EN ISO 6781-1:2023
(Main)Performance of buildings - Detection of heat, air and moisture irregularities in buildings by infrared methods - Part 1: General procedures (ISO 6781-1:2023)
Performance of buildings - Detection of heat, air and moisture irregularities in buildings by infrared methods - Part 1: General procedures (ISO 6781-1:2023)
This document specifies requirements and methodologies for infrared thermographic services for detection of heat, air and moisture irregularities in buildings that help users to specify and understand
a) the extent of thermographic services required,
b) the type and condition of equipment available for use,
c) the qualifications of equipment operators, image analysts, and report authors and those making recommendations, and
d) the reporting of results.
It provides guidance to understanding and utilizing the final results stemming from provision of the thermographic services.
This document is applicable to the general procedures for infrared thermographic methods as can be applied to residential, commercial, and institutional and special use buildings.
Verhalten von Gebäuden - Feststellung von wärme-, luft- und feuchtebezogenen Unregelmäßigkeiten in Gebäuden durch Infrarotverfahren - Teil 1: Allgemeine Verfahren (ISO 6781-1:2023)
Dieses Dokument legt Anforderungen und Methoden für infrarot-thermographische Dienstleistungen für den Nachweis von wärme-, luft- und feuchtebezogene Unregelmäßigkeiten in Gebäuden fest, die dem Anwender dabei helfen,
a) den Umfang der erforderlichen thermographischen Dienstleistungen,
b) die Art und den Zustand der zu verwendenden Ausrüstung,
c) die Qualifikationen der Ausrüstungsbetreiber, Thermograf und Berichtsautoren sowie der Personen, die Empfehlungen aussprechen,
d) die Berichterstattung über die Ergebnisse
festzulegen und zu verstehen. Mit diesem Dokument wird den Anwendenden ein Leitfaden an die Hand geben, wie die sich aus der Bereitstellung von thermographischen Dienstleistungen ergebenden Endergebnisse zu verstehen und zu nutzen sind.
Dieses Dokument ist für die allgemeinen Vorgehensweisen für infrarot-thermographische Verfahren bei Wohngebäuden, Geschäftsgebäuden und öffentlichen und Spezialgebäuden anwendbar.
Performance des bâtiments - Détection d'irrégularités de chaleur, air et humidité dans les bâtiments par des méthodes infrarouges - Partie 1: Modes opératoires généraux (ISO 6781-1:2023)
Le présent document spécifie les exigences et les méthodologies relatives aux services de thermographie infrarouge pour la détection d’irrégularités de chaleur, air et humidité dans les bâtiments, afin d’aider les utilisateurs à spécifier et à comprendre:
a) l’étendue des services de thermographie exigés;
b) le type et l’état de l’équipement pouvant être utilisé;
c) les qualifications des opérateurs de l’équipement, des analystes de données, des auteurs de rapports et des personnes qui émettent des recommandations; et
d) la présentation des résultats.
Il fournit des recommandations concernant la compréhension et l’utilisation des résultats finals découlant des prestations de services de thermographie.
Le présent document s’applique aux modes opératoires généraux des méthodes de contrôle par thermographie infrarouge qui peuvent être appliquées aux bâtiments résidentiels, commerciaux, institutionnels et à usage spécial.
Značilnosti stavb - Zaznavanje nepravilnosti toplote, zraka in vlage v stavbah z infrardečimi metodami - 1. del: Splošni postopki (ISO 6781-1:2023)
Ta dokument določa zahteve in metodologije za infrardeče termografske storitve za zaznavanje nepravilnosti toplote, zraka in vlage v stavbah, ki so uporabnikom v pomoč pri določanju in razumevanju:
a) obsega potrebnih termografskih storitev,
b) vrste in stanja opreme, ki je na voljo za uporabo,
c) kvalifikacij operaterjev opreme, slikovnih analitikov in avtorjev poročil ter tistih, ki dajejo priporočila, in
d) poročanja o rezultatih.
Podaja smernice za razumevanje in uporabo končnih rezultatov, ki izhajajo iz zagotavljanja termografskih storitev.
