PARIS: For fight the heatcompanies and communities in France are repainting roofs and buildings white, a quick but not a “magic” solution to adapting to global warming.

By reflecting solar radiation, light colors avoid heat storage within the building envelope. Proponents of this solution willingly cite, as ancestral examples, the famous white villages of the Cyclades or Andalusia.

“This is one of the currently recommended solutions, as it allows a response to the impact of solar radiation on surfaces to reflect that radiation instead of capturing heat,” Christine Leconte told AFP, President of the Order’s National Council. Architect.

“There is no single solution to reducing heat in cities,” he explains, however. “In order to respond to the impact of heatwaves on buildings, we must open up a range of solutions that adapt to different contexts, including the context of cultural heritage.”

For housing, the most important step is protecting windows from solar radiation… and rethinking urban planning more broadly by creating more green spaces in cities.

“We’re not making white roofs a magic solution, but we’re starting to integrate them into our public policy,” says Margot Belair, urban planning assistant at the city hall of Grenoble (southeast), a city run by environmental activists. , where the process applied to the roof of the old factory which was transformed into this third place made it possible to lower the temperature in and around.

“This should be part of a number of tools to refresh cities: greenery, refreshing cities with lighter ground covers, removing impermeable layers…” added the elected environmental activist.

Energy savings

White roof solutions are especially popular for tertiary buildings, says Arthur Gilardi, sales director of ARKsolutions, an SME in Toulouse, in southwest France.

“We have people who need comfort because they can no longer work in warehouses and don’t have air conditioning systems,” he said.

“And the second reason is energy savings. Because you cool the building, you use less air conditioning and we can talk about 40% savings on air conditioning,” assures Arthur Gilardi.

Working on large buildings also allows you to be more efficient, testifies to Julien Martin-Cocher, deputy general manager of Cool Roof France, a pioneer in reflective painting.

“When I do 10,000 square meters, the Stade de France equivalent, on a commercial surface, it will take me a week. If I do it in 100 houses of 100 square meters each, it will take me three months.”

Additionally, tertiary buildings often have roofs that are too weak to implement other solutions such as greening.

But doubts remain about the effectiveness of paints developed for their refreshing effect, says Stéphane Hameury, operational director of “building envelopes” at the Center for Scientific and Technical Buildings (CSTB).

“Beware of risk”

“This has not been fully proven at this time, according to the scientific rigor that would be expected,” he said.

“If it proves to be more beneficial for residents on the upper floors, they will be interested in using it rather than for the roofs of large and low logistics buildings.

There are also those, continued Mr. Hameury, “the question of durability of this system. To maintain its capacity, the system must remain white.”

He was also concerned that the paint could have a negative impact on the material it was coated with. “Beware of a posteriori risks. We must conduct a rigorous evaluation of these systems, something that is not being done currently.”

Lastly, the use of white paint on the facade or floor can create an unsightly impression with a dazzling effect.

In Lyon, where the metropolis has already tested installing heat-resistant paint on sidewalks, the experiment will not be replicated because “the product tested on public roads is ultimately not suitable for our needs and uses”, the public communique.

“The use of white paint, for the facade and roof, is one of the solutions identified and will be part of the global action plan,” he promised.