A Saturday in late June, third day of a heatwave: 37°C in the shade. You come home to your top-floor two-bedroom — bought last year, C-rated, recent windows, efficient boiler. At 11 pm the living room still reads 32°C; the bedroom under the roof is unusable, so you sleep in the living room, windows open onto a street stuck at 28°C. Your home performs well in winter — and is unbearable in summer.
This is not a diagnostic anomaly: the A-to-G label of the DPE (Diagnostic de Performance Énergétique — the French Energy Performance Certificate, EPC) measures conventional winter energy performance, not the ability to stay cool during a heatwave. A summer comfort indicator already appears on every DPE issued since July 2021 — but it is purely informative. On 15 July 2026, Housing Minister Vincent Jeanbrun announced "a new letter, for summer comfort", expected "within a few months" — a political announcement, with no text published. In parallel, the PNACC 3, France's climate adaptation plan, is preparing for 2028 a localised degree-hours indicator, separate from the A-to-G rating.
The DPE label says nothing about your summers: 40.2% of the summer comfort indicators filled in on French DPE reports are rated "insufficient", and 46.5% would be if the annex 9 rule were applied to the letter (OneDpe measurement on 9,663,670 certificates, ADEME base, July 2026 — unadjusted data). The three-level indicator has existed since the 2021 DPE (decree of 31 March 2021); the reinforced indicator the PNACC 3 is preparing for 2028 will be separate from the A-to-G rating.
What this article covers
What the A-to-G label measures; the indicator on your DPE since 2021 and the state of the housing stock; the "summer comfort letter" announced in July 2026 and the degree-hours indicator prepared for 2028; the five physical factors; the at-risk profiles; the effective works and what subsidies cover.
DPE and summer comfort: what the rules say today — and what they will say in 2028
The A-to-G label measures winter performance, not summer coolness
The DPE label rates the dwelling from A to G on its conventional primary energy consumption and greenhouse-gas emissions, calculated by the 3CL-DPE 2021 methodology (decree of 31 March 2021) across five uses: heating, domestic hot water, cooling, lighting and auxiliaries. Heating overwhelmingly dominates. The cooling item is only counted if air conditioning is actually installed: an apartment without it that climbs to 33°C every summer is not penalised by a single kilowatt-hour. The building's ability to stay cool — thermal mass, solar protections, natural ventilation — does not enter the displayed class: a dwelling can be rated C, or even B, and overheat every summer.
The summer comfort indicator already exists — but it is purely informative
Since the DPE reform of 1 July 2021, the decree of 31 March 2021 (annex 9) has required every report to include a three-level summer comfort indicator: insufficient, average or good. It is assessed in particular from the building's thermal inertia, solar protections on the glazed openings, a dual-aspect layout (openings on opposite façades) and fixed ceiling fans. But it has no influence on the A-to-G class, and no obligation — letting, selling or renovating — is attached to it. It appears on millions of reports without almost anyone reading it.
PNACC 3: a localised degree-hours indicator, separate from the DPE rating, by 2028
The PNACC 3 (France's third National Climate Change Adaptation Plan, March 2025) changes the scale, after the ministerial review announced in spring 2025 (Valérie Létard). Its measure 9 provides for a reinforced indicator calculated in degree-hours, on the model of the RE2020 (the French environmental regulation for new buildings): indoor temperature is simulated hour by hour over the hot season, and the excesses above a comfort threshold are added up. Unlike today's indicator, it factors in location: the same apartment does not face the same risk in Lille and in Marseille. According to the plan's "one year on" review of 17 June 2026, a CSTB study is designing the method, consultations are planned in 2026, and the indicator — scheduled by 2028 — will be separate from the A-to-G rating.
