Application of infrared thermography for in-situ determination of building envelope thermal properties

Thermal resistance of building envelope systems plays an important role in the building energy evaluation, design, and retrofit efforts; in-situ determination of the thermal resistance is highly desired for obtaining a realistic building energy performance picture. The conventional heat flow meter method for measuring thermal resistance requires a considerable number of sensor installations and also an appropriate definition of the homogeneous wall area. Therefore, a simpler and more practical measurement method is needed. Recent studies indicate that the infrared thermography method has the potential to be used as a quantitative technique for thermal resistance measurement. However, there are limitations in the previously developed infrared thermography method that may lead to difficulties in practical application. In the study reported in this paper, an innovative infrared thermography model is proposed and its effectiveness is validated by comparison with the heat flow meter method. A convective heat transfer coefficient model is also proposed, which can particularly be used for low-rise residential buildings. A recommended testing procedure is then given at the end of the paper for appropriate use of the proposed measurement method.