Comparison of thermal transmittance of in-situ HCB walls as determined by infrared and heat flow testing methods

Abstract

In many instances, it is hard to quantify the thermal insulating properties of existing walls in situ, using the standard heat flow method as described in ISO Document 9869:1994: Part 1. A feasible, yet effective procedure to determine the U-value of existing building elements in-situ is being studied as part of an R&D project involving industry and academia, by means of thermal imaging, whereby Uvalues are obtained with reasonable accuracy and in a relatively short period of time. This paper follows a research and innovation project spanning over a period of two years, whereby a a locally-produced hollow concrete block (HCB) with improved thermal insulating properties is being developed.. Results of U-values for prototype HCB’s are presented, based on the infrared method of measurement and compared to results obtained by the heat flow meter method. While the heat flow method is already consolidated by ISO standards, the infrared methodology is still being developed and its standard has not yet been finalised. The obtained results show potential for fast and reliable in-situ U-value measurements by way of infrared thermography.