Biodiversity credits

The OpenNAT method and the NORMATYS position

A biodiversity credit funds an ecological outcome. That outcome still has to be measured, verified, kept over time and described honestly. OpenNAT publishes its rules for this, with an open method and an open-source calculation engine.

OpenNAT logo

Status on 25 October 2026: OpenNAT maintenance contribution in force; OpenNAT 1 and OpenNAT Credits methods before the Biodiversity Standard Council, no credit issued. The French texts are the authoritative versions.

What a biodiversity credit is

A biodiversity credit, or nature credit, is a unit that funds the restoration or preservation of a natural habitat. A buyer acquires it to support that outcome. The market is young and its methods differ: some credit avoided loss without a shared measure of the threat, others allow credits to be resold, few publish their calculations.

In France, the green industry act of 23 October 2023 created state-approved nature compensation, restoration and renaturation sites (articles L163-1 et seq. of the Environmental Code), known as France Crédits Biodiversité sites. OpenNAT schemes stay outside that regime: they are voluntary and satisfy no obligation.

The rules OpenNAT sets itself

  • Measure a gain. A credit rewards a nature gain measured by the OpenNAT engine, in square metres of habitat equivalent, beyond what the site would have become without the project and beyond what regulation already requires. Additionality is calculated, not declared.
  • Prudence. The gain retained is the 10th percentile of 1,000 uncertainty draws, not the central value. A common reserve of 20 to 40 % of each issuance covers losses.
  • Observed before issuance. A credit is issued only for a gain achieved and observed by survey; expected gain stays as forecast units.
  • Duration. Gain maintained for 50 years, secured by a real environmental obligation and a funded management plan.
  • No avoided loss, no resale. Protecting a threatened site earns no credit; a credit is acquired for its buyer's own use, then retired.
  • Honest use. A retired credit supports a quantified contribution to the restoration of an identified site, never a claim of neutrality, offsetting or overall positive impact.
  • Separation of roles. NORMATYS writes the method, a third-party verifier verifies, the registry issues; none of them holds credits or is paid on credit price or volume.
  • Openness. Method, sourced tables and engine are public. The method was compared with the Verra Nature Framework, Plan Vivo PV Nature, the Biodiversity Credit Alliance principles and English Biodiversity Net Gain.

Three schemes, three statuses

  • OpenNAT 1 measures the nature a construction project consumes on its site (Cnat), through its materials and works (Inat), and its biotope coefficient (Bnat), over 50 years, with 191 habitat types. Method and engine published, before the Biodiversity Standard Council.
  • OpenNAT Credits, version 1 defines nature gain credits: 1 credit = 1,000 m²HE·year of creditable gain. Before the Biodiversity Standard Council; no credit issued.
  • Maintenance contribution, version 1 funds the verified ecological upkeep of Effinature-certified developments, EUR 1.50 excl. VAT per m² per year, paid after each successful Effinature HVE control. In force: rules and contract templates.

Frequently asked questions

What is a biodiversity credit?

A biodiversity credit, or nature credit, is a unit that funds the restoration or preservation of a natural habitat and that a buyer acquires to support that outcome. Under the OpenNAT Credits method, one credit equals 1,000 square metres of habitat equivalent per year of nature gain that is measured, verified and recorded in a public registry, roughly 20 m² of reference ecosystem in full integrity for 50 years.

Have OpenNAT credits been issued yet?

No. The OpenNAT Credits method, version 1 of 24 October 2026, is before the Biodiversity Standard Council, the scientific and technical committee of the NORMATYS standards. No credit is issued until it is approved. The OpenNAT maintenance contribution, which is not a credit, has been in force since 25 October 2026.

How does OpenNAT differ from France Crédits Biodiversité sites?

State-approved nature compensation, restoration and renaturation sites, known as France Crédits Biodiversité sites, fall under articles L163-1 et seq. of the French Environmental Code, introduced by the green industry act of 23 October 2023. OpenNAT schemes are voluntary, separate from that regime, and cannot satisfy a compensation obligation.

Can an OpenNAT credit be used to claim neutrality or to offset impacts?

No. A retired credit supports a quantified contribution to the restoration of an identified site. It supports no claim of neutrality, offsetting or overall positive impact, and it cannot be resold under version 1 of the method.

Why biodiversity credits in real estate?

Residential gardens, office surroundings and neighbourhood parks are the nature people see every day. Their value depends on upkeep year after year. The OpenNAT maintenance contribution funds that upkeep for Effinature-certified developments, after each successful Effinature HVE control carried out on site every two years by an independent certification body.

Resources

OpenNAT schemes are voluntary and separate from the approved nature compensation, restoration and renaturation sites known as France Crédits Biodiversité sites (articles L163-1 et seq. of the French Environmental Code). They cannot satisfy a compensation obligation.