Quantitative Appraisal Of Thermal Anomalies - FLIR InfraCAM User Manual

12 – Introduction to building thermography
Variations in the thermal properties of building structures, such as poorly fitted or
missing sections of insulation, cause variations in surface temperature on both sides
of the structure. They are therefore visible to the thermographer. However, many
other factors such as local heat sources, reflections and air leakage can also cause
surface temperature variations.
The professional judgement of the thermographer is usually required to differentiate
between real faults and other sources of temperature variation. Increasingly, thermo-
graphers are asked to justify their assessment of building structures and, in the ab-
sence of adequate guidance, it can be difficult to set definite levels for acceptable or
unacceptable variation in temperature.
The current Standard for thermal iamging of building fabric in the UK is BS EN
13187:1999 (BS EN 13187:1999, Thermal Performance of Buildings—Qualitative de-
tection of thermal properties in building envelopes—Infrared method (ISO 6781:1983
modified). However, this leaves interpretation of the thermal image to the professional
expertise of of the thermographer and provides little guidance on the demarcation
between acceptable and unacceptable variations. Guidance on the appearance of a
range of thermal anomalies can be found in BINDT Guides to thermal imaging (Infrared
Thermography Handbook; Volume 1, Principles and Practise, Norman Walker, ISBN
0903132338, Volume 2, Applications, A. N. Nowicki, ISBN 090313232X, BINDT, 2005).
12.3.8.3.1
A thermographic survey to demonstrate continuity of insulation, areas of thermal
bridging and compliance with Building Regulations should include the following:
Thermal anomalies.
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Differentiate between real thermal anomalies, where temperature differences are
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caused by deficiencies in thermal insulation, and those that occur through con-
founding factors such as localised differences in air movement, reflection and
emissivity.
Quantify affected areas in relation to the total insulated areas.
■
State whether the anomalies and the building thermal insulation as a whole are
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acceptable.
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12.3.8.4
A thermographic survey will show differences in apparent temperature of areas within
the field of view. To be useful, however, it must systematically detect all the apparent
defects; assess them against a predetermined set of criteria; reliably discount those
anomalies that are not real defects; evaluate those that are real defects, and report
the results to the client.
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Requirements

Quantitative appraisal of thermal anomalies

Publ. No. 1558299 Rev. a200 – ENGLISH (EN) – February 12, 2007