A transient model for analyzing the hygrothermal behavior of building constructions

While advanced models for combined heat and moisture transfer have been available in the community of building scientists within the last two decades, such models have not yet become an item in the toolbox of consultants, building designers or manufacturers of building components. Moisture dimensioning among the practitioners still takes place by rules of thumb or at best by use of the steady state Glaser method or modifications thereof. Originally developed in a doctoral study (Pedersen 1990) the model, MATCH (Moisture grid Temperature Calculations for Constructions of Hygroscopic Materials), comprises the common features of university models for one dimensional heat and moisture transfer. For instance, the model has an exact description of moisture influence on the thermal behavior of constructions by taking into account the transfer of latent heat. The model also provides a description of hysteresis in the moisture retention properties of the materials. MATCH has recently been rewritten into a user friendly format. Running on a PC, it provides practitioners with a sophisticated tool for transient calculation of the coupled transport phenomena. The paper introduces the theory behind the program and describes how latent heat and hysteresis effects are taken into account. Further, comparisons are given between predictions with the proposed model and measurements and between the model and the Glaser method.