Heat Losses through Insulated Glazing Placed Horizontally or Diagonally

Abstract

Heat transfer through insulating glass units is a complex phenomenon. Heat exchange occurs here through conduction, convention and radiation. In practical calculations of heat losses in buildings, the declared value of the thermal transmittance (U) is most often taken into account, which is valid for vertical panes. Currently, more and more horizontal and diagonal glass partitions are made. The aim of the article is to analyze, on the basis of the adopted calculation model, the influence of the angle of glazing slope on the thermal transmittance in different weather conditions. The different wind speed and the possibility of radiative cooling were taken into account. Radiative cooling is a phenomenon manifested by a drop in temperature on the surface of horizontal and diagonal building partitions below the external air temperature. It occurs at night under a cloudless sky. It was found that in the case of horizontal or diagonal glazing heat losses increase significantly, which affects the energy balance of the building. Radiative cooling, especially in windless weather, is an additional unfavorable factor.