying a tracer gas into the zone, but allowing the concentration to be distributed in principle
with the measurement.
2 © ISO 2017 – All rights reserved

ISO 12569:2017(E)
— If it is specified that “room concentration can be maintained uniform at all times”, continuous forced
mixing of air in the effective mixed zone is preferable. However, if the constant concentration method
is used, and if concentration is controlled by injecting the tracer gas at several places and air is
sampled at several locations, it is possible to assume that concentration is uniform without mixing.
— “Average exhaust concentration can be measured” can either mean instances in which concentration
in an effective mixed zone is made uniform using mixing, or instances whereby the pressure inside
a zone is kept lower than the outside when using the exhaust ventilation system, or the leakage area
is extremely low so the exfiltration rate may be ignored and exhaust pathways may be specified
beforehand.
— When using measurement methods that require the “known volume of an effective mixed zone”, the
volume of the effective mixed zone can be estimated using room dimensions. However, when using
the corresponding average inverse concentration method and average concentration method, high
accuracy for estimating the volume of an effective mixed zone is not needed if a sufficiently long
time is taken to evaluate the ventilation rate.
— Measurement methods that can be applied in instances where “fluctuation in ventilation rate can be
ignored” are designed on the assumption that the ventilation rate or specific airflow rate over time
does not change.
— The tracer gas volume is defined as the value of exhaust temperature converted into density. When
the room air is mixed well, the room temperature approximately matches the exhaust temperature.
— In addition to the measurement methods in Table 1, there is an intermittent dose method that allows
the measurement of the volume of an effective mixed zone and ventilation rate at the same time.
— For measurement of ventilation rate among the other measurements, if volume of an effective mixed
zone is known, the ventilation rate can be obtained by multiplying the volume of the effective mixed
zone by the specific airflow rate, and then converting to ventilation rate.
ISO 12569:2017(E)
Table 1 — Relationship of method, application and estimated quantities
Application and measured quantities
Application What is measured
Room
Room Flexibility
concentra- Average Fluctu-
concentra- Known Ventilation to signif-
Method
tion can be exhaust ation in
tion can be volume of rate or icantly
maintained concentra- ventilation
maintained effective specific air- transient
uniform tion can be rate can be
uniform at mixed zone flow rate ventilation
at initial measured ignored
all times rate
stage only
Concen- Two-
tration point Specific air-
— • — — — Δ
decay decay flow rate
method method
Multi-
point Specific air-
— • — — • 
decay flow rate
method
Step-
down
exhaust Specific air-

• — • — •
concen- flow rate
tration
method
Pulse Ventilation
— — • — • 
method rate
Continu- Aver-
ous dose age of
method inverse Ventilation
— • — • — Δ
concen- rate
tration
method
Average
concen- Ventilation
— • — • • 
tration rate
method
Sta-
tionary
Ventilation
concen- — — • — • 
rate
tration
method
Constant concen- Ventilation
— • — — — Δ
tration method rate
“•” indicates the necessary condition for the application to measure the quantity according to each method.
“—” indicates that it is not a necessary condition for each method to be applied.
“Δ” indicates reasonable applicability because the basic equation to derive the measurement method permits temporal
change in ventilation rate.
“” indicates difficulty because the basic equation to derive the measurement method assumes constant ventilation rate.
4.2 Concentration decay method
4.2.1 Principle
At the start of the test, the tracer gas is supplied in the zone where the ventilation rate is to be evaluated
based on the concentration decay data obtained. In case of the forced mixing for uniform distribution
or if the average exhaust concentration can be measured, the measurement point can be limited to one.
4 © ISO 2017 – All rights reserved

