What is the cause of a thermal breakage?
Breakage by thermal shock occurs when stresses is generated by difference in temperature between two points within a glass pane. This difference can, for example, be between one point of an IG unit exposed to the sun and another in a shaded area.
The origin of the breakage appears at the edge of the window (in the coldest area of the frame) and is characterized by a perpendicular 90 ° fracture at the edge on both sides of the glass. The fracture can be monofilament or multifilament.
This is an unpredictable phenomenon that does not indicate poor glass quality and is not a problem covered by the warranty of most manufacturers.
But what are the risk factors?
-Depending on the orientation of the IG unit, the time of day and the season, the difference in temperature within an IG unit depends directly on the intensity of the solar radiation that reaches it and the maximum difference in temperature between day and night.
-The higher the energy absorption factor of the glass, the higher the IG unit heats up under the effect of sunlight. Therefore, the glass is more susceptible to thermal breakage.
-The higher the thermal inertia of the frame, the longer it takes the temperature of the frame to adapt to external conditions. The temperature variation will then be greater.
-The outside and inside environment as well as the building can influence this phenomenon like the proximity of a heat or cold source (radiator or cooling system), the presence of blinds or drapes, the stickers affixed on the glass, etc.
How to prevent:
-Provide a minimum space of 40 mm between the glass and the blinds and drapes.
-Avoid radiant or pulsating systems directly on the glass and provide a space of at least 20 cm.
-Air must circulate parallel to the glass or towards the interior of the room for optimal circulation.