Ta dokument se uporablja za splošne postopke za infrardeče termografske metode, ki se lahko uporabljajo za stanovanjske, poslovne in institucionalne stavbe ter stavbe za posebno uporabo.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2023
Nadomešča:
SIST EN 13187:2000
Značilnosti stavb - Zaznavanje nepravilnosti toplote, zraka in vlage v stavbah z
infrardečimi metodami - 1. del: Splošni postopki (ISO 6781-1:2023)
Performance of buildings - Detection of heat, air and moisture irregularities in buildings
by infrared methods - Part 1: General procedures (ISO 6781-1:2023)
Verhalten von Gebäuden - Feststellung von wärme-, luft- und feuchtebezogenen
Unregelmäßigkeiten in Gebäuden durch Infrarotverfahren - Teil 1: Allgemeine Verfahren
(ISO 6781-1:2023)
Performance des bâtiments - Détection d'irrégularités de chaleur, air et humidité dans les
bâtiments par des méthodes infrarouges - Partie 1: Procédures générales (ISO 6781-
1:2023)
Ta slovenski standard je istoveten z: EN ISO 6781-1:2023
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 6781-1
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2023
EUROPÄISCHE NORM
ICS 91.120.10 Supersedes EN 13187:1998
English Version
Performance of buildings - Detection of heat, air and
moisture irregularities in buildings by infrared methods -
Part 1: General procedures (ISO 6781-1:2023)
Performance des bâtiments - Détection d'irrégularités Verhalten von Gebäuden - Feststellung von wärme-,
de chaleur, air et humidité dans les bâtiments par des luft- und feuchtebezogenen Unregelmäßigkeiten in
méthodes infrarouges - Partie 1: Modes opératoires Gebäuden durch Infrarotverfahren - Teil 1: Allgemeine
généraux (ISO 6781-1:2023) Verfahren (ISO 6781-1:2023)
This European Standard was approved by CEN on 24 June 2023.
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, 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.
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. EN ISO 6781-1:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 6781-1:2023) has been prepared by Technical Committee ISO/TC 163/SC 1
"Test and measurement methods" 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 February 2024, and conflicting national standards
shall be withdrawn at the latest by February 2024.
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 13187:1998.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, 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 the
United Kingdom.
Endorsement notice
The text of ISO 6781-1:2023 has been approved by CEN as EN ISO 6781-1:2023 without any
modification.
INTERNATIONAL ISO
STANDARD 6781-1
First edition
2023-08
Performance of buildings — Detection
of heat, air and moisture irregularities
in buildings by infrared methods —
Part 1:
General procedures
Performance des bâtiments — Détection d'irrégularités de chaleur,
air et humidité dans les bâtiments par des méthodes infrarouges —
Partie 1: Modes opératoires généraux
Reference number
ISO 6781-1:2023(E)
ISO 6781-1:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 6781-1:2023(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 2
3.2 Thermography terms . 4
4 Symbols and abbreviated terms.7
5 Example applications of use of thermography in building assessments .8
6 Customer preparation . 8
7 Qualification of personnel .9
7.1 Personnel — General guidance . 9
7.2 Application specific requirements . 10
7.2.1 Residential buildings — Qualification requirements . 10
7.2.2 Commercial buildings — Qualification requirements . 10
7.2.3 Institutional / Industrial buildings — Qualification requirements . 10
8 Equipment requirements for thermographic examination of residential,
commercial and institutional buildings .11
8.1 Equipment — General requirements . 11
8.2 Calibration and checking of equipment .12
9 Safety .12
10 Thermography techniques .12
10.1 General .12
10.2 Comparative thermography .12
10.2.1 General .12
10.2.2 Technique .13
10.3 Comparative qualitative thermography . 13
10.4 Comparative quantitative thermography . 14
10.4.1 General . 14
10.4.2 Comparative quantitative thermography — Limitations . 14
11 Non-contact infrared radiometry (spot radiometry) using infrared thermography
cameras .15
12 Air leakage and mass transfer .15
12.1 Air leakage . . 15
12.2 Mass transfer — Moisture . 15
13 Moisture detection .16
13.1 Conductivity test method — Moisture detection . 16
13.2 Capacitance test method — Moisture detection . 16
13.3 Phase change test method — Moisture detection . 16
