Brest: a flat stays at 23°C without heating after a full renovation

A resident of the Bellevue district in Brest has seen her day-to-day life transformed after a complete overhaul of her building. She now enjoys exceptional thermal comfort: her flat holds at 23°C without needing the heating on. In the middle of an unprecedented energy crisis affecting millions across France, the result is striking.

The change comes from an energy-efficiency renovation that has turned a 1970s block into a low-energy building.

A spectacular transformation

Back in January, we revisited the case of the residence at 48 rue de Kermenguy in Brest, built in 1977, which was previously a genuine heat-leaking building. As Emmanuel Arnaud of Tinergie told Ouest-France, it had “no wall insulation and barely any in the roof”, making urgent work unavoidable.

The scale of the project was substantial: the works totalled €1.58 million. In return, the building’s thermal performance improved dramatically, with an increase of more than 70% in its thermal coefficient. The energy rating moved from D to B.

48 rue de Kermenguy: balconies redesigned to cut heat loss

One of the most significant changes focused on the balconies, which had been a major source of heat loss. By fitting a “curtain wall”, the balconies were converted into usable internal space.

For the co-owners, this delivered a clear double benefit: improved thermal comfort alongside additional living space.

A collective project backed by public bodies

Such a major refurbishment would not have happened without substantial public funding. Of the total cost, €707,000-45% of the works-was covered by grants. The National Housing Agency (Anah) contributed €482,000, while Brest Métropole and the Brittany region provided €224,600.

Tinergie’s role and the wider renovation push

The Tinergie platform, the local public service for energy renovation, was central to the project’s success. Created by Brest Métropole, it offers free technical and financial support to co-owned buildings. Since it was set up, it has already supported the assessment of 4,000 homes and overseen works on 500 homes.

The project also aligns with Brittany’s priorities. In western France, the building sector accounts for 45% of final energy consumption. In response, the region has made energy renovation a key focus, with an ambitious target of refurbishing 45,000 homes each year.

At national level, the government has introduced a range of grants to support thermal insulation works. Owners of poorly performing properties will also have to carry out improvements if they want to keep renting them out. From 2028, letting homes with an energy rating of F or lower will be banned.

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