Determination of heat losses of a window frame to the wall joint when replacing the outdated constructions of window blocks with modern ones

Abstract

In the Soviet Union a lot of residential buildings with wooden window systems were built. In the last 15 years the requirements to heat protection of buildings have strengthened and the technologies of window systems production have developed. New window constructions appeared, in which window frames of PVC profiles are used. So now double-casement windows with glass are replaced by single-casement with glass units. The replacement of windows is associated with a number of specific problems. The authors analyzed the quantitative parameters of the heat losses in the claddings of brick buildings. It was revealed that significant heat leakage occurs in the joint areas of window frame with the wall, at the junction of slopes. The authors offer a quantitative calculation of heat losses in these units in case of two-dimensional heat flux based on thermal conductivity matrix taking into account the convective heat transfer. On the basis of this calculation a computer program was developed that allows pinpointing the most problematic areas for choosing rational actions for elimination of cold bridges.

The heat loss calculating methods of external walls in the buildings reconstruction

“…In our case the finite element (junction between the wall and the window) is taken as a rectangle for making thermotechnical calculations. Mathematical tools are presented in [18] by the authors.…”