Definition: CHP energy auditors use infrared scanning – also known as thermography – to detect thermal defects and air leakage in building envelopes. Infrared scanning measures surface temperatures on the interior or exterior of a building using infrared video and still cameras. These tools see light that is in the heat spectrum. Images on the video or film record the temperature variations of the building's skin, ranging from white for warm regions to black for cooler areas. The resulting images help the auditor determine whether insulation is needed. They also serve as a quality control tool, to ensure that insulation has been installed correctly.