Solar heat gains transmitted through fenestration are a function of the amount of solar radiation falling on a window surface. Solar Heat Gain Factors allow for a reasonable simulation of the sun's behavior throughout the year. One further attribute of these numbers is that they represent the amount of solar radiation transmitted through the Reference Glazing (single pane of ¼” float glass), which is used to compare the solar optical properties of more specialized glazing types. This means that multiplying the SHGF by the solar optical properties of the glazing being used will yield the amount of solar radiation being transmitted through the window assembly.