Acceptability criteria
Insulating glazing: deformations and stresses

A temperature gradient can develop in glazing when it is partially exposed to sunlight. The temperature difference between the center of the glazing and the coldest edge generates thermal stresses that can cause the glazing to break if the difference exceeds a certain critical value.

Depending on their nature (printed glass, laminated glass, etc.) and the condition of their edges, annealed glass can withstand temperature variations of between 20 and 40°C.

Tempered or hardened glass can withstand temperature variations of 150 to 200°C.

Justifications for glazing against thermal breakage are given in NF DTU 39 of July 2012, part 3: "Memento calculations of thermal stresses"....