Infrared Thermography
Infrared thermography is used in the field of building science to detect thermal variations in building envelope assemblies using non-destructive infrared (IR) radiation detector sensing equipment. Detection of these thermal variations can be used to identify:
- Air leakage through the building envelope assembly which elevates surface temperatures of the materials around the source of the leakage. A difference in temperature between the interior and exterior is required for this to be observed.
- Conductive heat loss through building envelope assembly components (e.g. as a result of thermal bridging, missing, and/or lack of insulation).
- Cooling of materials that have been heated by solar radiation from the sun during the day (or from heat generated by lighting).
- Cooling of materials via evaporation of absorbed moisture (i.e. rain or snow).
- Concealed building assembly components (i.e. insulation) in close contact with the radiating surface component (i.e. a roof membrane) that have an elevated moisture content in comparison to surrounding surfaces can result in variations in surfaces temperatures of the radiating surface due to solar radiation and storage of heat (for longer periods of time that the surrounding surfaces). Wet materials will retain and transfer heat more rapidly than dry materials (e.g. evaporate cooling).
- For curtain or window wall assemblies, since the materials do not absorb moisture and they cool quickly (due to minimal thermal storage capacity); air leakage and conductive heat loss through the assemblies are really the only factors that can be assessed by thermography. The materials generally have low emissivity surfaces which reduces the radiant energy transfer making it difficult to detect temperature variations. Reflective glass can result in varying surface temperature measurements that are misleading and not representative of actual conditions. Care is required when interpreting the data.
The successful use of thermography for building applications depends not only on a thorough knowledge of building construction and the principles of heat, air and moisture transmission, but also on an understanding of infrared radiation and the factors that can affect its detection and measurement. - Canadian Building Digest 229.
Related Projects
Attic Air Sealing, Insulation Upgrades
Ice Damming Investigation
Metal Roof Condition Assessment