14 Baseline measurements for building maintenance and condition monitoring .17
15 Data collection . .17
16 Field measurements of reflected temperature and emissivity, and attenuating
media .18
17 Comparative assessment criteria — Severity .18
18 Diagnosis and prognosis.18
18.1 Survey intervals . 18
iii
ISO 6781-1:2023(E)
18.2 Image interpretation . 18
18.3 Fault identification process . 19
19 Test report .19
19.1 General information. 19
19.2 Building-specific information . 20
19.3 Qualitative inspections . 21
19.4 Quantitative inspections . 21
19.5 Reporting of unsafe conditions . 22
Annex A (normative) Pro-forma safety rules and guidelines .23
Annex B (normative) Field measurements of reflected apparent temperature and
emissivity .24
Annex C (informative) Examples of buildings heat, air and moisture faults, failures and
anomalies detected by infrared thermography (IRT) .28
iv
ISO 6781-1:2023(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 whom 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment, Subcommittee SC1, Test and measurement methods, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 89, Thermal performance
of buildings and building components, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This first edition cancels and replaces ISO 6781:1983, which has been technically revised.
The main changes are as follows:
— now comprises the first part of the ISO 6781 series, which addresses the general user of thermography
and provides general requirements pertinent to thermography;
NOTE Further parts of the ISO 6781 series provide specific thermographic requirements pertinent to
thermographic practitioners, and the technical requirement for thermography of specific types of buildings.
— covers general requirements concerning detection of air leakage and moisture anomalies, using
thermographic methods, in addition to thermal anomalies;
— thoroughly updates the thermographic requirements resulting from the vast technological upgrades
in thermography since ISO 6781:1983 was published;
— provides general information and specific constraints concerning qualitative thermography and
quantitative thermography;
— provides general information and requirements regarding the qualification of thermographic
operators and report writers.
A list of all parts in the ISO 6781 series can be found on the ISO website.
v
ISO 6781-1:2023(E)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
vi
ISO 6781-1:2023(E)
Introduction
Infrared building thermography provides a tool to qualitatively identify the presence of energy-
wasting defects and anomalies within building structures. These defects and anomalies can include,
for example, thermal insulation defects, moisture content, and / or unwanted air movement or leakage
within the building enclosure.
Building thermography is carried out by means of an infrared thermography camera, which produces
an image based on the apparent radiance temperature of the target surface area. The thermal radiation
(infrared radiation density) from the target area is converted by the infrared thermography camera to
produce a thermal image (thermogram). This image (thermogram) represents the relative intensity of
thermal radiation from different parts of the surface. The radiation intensity indicated by the image is
related directly to
a) the surface temperature distribution,
b) the characteristics of the surface,
c) the ambient conditions, and
d) the sensor itself.
As a result, surface temperature distribution can be a key parameter for monitoring the performance of
building components, building enclosure and the diagnostics of problems. In use, via analysis of surface
temperature distributions, irregularities in the heat and moisture properties of building enclosures and
components, and air movement within the building enclosure, can be indicated. These irregularities
can be due to, for example, thermal insulation defects, moisture content, air leakage within components
or through assemblies, or incorrect installation of components which comprise the construction of the
building.
To realize its full utility as an initial qualitative screening technique, or an in-depth diagnostic
technique, thermography must often be supported and/or validated by other methods. These methods
include, but are not limited to, infrared photosensitive tracer gas methods, fan pressurization of the
building enclosure, heat-flow metres, smoke diffusion, anemometry, moisture metres and relative
humidity (RH) sensors.
