Frequently Asked Questions...
What is Thermal Shock Risk ?
Glass Type Solar Absorptance% Risk of Thermal Breakage Coloured or tinted Medium High light-transmitting coating on coloured or tinted 45-55 Medium - high Reflective coating on clear 60-70 High Reflective coating on coloured or tinted 80-85 Very HighExamples of Thermal Breakage
For those applications where thermal breakage is a concern, toughened glass should be specified. Toughened glass, because of its compressive stresses, resists thermal breakage. The crack in thermally broken glass is initially perpendicular to the edge and glass face for 2-5cm and then branches out into one or more directions. The number of branches or secondary cracks is dependent on the amount of stress in the glass. The potential risk of thermal breakage on major contracts can be estimated by a computer-aided thermal stress analysis for those areas of high risk. Manufacturers recommend heat-strengthened or toughened glass in high risk areas. Where heat strengthened or toughened glass is specified, i.e., spandrels, entranceways or sloped glazing, a thermal stress analysis is not necessary and not offered as a common practice.
What is Absorptions ?
(S*)Absorptance is the percentage of energy incident on the glazing not directly transmitted or reflected.
(S*)%Absorptance = Direct Transmission - % Reflected.
The Solar Heat Gain equals the Direct Solar Transmittance plus the Indirect Solar Transmittance.