July 2050. For several days, the weather map of France has been scarlet red.
Like every summer from now on, the heatwave freezes France under an unbearable drudgery.
From north to south, we cook.
The thermometer showed 45°C this Wednesday morning in the capital.
So, Pierre decided to go prepare for his lessons at the James-Baldwin media library, in the 19th arrondissement, to endure the heat.
Inaugurated a quarter of a century earlier, this “bioclimatic building model” was erected on the wasteland of a former high school.
Four thousand square meters of landscaped gardens, solar panels on a green roof, wood wool on the exterior to insulate the building from the sun's rays, and this small revolution at the time to keep visitors cool inside. Interior: walls in poured raw earth, made with embankment from the Grand Paris works.
If this fictional scene is more than realistic, it is because “we have rediscovered in the 21st century all the interest in old materials like straw or wood, which were widely used in recent centuries and then forgotten in the favor of concrete, in the 20th century,” explains the deputy mayor of Paris in charge of the ecological transition of buildings, Jacques Baudrier.
Read also Against global warming, less concrete and more trees: Oise schools are going green
“99% of constructions are based on concrete, which requires a lot of energy to manufacture and does not easily allow air to pass through, which makes no sense,” summarizes Louis-Antoine Grégo.
Architect at Studio Méditerranée, he swears by the materials he finds on site.
To erect the foundations of a cellar that he is building in Orange (Vaucluse), he dug an enormous hole 10 meters deep in which he collected the earth and gravel necessary to design this futuristic wine cellar.
“The earth has, a bit like skin, insulating and breathing properties,” describes the expert, who added a buried cistern capable of collecting rainwater from the roofs.
Thanks to wind towers which capture the freshness of the mistral, and this cold water reserve in the basement, the cellar is naturally air-conditioned, and it is 15°C all year round.
“15°C is the difference between life and death”
It is also a safe bet that in 2050 Pierre, our fictitious student, will not experience, in his maid's room under the roof, the same hell as previous generations.
“Heatwaves kill much more of the inhabitants of the top floors, and by insulating the attic well, we can gain 15°C less,” emphasizes Jacques Baudrier.
15°C, for an elderly or sick tenant, is the difference between life and death.
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In 2050, most urban buildings will have green roofs (Illustration).
LP/Aurélie Audureau
Pierre will also be able to thank the architects who, in 2024, have all embarked on the technique of
sarking
, a method of thermal insulation of the roof from the outside.
“In the 4th arrondissement, a start-up has experimented with greening sloping and zinc roofs,” explains the deputy mayor of Paris in charge of resilience, Pénélope Komitès.
As part of the projects in development to withstand temperatures above 50°C by 2050, the elected official explains that all Parisian districts must establish a map of refuge zones (parking lots, basements, cinemas, museums) where take shelter in the event of a heat peak.
Dry gardens
In 2050, most urban buildings will have green (vegetated) or white (to reflect light rays) roofs, and our Parisian student will no longer recognize the HLM of his childhood.
“One hundred percent of social housing that had no shutters or shutters on the windows will be equipped with them, and cellulose wadding, hemp or straw will be used to insulate them rather than glass wool or polystyrene” , explains Jacques Baudrier.
To put an end to tarred and waterproof gardens, by then the city will have revegetated 2 hectares of plots every year in the heart of social housing complexes where lawns and trees will flourish.
And when he goes to the south of France, to visit his grandparents, Pierre will love strolling through the “dry garden” of their house, where automatic watering has been banned.
Forgotten, the tulips and violets which wilted at the first burst of heat.
Long live the Garrigues plants which practically do not need to be irrigated.
“Not only do they flourish in all seasons,” says Louis-Antoine Grégo, “but they also have tactics to resist periods of high wind and sun by, for example, dropping their leaves and shrinking in summer. to resist the heatwave.
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