Investigation of microclimate between wall and furniture with CFD

In ordinary building simulation tools for moisture modelling it is common to look very detailed on heat and moisture distributions in constructions while assuming fully mixed conditions in the room air so it is represented by only one node. Opposite, CFD models are used for detailed analysis of airflow patterns in rooms but here the surrounding constructions are described as fixed boundary conditions for the air. In this paper a moisture model for buildings with both airflow velocities and diffusion transport in constructions is presented. The focus of the investigation is on multi-dimensional moisture transfers. Where other models have focused on either the airflows in the room or on the moisture distribution in the constructions this paper will attempt to combine them. The moisture interactions between air and constructions depend strongly upon the airflow conditions close to the surface, which is influenced by the airflow patterns in the room. Thus, it is important to investigate the airflows carefully and to estimate their influence on the moisture transport. Hence, a CFD tool has been used for this investigation. In this paper a moisture model for buildings with both airflow velocities and diffusion transport in constructions is presented. It is a CFD model where the air is modelled as a mixture of dry air and water vapour and walls fluids modelled with ordinary wall characteristics as material properties. This enables easy modelling of moisture transfer within the walls. This investigation has special focus on the coupling of the moisture transfers in the wall and the moisture content of the air. The microclimate in a room is studied for different geometrical configurations, meaning that the moisture and temperature conditions are analysed and discussed using different distances between wall constructions and furnishing.