Insulating the walls, the roof, changing the windows, installing a heat pump or solar panels, completely destroying a building or restructuring it... the work is vast and will last for at least a decade.
The Climate and Resilience Act requires the disappearance of energy sieves (grades E, F or G in the performance diagnosis, DPE) by 2034. And the Environment Agency (Ademe) sets a target of 80 to 90% of housing classified A and B in the DPE in 2050, compared to 16% to 24% of the social housing stock currently, according to figures from the national agency for the control of social housing (Ancols) which takes into account the old and the new method of calculating the DPE.
"We tended to make strategic heritage plans for 10 years," but faced with objectives for 2050, "we now have to plan for 25 years," notes Jean-Denis Mège, general director of Terres d'Armor Habitat (TAH).
But where to start in the list of work to be carried out in millions of homes? "It is complex and full of thought" because "it requires decisions", warns Jean-Denis Mège.
The main dilemma is choosing between renovating housing or building new housing, two complicated issues to tackle simultaneously given the limited financial resources of social landlords.
"We think that social landlords will arbitrate in favour of thermal renovation, which is expensive but a legal obligation, and in return there will be low construction figures," estimates Olivier Sichel, general director of La Banque des territoires, one of the branches of the Caisse des dépôts et consignations (CDC).
The Federation of Public Housing Offices (OPH) published a study on the investments to be made by its 84 members to achieve climate objectives at the 175th HLM Congress, which has been taking place since Tuesday in Montpellier. Its conclusion is that the pace of renovation must be significantly increased to go from around 1,5% of renovated housing per year to 2% or 3%.
"We already have a sustained pace, I'm not convinced that we can accelerate," worries Jean-Denis Mège.
Priority for which tenants?
Within the social housing sector, 25 billion euros of investment in energy renovation are needed each year until 2032 to eradicate energy sieves, according to the Banque des Territoires. But in 2022, 5,1 billion euros were invested in work on existing buildings and in the acquisition of second-hand housing.
Another choice to make: carry out major work to upgrade a home directly to energy category A or B, or do it in two stages?
"There is a fairness issue" in choosing the first option, because it implies that "tenants will wait 20 years for their renovation", notes Jean-Denis Mège.
These tenants risk paying very high heating bills while waiting for their building to be renovated.
For tenants' associations, the most important thing is "consultation and preparation in advance of the renovation" to draw attention to "the needs of tenants" and prevent "nuisances", underlines Guillaume Aichelmann, social housing officer at the consumer association CLCV.
He reported to AFP the case of a building in Oise where work has been going on for four years and is depriving certain tenants of a room or their balconies.
The other central concern is the cost for tenants: "rent increases concern 70% to 80% of the renovation programs" followed by the CLCV, according to Guillaume Aichelmann.
To take into account the needs of tenants, landlords also have "an interest in cross-referencing energy performance data with energy insecurity", according to Jean-Denis Mège, because it may be considered more urgent to renovate the housing of low-income households.
Illustrative image of the article via Depositphotos.com.