28.3
Typical field investigations
28.3.1
Guidelines
As will be noted in subsequent sections there are a number of general guidelines the
user should take heed of when carrying out building thermography inspection. This
section gives a summary of these guidelines.
28.3.1.1
General guidelines
■
The emissivity of the majority of building materials fall between 0.85 and 0.95.
Setting the emissivity value in the camera to 0.90 can be regarded as a good
starting point.
■
An infrared inspection alone should never be used as a decision point for further
actions. Always verify suspicions and findings using other methods, such as con-
struction drawings, moisture meters, humidity & temperature datalogging, tracer
gas testing etc.
■
Change level and span to thermally tune the infrared image and reveal more details.
The figure below shows the difference between a thermally untuned and a thermally
tuned infrared image.
10552103;a2
Figure 28.1 LEFT: A thermally untuned infrared image; RIGHT: A thermally tuned infrared image, after
having changed level and span.
28.3.1.2
Guidelines for moisture detection, mold detection & detection of
water damages
■
Building defects related to moisture and water damages may only show up when
heat has been applied to the surface, e.g. from the sun.
■
The presence of water changes the thermal conductivity and the thermal mass of
the building material. It may also change the surface temperature of building mate-
rial due to evaporative cooling. Thermal conductivity is a material’s ability to conduct
heat, while thermal mass is its ability to store heat.
28
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28 – Introduction to building thermography
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