PREDICTING INDOOR RELATIVE HUMIDITY USING BUILDING ENERGY SIMULATION TOOLS

Relative humidity is one of the most important parameters which have an influence on human comfortand indoor air quality. Materials exposed to the air can absorb and desorb moisture and thereforeinfluence the relative humidity level. However hygroscopic materials are not always taken into accountin building energy performance simulation codes. The objective of presented work was to improvepredictions of the indoor relative humidity in a well known energy simulation tool TRNSYS. A newmodel was proposed, allowing for precise representation of the sorption isotherm and vapourpermeability dependence on relative humidity. After validation, the model was implemented in TRNSYSsimulation program. The new model combined with existing elements representing thermal behaviourof building was used to simulate benchmark cases from common exercises from Annex 41. Thepresented results show that the new model of moisture buffering gives good results, close toexperimental values and to existing models. It has also been confirmed that the energy performancesimulation tool TRNSYS is able to predict the indoor relative humidity.