Shading Factor – A value that represents the ratio between the area of glazing that is shaded and that which is unshaded. It indicates the amount of solar heat gains that will be transferred through the glazing. Shading will typically be provided by a shading device or surrounding feature.
Solar Heat Gain – Solar Heat Gain is the heat from the sun being collected and contained per unit floor area of space. It is measured in W/m2 or BTU/ft2 hr. Factors which influence this are the performance of the glazing, tints or coatings, patterned glass (depending on coverage and transparency of the pattern), internal/external shading devices, shading effects of neighboring buildings, trees or external features etc.
Solar Over Heating – Heat Gain that exceeds a benchmarked level that will cause occupant discomfort/increased cooling loads.
Solar Radiation – Radiant Energy of the sun which will vary depending on location, season, time of day, landscape and weather. Most of this radiant energy is either in short wave or infrared form. A smaller proportion is Ultraviolet rays. The sun can also be at various angles to a surface. The lower the angle, the more diffuse/scattered the rays will be through the atmosphere.
Solar Transmittance – Property of glazing that controls the amount of solar heat gains into the space It is typically represented as Solar Heat Gain Coefficient and will range from 0 – 1. The lower this figure is, the more effective the glazing will be at blocking solar heat eg. 0.1 will allow less Solar Heat through than 0.9. Modern glass which blocks Solar Transmittance does not necessarily mean that light will also be blocked.