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Biodiversity Net Gain

Please note:

Natural England hasn’t yet published all the proposed policies and guidance relating to Biodiversity Net Gain.

The text below is based off published guidance and the Interim Biodiversity Net Gain Approach.

Biodiversity Net Gain for major developments will become a statutory requirement on 21 November 2023. At this point, we will be required to follow Natural England published policy and guidance. We will update the text below to represent this.

Definition of Biodiversity Net Gain

Biodiversity Net Gain is the principle of ensuring biodiversity will be in a measurably better state after new development has happened than before the development has taken place.

Implementing Biodiversity Net Gain

It will become mandatory for any application which is not:

  • Development impacting habitat of an area below a ‘de minimis’ threshold of 25 metres squared, or 5m for linear habitats such as hedgerows
  • Householder applications
  • Self and custom build houses
  • Biodiversity gain sites (where habitats are being enhanced for wildlife)

As outlined within The Environment Act 2021, Biodiversity Net Gain (BNG) will be implemented in the second half of November 2023 for major planning applications (see below) and April 2024 for minor planning applications (any development which does not qualify as a major application).

A major application is any application that involves:

  • Mineral extraction
  • Waste development
  • Residential development of between 10 or more dwellings
  • Residential development on a site area of 0.5 ha or more and the number of dwellings is unknown
  • Development of floorspace of 1,000 square metres or more
  • Development on sites over 1 ha or more
  • Change of use over 1,000 square metres or more

Interim Biodiversity Net Gain Approach Local Guidance

In September 2022, we adopted an Interim Biodiversity Net Gain Approach Local Guidance. This enables our Planning Officers to impose a 10% net gain of biodiversity on a project as deemed required before November 2023 for large sites and April 2024 for small sites.

View our Interim Biodiversity Net Gain Approach document (opens Microsoft Sharepoint).

For more details on the principles of BNG at a national level, view the Biodiversity Net Gain Brochure on the Natural England website (opens PDF). It was prepared in April 2022 and is a useful, simple guide.

Requirements for planning application

How to go through the Biodiversity Net Gain process:

Application and assessment

You must complete the latest version of the Biodiversity Metric spreadsheet and submit this within your planning application. Our Technical Officer will initially check this and:

  • Provide feedback if the documentation is incomplete or does not meet minimum standards and request resubmission
  • Pass correct documentation through to our assessment stage

During the assessment stage, a Planning Officer and a Wildlife Officer will review the documentation for approval / refusal. If the application has not been formally determined, you can still review and amend the active application.

Post-determination and post-development

Once approved, a condition will be attached to the planning application requiring the submission of a Biodiversity Gain Plan. This plan will describe how the 10% uplift in biodiversity will be achieved and must include the following information:

  • (a) Information about the steps taken or to be taken to minimise the adverse effect of the development on the biodiversity of the onsite habitat and any other habitat
  • (b) The pre-development biodiversity value of the onsite habitat
  • (c) The post-development biodiversity value of the onsite habitat
  • (d) Any registered offsite biodiversity gain allocated to the development and the biodiversity value of that gain in relation to the development
  • (e) Any biodiversity credits purchased for the development
  • (f) Such other matters as the Secretary of State may by regulations specify

You may also have a post-development requirement for monitoring and providing survey reports to the Local Planning Authority.

We will monitor commitments within the documentation, any conditions attached from assessment stage, and your purchase of credits.

We will set up data recording (onsite and offsite) and landscaping schemes within our Internal GIS Layer. We will establish a monitoring schedule for post-determination and post-development.

Providing documentation with your application

All planning applications which are not exempt from Biodiversity Net Gain will be required to submit:

  • A Biodiversity Gain Plan
  • A Biodiversity Metric Calculations Sheet

View the Biodiversity Metric documents on the Natural England website.

These documents will describe how the proposed application will impact the existing baseline level of biodiversity and how a 10% net gain in biodiversity will be achieved. If these documents show a 10% net gain achieved within the sites red line boundary, no further information is required.

You may require an ecologist to produce the above documentation. It should be assumed that all major applications will require ecological input, and most minor applications.

Visit the Chartered Institute of Ecology and Environmental Management (CIEEM) website to find an ecologist.

If a 10% net gain cannot be achieved on site, then the required biodiversity units as defined by the Biodiversity Metric Calculation will have to be sourced and / or purchased from an area outside of the red line boundary, either owned by the applicant or owned by a third-party.

If required, proof of purchase or agreement of the biodiversity units will be needed as part of the application or secured as a condition.

Registration for Biodiversity Unit Providers

Biodiversity Units are a proxy to describe biodiversity. There are three types of Biodiversity Units:

  • Area Units
  • Hedgerow Units
  • Watercourse Units

These are calculated in separate 'modules' of the Biodiversity Metric 4.0.

Landowners interested in using land to produce Biodiversity Units to sell to applications that require offsite units can register interest using our online form.

Registering interest will help the council match offsite units with developments in requirement of units.

The GOV.UK website will open a countrywide mandatory register for sites producing Biodiversity Units, which will be available for access in November 2023.

Further information

You can find further information about Biodiversity Net Gain on the following sites: