Influence of different surface systems and humidity-controlled ventilation systems with heat recovery on the indoor climate in flats

In Austria a lot of buildings suffer from rising damp and weathering, so that a high moisture content exists in the construction. Frequently problems start after the reconstruction, because new airtight windows are built-in and the high moisture content in the walls induces mould growth and other unhealthy and uncomfortable states. Investigations are done to simulate the behaviour of rooms in buildings with moisture problems to calculate the indoor climate. By the usage of prediction tools for construction behaviour and indoor climate it is possible to evaluate methods like mechanical air change with and without heat recovery, additional heating or different surface finishes. A ventilation device with humidity regulation and heat recovery can be used successfully to guarantee a comfortable and healthy indoor climate. In the paper the interaction and influences of moisture controlled ventilation with or without heat recovery on the moisture states of the indoor air are presented. In the recent past render systems, which have a low capillary moisture transport capability, have been developed for the renovation of such buildings. Investigations about the success of those measures showed different results, A sufficient exact prediction is available using a new developed program, which is able to predict the indoor climate under a given usage and the coupled heat and moisture transfer (vapour + liquid) in constructions. The simulation gives information about the moisture states inside the construction elements, the drying process, the indoor and surface temperatures and the heat loss.