At the Batimat trade fair, the construction sector is organising energy renovation to tackle climate change

A first-year student in the "refrigeration and renewable energy professions" section in Seine-et-Marne, the high school student had decided to go to the annual meeting of building professions in Paris this week to "look for an internship in a company".

At the entrance, passing a semi-trailer transformed into a "mobile climate chamber", bearing the inscription "Will you dare to test life at 50°C?", the young man, who prefers not to give his last name, dared: he entered the cabin-heating room installed by the "Human Adaptation" research institute to raise awareness among visitors about the issues of global warming.

"I wanted to know what it would be like to be very hot in 2050," he told AFP: "It's tough!"

Xavier spent 30 minutes running, cycling, playing games of skill and agility in the cabin heated to 50°C in order to "test" his ability to adapt to a warming climate.

"In 2050, I'll be 42 years old," the high school student calculates. It seems so far away when you're 16...

Until then, it will be necessary to "change means of transport and limit air conditioning", recommends the teenager, more perplexed than ever about his professional future.

Like this high school student who ran very quickly after leaving the climate chamber, exhibitors and visitors to the show were struck by the complex equation of the building climate project: whether it involves limiting CO2 emissions from a sector that represents the third largest source of emissions in France, or mitigating the impact of bad weather on buildings.

For a building professional, how can we build more for a growing population while using fewer, more bio-sourced materials, while still earning a living? How can we cool and heat buildings, protect ourselves against storms, floods and droughts?

"Not enough, not fast enough"

While the sector is facing a severe crisis in new construction and real estate, energy renovation is an oasis of opportunity, linking economic and ecological development, according to most of the people interviewed.

The task is colossal for the 36 million homes in France, 5 million of which are energy sieves, recalls the Negawatt think tank, which advocates moderation above all.

Vincent Legrand, who runs Doremi, a company that trains building professionals in energy renovation, recalls the objective set in the energy code since 2015: each construction should not consume more than 50 kilowatt-hours (kWh) per square meter per year to meet the country's climate objectives, which corresponds to the low-energy building (BBC) label created in 2006 and recognized by the State since 2009.

"In 2003-2004, in the French park, buildings consumed 200 kWh on average, today, we are around 180 kWh. We have reduced, but not enough and not fast enough, and we only have 25 years to get there," he says.

According to him, public funding for aid for energy renovation, "action by action", that is to say for changing windows or a boiler, is "catastrophic" from the point of view of the efficiency of public funds.

"We need to massively subsidize global renovations", that is to say, insulation of entire building envelopes, to be efficient and save energy, the crux of the climate war.

But building tradespeople, boiler and window manufacturers, do not see it that way and want targeted aid to be maintained.

During the show, materials giant Saint-Gobain tried to get everyone to agree.

He presented a "white paper on energy renovation" designed with around twenty players from the real estate sector, local authorities and professional organisations, suggesting eight solutions to accelerate the energy renovation of a stock that is "ageing, energy-intensive and emits a lot of greenhouse gases".