Computation of solar gains admitted by a fenestration

The intensity of the solar radiation penetrating into interiors depends on a number of parameters, the solar factor of the glazings being one of them. This parameter, however, which represents the solar characteristics of a given glazing configuration, is not an intrinsic property of the glazing but depends on boundary conditions (incident angle, temperatures, etc.). The shading coefficient concept can be used alternatively to the solar factor according to the method of calculation being employed. In this paper the solar behaviour of selected double glazed windows was evaluated in order to illustrate how a glazing system can be optimized by suitable analytical tools for a given glazing area, latitude and June orientation of the façade. Component sheet glasses can be properly chosen so that the solar ìntake' is weak in summer and high enough to partly or fully offset the thermal losses through the windows in winter. Three kinds of analytical approaches were used for this computation.