In this paper an experimental set-up measurement for the evaluation of the thermal transmittance of opaque elements has been developed. It is based on infrared thermography and it is suggested as alternative to the standard approach set by the ISO 9869:1994 based on heat flow meter (HFM) measurement which is widely accepted by scientific audience. The proposed method has been designed in order to overcome the following restrictions of HFM method: long measuring times (about 72 h), weather conditions as constant as possible and at least a difference of 10–15 °C between the temperatures of internal and external sides of walls. In this work, the alternative method proposed is widely described and applied on lab-made prototype walls: the results are encouraging, showing discrepancies with theoretical U-values, determined in accordance with international standard ISO 6946:2007, in the range −3.5 to 2.9%. The thermal transmittances were also calculated with a commercial software based on finite element analysis; the obtained results were in good agreement with the experimental ones. Moreover, the simulations pointed out that the values obtained on lab-made prototype walls are similar to those associated with partition walls which separate rooms with different environmental conditions. © 2016 Elsevier B.V.

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