Physical and Mathematical Models of Hygrothermal Processes in Historical Building Envelopes

Hygrothermal performance of a sandstone wall is assessed using three different mathematical models for description of coupled heat and moisture transport in porous building materials. Diffusion types of mathematical models are considered as they are usually used in the field of building physics. While Grunewald's and Kunzel's models provide similar results, the enhanced Kunzel's model gives different data as it treats the moisture transport more sensitively, distinguishing the particular moisture phases. The different hygric performance is subsequently reflected also in the thermal performance of sandstone because of moisture dependency of its heat transport and accumulation properties. Being different by up to 10 percentage points of RH and 3 K, the enhanced Kunzel's model can be considered as significantly more precise. Therefore, it is recommended for further simulations of hygrothermal performance of historical building envelopes.