oSIST prEN 16211:2023

Ventilation for buildings - Measurement of air flow rates on site - Methods

This document specifies methods for the measurement of air flow rates on site. It provides a description of the air flow rate measurement methods and how measurements are performed within the margins of stipulated method uncertainties. It gives the necessary measurement conditions (e.g. length of straight duct, uniform velocity profile) to achieve the stipulated measurement uncertainties.
The methods for measuring the air flow rate inside ducts do not apply to:
-   ducts that are not circular or rectangular (e.g. oblong ducts);
-   flexible ducts.

Lüftung von Gebäuden - Luftvolumenstrommessung vor Ort - Verfahren

Dieses Dokument legt Verfahren für die Messung von Luftvolumenströmen vor Ort fest. Es enthält eine Beschreibung der Verfahren für die Messung von Luftvolumenströmen und wie Messungen innerhalb der für das Verfahren vorgeschriebenen Toleranzen durchgeführt werden. Es enthält die notwendigen Messbedingungen (z. B. Länge der geraden Luftleitung, gleichmäßiges Geschwindigkeitsprofil) zur Erreichung der vorgegebenen Messunsicherheiten.
Die Verfahren zur Messung des Luftvolumenstroms in Luftleitungen sind nicht anwendbar für:
   Luftleitungen, die nicht kreisförmig oder rechteckig sind (z B. längliche Luftleitungen);
   flexible Luftleitungen.

Ventilation des bâtiments - Mesurages des débits d'air sur site - Méthodes

Le présent document spécifie des méthodes pour le mesurage des débits d’air sur site. Il fournit une description des méthodes de mesurage de débit d’air et indique la façon dont les mesurages sont réalisés dans les marges d’incertitude de la méthode stipulée. Il donne les conditions de mesure nécessaires (par exemple, longueur de conduit droit, profil de vitesse uniforme) pour atteindre les incertitudes de mesure stipulées.
Les méthodes de mesure du débit d’air dans les conduits ne s’appliquent pas:
-   aux conduits qui ne sont pas circulaires ou rectangulaires (par exemple, conduits oblongs);
-   aux conduits flexibles.

Prezračevanje stavb - Meritve pretoka zraka v sistemu prezračevanja - Metode

General Information

• Status: Not Published
• Public Enquiry End Date: 31-May-2023
• ICS: 17.120.10 - Flow in closed conduits
• ICS: 91.140.30 - Ventilation and air-conditioning systems
• Technical Committee: OGS - Heating for buildings
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 16-Mar-2023
• Due Date: 03-Aug-2023
• Completion Date: 25-May-2023
• Ref Project: prEN 16211 - Ventilation for buildings - Measurement of air flow rates on site - Methods

Relations

• Replaces: SIST EN 16211:2015 - Ventilation for buildings - Measurement of air flows on site - Methods
• Effective Date: 02-Sep-2020
• Revises: SIST EN 16211:2015 - Ventilation for buildings - Measurement of air flows on site - Methods
• Effective Date: 19-Jan-2023
• Revised: SIST EN 16211:2015 - Ventilation for buildings - Measurement of air flows on site - Methods
• Effective Date: 18-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 16211:2023
01-maj-2023
Nadomešča:
SIST EN 16211:2015
Prezračevanje stavb - Meritve pretoka zraka v sistemu prezračevanja - Metode
Ventilation for buildings - Measurement of air flow rates on site - Methods
Lüftung von Gebäuden - Luftvolumenstrommessung vor Ort - Verfahren
Ventilation des bâtiments - Mesurages des débits d'air sur site - Méthodes
Ta slovenski standard je istoveten z: prEN 16211
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
oSIST prEN 16211:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 16211:2023

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oSIST prEN 16211:2023


DRAFT
EUROPEAN STANDARD
prEN 16211
NORME EUROPÉENNE

EUROPÄISCHE NORM

March 2023
ICS 17.120.10; 91.140.30 Will supersede EN 16211:2015
English Version

Ventilation for buildings - Measurement of air flow rates
on site - Methods
Ventilation des bâtiments - Mesurages des débits d'air Lüftung von Gebäuden - Luftvolumenstrommessung
sur site - Méthodes vor Ort - Verfahren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 156.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

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

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

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


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16211:2023 E
worldwide for CEN national Members.

