Assessing the thermal performance of insulating glass units with infrared thermography: Potential and limitations

This paper investigates the potential of IRT for thermal performance estimation of IGU's. Firstly, a sensitivity analysis on the boundary conditions was conducted using numerical simulations. Subsequently, quantitative IR-measurements were conducted on different glass types, in the lab and in-situ. Results show that specular reflection should be avoided to obtain reliable measurements. Finally, the thermal resistance of IGU's was calculated with the measured surface temperature, both in the lab and in situ. This showed that the use of inaccurate outside and inside heat transfer coefficients and non-representative inside and outside temperatures renders inadequate thermal resistances, even if IRT was executed in cloudy windless weather and with a temperature difference over 15 °C across the IGU. In these conditions, only single glazing, IGU's without low-e and IGU's with low-e coating are distinguishable. This undermines the practical implementation of IRT as assessment tool for IGU's.