Infrared building thermography inspection methodologies can be used for either new-construction
quality control applications or in existing buildings as ongoing condition monitoring for periodic or
specific building-condition reporting. The latter applications may be accompanied with visual fault
symptoms, while the former may not necessarily present symptoms via visual faults.
vii
INTERNATIONAL STANDARD ISO 6781-1:2023(E)
Performance of buildings — Detection of heat, air and
moisture irregularities in buildings by infrared methods —
Part 1:
General procedures
1 Scope
This document specifies requirements and methodologies for infrared thermographic services for
detection of heat, air and moisture irregularities in buildings that help users to specify and understand
a) the extent of thermographic services required,
b) the type and condition of equipment available for use,
c) the qualifications of equipment operators, image analysts, and report authors and those making
recommendations, and
d) the reporting of results.
It provides guidance to understanding and utilizing the final results stemming from provision of the
thermographic services.
This document is applicable to the general procedures for infrared thermographic methods as can be
applied to residential, commercial, and institutional and special use buildings.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6781-3, Performance of buildings — Detection of heat, air and moisture irregularities in buildings by
infrared methods — Part 3: Qualifications of equipment operators, data analysts and report writers
ISO 7345, Thermal performance of buildings and building components — Physical quantities and definitions
ISO 9288, Thermal insulation — Heat transfer by radiation — Vocabulary
ISO 9869-1, Thermal insulation — Building elements — In-situ measurement of thermal resistance and
thermal transmittance — Part 1: Heat flow meter method
ISO 9972, Thermal performance of buildings — Determination of air permeability of buildings — Fan
pressurization method
ISO 10878, Non-destructive testing — Infrared thermography — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345, ISO 9288, ISO 10878
and the following apply.
ISO 6781-1:2023(E)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms
3.1.1
system
regularly interacting or interdependent group of associated entities (e.g. components, factors, members,
parts) forming an integrated whole and delineated by its spatial and temporal boundaries
Note 1 to entry: One or more of the associated entities define the boundary of the system.
3.1.2
analysis
careful scrutiny of constituent parts of a system (3.1.1) in order to thoroughly understand the whole
3.1.3
function
functional purpose of the building, building component or building system (3.1.1)
Note 1 to entry: The function is the activity assigned to, required of, or expected of the system.
3.1.4
residential building
building meeting the parameters defined in local building codes as small/residential building and as
agreed with the customer receiving thermographic services
3.1.5
parameter
numerical or other measurable factor forming one of a set that sets the conditions for measurement, or
defines the system and its operation
3.1.6
performance
behaviour, characteristics and efficiency of a building, building component or building system (3.1.1)
3.1.7
sign
characteristic parameter of a signal, which shows information about a state
3.1.8
symptom
perception, made by means of human observations and measurements (descriptors), which may
indicate the presence of one or more faults (3.1.12) with a certain probability
3.1.9
syndrome
group of signs (3.1.7) or symptoms (3.1.8) that collectively indicate or characterize an abnormal
condition
3.1.10
anomaly
something that deviates from what is standard, normal or expected, and an irregularity (3.1.12) or
abnormality (3.1.11) in a system (3.1.1)
3.1.11
abnormality
deviation from a standard condition
ISO 6781-1:2023(E)
3.1.12
irregularity
condition which significantly departs from the operational norm
3.1.13
fault
condition that occurs when a building or one of its components or assemblies degrades or exhibits
abnormal behaviour, which may lead to the failure (3.1.14) to perform in accordance with its design
intent
Note 1 to entry: A fault can be the result of a failure, but can exist without a failure.
Note 2 to entry: Planned actions or lack of external resources are not a fault.
3.1.14
fault propogation
characterization of the change in severity of a fault (3.1.12) over time
3.1.15
failure
termination of the ability of an item to perform a required function (3.1.4)
Note 1 to entry: Failure is an event as distinguished from fault (3.1.12), which is a state.
3.1.16
failure mode
effect by which a failure (3.1.14) is observed
3.1.17
diagnostics
examination of symptoms (3.1.8) and syndromes (3.1.9) to determine the nature of faults (3.1.12) or
failures (3.1.14) (i.e. kind, situation, extent)
3.1.18
root cause
either a set of conditions or actions, or both, that occur at the beginning of a sequence of events and
result in the initiation of a failure mode (3.1.15)
3.1.19
root cause failure analysis
RCFA
after a failure, the logical systematic examination of an item, its construction, application and
documentation in order to identify the failure mode (3.1.15) and determine the failure mechanism and
its basic cause
Note 1 to entry: Root cause failure analysis is often used to provide a solution to chronic problems.
