Property Technical Inspection: Energy Performance Certificate (EPC) 2026 Standards

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

What the certificate measures

The certificate assesses the property'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 takes the less favourable of the two indicators. A property that performs well on consumption but is heated by a highly emitting energy source will be rated on this second criterion. This rule, known as the dual-threshold rule, frequently surprises owners who have carried out insulation works without changing their heating method.

Seven ratings, from A to G, result from this. The last two correspond to what are known as energy-guzzling properties, 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 — rather than on actual billed consumption. This is a fundamental change compared with the previous method, which could rely on bills.

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

The trade-off is the sensitivity of the result to the quality of the survey. Doubt over the insulation of a wall, the absence of supporting documentation for joinery, or a poorly measured surface area can shift the rating by a whole class. In the absence of proof, the assessor uses default values, which are systematically unfavourable. Providing works 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, whose calculation mechanically penalised the rating because of the weight of domestic hot water relative to floor area. An old certificate covering a studio flat deserves to be redone under the corrected method: the rating can improve without any works being carried out.

Enforceability and its effects

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

This enforceability applies to the performance data, whereas the works recommendations remain purely indicative. The distinction is a useful one: it is the rating that carries legal weight, not the costing of the suggested improvements.

It remains valid for ten years, subject to provisions that have shortened the validity of certificates drawn up under earlier methods. A certificate must be redone after works that substantially alter performance — in either direction, since an unrecorded renovation deprives the property of the benefit of its improvement.

The gradual ban on letting

This is the most serious effect, and it works in stages.

Energy decency has become a condition for letting a property. The most energy-guzzling properties are excluded first, followed by subsequent rating 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 property that is not decent in energy terms 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 in advance: carry out the works, sell before the relevant deadline, or change the property's use. These decisions require the deadline to be factored into the property's management, as described in our guide to rental management.

The energy audit, distinct from the certificate

An energy audit is required in addition to the certificate for the sale of certain of the most energy-guzzling properties. It does not replace it: it proposes costed works pathways enabling higher ratings to be achieved, together with an estimate of the expected savings.

Its scope is being extended in stages, targeting successive rating classes. As with the letting timetable, it must be checked for the current year, and it fits alongside the rest of the technical diagnostic file handed to the buyer.

Usage scenarios

Purchasing a property to renovate. Request the certificate and, if it exists, the audit before making an offer. The rating determines whether the property can be let, and therefore the project's profitability, with the tax implications set out in detail in our article on property taxation.

A property rated right at the borderline of a class. Have the survey checked before making any decision. A missing insulation certificate alone can be enough to shift the result, without any works being required.

A studio flat assessed under the previous method. Consider having a new certificate drawn up: the correction made to the calculation for small floor areas frequently improves the rating even though the characteristics are unchanged.

Frequently asked questions

What does the rating depend on? On the property's physical characteristics, not on billed consumption. The rating takes the less favourable of the two indicators, primary energy consumption and greenhouse gas emissions.

How long is the certificate 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 alter performance.

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

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

Can a certificate be challenged? Yes, by commissioning a counter-assessment. Discrepancies most often stem from default values used for lack of supporting documents, which can be ruled out by producing works invoices.

What is the difference with the energy audit? The certificate rates the property; the audit proposes costed works pathways. The audit is required in addition to the certificate for the sale of certain energy-guzzling properties, without replacing it.

Key takeaways

Three points determine what use can be made of a property. The rating takes the less favourable of the two indicators, which means insulation alone is not enough when the heating method is a heavy emitter. 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 relied on from memory.

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