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prEN 16211:2023 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviated terms . 8
5 Expression of air flow rate . 10
5.1 Hydraulic diameter . 10
5.2 Flow disturbances . 11
5.3 Stability of the flow rate . 11
5.4 Air density . 11
5.5 Conversion of dynamic pressure into air velocity . 12
5.6 Correction and conversion of measured air flow rate . 12
5.6.1 General . 12
5.6.2 Correction of the air flow rate . 13
5.6.3 Conversion of the air flow rate . 14
6 Measuring instruments requirements . 14
6.1 General . 14
6.2 Air flow rate measuring instruments . 15
6.3 Differential pressure measuring instruments. 15
6.4 Air velocity measuring instruments . 15
6.4.1 General . 15
6.4.2 Anemometers . 15
6.4.3 Pitot static tubes . 15
6.5 Temperature measuring instruments . 16
6.6 Atmospheric pressure measuring instruments . 16
7 Methods for measurement of air flow rates . 16
7.1 Overview of described methods . 16
7.2 Multi‐point measurement in the duct cross‐section – with measurement plane
criteria (ID1) . 17
7.2.1 Principle . 17
7.2.2 Apparatus . 18
7.2.3 Measurement procedure . 19
7.2.4 Expression of results . 23
7.3 Multipoint measurement in the duct cross‐section – without measurement plane
criteria (ID2) . 25
7.3.1 Principle . 25
7.3.2 Apparatus . 25
7.3.3 Measurement procedure . 26
7.3.4 Expression of results . 34
7.4 Fixed devices for air flow rate measurement (ID3, ST1 and ET1) . 38
7.4.1 Principle . 38
7.4.2 Apparatus . 39
7.4.3 Measurement procedure . 39
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7.4.4 Expression of results . 39
7.5 Air flow rate measurement with tight bag at supply ATDs (ST2) . 40
7.5.1 Principle . 40
7.5.2 Apparatus . 41
7.5.3 Measurement procedure . 41
7.5.4 Expression of results . 42
7.6 Air flow rate measurement with flow hood (ST3 and ET2) . 42
7.6.1 Principle . 42
7.6.2 Apparatus . 43
7.6.3 Measurement procedure . 44
7.6.4 Expression of results . 46
Annex A (informative) Additional methods . 47
A.1 Tracer gas measurement (ID4) . 47
A.1.1 Principle . 47
A.1.2 Apparatus . 47
A.1.3 Measurement procedure – Conditions for homogeneous mixing of tracer gas . 48
A.1.4 Expression of result – Calculation of air flow rate . 49
A.2 Measurement using anemometer at air intake (IN1) or air exhaust (EX1) . 50
A.2.1 Principle . 50
A.2.2 Apparatus . 50
A.2.3 Measurement procedure . 50
A.2.4 Expression of results . 51
A.3 Point measurements using thermal anemometers on rectangular intake (IN2) and
exhaust (EX2) grilles on walls . 51
A.3.1 Principle . 51
A.3.2 Measurement instruments/Apparatus . 52
A.3.3 Measurement procedure . 52
A.3.4 Standard measurement uncertainty . 54
Annex B (informative) Measurement uncertainty . 56
B.1 Uncertainty of the result of a measurement . 56
B.2 Type B evaluation of standard uncertainty . 56
B.3 Combined standard uncertainty . 58
B.4 Expanded uncertainty . 59
B.5 Examples . 59
Bibliography . 64

