In the ongoing battle to harmonise development with conservation, the UK has taken a monumental step forward with the enforcement of Mandatory Biodiversity Net Gain (BNG).

As this transformative policy comes into force, accompanied by further guidance, it signals a resolute commitment to preserving and enhancing our natural heritage for generations to come.

On 12 February 2024, the mandatory requirement for developers to provide BNG came into force.

All new developments are required to deliver a net gain in biodiversity, ensuring that any ecological harm caused during construction is offset by measurable gains in habitat quality and quantity.

Myerson Solicitors' Commercial Property team explores what the BNG will mean and which planning applications it will apply to.

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Biodiversity Net Gain is now in force. What does it mean for you

What does the BNG mean?

The biodiversity gain plan must be submitted no earlier than the day after planning permission is granted, and it will only be approved by the local authority if it demonstrates the strategy for meeting the 10% biodiversity gain objective.

This objective is achieving a minimum 10% increase in post-development ‘biodiversity value’ compared to the pre-development biodiversity value of the development of the development site for which planning permission is granted.

Which planning applications will the BNG apply to?

BNG has only been commenced for planning permissions granted with respect to an application made on or after 12 February 2024.

Permissions granted for applications made before this date are not subject to biodiversity net gain.

The mandatory BNG provisions will apply to all planning applications made for ‘major development’, which includes:

The provision of more than ten dwellinghouses or, if the number of dwellings is now known, development on a site having an area of more than 0.5 hectares.
The provision of a building or buildings where the floor space to be created by the development is 1,000 sqm or more.
Development is carried out on a site having an area of 1 hectare or more.

From 1 April 2024, the requirements will apply to ‘small sites’, which will use a different small sites metric to ensure the BNG calculations are more proportionate to the development.

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How is BNG secured?

The habitat enhancements must be secured through a suitable mechanism and maintained for at least 30 years after the development is completed for the local planning authority to be satisfied that the BNG will be delivered.

This can be secured via (i) a planning condition, (ii) a planning obligation, or (iii) a conservation covenant (being a new statutory scheme under the Environment Act 2021).

The local planning authority will monitor the delivery of the BNG and take enforcement action if commitments are not met.

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Biodiversity Gain Plan

The new BNG condition requires a biodiversity gain plan to be submitted to and approved by the local planning authority before development can lawfully commence.

This plan should include an assessment of the value of the natural habitats onsite pre-development and post-development, and it should ensure that at least 10% BNG is achieved.

The biodiversity gain plan must include the following:

Information about steps to minimise the adverse effects of the development on the biodiversity of the onsite habitat and any other habitat;
The pre-development and post-development biodiversity value of the onsite habitat;
Any registered offsite biodiversity gain units allocated to the development and the biodiversity value of that gain to the development; and
Any statutory biodiversity credits purchased for the development.

Developers are encouraged to follow a hierarchy of mitigation measures to avoid, minimise, restore, and offset impacts on biodiversity.

Avoiding or minimising impacts on biodiversity should be prioritised.

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Challenges to BNG

In some cases, it may be challenging to achieve BNG on the development site itself.

Biodiversity offsetting enables developers to impair the habitat value of a site, provided they pay to restore another habitat site that has the potential to become at least the same quality as the habitat that will be lost.

Developers can meet the biodiversity requirement through offsite biodiversity habitat creation if the developer has access to additional land.

Finally, where BNG cannot be delivered onsite or offsite, then the impacts on biodiversity can be offset through the purchase of biodiversity credits.

While the implementation of BNG may present challenges, including upfront costs and regulatory complexities, the long-term benefits far outweigh the initial investment.

Crucially, the success of BNG hinges on collaboration and engagement across sectors.

Developers, planners, ecologists, and policymakers must work together to ensure that biodiversity gains are accurately quantified, monitored, and maintained over time.

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Biodiversity Net Gain Is Now in Force. What Does It Mean for You?