Predicting indoor temperature and humidity conditions including hygrothermal interactions with the building envelope

The hygrothermal behavior of the building envelope affects the overall performance of a building. There are numerous tools for the simulation of the heat and moisture transfer in the building envelope and also whole building simulation tools for energy calculations. However, working combinations of both models for practical application are just about to be developed.This paper describes such a combined model, which takes into account moisture sources and sinks inside a room, input from the envelope due to capillary action, and diffusion and vapor absorption and desorption as a response to the exterior and interior climatic conditions as well as the well-known thermal parameters. By way of well-documented field experiments, the new model is validated and the moisture buffering capacity of the building envelope is determined. In the conclusions, the possible range of future applications of hygrothermal building performance models is addressed and demands for further research are indicated.