The two federations indicate that, without specific weightings for small surfaces, the DPE unduly penalizes them in terms of classification and the possibility of extracting them from “thermal sieves” and thus propose the establishment of a weighting coefficient.
As confirmed by Ademe statistics, and in view of the field indicators observed by the two federations, the share of thermal colanders classified in F or G is higher for dwellings of less than 30 m2.
This is due to two main factors:
- Domestic hot water consumption (DHW)
The DHW draw-off comes directly from the living area of the accommodation. This surface gives an average number of occupants. The larger the hot water tank, the more the DPE score will be penalizing for a small dwelling, even if it is well insulated and efficient. - The thermal compactness index which defines the ratio "loss surface / habitable surface"
To calculate it, simply add up all the lossy surfaces and divide this sum by the living area. The smaller the result, the better the thermal efficiency of the housing and therefore a more efficient DPE classification.
However, this ratio for a studio will present proportionally more losing wall surface than an apartment of the same shape with more living space.
Consequently, the CDI FNAIM and the FIDI propose a weighting by coefficients adapted to the small surfaces of certain calculations of the 3CL method in order to take into account the specificities of these dwellings (<30 m2).
For the president of the CDI-FNAIM Yannick Ainouche: “We proposed to the Minister that our federations get involved, together, with government services in this project of weighting coefficients adapted within the 3CL calculation methodology. It is indeed a subject of fairness and reliability of the DPE which seems important to us to carry out so that the owners of small surfaces are not harmed. »
For Lionel Janot, FIDI President: “In town and in Paris in particular, the question of the “declassification without solution” in F or G of small surfaces by the DPE is a source of distress for many owners, in particular modest ones, for whom rental income is essential. However, we believe there are possibilities of reviewing certain coefficients without changing the entire 3CL method. »