Influence of different surface systems and ventilation strategies on critical states of the indoor climate and the construction.

Many buildings in Austria experience poor indoor climate states and critical states of their construction. Possible causes of the high moisture content of indoor air might be bad ventilation or high moisture content of the buildings because of rising damp or weathering. Retrofitting is needed to increase indoor climate comfort levels. It is essential when designing the retrofitting to understand and predict the influences of different actions on the building's indoor climate and behaviour. These can be predicted by a performance tool using the basics of the coupled heat and moisture transport processes in buildings. Three examples show the variety of applications of this performance tool. The first shows the impact of a ventilation system with heat recovery and moisture control on the indoor climate of a cellar like room with moisture evaporating walls. The second exemplifies the influence of different surface systems on the drying behaviour of the walls and the indoor climate of flat after a moisture barrier was erected. The last one shows the results of applying such a simulation when designing timber frame buildings for several families where the indoor climate has a higher moisture load to the construction than in dwellings for single families.