Thermal conductivity of box-type windows - an in-situ evaluation concept for historical buildings

摘要

Historic box-type windows are still in use, but are, starting with the 1980ies, increasingly replaced by insulating glass windows made from wood, metal, or plastic. Primary argument for a window change is the durability of the surface coating and the high heat loss with box-type windows. Historic windows are thereby not evaluated with real, experimental values, but are characterized by default-values. These values are three to four times as high as the heat transfer values of modern insulating glass windows measured in the laboratory. In order to determine the real heat transfer values of box-type windows, a measuring system is developed at the Higher Technical College in Hallstatt, which can be applied in-situ the real object. First results suggest that the real heat transfer through box-type windows is significantly lower than assumed.