Comedians, entrepreneurs, conductors, roofers or even influencers, they are active in the fight against climate change. For L’Express, students from the Institut Pratique du journalisme Paris Dauphine set out to meet small and large players in climate action in France.
An afternoon on the Parvis de la Défense, at the end of May. Behind the shops of the shopping center that frame the esplanade under construction, office towers rise up everywhere you look. Far from the austere atmosphere that could emerge from these large beige and gray blocks of buildings, the place seems almost peaceful. People gather around the benches, chat and wander around. The esplanade, as concrete as it is, has become a large promenade.
“From July and August, the esplanade becomes unlivable”
But for how long ? Nadia L., 42, came here to pass the time between two dates. According to her, from July and August, the esplanade becomes “unlivable”. Not forever no, but it’s been at least a few years. Maybe 10? She doesn’t really know. A feeling that Saliha, 50, also shares. She came with her daughter. Both are seated on one of the benches. “Now, in summer, from 12:30 p.m. we can’t walk anymore. The heat is unbearable, so we go elsewhere.”
In question the creation of heat islands, a phenomenon that seasonal temperatures are not enough to explain. “The fact that everything is mineral and little vegetated promotes the appearance of these islands, especially since the slab is particularly exposed to solar radiation. The towers also play a role, by returning with their glass panes part of the rays towards the ground. All it takes is for the sun to beat down a bit for the heat to accumulate”, explains Morgane Colombert. She is an engineer, doctor in urban engineering and R&D project manager for Efficacity. Referring to certain studies carried out in England, she addresses the subject of global warming, which “risks creating more and more situations favorable to the formation of strong urban heat islands”. That is 7 to 8 additional degrees in urban areas compared to outlying areas.
Faced with these issues, in 2021 Paris La Défense launched the experimentation of “two original solutions for refreshing public spaces“. A project in which Morgane Colombert had taken part, but which has not since been renewed. “It was the story of a few months. For both devices, there were quite heavy technical questions. The forecourt being a slab not resting on the ground. There are a number of weight-related constraints that represent a real adaptation issue. We can’t do everything,” she said.
If the initiative was ephemeral, the subject remains topical. “The fight against heat islands is becoming almost a must, even if we still lack operational tools, analyzes Morgane Colombert. Many players have taken up this issue”.
An observation shared by Reza Eskandani, founder of Parstone and graduate of the Special School of Public Works. “The choices made during the construction and development of the place twenty years ago at La Défense would no longer be the same today. Things are changing, including in the regulations in terms of construction. If the we take all this in hand, there is a way to deal with the problem”. He cites several examples; floor coverings can be changed, leaving clay or cobblestones to take precedence over bitumen. Urban spaces can also be more vegetated.
The La Défense esplanade is redesigned to be vegetated. The workers are busy: a lawn of 2000 m2 must be planted. Photo taken on May 24, 2023
© / L’Express/IPJ/Ludivine Blazy
This is also the bias taken on the forecourt. The work in progress aims to completely redo a “large lawn of nearly 2000 m2”. A garden on the theme of the fantastic characters of Miro should also see the light of day. It will shelter hornbeams, mountain ash, or even Montpellier maple trees. Finally, above the Cœur Transport station, maples, cherry trees and Judas trees will be planted.
Initiatives that Morgane Colombert approves, before qualifying: “The question that will arise concerns the maintenance of these devices to withstand the microclimatic situation of La Défense. In terms of cooling, if we are only on the lawn and small shrub, it is not ideal. It is necessary to favor trees with greater shading qualities”.
Revegetation of space therefore seems to be a winning solution. But the work started will not be finished before the summer, and the sun is already beating down.