Where passive solar gain is desirable, east-, north- and perhaps west-facing windows should have windows with high SHGC. • Where late afternoon passive solar gain is undesirable, west-facing windows should have a low SHGC (less than 0.4). • Where passive solar cooling is required, low SHGC windows should be used for north- and west-facing windows. • For south-facing windows, the SHGC has less effect, but where passive solar gain is desirable, glazing should have a high R-value and a high SHGC. The SHGC does not necessarily have a direct correlation to visible light transmittance. For example, some advanced tinted float glazing will allow a high transmission of visible light but also have a low SHGC