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oSIST prEN 16211:2023
prEN 16211:2023 (E)
European foreword
This document (prEN 16211:2023) has been prepared by Technical Committee CEN/TC 156 “Ventilation
for buildings”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 16211:2015.
In addition to a number of editorial revisions, the following main changes have been made with respect
to EN 16211:2015:
— the whole document has been rearranged;
— the method described previously in EN 12599:2012 to measure air flow rate in ductwork has been
included;
— the tracer gas method has been moved in Annex A (informative);
— two new methods to measure flow rate at exhaust and intake grille have been added in Annex A
(informative);
— parts dealing with uncertainty have been replaced by Annex B (informative);
— requirements on measuring devices are now expressed in MPME (Maximum Permissible
Measurement Error).

4

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oSIST prEN 16211:2023
prEN 16211:2023 (E)
Introduction
Measurement of the air flow rate in a ventilation system is of general interest that is not related to a
specific operation or stage (e.g. installation, inspection, commissioning or handover). It was therefore
agreed to take advantage of the simultaneous revision of EN 16211:2015 and EN 12599:2012 to address
this subject in a single document (prEN 16211:2023) rather than scattering or repeating it in various
documents.

5

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1 Scope
This document specifies methods for the measurement of air flow rates on site. It provides a description
of the air flow rate measurement methods and how measurements are performed within the margins of
stipulated method uncertainties. It gives the necessary measurement conditions (e.g. length of straight
duct, uniform velocity profile) to achieve the stipulated measurement uncertainties.
The methods for measuring the air flow rate inside ducts do not apply to:
— ducts that are not circular or rectangular (e.g. oblong ducts);
— flexible ducts.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12792, Ventilation for buildings — Symbols, terminology and graphical symbols
EN 14277, Ventilation for buildings — Air terminal devices — Method for airflow measurement by
calibrated sensors in or close to ATD/plenum boxes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12792 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
measuring interval
set of values of quantities of the same kind that can be measured by a given measuring instrument or
measuring system with specified instrumental measurement uncertainty, under defined conditions
Note 1 to entry: In some fields, the term is “measuring range” or “measurement range”.
[SOURCE: JCGM 200:2012, 4.7, modified – Note 2 has not been reproduced]
3.2
maximum permissible measurement error
extreme value of measurement error, with respect to a known reference quantity value, permitted by
specifications or regulations for a given measurement, measuring instrument or measuring system
Note 1 to entry: More information on the use of maximum permissible measurement error in measurement
uncertainty is given in Annex B.
[SOURCE: JCGM 200:2012, 4.26, modified – The accepted terms “maximum permissible error” and “limit
of error” have been removed, NOTE 1 and NOTE 2 have been removed, a Note 1 to entry has been added]
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3.3
standard uncertainty
measurement uncertainty expressed as a standard deviation
Note 1 to entry: More information on the use of standard uncertainty in measurement uncertainty is given in
Annex B.
[SOURCE: JCGM 200:2012, 2.30, modified – The preferred term and the first accepted term have been
removed and a Note 1 to entry has been added]
3.4
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards and corresponding
indications with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
[SOURCE: JCGM 200:2012, 2.39]
3.5
correction
compensation for an estimated systematic effect
[SOURCE: JCGM 200:2012, 2.53]
3.6
hypothetical
obtained by making hypothesis on the existing conditions
3.7
dynamic pressure
velocity pressure
pressure equivalent of the kinetic energy of the fluid at a point
