Hygric properties of porous building materials (II): Analysis of temperature influence

Hygric properties are indispensable input parameters for the hygrothermal analysis of building envelopes and indoor environments. The reliability of all analysis results depends largely on the accuracy of these properties. Nevertheless, the influence of temperature on hygric properties is generally neglected, without adequate support though. This paper looks into this by performing comprehensive and systematic measurements on the hygric properties of autoclaved aerated concrete, calcium silicate board and ceramic brick in the temperature range of 10-40 °C. Our results are in line with theoretical predictions and previously reported measurements. In general, the hygric transport properties are more susceptible to temperature changes than the hygric storage properties. Specifically, the influence of temperature on adsorption isotherms is material-dependent but overall limited. Neither the capillary moisture content nor the saturation moisture content suffers from any obvious temperature impact. The vapor permeability is neither significantly affected by temperature except for strongly hygroscopic materials in the high RH range. The capillary absorption coefficient on the other hand has strong and predictable temperature dependence.