Biodiversity net gain

From November 2023 it will be mandatory for most development to achieve a minimum 10% net gain in biodiversity. This will include the majority of developments covered by the Town and Country Planning Act with smaller developments (those with fewer than 10 residential buildings or under 0.5ha) being required to meet this target by April 2024. Biodiversity net gain will also become a mandatory condition for Nationally Significant Infrastructure Projects from no later than November 2025.

Biodiversity net gain is an approach which requires development to leave the natural environment in a better state than before. This means that instead of just offsetting any habitat destroyed, enough habitat has to be created or enhanced to ensure that the value of biodiversity is increased by a minimum of 10%.

The Environment Act 2021 is the legislation which introduces mandatory biodiversity net gain (referred to as “biodiversity gain”) into the planning system. It builds on commitments made in the Government’s 25 Year Plan for the Natural Environment and strengthens existing requirements for biodiversity net gain within the National Planning Policy Framework.

It is the responsibility of the developer to ensure their development results in measurable net gains for biodiversity. They can be delivered onsite, within the redline boundary of development, or offsite through an agreement with a landowner or through a habitat bank, which is a nature enhancement project that has been set up with the sale of biodiversity units in mind and has been added to the national biodiversity net gain register. In some cases, market platforms may be set up to connect developers with suppliers of biodiversity units. As a last resort, if developers can prove that they have been unable to achieve net gain through the approaches describe above, they will be able to purchase statutory biodiversity credits from the Government.

DEFRA have produced a metric which allows users to assess the impact of a development on biodiversity including any net gains. A completed assessment using this metric is required to be included in any planning applications alongside a biodiversity net gain plan which will explain how a developer intends to meet their minimum 10%. This tool should be used in conjunction with expert ecological advice. A separate metric is available for small site developments which requires less ecological expertise to use.

It is required that any biodiversity net gain be managed for 30 years, it is the responsibility of the developer to ensure measures are put in place for this, including the provision of funding. It is likely that the cost of management will be included in the overall cost of habitat creation and enhancement, but this should be confirmed and agreed between relevant parties.

The most likely mechanisms for securing biodiversity net gains will be through planning obligations, such as a Section 106 agreement, or the use of conservation covenants. These covenants are a legally binding agreement between the suppliers of biodiversity net gain units, such as a landowner, and a responsible body, who will be required to enforce the agreement. Conservation covenants may include, but do not require, developer involvement.

Further information and guidance can be found at the links below:

Government response and summary of responses: Consultation on Biodiversity Net Gain regulations and implementation.

Government Biodiversity Net Gain collection

Biodiversity net gain for Local Authorities

Natural England Biodiversity Net Gain Brochure

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