Exclusive study — wave 1
Summer comfort barometer 2026
4 in 10 homes poorly rated — but the official risk map misleads
Three heatwaves in summer 2026 and talk of a future "summer comfort rating" put home overheating in the spotlight. OneDpe analysed 11.2 million EPCs: 40.2% of homes are rated "insufficient", and 46.5% would be if the rule were applied to the letter. Crucially, the official indicator — blind to location — names the North, while the real risk concentrates in the South and Paris.
Figures frozen on · Source: OneDpe.fr
Key figures
- 40.2%
- homes rated "insufficient"
- 43.2% "average", 16.6% "good"
- 11,183,219
- EPCs analysed
- mainland France, houses + flats, excluding EPCs generated from a building-level one; indicator present on 86.4%
- 68.2%
- in Roubaix, worst city on the declared indicator
- old dense stock — but cool climate (Summer Score 64)
- 16.4%
- of verdicts inconsistent with their own criteria
- annex 9 rule re-applied to the 5 recorded parameters: 46.5% "insufficient" instead of 40.2%
Infographics
Free to reuse, including commercially, with the credit “Source: OneDpe.fr”. Click a thumbnail to enlarge and download — PNG 3200 px, editable SVG, greyscale proof.
The data
Map 1 — declared indicator: the North on top
| City | "Insufficient" homes | Median Summer Score |
|---|---|---|
| Roubaix | 68,2 % | 64 |
| Hazebrouck | 61,8 % | 67 |
| Tourcoing | 61,7 % | 67 |
| Armentières | 59,7 % | 67 |
| Paris | 59,6 % | 53 |
The top five. Old dense stock but cool climate: the Summer Score stays near the median (67) — except in Paris. Nine of the ten worst-rated towns are in the Nord and Pas-de-Calais; Paris (5th) is the only exception, and the only one also topping Map 2.
Map 2 — Summer Score (building + climate + urban heat): the South and Paris
| City | Median Summer Score | "Insufficient" homes (declared) |
|---|---|---|
| Aix-en-Provence | 52 | 33,5 % |
| Paris | 53 | 59,6 % |
| Perpignan | 54 | 27,0 % |
| Nice | 58 | 24,2 % |
| Montpellier | 58 | 24,7 % |
A panel of major cities, not a ranking: here climate dominates. The Summer Score is an integer, so ties are frequent — Nice and Montpellier belong to a group of 14 towns tied at exactly 58, occupying ranks 15 to 28 as a block. The strictly lowest scores belong to smaller towns: Agde, Apt and Roquebrune-sur-Argens are also at 54, tied with Perpignan.
Ranking, town by town
The two measures side by side for every ranked town. Search yours, or browse the rankings.
Loading…
Methodology
Published in full so anyone can check, replicate or challenge it.
Scope, definition, sources and limits
Scope
11,183,219 mainland EPCs (houses + flats), excluding EPCs generated from a building-level one. The declared indicator is measured as a full census; the OneDpe Summer Score and the annex 9 recomputation run on a 2.4-million EPC sample.
What the figure means
Summer comfort indicator = insufficient / average / good rating from Annex 9 of the order of 31 March 2021 (building only). OneDpe Summer Score = 0-100 rating crossing the building, the department’s climate and the address’s urban heat. The lower the score, the more exposed the home (national median: 67).
Sources
- ADEME open database — EPCs completed since July 2021
- Climate: CLIMADIAG Commune / DRIAS-TRACC (Météo-France), aggregated at department level
- Urban heat: Local Climate Zones (LCZ, WUDAPT), at address level
Limits — what this study does NOT say
- Unweighted statistics, not representative of the entire stock (completed EPCs only).
- 13.6% of EPCs do not fill in the indicator; the direction of the resulting bias is not established (coverage is identical for houses, 86.5%, and flats, 86.4%).
- No aggregate published under 100 homes; rankings limited to towns with more than 3,000 filled-in EPCs.
Quotes
Attributable and ready to publish. For an interview, see the contact below.
« The official indicator tells someone in Montpellier their home is fine, and someone in Roubaix theirs is insufficient. The reality of overheating is often the reverse: it is not only build quality that counts, it is where the home stands. »
Press coverage
Independent media that have covered this study. Extracts are quoted verbatim.
- CAFPIPierre Tranchand
DPE 2026 : ce que les baromètres révèlent sur la fiabilité et le confort thermique des logements
« OneDpe a passé au crible 11,2 millions de DPE réalisés en France métropolitaine. Le résultat est sans appel : 40,2 % des logements obtiennent un confort d'été « insuffisant ». »(in French)
Raphaël GarinotConfort d'été : quatre logements diagnostiqués sur dix jugés insuffisants
« Publié par OneDpe, le Baromètre du confort d'été 2026 s'appuie sur l'analyse de 11.183.219 diagnostics de performance énergétique réalisés en France métropolitaine. »(in French)
Stefan GodinVotre DPE dit « confort d'été insuffisant » ? Ce n'est pas le climat qu'il a mesuré
« Le baromètre est signé OneDpe, un éditeur d'outils payants de vérification de DPE »(in French)
Isabelle DahanLe confort d'été dans le DPE : l'indicateur officiel se trompe de villes
« Dans ce contexte, OneDpe publie un baromètre national fondé sur l'analyse de 11,2 millions de diagnostics de performance énergétique (DPE). »(in French)
Laetitia NavarraBaromètre du confort d'été 2026 : pourquoi Roubaix est-elle moins bien notée que Nice ?
« Selon le baromètre 2026 de OneDpe, 40,2 % des logements diagnostiqués affichent un confort d'été « insuffisant ». »(in French)
Julie SarfatiSubscribers onlyImmobilier et canicules : les failles du DPE sur le confort d'été dans les logements
« Elles sont documentées par un récent baromètre fondé sur l'étude de 11,2 millions de diagnostics et réalisé par la plateforme d'analyse du DPE OneDpe. »(in French)
About OneDpe
OneDpe.fr is an independent platform of analysis tools for the French energy performance certificate (DPE). It offers free tools — certificate consistency checks, discount estimation, 3CL simulation, simulation of the rating under the 1.7 factor of 1 January 2027, renovation works estimation — built on the analysis of several million certificates from the ADEME open data, cross-referenced with French property transaction data (DVF). OneDpe is published by RIANN SAS (Paris).
Going further
Journalist? Detailed figures, interviews and custom breakdowns: presse@onedpe.fr — reply within 24 hours.