1. Price decote formula
The price decote is the average price gap between a property of a given DPE label and an equivalent D-rated property (market reference). Source: OneDpe "green value" calibration on DVF transactions matched with DPE certificates (2025 corpus). External benchmark, cited for comparison and not as the source of our table: the Notaires de France "valeur verte" study on 2024 transactions (hedonic regression, 552,850 transactions modelled) measures -25% on G-rated houses and -12% on G-rated flats.
prix_attendu = prix_affiche × (1 - decote_pourcentage)
fourchette_basse = prix_affiche × (1 - decote_max)
fourchette_haute = prix_affiche × (1 - decote_min)The decote table is cross-referenced (DPE label × property type: house / apartment / building). Regional variants are applied automatically from the postal code for labels E, F and G: up to 11 calibrated regions (Paris intra-muros -10%, Lyon, Marseille, Aquitaine, rural Nouvelle-Aquitaine -27%, etc.); for apartments, an additional "Paris prime" variant applies (arrondissements 1-8, 16, 17 above €12,000/m², where land scarcity offsets part of the DPE penalty). For building-type properties and (label, region) pairs without a calibrated variant, a national average is applied with a disclaimer.
2. Energy cost projection
Annual energy cost is estimated from FINAL energy consumption — the energy that is actually billed — the living area and the average price of the main energy source. Consumption comes from the looked-up DPE when its number is provided; otherwise it is a reference value at the middle of the class range, not a per-building 3CL calculation. A DPE states consumption in primary energy: it is converted to final energy using the regulatory coefficient of the carrier before any price is applied, since the price is a price per billed kWh:
conso_finale = conso_primaire_kWh/m²/an ÷ coef_energie_primaire
cout_annuel = conso_finale × surface × prix_€/kWh
cout_N_ans = Σ_{i=0..N-1} cout_annuel × (1 + inflation)^i- Primary energy coefficient: for electricity, 1.9 (the scale at which ADEME's database is observed, where the certificate states no final energy); 1.0 for all other energies
- No COP is applied to the cost: a DPE's consumption already accounts for the installed generator's efficiency, heat pumps included. The heat pump type therefore does not enter this calculation.
- Default inflation: +3%/year (CRE 2025-2030)
3. Renovation budget & aids
The renovation budget estimates the cost to reach class D from the current label, based on a pre-calibrated typical bundle (roof / wall / window insulation, VMC, heat pump depending on the transition). MaPrimeRénov' aids and CEE are deducted based on the selected income category; the Éco-PTZ is NOT — it is a loan, which finances the remaining cost.
reste_a_charge = cout_total_travaux - aides_mpr - cee
eco_ptz_disponible = min(reste_a_charge, plafond_eco_ptz)4. Regulatory sources
- OneDpe "green value" calibration — DVF transactions, 2025 corpus (decote table per label × property type × region)
- External benchmark: Notaires de France — "La valeur verte des logements en France", 2024 transactions (hedonic regression, 552,850 transactions modelled) — cited for comparison, not the source of our table
- BDNB CSTB 2025 — Reference median price per commune (5,533 communes), for the median-price line in results
- CRE — Energy price trajectory 2025-2030 (default inflation +3%/year)
- ADEME — 3CL coefficients (kWh/m²/year per DPE label; primary-to-final conversion for electricity at a factor of 1.9 (the scale at which ADEME's database is observed, where the certificate states no final energy))
- ANAH — MaPrimeRénov' 2026 (subsidies by income category Bleu/Jaune/Violet/Rose)
- Climate & Resilience Law (Aug 22, 2021) — Rental ban schedule G (2025) / F (2028) / E (2034)
- Renovation bundles per transition (G→D, F→D, E→D…) — in-house calibration based on ANAH and CSTB feedback
5. Legal compliance (DGCCRF)
The DPE decote calculator applies our own "green value" table, calibrated on DVF transactions matched with DPE certificates (2025 corpus). The figures are indicative: actual property value depends on specific location, general condition and local market dynamics. In compliance with the DGCCRF, no individual valuation is promised — only a notary or real estate appraiser can value a specific property.
Our approach: (1) all values are presented as "indicative estimates"; (2) low/high ranges are systematically displayed to reflect uncertainty; (3) a disclaimer reminds users that a notary or real estate appraiser remains the sole legally enforceable valuation source; (4) the calculation runs in your browser — if you are signed in, its result is saved to your account so you can find it again.
6. Known limitations
- Regional variants: applied to labels E, F and G — up to 11 regions (house and apartment), plus a "Paris prime" variant restricted to apartments. Building-type properties and non-calibrated (label, region) pairs fall back to the national average.
- Price/m² estimation: at COMMUNE level, via CSTB's BDNB 2025 (5,533 communes), with a fallback to our hand-curated price table (1,117 postcodes, incl. overseas France and Corsica). Outside coverage, the commune concerned is named on screen instead of the line simply disappearing — the percentage decote still applies.
- Granularity: the price reference is at COMMUNE level. In a large or contrasted commune, two neighbourhoods can differ widely from that median — read the gap between the asking price and the commune median with that caveat in mind.
- Energy consumption: middle of the DPE label range (unless actual consumption is entered). For the unbounded G class: 470 kWh/m²/yr (observed G-stock average ≈ 440-500 per Anah).
- Renovation bundle: pre-calibrated per transition (G→D, F→D, etc.). For a custom plan (non-standard combination, condominium), use the dedicated "Renovation Works" tool.