EN ISO 12569:2012

SLOVENSKI STANDARD
01-marec-2013
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SIST EN ISO 12569:2001
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Thermal performance of buildings and materials - Determination of specific airflow rate in
buildings - Tracer gas dilution method (ISO 12569:2012)
Wärmetechnisches Verhalten von Gebäuden und Werkstoffen - Bestimmung des
spezifischen Luftvolumenstroms in Gebäuden - Indikatorgasverfahren (ISO 12569:2012)
Performance thermique des bâtiments et des matériaux - Détermination du débit
volumique d'air dans les bâtiments - Méthode de dilution de gaz traceurs (ISO
12569:2012)
Ta slovenski standard je istoveten z: EN ISO 12569:2012
ICS:
91.120.10 Toplotna izolacija stavb Thermal insulation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 12569
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2012
ICS 91.120.10 Supersedes EN ISO 12569:2000
English Version
Thermal performance of buildings and materials - Determination
of specific airflow rate in buildings - Tracer gas dilution method
(ISO 12569:2012)
Performance thermique des bâtiments et des matériaux - Wärmetechnisches Verhalten von Gebäuden und
Détermination du débit d'air spécifique dans les bâtiments - Werkstoffen - Bestimmung des spezifischen
Méthode de dilution de gaz traceurs (ISO 12569:2012) Luftvolumenstroms in Gebäuden - Indikatorgasverfahren
(ISO 12569:2012)
This European Standard was approved by CEN on 17 November 2012.

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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12569:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 12569:2012) 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 June 2013, and conflicting national standards shall be withdrawn at
the latest by June 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 12569:2000.
According to the CEN/CENELEC Internal Regulations, the national standards organisations 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 12569:2012 has been approved by CEN as a EN ISO 12569:2012 without any modification.

INTERNATIONAL ISO
STANDARD 12569
Second edition
2012-12-01
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 12569:2012(E)
©
ISO 2012
ISO 12569:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 12569:2012(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Terms and definitions . 1
3 Measurement method and its selection . 2
3.1 General . 2
3.2 Concentration decay method . 4
3.3 Continuous dose method . 7
3.4 Constant concentration method . 9
3.5 Type of tracer gas.10
3.6 Measurement apparatus .11
4 Procedure.13
4.1 Building preparations .13
4.2 Ancillary measurements .13
4.3 Concentration decay method .13
4.4 Continuous dose methods .20
4.5 Constant concentration method .25
5 Accuracy .27
5.1 Tracer gas dose procedure and room concentration distribution .28
5.2 Tracer gas sampling and storage method .28
5.3 Tracer gas concentration measuring instruments .28
5.4 Changes in outside wind and outside air temperature and schedule of air
conditioning system .29
6 Test report .29
6.1 General .29
6.2 All details necessary to identify the simulation tested.29
6.3 Details of heating and ventilation systems .29
6.4 Test conditions and apparatus .30
6.5 Collected data and results .30
6.6 Date of the test .30
Annex A (normative) Confidence intervals .31
Annex B (normative) Method to estimate ventilation rate Q and effective mixed zone volume V
V emz
[3,4]
simultaneously .34
Annex C (informative) Considerations when measuring the ventilation rate of large spaces .39
Annex D (informative) Effects of internal and external temperature difference, temperature
change, and outside air concentration change during the measurement period .40
Annex E (informative) Estimation error minimizing method in 2-point and multi-point
decay method .44
Annex F (informative) Propagation of error analysis .49
Bibliography .51
ISO 12569:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 12569 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 second edition cancels and replaces the first edition (ISO 12569:2000), which has been
technically revised.
iv © ISO 2012 – All rights reserved

