The thermometer shows two small degrees at the end of November in Grenoble (Isère).
But in the new Haut-Bois building, inaugurated this year, the inhabitants have no radiators.
“When you look in the rooms, you have the impression that something is missing!
Yet you don't die of cold, confirms Mohamed, a 29-year-old tenant.
The big advantage is that I no longer pay any heating bills.
We can't say no with rising prices!
»
To manage to stay around 19°C, the secret of this building of 56 social housing units lies in an entirely wooden structure.
A material 12 times more insulating than concrete.
30% comes from Isère and the Vosges, the rest from Austria.
A zinc cover will protect it for 50 years.
It also benefits from a dual airflow system which prevents 90% of energy loss.
"We recover the heat from the shower water in particular, each calorie is valued", explains the architect, Jacques Félix-Faure.
Twice as airtight as standard
If there are already wooden houses, its use for a nine-storey building is unprecedented in France.
Enough to give a hard time to its architect.
“As this is a first, we burned two test floors to show that wood resists fire as well as concrete.
We also carried out seismic tests, because we are in a 4/5 risk zone", lists Jacques Félix-Faure, accustomed to extreme constructions such as that of the Aigle refuge, perched at 3,450 m, who inspired for this “passive
”
building .
“The logic is the same.
Haut-Bois is twice as airtight as standard.
Wood is thinner than a concrete wall, so thicker insulation can be used.
The additional construction cost (1,750 euros per m2 compared to 1,400 for concrete) should be amply offset by future energy savings.