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At the forefront of environmental sustainability, the Government has ushered in a transformative legal requirement: that certain developments in England achieve a Biodiversity Net Gain (BNG) of at least 10%, compared with the pre-development biodiversity value of the site.

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What is Biodiversity Net Gain (BNG)?

BNG has been around for some time, and was introduced to counteract the decline in the UK's wildlife. The Environment Act 2021 introduced a requirement, which eventually came into force on 12 February 2024, that the biodiversity value of most development sites after development must be at least 10% higher than their pre-development state, and that the mechanisms for achieving this enhancement must be secured for at least 30 years.

A complex metric will be used to calculate the pre and post development biodiversity values of sites. Ecologists will need to be employed to navigate the metric and calculate the figure.

How can developers comply with the new requirements?

There are three ways in which developers can ensure compliance:

On-site habitat creation

This could include wildflower meadows as part of the development site. On-site delivery is the Government’s preferred method.

Off-site solutions

If achieving the 10% BNG target solely on-site isn't feasible, developers can create or enhance habitats on off-site land, ideally close to the development site. Alternatively, units can be procured from local landowners, who have created or enhanced habitats and are selling units to developers (known as ‘habitat banking’). If local options are insufficient, off-site solutions further afield may be permissible.

Statutory credits

If the requirements cannot be met using either option above, developers can secure statutory credits from Natural England. However, the Government hopes that these will be a last resort. As a result the credits are very expensive, and developers will need to show that on and off site solutions are not available.

BNG Housing Development

Biodiversity Net Gain Plan

Securing compliance involves meticulous planning. Developers must present a detailed biodiversity gain plan to local authorities and gain approval before they can commence construction of a development.

Additionally, in order to ensure the successful delivery of the plan over the required 30-year period, developers will likely need to enter into a Section 106 agreement with the relevant local authority.

Challenges and opportunities

The ambitious and complex nature of the new BNG legislation presents both challenges and opportunities for developers, landowners and local authorities.

What does BNG mean for local authorities?

For local authorities, navigating the complexities amidst increasing resource constraints poses a significant hurdle.

There are also concerns about unintended consequences, as some fear that the requirements might make brownfield sites less attractive to developers. Brownfield sites are often untouched for significant periods and can harbour a variety of flora and fauna, resulting in a high pre-development value. As such, achieving a 10% increase in BNG could mean significant obligations, in addition to potentially high remediation costs if, for example, the soils are contaminated. 

What does BNG mean for developers?

The new requirements pose a significant challenge for developers amidst rising costs. Employing ecologists, preparing detailed biodiversity gain plans and negotiating potentially complex s106 agreements will lead to delays and added expense.

What does BNG mean for landowners?

There are significant opportunities for landowners, particularly in habitat banking, but these opportunities can also entail significant effort and cost, including engaging ecologists, establishing management plans, registering the land, and setting unit prices. Landowners will also have to agree to the land being tied up and unavailable for other uses for at least 30 years.

Contact our BNG specialists

Navigating the intricate landscape of Biodiversity Net Gain requires expert guidance, which our planning and property solicitors can provide.

Whether you're grappling with BNG concerns or planning, land, or environmental legal matters, you can do so with the reassurance that our team has paid meticulous attention to all compliance and risk management issues.

You can contact our team by completing the form below.

Key Contacts

David Harries

David Harries

Partner | Head of Planning, Environmental, Energy and Regulatory

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Mark Turner

Mark Turner

Planning, Environmental, Energy and Regulatory Partner

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