ISO 12569:2012(E)
Introduction
The aim of ventilation is to maintain a proper hygienic status of the room by introducing outdoor air into
a room, 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.
INTERNATIONAL STANDARD ISO 12569:2012(E)
Thermal performance of buildings and materials —
Determination of specific airflow rate in buildings —
Tracer gas dilution method
1 Scope
This International Standard establishes an engineering standard by which to obtain the ventilation
rate/specific airflow rate, using a tracer gas in a building space, which is considered to be of a single zone.
The measurement method is valid in 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 International Standard provides three measurement methods using a tracer gas: (1) concentration
decay method, (2) continuous dose method, and (3) constant concentration method.
NOTE Specific measurement conditions are given in Table 1.
2  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
single zone
V
space where the ventilation rate/specific airflow rate is measured and which only exchanges air
with the outside
NOTE 1 Measured in cubic metres.
NOTE 2 Conditions needed for measurement are different for each measurement method, and details are
given in Clause 4.
2.2
effective mixed zone
V
emz
space within a single zone, excluding sealed furniture or storage space, in which tracer gas supplied to
the zone is regarded as uniformly distributed
NOTE 1 Measured in cubic metres.
NOTE 2 Forced mixing of air in the zone is often needed to keep uniform tracer gas concentration.
2.3
ventilation rate
Q
v
total volume of air passing through the zone to the outdoor air per unit of time
3 3
NOTE Measured in m /s or m /h.
2.4
specific airflow rate
N
ratio of the Qv to the volume of the effective mixed zone, per second or per hour
ISO 12569:2012(E)
2.5
building envelope
boundary or barrier separating the interior volume of a building from the outside environment
2.6
tracer gas
gas that can be mixed with air and measured in very small concentration in order to study airflow rate
NOTE 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.
2.7
concentration decay method
method by which the specific airflow rate is obtained from the decaying curve of concentration observed
after the end of the injection of tracer gas.
2.8
continuous dose method
method by which the ventilation rate is obtained from the concentration resulting from continuous
generation or injection of the tracer gas
2.9
constant concentration method
method by which the ventilation rate is obtained from the injection rate of tracer gas dosed for constant
concentration in the space
3 Measurement method and its selection
3.1 General
One of the three measurement methods concentration decay method, continuous dose method and
constant concentration method, is used to measure the ventilation rate/specific airflow rate. Selection
of a measurement method and data processing depends on a building structure, ventilation system and
measurement instrument employed. 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 measuring the ventilation rate/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/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.
— 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
2 © ISO 2012 – All rights reserved

ISO 12569:2012(E)
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” may 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,
if a sufficiently long time is taken to evaluate the ventilation rate, high accuracy for estimating the
volume of an effective mixed zone is not needed.
— 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/specific airflow rate over time
does not change.
Table 1 — Method, application and measured quantities
Application and measured quantities
Application What is measured
Room Room Average Known Fluctuation Ventilation Flexibility
concentra- concen-tra- exhaust volume of in ventila- rate or spe- to transient
Method
tion can be tion can be concen-tra- effective tion rate can cific airflow ventilation
maintained maintained tion can be mixed zone be ignored rate rate
uniform at uniform at measured
initial stage all times
only
Concentra- 2-point
Specific air-
tion decay decay ○  Δ
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
NOTE In addition to the measurement methods above, there is an intermittent dose method that allows the measurement
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. The measurement
methods marked with “Δ” in the “flexibility to transient ventilation rate” column can apply, in principle, to the case where
changes in ventilation rate/specific airflow rate cannot be ignored, however, because the measurement is based on time-
mean ventilation rate/specific airflow rate, it indicates that it does not meet the measurement of transient ventilation
rate/specific airflow rate. The constant concentration methods marked with “○” indicate it meets measurement of transient
ventilation rate if the dose of the tracer gas responds accurately to the transient ventilation rate with internal concentration
maintained at a constant level.
ISO 12569:2012(E)
Table 1 (continued)
Application and measured quantities
Application What is measured
Room Room Average Known Fluctuation Ventilation Flexibility
concentra- concen-tra- exhaust volume of in ventila- rate or spe- to transient
Method
tion can be tion can be concen-tra- effective tion rate can cific airflow ventilation
maintained maintained tion can be mixed zone be ignored rate rate
uniform at uniform at measured
initial stage all times
only
Continu- Aver-
ous dose age of
method inverse Ventilation
○ ○ Δ
concen- rate
tration
method
Average
concen- Ventilation
○ ○ ○
tration rate
method
Station-
ary
Ventilation
concen- ○ ○
rate
tration
method
Constant concentra- Ventilation
○  ○
tion method rate
NOTE In addition to the measurement methods above, there is an intermittent dose method that allows the measurement
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. The measurement
methods marked with “Δ” in the “flexibility to transient ventilation rate” column can apply, in principle, to the case where
changes in ventilation rate/specific airflow rate cannot be ignored, however, because the measurement is based on time-
mean ventilation rate/specific airflow rate, it indicates that it does not meet the measurement of transient ventilation
rate/specific airflow rate. The constant concentration methods marked with “○” indicate it meets measurement of transient
ventilation rate if the dose of the tracer gas responds accurately to the transient ventilation rate with internal concentration
maintained at a constant level.
3.2 Concentration decay method
3.2.1 General
At the start of measurement, the tracer gas is supplied in the zone to be measured, and ventilation
rate/specific airflow rate is 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. 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 follows:
dV ()t
gas
3 3
=−Ct()Qv()t (m /h or m /s)
E
dt
(1)
where
4 © ISO 2012 – All rights reserved