ISO 12569:2017(E)
The amount of tracer gas needed is very small for one measurement, and it is not required to accurately
measure the amount of injected gas except for the pulse method.
The basic equation that can be commonly applied to the methods is as given in Formula (1), expressed
3 3
in m /h or m /s:
dV t
()
gas
=−Ct Qt (1)
() ()
E v
dt
where
t is the time, in h or s;
V (t)
gas
 
is the total volume of tracer gas in a zone at time t = Cx,tdV , in m ;
()
V
∫∫∫
 
x is the location in a zone;
3 3
C(x, t) is the concentration at t, x in a zone, in m /m ;
Q (t) is the ventilation rate at t, in m /h;
v
3 3
C (t) is the average exhaust concentration at “t”, in m /m .
E
NOTE Formula (1) assumes that indoor-outdoor air density difference, mostly resulting from temperature
difference, can be neglected.
4.2.2  Two-point decay method
With the concentration in an effective mixed zone continuously made uniform, the time average air
change rate of measuring period is calculated from the measurement start point to the end point. It is
not necessary for the specific airflow rate to be constant during measuring.
Formula (2) is established from the above conditions:
Vt =⋅VC t
() ()
gasemz
(2)
Ct =Ct
() ()
E
where
3 3
C(t) is the concentration in an effective mixed zone (uniform distribution) at t, in m /m ;
V is the volume of an effective mixed zone (no time changes are assumed)
emz
 
= Cx,tdVC t , in m .
() ()
VE
∫∫∫
 
Formula (1) and Formula (2) provide Formula (3) to give Formula (4):
t t Qt
()
2 dC 2
=− dt (3)
∫∫
t t
Ct V
()
1 1
emz
Ct
()
N = log (4)
e
tt− Ct
()
21 2
where
ISO 12569:2017(E)
t is the time, in h;
t is the measurement start point, in h;
t is the measurement end point, in h;
 t Qt 
()
1 2
is the time-mean specific airflow rate = dt , in 1/h.
 
N
∫
t
tt− V
 1 
21 emz
 
Based on the measured concentration data of two different time points, the time average specific
airflow rate during measuring period is calculated for that period. During the measurement period, the
concentration in the effective mixed zone shall be uniformly maintained. It is necessary for the accurate
measuring of specific airflow rate that the difference in concentration between the measurement start
point and end point be sufficiently greater than the concentration measurement error.
4.2.3 Multipoint decay method
Specific airflow rate is calculated when the concentration distribution in an effective mixed zone is
maintained uniform and the ventilation rate does not fluctuate over time.
Formula (5) is obtained when the ventilation rate in Formula (3) is made constant and the formula is
transformed:
loglCt = og Ct −−Nt t (5)
() () ()
ee 11
where
N is the specific airflow rate, in h.
Specific airflow rate is calculated by applying the measured data of concentration using the least
square method to a straight line shown in Formula (5). The precondition that specific airflow rate does
not fluctuate over time is confirmed when log C(t) is plotted against t and there is a linear relationship.
e
Lack of a linear relationship indicates that ventilation rate is not constant, so the specific airflow rate
obtained using this method is not the time-mean specific airflow rate. In this instance, the two-point
decay method should be applied.
4.2.4  Step-down exhaust concentration method
The specific airflow rate is calculated when the average exhaust concentration is measurable, the
distribution of the concentration in an effective mixed zone at the measurement start point is uniform,
and the ventilation rate does not fluctuate over time. It can also be applied when the concentration
is distributed after the start of measuring. Simultaneous measurement with the mean age of air
distribution is possible.
6 © ISO 2017 – All rights reserved

