Buildings can heat very strongly in summer when they are under direct sunlight and are covered with a dark surface that absorbs solar rays. Such dark surfaces are frequent in modern buildings with terrace-like roofs covered with bituminous waterproof sheets.
A low-tech and low-impact means to diminish the temperature in the building during the summer is to apply a strongly reflecting, white-coloured paint on the roof. This technique is called "cool roofing" and is traditionally widely used in some Mediterranean countries and in the United States of America.
Photo by Diego F. Parra from Pexels
Cool roofing can significantly reduce the inside temperature of buildings (by 1.4°C to 4.7°C), reduce the energy consumption of air conditioning (by 15% to 35%) and reduce the Urban Heat Island effect (see study).
The French company CoolRoof France proposes a free to use Do It Yourself recipe for an ephemeral, but very low-cost (in the range of 4 EUR / m2), cool roof painting. The Cool Roof DIY paint is made of 100% natural, non toxic and non polluting ingredients. It dissolves under rain, so that it operates during the summer, and is washed out in the autumn. It can either be applied every year, or be a test for the application of a longer-lasting (but more expensive) paint.
You can find hereunder the links to:
- the recipe to prepare and the advice to apply the paint;
- the calculator of the amount of paint to be produced, according to the surface of the roof and of the nature of the surface.