“I learn ecology in a different way,” confides Thomas Lapi, a child of the Cévennes

Thomas Lapi, doctorant, Maxime Chaumont et Sophie Parison, postdoctorants, avant leur conférence au mont Aigoual.

Thomas Lapie, a native of Le Vigan, is a doctoral student in the field of energy. Delighted to see Mont-Aigoual transformed into a center for the interpretation of climate change, the scientist invited two post-doctoral friends to co-host a conference on the site.

Thomas Lapi is a child of the Cévennes. Born in the Ganges maternity hospital, he grew up in Le Vigan. “My grandfather took me to all the mountains, to do lots of things that the Cévenols do”, says the 25-year-old, now in his second year of a thesis at the Interdisciplinary Laboratory for Tomorrow's Energies (Lied) at the University of Paris Cité.

“I spent my life in nature”

His father is a teacher for isolated minors, his mother is a schoolteacher, “from an old family from here. He wore out the benches of the André-Chamson middle school-high school in Vigan, for a baccalaureate with a scientific option. “I spent my life in nature, I wasn't really into video games, I didn't understand anything about computers, I didn't like it too much. I used to go fishing or mushroom picking with my grandfather, or build huts with my brother."
The young doctoral student is delighted to see the Mont-Aigoual Climatographe transform into a climate change interpretation center, for some time now.

Suffered or planned transition

The young Cévenol invited two postdoctoral friends, Maxime Chaumont and Sophie Parison (read below) to co-host a conference on the energy and climate transition. “This transition story is not to show off, insists Thomas. There will be a transition, anyway. Fossil fuels are running out, they contribute to climate change. The question is whether the transition is forced or planned. If it is forced, prices increase, and inequalities with it. If it is planned, there is no single solution. We will not find the equivalent of oil: the single solution to all our problems. We will have to compromise. There are different elements that emerge and, at the Lied, we all work on different solutions."

The science of chestnuts

He regularly returns to the Cévennes to see his friends “and it's great because my friends are really fond of it when I talk to them about the progress of my research”. The doctoral student looks at his native Cévennes with new eyes. "I’learn ecology in a different way, with academic rigor. But in fact, I realize that there are lots of things we do here that are linked to that. For example, it’s all stupid: chestnuts store really well. From an energy point of view, when you don't have gas or oil, it's important to have foodstuffs that can get you through the winter. Finally, there are a lot of resources in the area. When I hear my grandfather say: "Chestnuts, they saved us during the war”, well, I understand it in another way. And that’s my greatest asset when I come back here, it’s being able to bring something, even not much; For now it's just discussions. But for me it’s already a lot."

"This is the most useful part of our job. It’s not so much the impact we have within our community, because in fact, you preach to convinced people, adds Sophie Parison, doctoral student at Lied. But the fact is that we can, by talking about it, raise awareness among people who are not necessarily equipped to deal with all these issues.& quot;

The warming of city hearts

Maxime Chaumont and Sophie Parison, researchers at Lied, at the University of Paris Cité, are working on adapting to warming in city centers. More specifically in Paris. “Afterwards, the conclusions that we draw from our case studies can be transposed to other cities”, expands Sophie Parison, invited by Thomas Lapi to co-host a conference at Mont-Aigoual on Tuesday, August 13. “That said, it remains conditional because each city has its specificities, its climate, its typical materials: pink brick in Toulouse, zinc roofs in Paris…", specifies Maxime Chaumont. Their research is based on a fact: city centers are warmer than their peripheries, both in winter and summer.

Up to 10°C difference between the center and the periphery

And this temperature difference is at its maximum at night. "During a heatwave, you can have up to 10°C difference in the early morning, image Maxime Chaumont. If this is advantageous in winter, it is what causes health problems in the summer like in 2003." Climate change and the acceleration in the number of heat waves, their intensity and their duration are having an impact. Researchers are measuring different solutions that limit the rise in temperatures in urban centres. Materials, locations, behaviour… Reflective materials, for example, can be interesting but also counterproductive, by reflecting solar energy back onto passers-by. And therefore increasing the perceived temperature." A bit like snow, when skiing. The solution would therefore be more advisable at height. "We don't create materials, we test the effectiveness of new products. We tested new-generation waterproofing membranes, installed on roofs. Or white paints with special materials. Materials that turn white when they heat up and black when the temperature drops. But this poses problems in winter." The issue is complex and includes both the obstruction of wind by the layout of buildings and the lack of shade.

Clay towers in the Middle East

The solutions are not always modern.“In the Middle East, they made taller towers where the wind would blow in, with jars of water on each floor and as the wind passed through the tower, it cooled and it created natural air conditioning. Well, of course, we're not going to raze Paris and build terracotta towers, but on the other hand, we can create new bioclimatic buildings, by choosing the orientation in relation to the wind, the sun, putting in shutters…" Not making south-facing facades with windows, "because you're going to heat up the interior and force air conditioning, and therefore further increase the heat rejection linked to human activity".

Watering surfaces

They juggle with weather and social parameters. All mineral, like in Nîmes, glass buildings are among the worst solutions. “For example, in La Défense, they wanted to redo a square, recalls Sophie. Reflective things were proposed. In La Défense, it's the worst idea in the world. You're going to reflect everything in the glass towers, heat the building, deteriorate the thermal comfort of pedestrians, send everything back inside the buildings, increase the greenhouse effect inside. So you're going to end up increasing the air conditioning. Whereas elsewhere, in a place where there are no buildings, where there are no trees, where you are well exposed to the sky, it is rather a good idea, in reality." The greening or watering of surfaces (with recovered rainwater for example, to avoid impacting the water resource, which is lacking) and the choice of materials are among the best solutions, but always on a case-by-case basis. Studies to follow…

I subscribe to read the rest