July 2026: the announcement of a "summer comfort letter"
On 15 July 2026, during questions to the government at the National Assembly, Housing Minister Vincent Jeanbrun announced — replying to MP Daniel Labaronne — "a new letter, for summer comfort", to be presented "within a few months". At this stage it is a political announcement: no draft text, no public consultation. Until an official text appears, the only summer comfort rule in force remains the indicator of the decree of 31 March 2021. Our full breakdown of the announcement: Summer comfort letter: what we know.
| Milestone | What changes | Text / source |
|---|---|---|
| 1 July 2021 | Three-level summer comfort indicator on every DPE report — purely informative | Decree of 31 March 2021 (annex 9) |
| March 2025 | PNACC 3 published: reinforced indicator announced, €500,000 budget, RE2020-style degree-hours methodology | PNACC 3 (measure 9) |
| 8 July 2026 | Housing Bill adopted in the Senate: summer comfort becomes the 7th work category of a comprehensive renovation and enters condominium works plans — National Assembly reading next | Housing Bill, art. 6 bis |
| 15 July 2026 | "Summer comfort letter" announced, "within a few months" — a political announcement, no text published | Questions to the government, National Assembly |
| 18 July 2026 | 5.5% VAT in force on fixed reversible air conditioning (conditions — see below) | Order of 13 July 2026 |
| 1 January 2028 (proposed) | Display on property listings: proposal stalled in committee — the tabled text sets no temperature threshold | Bill no. 1735, National Assembly |
| Horizon 2028 | Reinforced indicator in localised degree-hours, separate from the DPE rating — CSTB study under way | PNACC 3, "one year on" review |
We measured the state of the housing stock on the full ADEME base (11,183,219 certificates, July 2026, unadjusted data). Of the 9,663,670 DPEs that fill the indicator in, 40.2% are rated "insufficient", 43.2% "average" and 16.6% "good"; 13.6% carry no indicator at all. And when we re-apply the annex 9 rule ourselves to the five criteria recorded on each report, 16.4% of the indicators turn out to be inconsistent with the characteristics declared on the certificate itself — on that basis the "insufficient" share would rise to 46.5%.
A useful comparison: the overseas DPE methodology is already adapted to the local climate, and tropical thermal comfort is already at the heart of the overseas DPE. Mainland France is still catching up.
The five physical factors that make (or break) summer comfort
A dwelling's summer behaviour comes down to five physical parameters. The first four already feed the current indicator; the fifth — the roof and the immediate environment — will weigh more in the 2028 methodology, which factors in location. None of them appears in the A-to-G label.
The building's thermal inertia: the mass that dampens the heat
Thermal inertia is the capacity of the walls to absorb heat by day and release it slowly at night. A dressed-stone Haussmann building or a poured-concrete house absorbs a heatwave day with a few degrees of rise, provided it is ventilated at night; a lightweight construction — light frame, plasterboard partitions, converted attics — heats up within hours. It is the first parameter assessed by the indicator — and the one renovation can least change: you compensate with the other four levers.
Solar protections and the orientation of glazed openings
Direct solar radiation through glazing is a dwelling's main summer heat input. An external protection — shutter, louvre, adjustable sun-breaker — stops it before the glass: radically more effective than an internal curtain or blind, which traps the heat inside. Orientation matters: large west-facing windows receive low-angle sun in the late afternoon; south-facing windows are easier to shade with an overhang or balcony.
Dual-aspect layout, ceiling fans — and the roof
A dual-aspect dwelling, open on two opposite façades, allows night-time over-ventilation: open everything once the outdoor temperature drops, and the draught flushes out the heat stored in the walls. A single-aspect dwelling cannot — heat builds up day after day. Fixed ceiling fans, the fourth parameter, do not cool the air but markedly improve perceived comfort. The fifth factor is decisive yet absent from the current indicator: a top floor under a poorly insulated roof receives direct radiation all day, and a dwelling in climate zone H3 (the Mediterranean rim) or an urban heat island no longer gets nights cool enough to discharge the building — exactly what the future location-aware method will make visible.
What to check on your DPE: the summer comfort indicator appears in the first pages of every DPE issued since 1 July 2021, as a level — insufficient, average or good — with the characteristics taken into account: inertia, solar protections, dual-aspect layout, ceiling fans. Every missing characteristic is an already-identified renovation lever. If your certificate predates July 2021, the indicator is not on it.
At-risk homes: when a winter C hides an unbearable summer
Some dwelling profiles concentrate the discomfort factors. If you are buying, renting or already own one of the following, the summer comfort indicator should weigh as much as the label in your decision — and if you rent your home, see our guide to summer comfort and heatwaves for tenants.
Profile 1 — Converted attics and top floors under the roof: the roof receives direct radiation from morning to evening. Poorly insulated, it turns the room into an oven by the second day of a heatwave, whatever the DPE class.