ISO 12569:2017(E)
When time is integrated up to ∞ by making constant the ventilation rate in Formula (1), Formula (6) is
obtained:
∞∞
dV tQ= vC tdt (6)
() ()
gasE
∫∫
tt
If the concentration in an effective mixed zone is made uniform at the measurement start point, the
result is
Vt =⋅VC t
() ()
gase11mz
and after sufficient time has elapsed, the result is
V ∞ =0
()
gas
which provides Formula (7):
ct
()
N = (7)
∞
Ct dt
()
E
∫
t
That is, the reciprocal value to the mean local age of air in the exhaust outlet becomes the specific
airflow rate in the room. In the event of multiple exhaust outlets, the average exhaust concentration
weighted depending on the exhaust airflow rate at each exhaust outlet is used.
NOTE Refer to Annex F if the difference between the exhaust temperature and room temperature cannot be
ignored.
4.2.5 Pulse method
The ventilation rate is calculated when the average exhaust concentration is measurable and the
ventilation rate does not fluctuate over time. The tracer gas volume supplied at the measurement start
point needs to be accurately evaluated, but the concentration distribution in a zone does not need to be
uniform.
In this instance, in Formula (6), V (t ) is already known, and after sufficient time has elapsed, the
gas 1
result is
V ∞ =0
()
gas
which provides Formula (8):
Vt
()
gas 1
Q = (8)
v
∞
Ct dt
()
E
∫
t
where
V (t) is the tracer gas volume ( = supplied tracer gas volume) retained in the room at the meas-
gas
urement start time t , in m .
NOTE For the tracer gas volume, a value of exhaust temperature converted into density is used.
ISO 12569:2017(E)
4.3 Continuous dose method
4.3.1 Principle
With the tracer gas being supplied continuously in the zone, the ventilation rate is measured by the
amount of the dosage and concentration measurement data. If a measurement method that requires
uniformly distributed concentration throughout the effective mixed zone with the tracer gas supplied is
used, it normally requires multiple concentration monitoring points to verify the uniform distribution
of the concentration. The amount of the tracer gas supplied increases as the measurement time
extends; however, the method can be applied to measurement that extends for a long time. The passive
measurement that uses carbon dioxide generated by exhalation of residents as the tracer gas is also one
of the continuous concentration methods.
The basic formula that can be commonly applied to the methods is as given in Formula (9):
dV t
()
gas
=mt −Ct Qv t (9)
() () ()
E
dt
where
m(t) is the dosage of tracer gas at t, in m /h.
4.3.2 Average inverse concentration method
The time-mean specific airflow rate is calculated from the start to the end of measuring, where the
concentration distribution in an effective mixed zone is maintained uniform. It is not necessary for
the ventilation rate to be constant during measuring, but the instantaneous concentration during
measurement, the instantaneous dosage of tracer gas, and the volume of the effective mixed zone are
required.
Formula (10) is established based on the assumed conditions:
Vt =⋅VC t
() ()
gasemz
(10)
Ct =Ct
() ()
E
where
3 3
C(t) is the concentration in an effective mixed zone (uniform distribution) at t, in m /m ;
V is the volume of an effective mixed zone, in m .
emz
Formula (9) and Formula (10) provide Formula (11), which gives Formula (12):
t t mt t
()
2 dC 2 2
V = dt − Qt dt (11)
()
emz v
∫∫ ∫
t t t
Ct Ct
1 () 1 () 1
Ct
m V ()
 
emz
Q = + log (12)
v e
 
C tt− Ct
()
 
21 2
where
8 © ISO 2017 – All rights reserved

ISO 12569:2017(E)
t is the time, in h;
t is the measurement start point, in h;
t is the measurement end point, in h;
 t 
1 2
is the time-mean specific airflow rate = Qt dt , in m /h;
()
 
Q v
∫
v
t
tt−
 21 
t mt
()
1 2
m
 
= dt , in m /h.
  ∫
t
tt−
Ct
C 1 ()
 
mC is in general different to mC . When the tracer gas dose during measuring is constant and is
()
()
m, mC is replaced by 1 C . When there is sufficient measuring time, the effect of the second term on
() ()
the right side in Formula (12) is diminished; so in such circumstance, this method may be applied also
to instances where sufficient accuracy is not obtained for estimation of the volume of the effective
mixed zone. Immediately after the start of tracer gas dosing, the concentration is generally small, which
tends to have a strong effect of delaying the response to the concentration measurement system
including the sampling system, and causing errors in the measured concentration value, so at this point
data shall not be used for calculating the ventilation rate.
4.3.3 Average concentration method
The ventilation rate that does not fluctuate over time when the concentration distribution in an effective
mixed zone has been made constantly uniform is calculated. When there is sufficient measuring time,
calculation is possible using only the time-mean tracer gas dose and time-mean concentration during
the measuring.
Once Formula (10) is supposed for Formula (9), integration in the measuring time provides Formula (13):
t t t2
2 2
Ct Qt dt = mt dt −VdC (13)
() () ()
emz
∫∫ ∫
t t t1
1 1
If Q (t) = Q without the ventilation rate changing over time, Formula (14) is obtained:
v v
Ct −Ct 
V () ()
m
emz
Q =− (14)
 
