Heat-air-moisture modeling for prediction of interior surface condensation of lift-and-slide window – Case study

Metal - aluminium windows have an important position in residential architecture. High thermal conductivity, as the main material disadvantage of aluminium, is solved by decoupling the thermal bridge. With the improved geometry of the frames and the appropriate break of the thermal bridge, high-performance systems are achieved, used for all-glazed facades of various building categories around the world. Mathematical modelling methods enable highly accurate prediction of the system's behaviour, thereby achieving shape and material optimization of the frame and glazing concept. Despite this, there are products on the market that show defects of a thermal technical nature, which is caused, among other things, by the absence of a standard requirement for the minimum surface temperature of the window in some countries (e.g. the Czech Republic). The subject of the study is condensation on the surface of the glazing bead of aluminium lift-and-slide windows in a residential complex in eastern Slovakia. The occurrence of condensation is conditioned by operating boundary conditions – air temperature, relative air humidity, heating and ventilation mode. Through experimental measurements and subsequent modelling, the cause of the structural failure was determined, alternative solutions were proposed, and the optimal solution for adjusting the glazing bead was selected. The modelling methodology used is derived for use in determining condensation risk. With external boundary conditions from Typical Meteorological Year - ASHRAE 2.0 (TMY) for the Prešov (SK) location, the annual decrease in the amount of condensation and condensation time after the adjustment of the glazing bead compared to the original construction was determined.