3.1.20
prognostics
analysis of the symptoms of faults (3.1.12) to predict a future condition and remaining useful life
3.1.21
prognosis
result of the prognostics process
3.1.22
qualitative
relating to measuring, or measured by the quality of something, rather than its quantity
3.1.23
quantitative
relating to measuring, or measured by the quantity of something, rather than its general qualities
ISO 6781-1:2023(E)
3.2 Thermography terms
3.2.1
infrared
IR
portion of the electromagnetic spectrum extending from the red visible wavelength, 0,75 μm to 1 mm
Note 1 to entry: Because of instrument design and infrared transmission characteristics of the atmosphere, most
infrared measurements are made between 0,75 μm and 15 μm wavelengths.
3.2.2
thermography
representation of the temperature distribution of a surface, in a thermal image
3.2.3
thermographic analysis
interpretation and determination of the casual mechanisms producing variations and irregularities in
the thermal image
3.2.4
quantitative thermographic examination
examination of whole buildings, structures or components using thermographic methods with the
objective of providing quantitative (3.1.22) output
Note 1 to entry: Reporting requirements for both qualitative and quantitative examinations are specified in
Clause 19.
3.2.5
infrared thermography camera
IRT camera
instrument that collects the infrared radiant energy from a target surface and produces a monochrome
(black and white) or colour image, where the grey shades (monochrome) or colour hues are related to
the target surface apparent temperature
3.2.6
thermal image
image which is produced by an infrared thermography camera and which represents the apparent
radiance temperature distribution over the target surfaces
Note 1 to entry: Such images are sometimes called "infrared thermograms".
3.2.7
temperature isotherm
enhancement feature applied to an image, which marks an interval of equal apparent temperature
3.2.8
radiation density isotherm
region on an infrared (IR) (3.2.1) display consisting of points, lines or areas having the same infrared
radiation density
3.2.9
isotherm image
output from an infrared thermography camera showing temperature isotherms (3.2.7) and radiation
density isotherms (3.2.8)
3.2.10
ironbow palette image
image comprising a colour palette running from black through blue, magenta, orange, yellow to white
that creates best contrast, in particular regarding edges and shapes
ISO 6781-1:2023(E)
3.2.11
image interpretation
processing and comparing apparent surface temperatures and thermal patterns against those
representative of the ideal design, construction, installation and maintenance criteria
Note 1 to entry: In the case of a thermal image or thermogram this can include temperature scaling, spot
temperature measurements, thermal profiles, image manipulation, subtraction and storage.
3.2.12
apparent temperature
uncompensated reading from an infrared thermography camera containing all radiation incidents on
the detector, regardless of its source
3.2.13
attenuating media
windows, filters, atmospheres, external optics, materials or other media that attenuate the infrared
radiation emitted from a source
3.2.14
black body
ideal perfect emitter and absorber of thermal radiation at all wavelengths
Note 1 to entry: The emissivity (3.2.15) of a black body is 1… ε = 1.
Note 2 to entry: This is described by Planck's law.
3.2.15
emissivity
ε
ratio of a target surface’s radiance to that of a black body (3.2.14) at the same temperature and over the
same spectral interval
3.2.16
total radiance
radiant heat flow rate divided by the solid angle around the direction ∆ and the projected area normal
to this direction
Note 1 to entry: Radiance includes emitted radiation from a surface as well as reflected and transmitted radiation.
3.2.17
apparent radiance temperature
temperature determined from the measured total radiance
Note 1 to entry: This temperature is the equivalent black body (3.2.14) temperature which would produce the
same total radiance.
3.2.18
reflectivity
ρ
ratio of the total reflected energy from a surface to total incident energy on that surface
Note 1 to entry: ρ = 1 – ε - τ ; for a mirror, reflectivity approaches 1,0; for a black body, ρ = 0.
