Planning and Biodiversity

Biodiversity Net Gain

The biodiversity net gain (BNG) process introduces a quantitative framework for securing and demonstrating net gain. It does not replace the requirement to carry out other assessments of impacts on biodiversity, for example, submission of bat survey information. Where there is the potential for impacts on European sites, such as Special Areas of Conservation or Special Protection Areas, the authority will still need to undertake a Habitats Regulations Assessment.

Compliance with several other environmental planning policies will still need to be demonstrated by the developer. This includes requirements relating to:

• protected or important nature conservation sites
• protected or important species
• irreplaceable habitats

For those developments that fall outside the scope of mandatory BNG the Peak District National Park encourages proportionate biodiversity net gain as per policy L2 of the Core Strategy and policy DMC11 of the DMP document. This approach aligns to the National Park’s first purpose to conserve and enhance the natural beauty, wildlife and cultural heritage of the national park

The following outlines the requirements for mandatory Biodiversity Net Gain. The full advice note can be found here

What is mandatory Biodiversity Net Gain?

Biodiversity Net Gain is the practice of, when carrying out most new development (with some exceptions), leaving the natural environment in a measurably better state than it was before. This means ensuring that the biodiversity value of a site has increased post development. A metric must be used to convert the value of the habitat, pre and post development. This calculates how much habitat is lost through development and provides a numerical value as to how much needs to be provided to achieve a net gain.

Under the Environment Act 2021, certain development in England must deliver at least 10% Biodiversity Net Gain, otherwise planning permission cannot be granted. This became mandatory from 12 February 2024 for major development sites, and from 2 April 2024 for small scale sites.

Biodiversity Net Gain will be measured using a biodiversity metric and habitats will need to be secured for at least 30 years. A planning application should indicate generally how the Biodiversity Net Gain will be met with a pre-commencement condition attached to planning permissions requiring full details. This means that before development can take place the details of how a 10% net gain will be achieved must be submitted to and agreed by the National Park Authority.

You will need to understand the requirements of biodiversity net gain if you are a developer or a land manager.

Which sites are affected by mandatory biodiversity net gain?

From 12 February 2024 major development must deliver mandatory biodiversity net gain. For the purposes of mandatory biodiversity net gain, major development is defined as residential developments with 10 or more dwellings, or where the site area is greater than 0.5 hectares (as per the NPPF definition).

From 2 April 2024 small sites must deliver mandatory biodiversity net gain. Small sites are defined as not major developments under the Town and Country Planning (Development Management Procedure) (England) Order 2015). This means:

• Residential development where the number of dwellings is between 1 and 9, or if unknown the site area is less than 0.5 hectares;
• Commercial development where floor space created is less than 1,000 square metres or the total site area is less than 1 hectare;
• development that is not the winning and working of minerals or the use of land for mineral-working deposits; or
• development that is not waste development.

The following sites are exempt from mandatory biodiversity net gain:

• development impacting habitat of an area below a ‘de minimis’ threshold of 25 square metres - for example, 5 metres by 5 metres
• householder applications
• biodiversity gain sites - where habitats are being enhanced for wildlife
• small scale self-build and custom housebuilding

However, where appropriate, development should still provide proportionate biodiversity net gain as per policy L2 of the Core Strategy and policy DMC11 of the DMP document

What do I need to do?

The biodiversity net gain process is built around the pre-commencement condition, which is when the full details of the metric calculations and of the measures to be taken to secure 10% net gain are required. (However, enough information will need to be submitted with the planning application for the authority to be satisfied that a suitable net gain solution exists for that development).

Where development falls within the above categories, the application must be accompanied by minimum information set out in Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015:

• a statement as to whether the applicant believes that planning permission, if granted, would be subject to the biodiversity gain condition;
• the pre-development biodiversity value of the onsite habitat on the date of application (or an earlier date) including the completed metric calculation tool used showing the calculations, the publication date and version of the biodiversity metric used to calculate that value;
• where the applicant wishes to use an earlier date, the proposed earlier date and the reasons for proposing that date;
• a statement confirming whether the biodiversity value of the onsite habitat is lower on the date of application (or an earlier date) because of the carrying on of activities (‘degradation’) in which case the value is to be taken as immediately before the carrying on of the activities, and if degradation has taken place supporting evidence of this;
• a description of any irreplaceable habitat (as set out in column 1 of the Schedule to the Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations [2024]) on the land to which the application relates, that exists on the date of application, (or an earlier date); and
• a plan, drawn to an identified scale which must show the direction of North, showing onsite habitat existing on the date of application (or and earlier date), including any irreplaceable habitat.

Biodiversity net gain maintains the mitigation hierarchy of avoiding impacts first, then mitigating and only compensating as a last resort. It cannot be used to bypass the mitigation hierarchy.