Assessment of the effects of temperature and moisture content on the hygrothermal transport and storage properties of porous building materials

Heat and moisture transfer models are increasingly used in building thermal and energy simulation tools. These phenomenological transfer models are based on experimentally evaluated input data. Therefore, to ensure a better prediction of the hygrothermal behavior of the building envelope, a correct and reliable experimental evaluation of these parameters is required. Indeed, these input data are the thermal and hygric properties of the materials constituting the wall. However, the hygrothermal properties available in the databases are far from complete, particularly regarding the evolution of these properties with changes in the water content and temperature of the material. In this paper, an experimental characterization campaign of the main transfer and storage hygrothermal properties is conducted, with particular interest in the variation of these properties as a function of the temperature and the water content of the material. In this work, different materials are analyzed: cinderblock, plaster, chipboard and red brick. This study includes analysis of the thermal conductivity, the specific heat capacity, the water vapor permeability, and the moisture storage capacity. The obtained results confirmed that the water content and the temperature of the material have considerable effects on the values of its hygric and thermophysical properties. Indeed, the thermal conductivity and the specific heat capacity of a hygroscopic material as plaster can reach an increase of 2 times between dry and saturated states. Concerning water vapor permeability, a relative gap of 30% is observed between the values obtained at 20 degrees C and 30 degrees C. Therefore, enriching existing databases with this type of information is essential to ensure a reliable prediction of the hygrothermal behavior of the whole building.