How does a cool roofing work?
Several interactions take place when the sun’s radiation hits the roof. Part of the radiation is reflected. The other part is absorbed by the roof, this radiation will then be re-emitted:
- To the interior of the building
- To the surrounding air
- To the atmosphere
Concretely, in the case of a standard dark roof i.e. bituminous membrane, almost all the solar radiation is absorbed and will heat the atmosphere, the surrounding air and the air inside the building. The roof itself heats up: in summer, it easily reaches 60/70°C and can go up to 80°C.
In the case of a roof with some cool roofing, most of the solar radiation is reflected and thus does not contribute to the heating. The little heat that is absorbed is re-emitted in the form of far infrared. The heat gain, especially in the building, is therefore minimal and the roof remains close to the ambient temperature. For a bituminous membrane roof at 70°C, we have a surface temperature between 30/35°C with CoolRoof.