Profile 2 — Large west- or south-facing windows without external protection: unprotected glazing lets in a massive heat load. West is the worst orientation: low-angle sun at the end of the day.
Profile 3 — Lightweight, low-inertia construction: light-frame houses, extensions, added storeys and plasterboard partitions heat up fast and store little night-time coolness. Good winter insulation does not correct this defect.
Profile 4 — Single-aspect dwelling: no second façade, no through-draught, no night-time over-ventilation. The heat accumulated by day is never fully evacuated and the dwelling "charges up".
Profile 5 — Climate zone H3 and urban heat islands: on the Mediterranean rim and in dense city centres, tropical nights prevent the building from discharging. It is the parameter the current indicator ignores — and the 2028 methodology will integrate.
Accumulation creates the risk: a studio under the roof, single-aspect and west-facing, in a Mediterranean city centre, stacks four profiles out of five — while still displaying a C label thanks to a recent heating system. It is precisely this gap that the reinforced indicator prepared for 2028 is designed to make visible.
"Summer" works: effective, but poorly covered by MaPrimeRénov'
The technical solutions are well known and mostly energy-frugal; their weak point is financial. MaPrimeRénov' (the French national energy renovation grant) covers summer comfort poorly in mainland France: fixed ceiling fans and external solar protections are only funded within the guided comprehensive-renovation pathway ("parcours accompagné"), and there is no residential "summer comfort" CEE scheme (Energy Saving Certificates). Air conditioning remains excluded from the grant — though fixed reversible units get 5.5% VAT since 18 July 2026.
| Works | Effect on summer comfort | Subsidy coverage in mainland France |
|---|---|---|
| External solar protections (shutters, sun-breakers) | Block radiation before the glazing — lever no. 1 on exposed windows | MaPrimeRénov' only within the guided pathway; standalone measure possible in the overseas departments |
| Roof insulation | Cuts the main heat input of top floors; also improves the winter label | Subsidised — as an insulation measure |
| Through-ventilation and night-time over-ventilation | Flushes out at night the heat stored by day | Not subsidised as such |
| Fixed ceiling fans | Improve perceived comfort for a negligible consumption | MaPrimeRénov' only within the guided pathway |
| Greening (façades, surroundings, shading) | Lowers wall temperatures and the heat-island effect | Not subsidised by MaPrimeRénov' |
| Air conditioning | Cools the interior, but consumes energy and rejects heat outside | Excluded from MaPrimeRénov' — but 5.5% VAT since 18 July 2026 (order of 13 July 2026): A++ single-split / A+ multi-split (SCOP and SEER), ≤ 12 kW, dwelling over 2 years old, professional installation |
Only one family of works is subsidised as a standalone measure in mainland France: roof insulation, financed as "winter" insulation, is also the most cost-effective summer measure under the roof. If your budget is tight and your home matches Profile 1, start there. To cost a package and its impact on your certificate, the OneDpe renovation works simulator lets you test measures item by item.
The market is not waiting for 2028: informed buyers already ask for the indicator, just like the label. And while the winter calendar keeps tightening — the rental ban on E-rated dwellings arrives in 2034 — summer comfort is establishing itself as the second axis of property valuation.
⚠️ The French "housing recovery" bill (projet de loi relance logement) — not voted to date: announced on 23 April 2026 and presented to the Council of Ministers on 24 June 2026, this bill would allow an F- or G-rated dwelling to be put back on the rental market under a renovation commitment — 3 years for a single-family house, 5 years in a condominium — formalised in a works contract signed with a company; the Government's stated aim is to keep or return 650,000 to 700,000 homes to the market. This would be a derogation, not a postponement: the timetable of article L. 173-1-1 of the French construction and housing code does not move (G banned since 1 January 2025, F on 1 January 2028, E on 1 January 2034). The text has not been voted to date — a vote is hoped for before the end of 2026 — and its entry into force would depend on implementing decrees, to which the content of the works contract is expressly referred; nothing is specified for ongoing leases. Full breakdown: our analysis of the 2026 French housing recovery bill.
Key takeaway: the works that will improve the reinforced 2028 indicator are already known — external solar protections, roof insulation, through-ventilation, ceiling fans, greening. Doing them before the reform means buying tomorrow's value criterion at today's price.