3.8
static pressure
pressure exerted, in a moving fluid, on an element moving at the same velocity as the fluid
3.9
total pressure
total gauge pressure
sum of static gauge pressure and dynamic pressure (3.6) at any point of a fluid
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4 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in Table 1 apply.
Table 1 — Symbols and abbreviated terms
Symbol Description Unit
Abbreviated
terms
a/D Relative distance —
h
A Cross-section area 2
m
A Free cross-section area of the duct 2
K m
A Effective cross-section area of the probe 2
g m
W Width of the duct mm
C Initial tracer gas concentration ppm
i
C Tracer gas concentration in the sampling cross-section ppm
s
D Diameter m
D Hydraulic diameter m
h
D Centroidal ring of the annulus
i
D Probe diameter mm
so
e Device’s flow exponent given by the manufacturer (usually 0,5) —
H Height of the duct mm
i Ordinal number of the measuring point (on a measurement straight —
line)
I Irregularity of the velocity profile —
k Characteristic of the fixed device depending on its setting —
(k-factor)
k Coverage factor —
k Correction factor (for method IN2 and EX2) —
k Correction factor for density —
1
k Correction factor for duct shape —
2
l Length m
L Smaller dimension of a rectangular duct mm
1
L Larger dimension of a rectangular duct mm
2
MPME(p ) Maximum permissible measurement error at the measured dynamic —
d
pressure
n Number of measuring points or measurement —
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Symbol Description Unit
Abbreviated
terms
n Number of annular rings —
n Number of measuring points along the smaller dimension —
L1
n Number of measuring points along the larger dimension —
L2
p Atmospheric pressure Pa
atm
p Atmospheric pressure in actual conditions Pa
atm,act
p Atmospheric pressure in device hypothetical condition Pa
atm,hyp
p Atmospheric pressure in standardized conditions (101 325 Pa) Pa
atm,std
p Dynamic pressure Pa
d
p Static pressure Pa
s
p Total pressure Pa
t
P Perimeter of the cross-section m
q Air flow rate 3
m /s, l/s
q Tracer gas flow rate 3
s m /s, l/s
q Tracer gas flow rate at duct temperature 3
sϑduct m /s, l/s
q Tracer gas flow rate at rotameter temperature 3
sϑtracer m /s, l/s
q Actual air volume flow rate (in actual conditions) 3
v,act m /h
q Hypothetical air volume flow rate assuming device default conditions 3
v,hyp m /h
q Measured air volume flow rate 3
v,m m /s
q Standardized air volume flow rate (in standard conditions) 3
v,std m /h
Re Reynolds number —
t Time s
T Air temperature in actual conditions K
act
T Air temperature in device default condition K
hyp
T Air temperature in standardized conditions (293,15 K) K
std
u Combined standard uncertainty —
c
U Expanded uncertainty —
v Air velocity m/s
v Actual air velocity m/s
act
v Air velocity reading m/s
g
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Symbol Description Unit
Abbreviated
terms
v Air velocity for measuring point k m/s
k
v Average air velocity m/s
m
v Maximum of the arithmetic mean of velocities in a quarter of the cross- m/s
max
section or at a radius
v Minimum of the arithmetic mean of velocities in a quarter of the cross- m/s
min
section or at a radius
V Volume 3
m
x Coordinate of the measuring point —
i
y Coordinate of the measuring point —
i
y Distance from wall mm
i
W Width of the duct mm
θ Air temperature in actual conditions (= T −273,15) °C
act act
ρ Air density 3
kg/m
ρ Air density in actual conditions 3
act kg/m
ρ Air density in device default condition 3
hyp kg/m
ρ Air density in standardized conditions 3
std kg/m
ϑ Temperature of air °C
ϑ Temperature inside the duct °C
duct
ϑ Temperature of tracer gas °C
tracer
ATD Air terminal devices —
MPME Maximum Permissible Measurement Error —
RH Relative Humidity of the air —

5 Expression of air flow rate
5.1 Hydraulic diameter
The hydraulic diameter, D , is the diameter of a circular duct which causes the same pressure drop, at
h
equal air velocity and equal roughness factor, than the considered duct and is defined by Formula (1).
A
D 4⋅ (1)
h
P
where
10
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2
 A is the area of the cross-section, in m ;
 P is the perimeter of the cross-section, in m.