Note 2 to entry: Technically, reflectivity is the ratio of the intensity of the reflected radiation to the total radiation;
reflectance is the ratio of the reflected flux to the incident flux. In infrared thermography (IRT), the two terms
are often used interchangeably.
3.2.19
reflected apparent temperature
T
refl
apparent temperature of other objects that are reflected by the target into the thermography camera
ISO 6781-1:2023(E)
3.2.20
repeatability
capability of an instrument to repeat exactly a reading on a fixed target over a short- or long-term
interval
Note 1 to entry: Repeatability is expressed in ± degrees or a percentage of full scale.
3.2.21
spatial measurement resolution
measurement-spot size in terms of working distance
EXAMPLE In an infrared radiation thermometer, this is expressed in milliradians or as a ratio of the target-
spot size (containing 95 % of the radiant energy, according to common usage) to the working distance. In
scanners, cameras and imagers it is most often expressed in milliradian.
3.2.22
instantaneous field of view
IFOV
measurement of a sensor's intrinsic field of view, as distinct from what the sensor can perceive when a
scanning motion is incorporated into the imaging system
Note 1 to entry: The instantaneous field of view corresponds to the solid angle that admits light to a sensor at any
given instant.
3.2.23
target
object surface to be measured
3.2.24
working distance
distance from the target to the instrument, usually to the primary optic
3.2.25
diffuse surface
surface from which light or other electromagnetic radiation is scattered, rather than reflected
3.2.26
specular surface
surface from which light or other electromagnetic radiation is strongly reflected, rather than randomly
scattered
3.2.27
transmissivity / transmittance
τ
proportion of infrared radiant energy impinging on an object surface, for any given spectral interval,
that is transmitted through the object
Note 1 to entry: Transmissivity: τ = 1 − ε − ρ
where
τ is transmissivity;
ε is emissivity;
ρ is reflectivity.
Note 2 to entry: For a black body, τ = 0. Transmissivity is that fraction of incident radiation transmitted by matter.
ISO 6781-1:2023(E)
3.2.28
thermal index
TI
ratio of temperature drop across the building enclosure, to the total temperature drop between inside
and outside environmental temperatures
Note 1 to entry: Thermal index is calculated as follows: TI= [(T −T ) / (T −T )] × 100 %
surface outside inside outside
where
T is the surface temperature of a part of the building enclosure;
surface
T is the localized outside air temperature measured by the user;
outside
T is the air temperature inside the structure measured by the user.
inside
Note 2 to entry: Example: T = 60 °C; T = 70 °C; T = 30 °C.
surface inside outside
Therefore TI = [(60 − 30) / (70 − 30)] × 100 = 75 %.
4 Symbols and abbreviated terms
L Radiance
e
ε(λ) Spectral emissivity
ρ(λ) Spectral reflectivity
τ(λ) Spectral transmissivity
α(λ) Spectral absorptivity
ΔT Differential temperature
FOV Field of view
Hz Hertz
IFOV Instantaneous field of view for detection (3.2.22)
IRT Infrared Thermography
MDT Minimum detectable temperature
MRTD Minimum resolvable temperature difference
NETD Noise equivalent temperature difference
NUC Non-uniformity correction
MIFOV Instantaneous field of view for measurement
mrad milliradian
TI Thermal index
ISO 6781-1:2023(E)
5 Example applications of use of thermography in building assessments
The following list gives examples of where thermography may be applied as an initial or screening tool
in the context of building examinations. These examinations can be conducted from inside or outside of
the building. The list given below is not exhaustive:
a) surface temperature variations;
b) uniformity of building component installation;
c) thermal anomalies, e.g. thermal bridges, thermal insulation deficiencies, variances, or misfits;
d) location(s) of air movement;
e) extent of air movement through (i) a wall (ii) single component (iii) inter-component (iv) interstitial
space, and determination of volumes of air movement when pressure differentials are known;
f) moisture transport due to temperature or pressure differentials;
g) moisture ingress and egress;
h) the extent and phase of moisture present during inspection;
i) thermal comfort;
j) delaminating of coatings or renderings;
k) as a standard for training personnel;
l) provide a basis / set a performance standard / level of qualification for certifying thermographers;
m) energy efficient renovation of buildings;
n) location of under-floor heating;
o) building condition assessments of existing structures;
p) quality control assessments of renovations to existing buildings;
q) quality control assessments of new construction, part of building enclosure commissioning;
r) quality control assessment of repairs to new construction;
s) re-commissioning of building enclosure;
t) detection of structural components within masonry wall assemblies;
u) detection of structural reinforcing in poured concrete assemblies;
v) location of roof leaks, severity of leak and path of drainage through structural components;
w) moulds and fungus.
