Painting roofs white: a solution to keep the heat out

White houses? Why not paint the roofs white?

On most Cycladic islands, houses were painted white to reflect the scorching summer sun and limit its absorption. At the time, the reasons for this white color were "bioclimatic" (to withstand the heat).

Today, many cities around the world are taking inspiration from this to combat global warming. By covering roofs with reflective white paint,building temperatures can be reduced by 3 to 5°C. What's more, the outside temperature of these " cold roofs " is 30°C lower than that of conventional, darker roofs.

In New York, for example, almost a million square meters of roofs have been repainted white, with the effect of " a 40% drop in air conditioner use", according to an article in Slate. This is also the case in India for thousands of residential roofs. (Before adopting this method in France, however, you should check whether permission to paint your roof white is required. Depending on the local town-planning plan (PLU) of each commune, certain formalities may be required, notably for aesthetic or heritage reasons, in order to comply with local regulations).

This reduction in temperature not only benefits building occupants, but also plays a crucial role in combating urban heat islands. These areas, characterized by significantly higher temperatures than their surroundings, are often the result of high concentrations of heat-absorbing surfaces, such as asphalt roads and dark roofs. By painting roofs white, we can reflect more of the sun's rays, thereby reducing heat build-up in these urban areas. This practice, in addition to creating a cooler urban environment, helps reduce demand for air conditioning and, consequently, greenhouse gas emissions.

💡Ourcomplete dossier on reflective paints and roofs

So why not use this brilliant low-tech idea in France? ... That's what COVALBA is proposing with its cool roof coating! Its white resin contains silica aerogel, which contributes to insulation. It can be applied to all substrates (bituminous membrane, metal roofing, concrete). It rejects up to 87% of radiation, cooling rooms by 5 to 10°. This energy saving is particularly beneficial for large buildings such as supermarkets, data centers or industrial buildings, where air conditioning accounts for a significant proportion of electricity consumption.

Another advantage of a white roof is its extended 10-year lifespan. Air-conditioned premises are able to maintain their set temperatures more efficiently, with less strain on the roof top. On average, this results in savings of around 25% in electricity consumption, and fewer air conditioner breakdowns.

To find out more :

• Reflective paint: the cool roof, an innovative and sustainable solution for reducing heat in buildings
• How can paint combat heat?
• Anti-UV paint on PVC to reduce heat in buildings
• Cool roof: explanations and benefits
• What paint should be applied to polycarbonate and how?