ISO 12569:2012(E)
t is time, hours or seconds;
V (t)
gas
is total volume of tracer gas in a zone at time “t” ( = Cx,tdV ) (m³);
∫∫∫ ()
V
x is location in a zone;
3 3
C(x, t) is concentration at “t”, “x” in a zone (m /m );
Qv(t) is ventilation rate at “t” (m /h);
3 3
C (t) is average exhaust concentration at “t” (m /m ).
E
NOTE Formula (1) assumes that indoor-outdoor air density difference, mostly resulting from temperature
difference can be neglected.
3.2.2 2-point decay method
With the concentration in an effective mixed zone continuously made uniform, the time-mean air charge
rate 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.
The following equation is established from the above conditions.
Vt() =⋅VC(t)
gasemz
Ct()= Ct() (2)
E
where
3 3
C(t) is concentration in an effective mixed zone (uniform distribution) at t (m /m );
V
emz
is volume of an effective mixed zone (no time changes are assumed) [,= ∫∫∫ Cx tdV /]t
() ()
V C
E
(m ).
Formula (1) and Formula (2) provide Formula (3) to give Formula (4).
Qt
dC ()
t t
2 2
=− dt (3)
∫ ∫
t t
1 1
Ct
()
V
emz
C
1 ()
t
N = (4)
log
e
− C
()
tt t
21 2
where
t is time (t : Measurement start point, t : Measurement end point) (h);
1 2
Qt
()
t
is time-mean specific airflow rate ()= dt (1/h).
N ∫
t
− 1
tt
21 V
emz
Based on the measured concentration data of two different time points, the time-mean specific airflow
rate is calculated for that period. During the measurement period the concentration in the effective mixed
zone must 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.
ISO 12569:2012(E)
3.2.3 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 equation
is transformed.
Ct =−C Nt − (5)
() () ()
loglog t t
ee
where N is specific airflow rate (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 2-point decay
method should be applied.
3.2.4  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.
When time is integrated up to ∞ by making constant the ventilation rate in Formula (1), Formula (6) is
obtained
∞ ∞
∫ d ()tQ= v ∫ ()tdt (6)
V C
gas E
t t
1 1
If the concentration in an effective mixed zone is made uniform at the measurement start point, the result is
=⋅C
() ()
Vt V t
gas1 emz 1
and after sufficient time has elapsed the result is
∞=0
()
Vgas
which provides Formula (7).
C
()
t
N = (7)
∞
tdt
∫ ()
C
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.
3.2.5 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.
6 © ISO 2012 – All rights reserved

