Transient analysis of the thermal and moisture physical behaviour of building constructions

Abstract For the transient analysis of the thermal and moisture conditions in multilayer constructions a numerical algorithm and a computer program based on the Crank-Nicholson method and quasi-linearization are are formulated. Constitutive equations for simultaneous heat and mass transfer in porous material are derived from the integrated mass, momentum and energy balance equations using the volume averaging technique. The temperature and moisture content are used as transport potentials due to general practice. In energy balance equations the conduction, convection and accumulation of heat and heat sources due to interstitial phase changes are considered. In moisture balance equations the accumulation of moisture, the diffusion flow of water vapour, the capillary and surface diffusion flow of liquid water and the viscous flow of humid air and water are considered. The boundary layer and interfacial balance equations are derived, too. The accuracy of the numerical algorithm is compared with an analytical solution for thermally semi-infinite body. The validity of the simulation method is verified by two experiments.