Heat and moisture transfer investigation of surface building materials

Numerical investigation of the capacity of porous hygroscopic building materials to damp indoor humidity variations is the aim of our present study. By means of CFD-FEM multiphysics transient simulations, taking into account relative humidity and temperature variation inside different material samples referring to the fundamental experimental test protocol on the “Moisture Buffering of Building Materials” (the well-known NORDTEST), all the thermo-hygrometric properties, connected to the moisture content capacity and moisture buffer effect of some building materials, were assessed. Sorption isotherm curves, that provide moisture content as a function of relative humidity, were considered. An energy balance coupled with mass transfer equation for moisture was solved considering the porous structure of the studied media. The non-isothermal method implementation allowed the investigation on the coupled relative humidity and temperature periodic variations, happened during the NORDTEST experimental application, that were used for simulate thermo-hygrometric constraints. The proposed method can be used for the efficacy evaluation of porous materials used as indoor building envelopes for passive control technique and relative humidity amplitude control. Our research can be a useful tool for defining fundamental guidelines for any project aimed to the building-plant system energy consumption reduction and building user comfort.