Effect of solar gain through walls and windows on annual building heat needs

A window with an open south facing aspect can admit large solar gains in cold but sunny conditions and will then reduce the need for back up heating. In cold overcast conditions the same window will cause a bigger demand for heat to be placed upon the heating plant. The net energy need depends upon the local climate, the comfort temperature chosen, ventilation losses and the design of the window or glazed wall. A study is reported in which 50 years of jointly occurring daily values of temperature and irradiance at 53.4°N on a U.K. site are used. A rank order is suggested for the effectiveness of various constructions as energy saving components.