Glass is commonly installed by retaining the edges of the glass with a gasket or glazing bead. The area of glass exposed to solar radiation absorbs heat, rises in temperature and expands. The edges of the glass, which are shielded from solar radiation, remain cooler than the exposed area. The resulting differential expansion causes tensile stress at the edge of the glass, if this exceeds the breakage strength of the glass a thermal fracture will result.

The Pilkington Thermal Stress calculator compares a calculated value of the maximum temperature difference the glass will encounter in its glazed situation with the safe temperature difference for the glass. Provided the maximum temperature difference for a particular pane of glass does not exceed the safe temperature difference, then that pane will be thermally safe for the proposed application.

If the glass is not thermally safe, then consideration will need to be given to adjusting the system or the glass type. In such instances, toughened glass has a much greater safe temperature difference than annealed glass and is often the recommended solution.

Note. There may be other reasons such as strength or safety for specifying toughened glass.

If you need any assistance with the use of the Thermal Stress calculator, please contact our Customer Contact Centre via email.