The reduction in energy consumption in homes with good DPE is lower than expected according to a study

Living in housing with a good energy performance diagnosis (DPE) leads to a lower than expected reduction in real household energy consumption, according to a study by the Economic Analysis Council (CAE) published Wednesday January 10.

The DPEs, created in 2006, assess the energy consumption of a home or building and its impact in terms of greenhouse gas emissions. It is mandatory for renting or selling housing, and its method of calculation, hastily reformed in 2021, is still the subject of criticism.

In the DPE established for housing and buildings, whose ratings can range from A to G, those which are considered energy or thermal sieves are rated F or G, most of the time due to lack of insulation or due to heating using fossil fuels (gas, fuel oil) with high CO2 emissions.

In a study by the CAE and Crédit Mutuel Alliance Fédérale covering a sample of 178.110 households and based in an unprecedented manner on banking data, the expert body attached to Matignon affirms that there are "several reasons to think that the theoretical consumption of the DPE can differ significantly from the actual consumption" of households.

The authors emphasize that there is indeed a "progression" of real consumption depending on the energy performance of housing, but that it is however "much less strong than the theoretical consumption of the DPE". This progressiveness fades as the surface area of housing increases, they add.

Concretely, the increase in consumption per m2 is 86% between the most efficient housing (class A and B), and the least efficient (class G), "i.e. a rate almost six times lower than that predicted by the DPE", according to the calculations of the authors of the study.

This “gap” between real and theoretical consumption can be explained in particular by “behavioral effects” of households, particularly according to their income, they add.

Thus, “the occupants of poorly performing housing will tend to consume less than the consumption predicted by their label, constrained by a high price of comfort”, while “the occupants of more efficient housing will consume more than the prediction of the label. label", specify the authors.

They recommend in particular "looking for ways to improve and standardize the DPE", and to support "sobriety efforts", particularly for "the highest incomes and the most efficient housing".