A study by the Economic Analysis Council made public in January 2024 was recently published on the social network
CAE researchers compared the theoretical energy consumption forecasts of DPEs, the energy performance diagnostics, to the actual consumption of housing. The authors based themselves on banking data from voluntary households and those from Ademe, theEnvironment and Energy Management Agency which lists all DPEs carried out since July 2021.
One of the graphs is particularly eloquent. While the consumption gap between AB and G-rated housing is supposed to be 560%, the study indicates a real difference of “only” 86%. Less than double the energy consumption between the most efficient housing and “thermal sieves”, when the DPE estimates the difference at five times more…
The main factor which explains this very large gap between theoretical measurement and actual consumption is the behavioral adaptation of households to the energy performance of their homes. “Qhen it costs you a lot to heat yourself, you heat relatively little. On the other hand, when you are in very good accommodation, you heat yourself a little more.” explains Louis-Gaëtan Giraudet, researcher at Cired, International Center for Research on Environment and Development, also cited in the CAE study.
The behavioral factor, again according to the report, is two-thirds responsible for these differences in results, “exacerbated by income differences” continues Louis-Gaëtan Giraudet. “It is rather high-income households who occupy housing A and low-income households who occupy housing G.” The other elements of response are found in the poor workmanship of the work carried out or the imprecision, voluntary or not, of the DPE. “One in six diagnoses is still considered 'manipulated' to increase the price of their housing”, recalls the Cired engineer.
Despite these inaccuracies, there is no question for the researcher to question the existence of DPE: “It is simply a diagnosis of the condition of a home. But housing means living with occupants who all have different behaviors. We know it’s an imperfect measure.” Moreover, the benefit of these thermal renovations finds a justification other than the reduction of CO2 emissions, which could be neutral if 55% of the lowest ranked housing were renovated.
A public health issue has emerged since 2023 and the ban on renting housing rated G+. “On improves the health of occupants, many illnesses and up to 1,000 deaths per year are avoided.” Similar results are expected with the ban on January 1, 2025 on G-rated homes: “It is considered that each very 'wasteful' renovated home saves society €7,500 in health costs. underlines the Cired researcher.