The four mistakes to avoid on summer comfort
Mistake no. 1 — Buying a top floor without reading the indicator
You visit a bright top-floor apartment in October, C-rated, and sign without ever opening the "summer comfort" page of the DPE. Yet the information was there: insufficient level, no solar protections, single-aspect. The first heatwave turns the purchase into a daily problem — and summer comfort no longer goes unnoticed: buyers ask for the indicator, and a stalled bill even proposes displaying it on listings. Before any offer on an at-risk property, demand the full DPE report and read the indicator, not just the label.
Mistake no. 2 — Counting on air conditioning
One thing has changed since 18 July 2026: fixed reversible air conditioning now qualifies for the reduced 5.5% VAT rate (order of 13 July 2026, article 278-0 bis A of the French General Tax Code), under the conditions listed in the table above. The substance has not: air conditioning remains excluded from MaPrimeRénov', and it treats the symptom without correcting the building. In a heat sieve (bare roof, unprotected windows) it runs continuously — and once installed, its cooling consumption enters the DPE's five uses and can weigh down the displayed consumption. The virtuous order: first reduce the heat inputs (protections, roof), then evacuate (ventilation), and only as a last resort compensate.
Mistake no. 3 — Confusing the label with comfort
"It's a C, so it's comfortable": wrong in both directions. The label measures a conventional consumption dominated by heating; it says nothing about overheating. A lightweight, single-aspect C can be unbearable in August, while a dual-aspect, high-inertia Haussmann E stays liveable without air conditioning. Until a reinforced indicator — or the announced "summer comfort letter" — materialises, the A-to-G class and the summer comfort level declared in the DPE must be read separately.
Mistake no. 4 — Waiting until 2028 to care
The 2028 horizon concerns the measuring tool, not the phenomenon: heatwaves are not waiting. The regulatory agenda is moving on several fronts — the Senate made summer comfort the seventh work category of a comprehensive renovation on 8 July 2026, a "summer comfort letter" was announced on 15 July 2026 with no text published, and bill PPL 1735 proposes displaying summer comfort on listings (stalled in committee). Waiting means enduring summers of discomfort and paying tomorrow's prices for the works. The assessed parameters, by contrast, are known and stable: dealing with the subject now aligns your property with the criterion before it becomes public.
⚠️ Warning: buying an at-risk property today (top floor, large west-facing windows, zone H3, single-aspect) without weighing summer comfort exposes you to a double penalty: real discomfort from the next heatwave, and a potential discount the day summer comfort becomes visible to buyers — its display on listings remains a stalled bill, and the letter announced on 15 July 2026 has no published text.
Check your DPE's summer comfort indicator now
Test your home's summer comfort
The summer comfort indicator already appears on your DPE — our tool analyses your full certificate, including the parameters that drive this indicator: building inertia, solar protections, dual-aspect layout, ceiling fans. Enter your DPE number (13 characters, on the first page) to spot inconsistencies and missing data.
To go further: simulate renovation works and their impact on your home.
Conclusion
The DPE's A-to-G label measures conventional winter performance — it says nothing about heatwaves. The three-level summer comfort indicator (decree of 31 March 2021, annex 9) partially fills that gap but remains purely informative — and 40.2% of the indicators actually filled in are rated "insufficient" (OneDpe measurement, ADEME base, July 2026 — unadjusted data). Next, two tracks: the PNACC 3 is preparing for 2028 a reinforced indicator in localised degree-hours, separate from the A-to-G rating (CSTB study under way); and the "summer comfort letter" remains a political announcement of 15 July 2026, no text published.
At-risk homes — converted attics, unprotected west-facing windows, low inertia, single-aspect layouts, zone H3 — can be identified today, and the effective works are known, even if most are only subsidised via the guided pathway. Before buying or starting works, first estimate your home's summer comfort. To go further, the OneDpe DPE verification tool compares the indicator declared in your DPE against a recalculation under annex 9 of the French order of 31 March 2021. To place your home within the wider stock, our 2026 summer comfort barometer measures 40.2% of "insufficient" indicators across 11.2 million DPEs — and shows why the map of real risk does not match the official ranking.