tt−
C C
 
 
where
t
m= mt dt , in m /h;
()
∫
t
tt−
t2
3 3
C = Ct dt , in m /m .
()
∫
t1
tt−
When there is sufficient measuring time, the effect of the second term in Formula (14) is relatively
minor and can be ignored. However, in the event that the ventilation rate changes over time, if the mean
value theorem in Formula (13) were applied, Formula (15) would be obtained.
 
Ct −Ct
V () ()
m
emz
≤≤
Qv()ξξ=− , tt (15)
 
tt−
C C
21  
 
The ventilation rate obtained in Formula (15) provides the ventilation rate at a time during measuring,
but it does not end up as the time-mean ventilation rate. The ventilation rate obtained from Formula (15)
ISO 12569:2017(E)
is suitable in cases where the purpose is to simulate generation of the contaminating substance in the
room using tracer gas dosing, and estimate the time-mean concentration to which the inhabitant is
exposed. Therefore, when it is possible to measure the instantaneous concentration and instantaneous
dosage of tracer gas for the purpose of measuring the mean ventilation rate, the inverse concentration
method should be used.
4.3.4 Stationary concentration method
The ventilation rate is calculated when the ventilation rate does not fluctuate over time, under
conditions in which the average exhaust concentration is measurable. It can also be applied when
concentration in a zone is distributed.
Formula (16) is obtained when a stationary state is reached and there are no temporal changes in
Formula (9):
m
Q = (16)
v
C
E
where
m is the tracer gas dose, in m /h;
3 3
C is the average exhaust concentration, in m /m .
E
That is, the ventilation rate is obtained by dividing the constant concentration by the tracer gas dose.
4.4 Constant concentration method
In order to make the concentration in an effective zone regularly constant at targeted value, the tracer
gas dose should be controlled and the ventilation rate evaluated from the dosage of tracer gas. Even
when the internal air is not uniformly mixed, by establishing multiple tracer gas dose points and
measuring points, it is possible to make the concentration distribution uniform. Special equipment is
necessary to control the tracer gas dose.
The basic equation to be applied is given in Formula (17) (background concentration has been set at 0
for ease of understanding):
dV t
()
gas
0= =mt −CQ t (17)
() ()
target
dt
where
3 3
C is the target concentration for constant concentration method, in m /m ;
target
Q (t) is the ventilation rate at time t, in m /h;
v
m(t) is the tracer gas dose at time t, in m /h.
Accordingly, ventilation rate is calculated using Formula (18):
mt()
Qt = (18)
()
C
target
4.5 Type of tracer gas
Six types of tracer gas as listed in Table 2 are used to measure the ventilation rate in a zone.
10 © ISO 2017 – All rights reserved

ISO 12569:2017(E)
Table 2 — Types of tracer gas
Sulfur hexafluo- Perfluoro Nitrogen
a b e
Type of gas Helium Carbon dioxide Ethylene
c d f
ride carbon monoxide
CF (PFC-14)
Chemical
b c
He CO SF C H N O
2 6 2 4 2
symbol
C F (PFC-16)
2 6
Infrared gas
Infrared Infrared
Measure- absorption Infrared gas
GC-TCD gas ab- GC-ECD gas ab- GC GC-ECD
ment method and FID absorption
sorption sorption
and GC
Example of
−6 −6 −6 −6 −6 −6
lower limit  300 × 10 1 × 10 70 × 10 0,001 × 10 — 0,1 × 10 0,1 × 10
detection
Permissible
−6 −6 −6
concentra- — 5 000 × 10 1 000 × 10 — — 25 × 10
tion
EXAMPLE:
Relative
density 0,138 1,54
...