ISO 12569:2012(E)
In this instance, in Formula (6), V (t ) is already known, and after sufficient time has elapsed, the result is
gas 1
V ()∞=0
gas
which provides Formula (8).
()
Vtgas1
Qv = (8)
∞
tdt
∫ ()
C
E
t1
where V (t) is tracer gas volume ( = supplied tracer gas volume) retained in the room at the measurement
gas
start time t (m ).
NOTE For the tracer gas volume, a value of exhaust temperature converted into density is used.
3.3 Continuous dose method
3.3.1 General
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 equation that can be commonly applied to the methods is as follows:
dV ()t
gas
=−mt() Ct()Qv()t (9)
E
dt
where m(t) is dosage of tracer gas at “t” (m /h).
3.3.2 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.
The following equation is established based on the assumed conditions.
t =⋅Ct
() ()
V V
gasemz
(10)
tC= t
()
C ()
E
where
3 3
C(t) is concentration in an effective mixed zone (uniform distribution) at t (m /m );
V is volume of an effective mixed zone (m ).
emz
Formula (9) and Formula (10) provide Formula (11), which gives Formula (12).
mt
()
dC
t t t
2 2 2
∫ = ∫ dt − ∫ Qv t dt (11)
()
V
emz
t t t
1 1 1
Ct Ct
() ()
ISO 12569:2012(E)
C
  ()
m t
V 1
emz
Qv =+ (12)
log
 
e
− C
()
C
  tt t
21 2
where
t is time (t : Measurement start point, t : Measurement end point) (h);
1 2
t
is time-mean specific airflow rate ()= Qv tdt (m /h);
∫ ()
Qv
t
− 1
tt
mt
()
  1
m
t
= dt (m /h).
∫
 
− t
C tt Ct
  21 ()
(mC/) is in general different to (/mC) . When the tracer gas dose during measuring is constant and is m,
(mC/) is replaced by mC(/1 ) . 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 must not
be used for calculating the ventilation rate.
3.3.3 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 t
2 2 2
∫ Ct Qt dt = ∫ mt dt − ∫ dC (13)
() () ()
V
emz
t t t
1 1 1
If Q (t) = Q without the ventilation rate changing over time, Formula (14) is obtained.
v v
 
C −C
V () ()
m t t
emz
Q =− (14)
 
−
C C
tt
21  
 
where
t
m = mt dt (m /h);
∫ ()
t
− 1
tt
8 © ISO 2012 – All rights reserved

ISO 12569:2012(E)
t
3 3
C = ∫ Ct dt (m /m ).
()
− t
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.
 
C −C
() ()
m t t
V 21
emz
Qv ξξ=− , ≤≤ (15)
()  
tt
−
C C
tt  
 
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)
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.
3.3.4 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
Qv= (16)
C
E
where
m is tracer gas dose (m /h);
3 3
C is average exhaust concentration (m /m );
E
That is, the ventilation rate is obtained by dividing the constant concentration by the tracer gas dose.
3.4 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 as follows (background concentration has been set at 0 for ease of
understanding).
d t
()
V
gas
0 ==mt()− Qt() (17)
C
target
dt
where
ISO 12569:2012(E)
3 3
C is target concentration for constant concentration method (m /m );
target
Qv(t) is ventilation rate at time t (m /h);
m(t) is tracer gas dose at time t (m /h);
Accordingly, ventilation rate is calculated using the following equation,
mt
()
Qt = (18)
()
C
target
3.5 Type of tracer gas
Six types of tracer gas as listed in Table 2 are used to measure the ventilation rate in a zone.
Table 2 — Types of tracer gas
Sulfur hexafluor- Perfluoro  Nitrogen mon-
a b e
Type of gas Helium Carbon dioxide Ethylene
c d f
ide carbon oxide
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
Infra- Infrared gas
Infrared
Measurement red gas absorption Infrared gas
GC-TCD GC-ECD gas absorp- GC GC-ECD
method absorp- & FID absorption
tion
tion & 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
— 5 000 × 10 1 000 × 10 — — 25 × 10
concentration
Example,
Relative den-
sity against 0,138 1,545 5,302 0,974 1,53
PFC-14: 3,06
air [-]
PFC-16: 4,80
Example,
Global warm-
ing potential — 1 23 900 — 310
PFC-14: 6 500
(GWP)
PFC-16: 9 200
NOTE 1 In addition to those gases above, nitrogen, carbon monoxide, ethane, methane, isobutene, cyclobutanoctofluoride,
Bromomethanetrifluoride, dichlorodifluoridemethane, and dichlorotetrafluoridemethane can be also used as tracer gas.
NOTE 2 The GC in the table indicates general Gas Chromatography, the GC-TCD is the gas chromatography using Thermal
Conductivity Detector and GC-ECD using Electron Capture Detector.
NOTE 3 The Global Warming Potential is defined as relative green house effect potential per weight against carbon dioxide.
NOTE 4 Infrared gas absorption includes both TS (transmission spectroscopy) and PAS (photoacoustic spectroscopy).
a
Helium is chemically stable.
b
CO is dissolved in water and can be adsorbed with building materials or furniture, and is not suited for precise
measurement. However, if the measurement does not require critical accuracy, CO is often used. CO generated by occupants
2 2
or any other internal source shall be taken into account. If this CO emission rate is not known, this tracer cannot be used.
c
SF has a large global warming potential and should not be used in a large amount. SF is an inactive gas. If it is heated to
6 6
500 °C it generates toxic gases. Therefore, it should not be used in a space where a fan heater is used and SF flows through
the heat source.
d
PFC has a large Global Warming Potential and should not be used in large amounts.
e
Ethylene is flammable and should be handled with a great care.
f
N O has a large Global Warming Potential and should not be used in large amounts. N O is dissolved in water, and
2 2
reacts with aluminium. It ignites at a high temperature. Great care must be exercised not to use it over its permissible
concentration as it affects health.
10 © ISO 2012 – All rights reserved

