AT-2482 -- Application of Aerial Infrared Thermography to the Measurement of Building Heat Loss PDF

The measurement of building heat loss through a roof structure and the determinationof the structure's thermal resistance using an airborne infrared scannerare examined. The analysis assumes the infrared scanner operates perfectly andno absorption, emission, or scattering occurs in the atmosphere between theground and the scanner. In addition, quasi-steady, one-dimensional heat flowthrough the roof is assumed. The study consists of two parts. First, the effectsof the thermal resistance and the heat flow through the roof on the outersurface temperature of the roof are determined., Second, the effects of the surfacetemperature, surface properties, sky radiation and other parameters on thetotal infrared radiation leaving the roof surface are calculated. There are anumber of factors which affect the interpretation of the infrared thermographs.These include uncertainties in surface properties, sky radiation, microclimate,roof orientation and ventilation in an air space underneath the roof. Optimumconditions for operation of infrared scanners to determine building envelopeheat loss can be deduced from the calculations.