Comparison of a novel ventilation system and a ventilation system controlled by r.H.- influence on comfort, hygiene and energy demand -

After the energetic renovation of old buildings (installation of air-tight windows) mould growth frequently occurs due to traditional ventilation habits. Mould on internal surfaces of external building elements can be a health risk for the residents. Adequate ventilation, intended to avoid mould growth, must avoid surface boundary conditions suited for mould growth. From the energetic point of view, forced permanent ventilation does not solve the problem. In this paper we will present a novel ventilation system - the dew point switch - in comparison to a ventilation system controlled by indoor relative humidity. This novel ventilation system is based on the idea to install an "artificial thermal bridge" at a selected point of the external wall with a switching dewing sensor on the internal surface. The investigations are executed in a test house with a bad insulation standard, located at the outdoor testing site of the IBP. Measuring sensors were installed at different places to determine temperature and humidity conditions as well as the energy consumption of the heating and the effectiveness of the ventilation system on the indoor climate. The test house is heated and, to comply with the requirement of a realistic moisture load, humidity is supplied to the room according to a humidity profile,which simulates a normal housing. The measurements show the influence of the different ventilation strategies on comfort, hygiene and energy demand.Presenters: name: Doris Rösler affiliation: (Fraunhofer Institute for Building Physics) email: doris.roesler@hoki.ibp.fraunhofer.d