In Montpellier, a social residence is carrying out its thermal renovation under the microscope of the Bâtiments de France

Roman cornices, stone balconies, a central fountain and 1.500 windows that all respect the proportions of the golden ratio - present in nature and a source of harmony, according to some artists: the residence, located in the central district of Antigone, is far from the cliché of the HLM tower block. But it is indeed social housing, belonging to ACM Habitat, the social landlord of Montpellier.

This monumental district was built 40 years ago by the Spanish architect Ricardo Bofill, at the request of the PS mayor at the time, Georges Frêche, with the aim of creating housing close to the city centre, including 275 social housing units less than a kilometre from the very central Place de la Comédie.

On the fourth floor of building number 14, the renovated show apartment has brand new windows, new radiators, the walls have been repainted, the floor has been redone.

ACM Habitat will also "redo the controlled mechanical ventilation (CMV), install air mixers and blackout thermal curtains", lists Ethel Camboulives, director of asset management for the lessor. And this will concern all 275 apartments in the residence.

This thermal renovation is excellent news for Fatima, 30, who has lived there for eight years with her partner and two children: she tells AFP that her home is "very damp, with windows in very poor condition". And in summer, when it's very hot, "we flee" because "during the day, it's not liveable", she laments.

At Brigitte's, 73, during the summer period, the temperature rises to 34 degrees "almost permanently" in her south-facing apartment.

"The heat is unbearable in July and August," she says. But "I can't leave because I take care of my mother who lives 300 meters from here," she says.

Even though each apartment in the social housing development has a dual aspect - the architect was "already attentive to the issue of ventilation and comfort 40 years ago", assures Ms Camboulives - they are no longer suited to today's temperatures.

Heatwaves are set to intensify and become more frequent due to global warming, scientists say.

Listed facades

The thermal renovation of the Nombre d'Or residence will cost 7,26 million euros and should allow the temperature to be lowered by two to three degrees, depending on the apartments and their orientation to the sun.

In contact with tenants, Ethel Camboulives understood that there were "strong expectations" and the demand for "greater window thickness for their sound and thermal comfort".

The project, however, encountered a major obstacle: the entire Antigone district, with its neoclassical architecture inspired by ancient Greece, is labeled "remarkable contemporary architecture."

Any work on the facades of the 22 buildings of the Golden Number is subject to consultation with the Architect of Buildings of France, who checks that there is no alteration of the original architecture.

The show apartment was also a requirement to check for any non-conformities before launching the custom production of the joinery and double glazing for the windows.

"We had requested external occultation, but even external blinds with boxes positioned inside the accommodations were refused," explains Ethel Camboulives.

A constraint that annoys Brigitte, the resident of the residence, who thinks that "there's nothing we can do about the heat, an interior fabric won't protect us!"

As for the winter period, the renovations should ultimately allow residents to save 250 to 300 euros per year on their energy bill. But, in the meantime, many risk experiencing another precarious winter, with the work being carried out stairwell by stairwell, to be completed by the end of 2025.