For a rectangular duct, Formula (1) becomes Formula (2).
LL⋅
12
D 2⋅ (2)
h
LL+
( )
12
where
 L
is the smaller dimension of the rectangular duct, in mm;
1
 L
is the larger dimension of the rectangular duct, in mm.
2

For a circular duct, Formula (1) becomes Formula (3).
D = D (3)
h
5.2 Flow disturbances
Within an air flow, disturbances result in irregular velocity profiles. Irregular velocity profile can induce
additional measurement errors and complicate the measurement. Away from any disturbance the
velocity profile gets more and more regular. For some methods, requirements are set regarding the
position of the measurement device from flow disturbances.
NOTE Flow seldom has a symmetrical appearance except after long straight sections. The symmetry is often
disturbed by varying resistance, for example after a bend, an area decrease or an area increase. The velocity profile
also becomes disturbed by a damper and T-piece as well as before and after a fan.
5.3 Stability of the flow rate
Measurement methods described in this document are based on the assumption that the air flow rate
does not change during the measurement time.
NOTE Variation of the air flow rate increases the measurement uncertainty.
5.4 Air density
The density of dry air, ρ, varies with atmospheric pressure and temperature in accordance with
Formula (4).
p 273,15
atm
(4)
ρ=1,293⋅⋅
101325 273,15+ϑ
where
 p
is the atmospheric pressure, in Pa;
atm
 ϑ is the temperature of the air, in °C.

NOTE More information is available in CEN/TS 17153.
11
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The relative humidity of the air (RH) has very little influence on the density of air at room temperature.
The density of air at 20 °C and 101 325 Pa which is saturated with water vapour is only approximately
1 % less than equivalent dry air.
In a low-pressure system it is hardly necessary to consider the influence of static pressure on air density.
In a high-pressure system, however, it can be necessary. The calculation is then performed using
Formula (5).
pp+ 273,15
atm s
ρ=1,293⋅⋅ (5)
101325 273,15+ϑ
where
 p
is the static pressure in the ductwork, in Pa;
s
 p
is the atmospheric pressure, in Pa.
atm

5.5 Conversion of dynamic pressure into air velocity
Dynamic pressure within an air flow can be measured with a Pitot static tube connected to a manometer
(see Figure 1 in 6.4.3).
Air velocity can be calculated from dynamic pressure using Formula (6).
2p
d
(6)
v =
act
ρ
act
where
 v
is the actual air velocity (in prevailing conditions);
act
 p
is the dynamic pressure;
d
 ρ
is the air density in prevailing conditions.
act

5.6 Correction and conversion of measured air flow rate
5.6.1 General
By nature, air flow rate measurements on site are done in actual conditions (i.e. conditions existing in a
particular place and at a particular time).
The actual conditions refer to the place where measurements are made. For measurements in ducts,
atmospheric pressure may be measured outside the duct for practical reasons. In this case, the static
pressure in the duct should be added to the atmospheric pressure for calculation purpose. When the static
pressure in the duct is below 2 000 Pa in absolute value it may be neglected.
However, depending on their settings, some measuring systems may:
— give uncorrected air flow rate, q , by making the hypothesis that the air is at the device default
v,hyp
3
condition (e.g. 1,204 kg/m corresponding to 293,15 K and 101 325 Pa). This hypothetical air flow
rate is neither the actual air volume flow rate nor the standardized air volume flow rate and
corrections given in 5.6.2 shall be done;
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— automatically calculate or convert quantity values into different than actual conditions (e.g. standard
conditions). In this case, conversion to actual conditions, as given in 5.6.3, shall be done.
In any case, the technical data sheet should be consulted to find out to which conditions (actual, standard,
etc.) the indicated quantity values correspond and how to correct or convert them into actual conditions.
5.6.2 Correction of the air flow rate
The formula to convert hypothetical air volume flow rate into actual air volume flow rate (air volume
flow rate occurring in actual conditions) depends on the measuring device used.
To obtain the actual air volume flow rate, the user shall refer to manufacturer specifications to determine
whether:
— the correction is done automatically, in this case no further corrections sh
...