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Ecology and transition

Nature parks, renewable energy, heat networks, cycling, water and air quality, transition support.

Photo: L. Pages - Ville de Cergy · CC BY-SA 4.0 (new tab) · Wikimedia Commons (new tab)

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Ecology and transition

Nature parks, renewable energy, heat networks, cycling and land sobriety: what Val-d'Oise is building for a successful transition.

Key figures

Preserved natural areas

Two regional nature parks extend over the département: the Vexin français (97 listed municipalities) and Oise - Pays de France (70 municipalities, 25 of them in Val-d'Oise). About one hectare in five (19 %) is woodland and nearly half (48 %) is farmland: a preserved setting in the heart of Île-de-France.

Région Île-de-France (rapport CR 2026-004) et Parc naturel régional du Vexin français, 2026-01 ; Institut Paris Région, Mos 2025, 2025.

Renewable energy

Connected solar capacity rose from 18.8 MW at the end of 2024 to 44.9 MW at the end of 2025, then 53.3 MW in the 2026 national register. The register's bioenergy sector totals 49.9 MW, and one plant in Bonneuil-en-France injects biomethane into the gas grid (12.5 GWh a year).

Renewable energy

View the chart data
Renewable energy
MW
202210.6 MW
202418.8 MW
202544.9 MW
202653.3 MW

Source : ODRÉ (RTE, Enedis, ELD), registre national des installations de production, 2022-2026.

ODRÉ (RTE, Enedis, ELD), registre national des installations de production, July 31, 2026.

Heat networks

18 heat networks are in service, 8 of them running mostly on renewable and recovered energy. Cergy-Pontoise delivers 273.7 GWh (69.4 % renewable or recovered), Sarcelles-Lochères 161.3 GWh (67.6 %), and the Villiers-le-Bel and Gonesse network produces 34.2 GWh of geothermal heat.

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View the map data as a list
Heat networks in service
Argenteuil
Bezons
Bonneuil-en-France
Bouqueval
Cergy
Cormeilles-en-Parisis
Éragny-sur-Oise
Ermont
Franconville
Garges-lès-Gonesse
Gonesse
Goussainville
Le Plessis-Gassot
Pontoise
Roissy-en-France
Saint-Ouen-l'Aumône
Sannois
Sarcelles
Taverny
Vémars
Villiers-le-Bel
Source : France Chaleur Urbaine. Base map: IGN.

France Chaleur Urbaine, 2024.

Projects under way

  • Land sobriety

    Natural, farm and forest land consumed fell from 111.7 ha a year (2011-2021) to 71.5 ha a year (2021-2025), 36 % less.

    Land sobriety

    View the chart data
    Land sobriety
    ha
    2020-21133.8 ha
    2021-2272.4 ha
    2022-2375.3 ha
    2023-2475.7 ha
    2024-2562.7 ha

    Source : Cerema (fichiers fonciers), 2020-2025.

    Cerema (fichiers fonciers), Jan. 1, 2025.

  • Cycling and soft mobility

    The Vélo Île-de-France network plans 750 km of secure routes by 2030, half of them already in service, with 300 M€ invested by the Region.

    Région Île-de-France, Sept. 11, 2026.

  • Renewable heat

    8 of 18 networks exceed 50 % renewable and recovered energy.

    France Chaleur Urbaine, 2024.

Water and air: improving trends

In 2025, of 3,130 drinking-water samples taken in official health checks, none exceeded a bacteriological quality limit and 96.8 % met every quality limit. As for air, nitrogen dioxide concentrations fell 50 % and fine particles 60 % over twenty years in Île-de-France; about 1,500 residents remain exposed to a limit-value exceedance. 2025 levels are slightly above 2024.

Hub’Eau, qualité de l’eau potable (résultats du contrôle sanitaire, ministère de la Santé / ARS), 2025 ; Airparif, bilan 2025, April 16, 2026.

Companies and transition support

447 active companies headquartered in Val-d'Oise work in recycling, waste collection and treatment and depollution, 215 of them in sorted-waste recovery. Business transition support is available from ADEME, the Île-de-France Region and Bpifrance.

Insee, répertoire Sirene (API Recherche d’entreprises), Oct. 4, 2026.

Check the risks at an address

Before choosing land or premises, the official Géorisques service gives the natural and technological risk status of the address. Open Géorisques

Sources

  1. Source: Airparif, bilan 2025, data from April 16, 2026.
  2. Source: Cerema (calcul sur les deux périodes), data from Jan. 1, 2025.
  3. Source: Cerema (fichiers fonciers), data from Jan. 1, 2025.
  4. Source: France Chaleur Urbaine, data from 2024.
  5. Source: France Chaleur Urbaine (ministère de la Transition écologique, ADEME), data from 2024.
  6. Source: Hub’Eau, qualité de l’eau potable (résultats du contrôle sanitaire, ministère de la Santé / ARS), data from 2025.
  7. Source: Insee, répertoire Sirene (API Recherche d’entreprises), data from Oct. 4, 2026.
  8. Source: Institut Paris Région, Mos 2025, data from 2025.
  9. Source: ODRÉ (RTE, Enedis, ELD), registre national des installations de production, data from July 31, 2026.
  10. Source: ODRÉ (registre des points d’injection de biométhane), data from Sept. 4, 2026.
  11. Source: ODRÉ, registre national au 2022-12-31, data from Dec. 31, 2022.
  12. Source: ODRÉ, registre national au 2024-12-31, data from Dec. 31, 2024.
  13. Source: ODRÉ, registre national au 2025-12-31, data from Dec. 31, 2025.
  14. Source: Parc naturel régional Oise - Pays de France, data from Jan. 18, 2021.
  15. Source: Région Île-de-France, data from Sept. 11, 2026.
  16. Source: Région Île-de-France, data from 2026.
  17. Source: Région Île-de-France (rapport CR 2026-004) et Parc naturel régional du Vexin français, data from 2026-01.

Each figure was read twice, independently, on Oct. 4, 2026; both readings are recorded in the site's sources file.