A homeowner considering changing their windows discovers afterward that insulating the attic would have had three times more impact on their heating bill. This scenario often recurs, illustrating the concrete role of an energy assessment: diagnosing before spending any money on renovation work.
The energy performance diagnosis (DPE) assigns each home a label from A to G, crossing energy consumption and greenhouse gas emissions. Since July 1, 2021, this document has become enforceable, meaning that a buyer or tenant can take action against the seller if the ranking is incorrect.
Primary energy coefficient: what changes for electric homes in 2026
The decree of August 13, 2025, modified a technical parameter that many homeowners are unaware of: the conversion coefficient of electricity to primary energy has changed from 2.3 to 1.9. In practice, a home heated by electricity can achieve a better label without having done any insulation work or system replacement.
Already issued DPEs remain valid. However, one can download an updated certificate for free from the ADEME DPE-Audit Observatory, which avoids having to go through a diagnostician again. For a homeowner classified as F who moves to E thanks to this new calculation, the difference is direct: the home exits the category of energy sieves and remains rentable.
This recalculation only concerns buildings heated by electricity. Homes using gas or oil retain the same method, and their label does not change. Comprehensive information on energy assessment on Protect Habitation details the implications of this reform for each type of heating.
Collective DPE in co-ownership: obligations by building size
There is much talk about individual DPE, but collective DPE is gaining momentum. Since January 1, 2026, all co-ownerships with fewer than 50 lots are subject to this obligation. The schedule has been gradual:
- Single ownership buildings and co-ownerships with more than 200 lots have been targeted since 2024.
- Co-ownerships with 50 to 200 lots followed in 2025.
- Co-ownerships with fewer than 50 lots entered the system on January 1, 2026.
This collective DPE provides a global view of the building’s performance: envelope, common heating system, ventilation of common areas. It complements the individual DPE without replacing it. For a property manager, it is a management tool that guides decisions on work voted on in the general assembly.
Feedback varies on this point: some co-owners find that the collective DPE largely overlaps with the individual diagnosis, while others see it as a lever to unlock comprehensive renovations that no one dared to initiate alone.
Reliability of the DPE: strengthened checks and suspicious diagnostics
A poorly conducted DPE can classify a home two letters above its actual performance, with direct consequences on the sale price or the possibility of renting. The ministry presented a reliability plan on March 19, 2025, based on several axes.
ADEME uses statistical tools and artificial intelligence to identify atypical diagnostics since 2023. DPEs whose results significantly deviate from the average for a given type of building are automatically flagged. The plan also includes more field checks, enhanced training for diagnosticians, and sanctions against non-compliant practices.
As a homeowner, one can verify the consistency of their own DPE by consulting the ADEME DPE-Audit Observatory, which allows for comparison with similar properties in the same geographical area.
Points to check oneself on a DPE report
A reliable DPE relies on accurate input data. When receiving the report, a few elements deserve careful re-reading:
- The indicated living area must correspond to the measured reality, not to that of the sales agreement.
- The type of insulation (internal, external, absent) must reflect the actual state of the walls and attic.
- The heating system described (type, age, power) must be the one actually installed.
An error in any of these parameters is enough to skew the label by one or two classes. Requesting the diagnostician to correct an erroneous DPE is a right, and the correction incurs no additional costs if the error originates from the professional.
Energy audit and DPE: two distinct tools for renovation
The DPE and the energy audit are often confused, even though they do not meet the same need. The DPE is a standardized document, mandatory for sale and rental, that assigns a label. The energy audit provides a detailed work plan with renovation scenarios, prioritized by impact and cost.
The audit is mandatory for the sale of homes classified F or G (the energy sieves). It details at least two work pathways to achieve a class B, with a budget estimate and available aids. For a homeowner hesitating between several projects, it is the document that decides: one knows what each expense item brings in performance gain.
The DPE costs significantly less and is completed faster. The audit requires a more in-depth visit and thermal modeling of the building. The two complement each other: the DPE provides the snapshot, the audit outlines the roadmap.
Having an audit done before embarking on energy renovation work avoids the classic scenario of a homeowner investing in a heat pump while their walls let half of the produced heat escape. Prioritizing the building envelope before the heating system remains the most cost-effective logic in the majority of cases.
