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Biodiversity Net Gain

Biodiversity net gain is an approach to development that leaves the natural environment in a measurably better state than it was before the development occurred.

Under the Environment Act 2021, all planning permissions granted in England, with a few exemptions, will have to deliver 10% biodiversity net gain. This is known as mandatory Biodiversity Net Gain (BNG) and developers will be required to demonstrate that proposals deliver BNG.

The new rules will apply to major planning applications from 12th February 2024 and most other development from 2nd April 2024.

Government has published draft biodiversity net gain planning practice guidance (Draft biodiversity net gain planning practice guidance - GOV.UK (www.gov.uk) which will come into force on the date that mandatory biodiversity net gain is commenced.

Defra guidance for biodiversity net gain has also been published Biodiversity net gain - GOV.UK (www.gov.uk)

Why it’s important

Biodiversity Net Gain is important because:

  • the natural environment provides benefits to us all and is essential for the processes that support life on this planet.
  • it delivers measurable improvements for biodiversity by enhancing or creating new habitats in association with development.

You can find a short video introduction to Biodiversity Net Gain from Natural England here, and also read Natural England’s Biodiversity Net Gain Brochure for an overview of BNG and its benefits.

How it's measured

Biodiversity Net Gain is calculated using the biodiversity metric, produced by the Government, which is used to measure the biodiversity value of habitats on a site in Biodiversity Units.

Following the identification of habitats and their condition, the metric uses the biodiversity value of habitats found on a site before development, alongside the proposed habitats after development, to determine if there is a loss or gain in biodiversity.

For mandatory biodiversity net gain, developers must use the statutory biodiversity metric (Statutory biodiversity metric tools and guides - GOV.UK (www.gov.uk) to calculate a minimum 10% biodiversity net gain from the pre-development biodiversity value of their development site.

Achieving 10% Biodiversity Net Gain means fully compensating for losses of habitat on a development site, and then going further so that, overall, there is a gain in Biodiversity Units of at least 10% as a result of the development process.

See the guidance about using the biodiversity metric on GOV.UK.


Further information can be found here: Biodiversity Net Gain in Planning Applications