An energy performance certificate states a thickness of loft insulation that does not exist. After the purchase, the buyers find numerous defects and obtain a court-ordered expert appraisal (expertise judiciaire). What can they claim, and from whom? The ruling of the Third Civil Chamber of 17 October 2024 answers two questions: the status of a seller who works as a property negotiator, and the nature of the loss caused by an incorrect DPE (diagnostic de performance énergétique, the French energy performance certificate).
The facts
By deed of 24 July 2015, a couple bought a house from sellers who had themselves acquired it in November 2014 and resold it after works. The deed contained a clause excluding the warranty against hidden defects (vice caché). The husband had described himself in the deeds as an estate agent; he actually held a salaried position as a property negotiator. Having found defects, in particular in the insulation and the energy performance, the buyers obtained the appointment of a court expert in summary proceedings, then sued the sellers under the hidden defects warranty and the energy surveyor for professional liability.
The Pau Court of Appeal held that the sellers were not professional sellers and were therefore protected by the exclusion clause. It ordered the energy surveyor to pay €20,268.34 for a lost chance assessed at 50 %.
The decision
The Cour de cassation (the French supreme court for civil and commercial matters) dismissed the buyers’ appeal (Cass. 3e civ., 17 October 2024, appeal no. 22-22.882).
On the status of the seller, it approved the Court of Appeal for finding that the initial project was a buy-to-let investment, that the resale after works had been decided only because of the seller’s state of health, and that it was an isolated transaction in the management of private assets. The couple were therefore not professional sellers, “regardless of whether he was an estate agent or a property negotiator”, and could rely on the clause excluding the hidden defects warranty (articles 1641 and 1643 of the French Civil Code).
On the energy surveyor, the Court recalled that under article L. 271-4, II, of the Construction and Housing Code, as worded by the law of 24 March 2014, the DPE “unlike the other documents making up the technical diagnosis file, has only informative value”. The surveyor had delivered an incorrect DPE before the preliminary agreement, then a corrected one, late, before the final deed. His breach of the duty to inform caused the buyers to lose “a chance to negotiate a reduction of the sale price”, which the Court of Appeal assessed at 50 % in the exercise of its discretion.
A useful clarification: since the law of 23 November 2018, and for sales completed after 1 July 2021, the DPE has become legally binding on the seller, except for its recommendations. The solution adopted here concerns a 2015 sale. For recent sales, the surveyor’s liability arises in a stricter framework, but the reasoning on how the loss is measured remains instructive.
What the expert takes from it
The loss is measured against the price, not against the works. A lost chance to negotiate requires establishing what the property was worth with its actual insulation, compared with the price paid. That is a valuation exercise: value of the property as described, value of the property as it is, and the difference. The cost of the insulation works is only one indication of that difference, and often exceeds the discount the market would actually have granted.
The lost chance is a fraction. The judge assesses the probability that the negotiation would have succeeded; here 50 %. The expert does not rule on that fraction, but the expert’s figure for the difference in value is its base. The better the difference is documented by comparable sales, the more defensible the compensation.
The seller’s status changes the legal basis, not the figure. Faced with a non-professional seller protected by an exclusion clause, the claim shifts to the surveyor or to other grounds; the amount of the loss is calculated the same way. On the weight of energy performance in value, the Charte de l’expertise en évaluation immobilière (the French property valuation charter, 6th edition, November 2025, Title IV) and Part VI of the European Valuation Standards 2025 require the expert to take energy performance and renovation obligations into account in the valuation.
Further reading
The Property loss of value page describes how a discount after a defect is quantified, with the timescale and the fee. On the same theme: Energy certificate reform 2026: what impact on market value? and Non-compliant septic system: hidden defect and price reduction. The ruling is available on Légifrance.
What next
An incorrect survey discovered after the purchase?
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