ISO 12569:2012(E)
3.6 Measurement apparatus
3.6.1 General
Measurement instruments required are listed in Table 3 in accordance with the group of measurement
methods listed in Table 1. Each apparatus is defined as a means of dosing and distributing the tracer gas,
collecting air samples, serving as an analyser to measure gas concentration, and other measurement devices.
Table 3 — Group of measurement methods and measurement instruments
Measurement instrument
Tracer gas
Measurement method
Tracer gas Tracer gas Tracer gas Other equip-
concentration
generator distributor collector ment
instrument
Cylinder and Blower for Manual Gas concentra- Reader or
valve with flow mixture suction and tion detector or recorder
2-point decay
a
meter bag made of gas concentra-
method
polyvinylidene tion analyzer
fluoride
Cylinder and Blower for Teflon tube Concentration 2-point decay
valve with flow mixture or and gas suc- analyser method
Multi-point decay
Concen- a
meter pipe for dis- tion pump
method
tration decay
tribution and
method
duct mesh
Step-down method  Cylinder and Blower for Teflon tube Concentration Recorder and
f
at exhaust concen- valve with flow mixture and gas suc- analyser PC
a
tration meter tion pump
Container of Not required Teflon tube Gas concentra- Recorder and
Pulse method known vol- and gas suc- tion analyser PC
c
ume tion pump
Average of inverse Precision flow Blower for Teflon tube Concentration Recorder and
concentration meter system mixture and gas suc- analyser PC
b
method and cylinder tion pump
a. Active Precision flow Blower for Teflon tube Concentration Recorder and
method meter system mixture and gas suc- analyser PC
Average
b
and cylinder tion pump
Continuous concen-
dose method tration
b. Pas- Specific gen- N.A. Specific sam- Concentration N.A.
method
d g
sive erator (doser) pler analyser
method
Precision flow Not required Teflon tube Concentration Recorder and
Stationary concen-
meter system and gas suc- analyser PC
tration method
and cylinder tion pump
Cylinder with Blower for Teflon tube Concentration Process con-
Constant concentration method feedback mixture and gas suc- analyser troller
e
control tion pump
a
Including a float type flow meter.
b
Including valve with accurate orifice flow meter or electronic mass-flow controller. Generally, the cylinder should have a
pressure of 1 MPa, and capacity of 10 l to 15 l and a weight of between 5 kg and 10 kg.
c
Ex: graduated syringe or mass flow meter with timing controller.
d
Including aluminium tube of finger size for dosing carbon hydride by evaporating it gradually.
e
Doser of compressed tracer gas, having a combination of a flow meter and feedback control s
...