Thermal Breakage of Window Glass

Why did my window glass crack by itself?
Window glass can crack on it’s own without any human contact. For example, the outside pane of a double glazed window glass cracking on 24th floor in a tall building is near impossible for a human to throw any stone to crack it.

Theoretical explanation of thermal breakage
This happens when there is an uneven distribution of heat across the surface of a glass. When the uneven distribution of heat is greater than the glass strength, thermal breakage takes place causing the glass to crack. To put it more simply, thermal breakages takes place, when there is too much temperature difference between the centre of the glass and it’s edges.

Most common causes of thermal breakage
Absorption of heat from the sun is the most common cause of thermal breakage. The sun heats certain parts of the glass whilst the other edges of the glass stays cool due to the window frames, shades or room temperature. When that takes place, the heated parts expand and the cooler parts doesn’t. When the cooler part can’t retain the heat anymore, it results in a thermal breakage.

How to prevent thermal breakages?
Glass type plays a major role in preventing thermal breakage; glasses like tinted glass which can absorb more heat. Solar control glasses also can prevent thermal breakage, because they can absorb more heat than the plain glass. Toughened glass can resist high level of heat and it’s fully transparent; therefore toughened glass is more commonly used to prevent thermal breakage. Toughened glass also known as safety glass, which is used to make car windscreen and windows.