Determination of thermal performance of IGU's with infrared thermography

Infrared thermography (IRT) is a non-destructive measurement tool by which surface temperatures of buildings are instantly visualized. The technique may offer a quick way to estimate the thermal performance of a building component. In previous research, simulations showed the potential of IRT for quantitative analysis of the thermal performance of insulating glass units (IGU). This paper discusses IRT measurements to quantify the thermal resistance (R-value) of a double glazed panel with an air cavity. The 1m(2) glass pane was installed in a heated test box and placed in indoor (static) and outdoor conditions (dynamic) to examine the influence of changing boundary conditions. Next to that, the heat flux, surface temperatures, in- and outdoor temperatures were logged. The obtained R-values were also compared with the results from in-situ measurements on the same type of glazing. In static conditions, the R-value obtained with IRT was comparable with the results from the other measurement techniques. Under dynamic conditions however, the R-values derived from IRT varied due to the clear sky conditions and the uncertainty of the wind velocity. In the case of low wind velocities and clouded sky however, IRT seemed to give reliable results when using appropriate correlations for the surface heat transfer coefficients. In the in-situ measurement, bad weather conditions could be addressed when combining IRT on the inside and outside surface. Future research will focus on determining constraints for the wind velocity during a thermographic survey and the use of coatings and foils in IGU's on the applicability of this measurement tool. (C) 2015 The Authors. Published by Elsevier Ltd.