NOTE The presence of moisture in materials can lead to formation of surface or interstitial mould and
fungus.
6 Customer preparation
The customer of an infrared thermography (IRT) service shall, as applicable:
a) provide access to the building / facility to be inspected;
b) provide the thermographer with details of any potential safety hazards related to the building /
facility use;
ISO 6781-1:2023(E)
c) disclose the history of any prior problems;
d) provide or help develop an inventory of building enclosure, architectural & structural assemblies,
building components, etc., to be inspected, in a logical and efficient route with "line of sight"
viewing;
e) make available any building, architectural and structural shop drawings;
f) make available any building equipment operating manuals and building "as built" drawings;
g) identify fire zones;
h) provide qualified guide(s) knowledgeable in the operation and maintenance history of the building
/ facility to be inspected. This person(s) shall accompany the infrared thermographer during the
examination and shall be qualified and authorized to:
— gain access to the inner and outer parts of the buildings to be inspected and to notify the building
owner, occupants, operating and maintenance personnel, etc. of the IRT examination activities;
— open and make accessible any requested areas immediately before examination by the infrared
thermographer;
— either close or secure these areas, or both, immediately after examination by the infrared
thermographer;
— operate, as possible, any building architectural, structural, mechanical and/or electrical
equipment;
— assure that building systems are operating normally, or placed in a state as requested by the
infrared thermographer and allow sufficient time for stable thermal patterns to be attained
— take full responsibility for consequences resulting from actions taken, or not taken, as a result
of information provided by an infrared examination;
— provide information on the results of follow up examination and repair activities.
7 Qualification of personnel
7.1 Personnel — General guidance
The requirements for operator competence and qualifications vary with the type of structure being
investigated and methodologies employed. The building thermographer's qualification classification
shall be agreed upon by the customer and service provider. The thermographer shall provide evidence
of qualification to that classification prior to the commencement of any work. Building thermographers
shall possess knowledge, skills and abilities assessed in accordance with the classification requirements
of ISO 6781-3.
The following provides an outline summary of classification levels:
Class I: Conversant and capable in knowledge, skills and abilities regarding camera operation, heat
transfer basics, infrared basics, applications basics, baseline imaging, thermal signatures, problem
identification, recognition of special (atypical) problems, fundamental analysis and reporting, safety
considerations, and the ability to think and conceptualize ‘thermally’.
Class II: All Class I requirements plus knowledge, skills, abilities, baseline experience in building
physics and technology, building materials and construction methods, thermographic methodologies,
building thermographic procedures, infrared radiometrics, diagnostic imaging, thermographic infrared
measurement, and basic Infrared thermography program management.
Class III: All Class II requirements plus knowledge, skills, abilities, experience and advanced
knowledge in building physics, building technology, materials and construction methods plus advanced
ISO 6781-1:2023(E)
thermographic methodologies in thermographic program management, cost / benefit accounting,
specialized diagnostics, advanced radiometry, technology planning, and training and certification.
7.2 Application specific requirements
7.2.1 Residential buildings — Qualification requirements
7.2.1.1 Thermographic inspections
Personnel operating equipment performing thermographic inspections / investigations on residential
buildings, where standard construction is employed, shall be qualified to building-thermography
qualification Class I or higher in accordance with I
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