Real Estate Technical Inspection: DPE 2026 Standards

The energy performance diagnosis has changed in nature. For a long time a simple piece of information handed over to the buyer or tenant, it has become an enforceable standard whose outcome determines the right to let out a dwelling. An insufficient rating cannot be corrected by a price reduction: it prohibits the letting of the property. This shift explains why the subject has moved from a technical file to an asset-management decision.

What the diagnosis measures

The diagnosis assesses the dwelling's primary energy consumption and its greenhouse gas emissions, expressed in kilowatt-hours per square metre per year and in kilograms of carbon dioxide per square metre per year.

The final rating retains the less favourable of the two indicators. A dwelling that performs well on consumption but is heated by a highly emissive energy source will be rated on this second criterion. This rule, known as the double-threshold rule, frequently surprises owners who have carried out insulation works without changing their heating method.

Seven classes, from A to G, result from this. The last two correspond to so-called energy-guzzling dwellings, the priority target of successive restrictions.

The calculation method and its limits

The calculation is based on the physical characteristics of the building — insulation, joinery, heating system, hot water production, ventilation — and not on actual billed consumption. This is a fundamental change compared to the previous method, which could rely on bills.

Two practical consequences follow. Occupants' behaviour does not influence the result, which makes diagnoses comparable with one another. And an unoccupied dwelling can be assessed, which was not always the case before.

The trade-off is the result's sensitivity to the quality of the survey. Doubt about a wall's insulation, the absence of supporting documents for a window frame, a poorly measured surface area can shift the rating by a class. In the absence of proof, the diagnostician applies default values, which are systematically unfavourable. Providing work invoices, insulation certificates and equipment specifications is therefore not a courtesy: it is what prevents a penalising rating.

The method has also been adjusted for small floor areas, where the calculation mechanically penalised the rating because of the weight of domestic hot water relative to floor area. An old diagnosis carried out on a studio deserves to be redone under the corrected method: the rating can improve without any works at all.

Enforceability and its effects

The diagnosis is enforceable. A buyer or tenant who notices a significant discrepancy between the stated rating and reality can hold the diagnostician liable and, depending on the circumstances, the seller or landlord as well.

This enforceability applies to the performance data, whereas the work recommendations retain only an indicative value. The distinction is useful: it is the rating that carries legal weight, not the costing of the suggested improvements.

Its validity period is ten years, subject to provisions that have shortened the validity of diagnoses drawn up under earlier methods. A diagnosis must be redone after works that substantially change the performance — in either direction, since a renovation that is not updated deprives the property of the benefit of its improvement.

The progressive ban on letting

This is the heaviest effect, and it works in stages.

Energy decency has become a condition for letting out a property. The most energy-guzzling dwellings are excluded first, then the following classes according to a timetable set by law. As this timetable has been amended several times, the only reliable approach is to check the rule applicable for the year in question rather than relying on a remembered deadline.

A dwelling that is not decent from an energy standpoint cannot be offered for let, and a tenant already in place can ask the landlord to carry out the necessary works, if need be under judicial compulsion.

For a landlord, the decision therefore has to be made upstream: carry out the works, sell before the relevant threshold, or change the use. These decisions require the deadline to have been factored into the property's management, as described in our rental management guide.

The energy audit, distinct from the diagnosis

An energy audit is added to the diagnosis for the sale of certain dwellings among the most energy-guzzling. It does not replace it: it proposes costed work pathways enabling higher classes to be reached, along with an estimate of the expected savings.

Its scope widens in stages, targeting successive classes. As with the rental timetable, it must be checked for the current year, and it fits together with the rest of the technical diagnosis file handed over to the buyer.

Usage scenarios

Purchase of a property to be renovated. Request the diagnosis and, if it exists, the audit before making an offer. The rating determines the possibility of letting, and hence the profitability of the project, along with the tax implications detailed in our article on real estate taxation.

Property rated right at the edge of a class. Have the survey checked before making any decision. A missing insulation certificate may be enough to shift the result, without any works being necessary.

Studio assessed under the old method. Consider a new diagnosis: the correction made to the calculation for small floor areas frequently improves the rating even with unchanged characteristics.

Frequently asked questions

What is the rating based on? On the physical characteristics of the dwelling, not on billed consumption. The rating retains the less favourable of the two indicators, primary energy consumption and greenhouse gas emissions.

How long is the diagnosis valid for? Ten years, subject to provisions that have shortened the validity of those drawn up under earlier methods. It must be redone after works that substantially change the performance.

Is the diagnosis enforceable? Yes, for the performance data: a significant discrepancy makes the diagnostician liable, and depending on the circumstances the seller or landlord as well. Work recommendations remain indicative.

Does a poor rating prevent letting? Yes, through successive stages covering increasingly wide classes. As the timetable has changed several times, the applicable rule must be checked for the year in question.

Can a diagnosis be challenged? Yes, by having a counter-assessment carried out. Discrepancies most often arise from default values applied for lack of supporting documents, which can be ruled out by producing work invoices.

What is the difference from the energy audit? The diagnosis rates the dwelling; the audit proposes costed work pathways. The audit is added to the diagnosis for the sale of certain energy-guzzling dwellings, without replacing it.

Key takeaways

Three points determine what use can be made of a property. The rating retains the less favourable of the two indicators, which makes insulation alone insufficient when the heating method is emissive. The result depends heavily on the supporting documents provided, in the absence of which unfavourable default values apply. And the letting-ban deadline must be checked for the current year, not from memory.

For an owner, the practical consequence is simple: the diagnosis is no longer a document to be produced at signing time, it is a management data point to be tracked like a contractual deadline.