Comparing different approaches to in situ measurement of building components thermal resistance

This paper introduces a comparison of different measuring methods of buildings fabric thermal resistance, including the test wall measuring points arrangements and measurement results, conducted in a test chamber in Cagliari (Italy) in summer 2009.Two methods and their measurement uncertainties are presented and compared by the compatibility of measurement study.The non-destructive method involves the heat-flow rate measurement through the test wall and its surface temperatures. The reliability of this method depends on the temperatures difference between the two environments separated by the building envelope. Thus two measurement series with different temperatures were carried out on the test wall.The destructive method instead foresees the acquisition of a sample by the use of a hollow drill, the building envelope layers thickness measurement and the thermal properties assignment to each different material. The wall R-value is the sum of each layer thermal resistance.The comparison shows that the R-values measured by the non-destructive method with a temperature difference of 10 °C and 7 °C and the one calculated from the destructive method obey the compatibility of measurement principle.

► Different measuring methods of building thermal resistance are compared.
► Uncertainties of destructive and non destructive methods are evaluated.
► Climatic limits of thermal resistance measurement are investigated.
► Measurement uncertainty influences up to 16% the evaluation of energy consumptions.