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Biodiversity Net Gain (BNG)

BNG is an approach to development and land management that leaves biodiversity in a measurably better state than before, after first avoiding and minimising harm.

Current planning policy encourages developments to provide a BNG, but prohibits net losses.

To measure BNG and assess the impacts of planning applications we use Defra’s Biodiversity Metric. Guidance on how the Council expects the biodiversity metric to be used is provided below:

The Council will work with developers to pursue BNG when assessing planning proposals. However, sometimes it is not always possible to develop land and avoid a causing a net loss. Where residual losses of biodiversity are unavoidable, developers can arrange for the creation habitat of equal or greater value to wildlife. This is called ‘biodiversity offsetting’ and is a key mechanism to deliver BNG.

Biodiversity offsetting is a form of compensation, the final step in the mitigation hierarchy. Developers should be able to demonstrate that impacts on ecology and biodiversity could not reasonably be avoided or mitigated before biodiversity offsetting will be considered.

Biodiversity offsetting may not be suitable in all instances, particularly when proposals impact designated sites, irreplaceable habitats or priority habitats. Biodiversity offsetting is provided at the discretion of the Council following a comprehensive review of the proposed development.

Where biodiversity offsetting is required this can be achieved on other land owned by a developer, or there are a number of offsetting providers who are able to deliver biodiversity offsetting agreements, including the Trust for Oxfordshire’s Environment and Environment Bank.

Mandatory BNG – What do we know so far?

From November 2023 onwards, Part 6 of the Environment Act 2021 will require that most development delivers a mandatory minimum of 10% BNG. As of August 2023, detailed secondary legislation and associated guidance has not yet been published by HM Government. The best available information suggests:

  • Mandatory BNG will apply to major development from November 2023 onwards, and minor development from April 2024 onwards. The precise timing of this has not been confirmed yet.
  • Householder development will likely be exempt from mandatory BNG, along with permitted development and proposals which have a very small (<25m2 area or <5m length) or temporary (<2 years) biodiversity impacts.
  • Relevant developments will be subject to a general pre-commencement planning condition. This planning condition will require that developers submit and have approved by the Council a ‘biodiversity gain plan’ before any works can begin.
  • The ‘biodiversity gain plan’ is a document describing how the developer will achieve a 10% BNG, informed by a biodiversity metric assessment. It is understood that a standardised template for the ‘biodiversity gain plan’ will be published.
  • If 10% BNG cannot be achieved within the red line boundary of the planning approval, offsite habitat creation will need to be relied upon. The ‘biodiversity gain plan’ will need to evidence this.
  • Offsite habitat creation can only be accepted as part of the ‘biodiversity gain plan’ where that habitat has been secured with a legal agreement and entered into the new statutory ‘biodiversity gain sites register’.
  • Where a developer is unable to achieve 10% BNG onsite or offsite, statutory credits will be available to purchase. These credits will be intentionally expensive to encourage the delivery of BNG onsite or close to the development site.

Further guidance on mandatory BNG is available here.

This page will be updated as and when further legislation and guidance is published.

Last updated: August 2023