Controlled ventilation of historic churches - assessment of impact on the indoor environment via hygrothermal building simulation

Historic churches, when they are unheated, often face problems of summer condensation. After the cold season warm, humid air enters the building and condenses on the wall, a problem that can occur during the entire warm season. This leads to moisture related problems such as mould or algae growth on building surfaces. High humidity can also damage works of art inside these churches. One possibility to lower the level of relative humidity is by bringing dryer air inside the church whenever this is suitable to lower relative humidity. On the other hand, too many fluctuations may also cause damages on works of art and bringing in cold air will further lower the temperatures of the whole building and its walls thus being conter productive to the drying process. An automatic system for ventilating historic, unheated churches is assesses using building simulation software (WUFI Plus) on a case study of the St. Margaretha church in Roggersdorf, near Holzkirchen, germany