Biodiversity Net Gain is a reality: the basics

Alastair Lewis and Emily Knowles looks at the latest developments in relation to Biodiversity Net Gain, including the all-important start dates for major and small developments.

This is the first in what we expect will be a series of posts on Mandatory Biodiversity Net Gain (BNG). BNG is one of the most significant recent developments in planning law, and the government have announced that it will go live on Monday 12 February 2024. A set of regulations has been made and local planning authorities and developers alike now need to familiarise themselves with them to ensure a seamless implementation of the new procedures.

From and including 12 February 2024 every grant of planning permission under the Town and Country Planning Act 1990 (1990 Act) for major development (unless exempt) will be deemed to be granted subject to a general BNG condition. The condition cannot be varied or removed – it is set in legislation and deemed to apply. It will apply to applications for small developments from 2 April 2024. The effect of the condition is to secure that the biodiversity gain objective is met. This means at least a 10% increase in the biodiversity value of the habitat on the land to which the planning permission relates (“the onsite habitat”). The condition requires that development may not be begun unless a biodiversity gain plan has been submitted to the planning authority, and the planning authority has approved the plan. We’ll produce a more detailed note on what plans must provide.

Here’s a quick summary of some important things we already knew or that we’ve learned over the last few days:

1. Major development – which will be caught from 12 February – includes residential developments with 10 or more dwellings or other residential development where the site area is 0.5 hectares or more and the number of dwellings isn’t known. It also includes the provision of buildings (residential or otherwise) where the floor space to be created is 1000 square metres or more, or any development carried out on a site having an area of 1 hectare or more.
2. BNG for small development will apply from 2 April 2024 – small developments are developments that aren’t major development so includes 1 – 9 dwellings or a residential site smaller than 0.5 hectares and buildings with less than 1,000 sqm of floorspace or development carried out on a site having an area of less than 1 hectare.
3. Currently BNG only applies to applications for planning permission under Part 3 of the 1990 Act, not other types of permission and not in relation to development to which section 73A of the 1990 Act applies (planning permission for development already carried out). Further regulations will modify the procedure for other types of permission. Nationally significant infrastructure projects are not caught – yet.
4. Under the transitional provisions, BNG will not apply to planning permission for major development where the planning application was made or planning permission granted before 12 February 2024, nor will it apply to applications under section 73 of the 1990 Act to vary a planning condition on a major development permission granted or applied for prior to 12 February 2024. Similarly, the condition won’t apply to small developments where the application for planning permission was made prior to 2 April 2024.
5. Exemptions: Under the Biodiversity Gain Requirements (Exemptions) Regulations 2024, which also go live on 12 February, certain exemptions from the condition will apply.
   1. Development below a de minimis threshold: development that does not impact a priority habitat (as set out in the government’s list of priority habitats and species in England) and impacts (a) less than 25 square metres of non-priority onsite habitat that has biodiversity value greater than zero and (b) less than 5m of onsite linear habitat. The government has confirmed that this will generally be demonstrated by a decrease in the biodiversity value, determined by the biodiversity metric. “Impact” (used here as a verb) and “linear habitat” are defined in the regulations.
   2. Householder development: development to an existing house, but not including a change of use or a change to the number of dwellings.
   3. Biodiversity gain sites: for example developments which solely enhance biodiversity to achieve the BNG condition for other developments by providing off site biodiversity gain (another topic we’ll cover in more detail later).
   4. Small scale self-build and custom housebuilding: this only applies to development of no more than 9 dwellings, on an area no larger than 0.5 hectares and exclusively consisting of dwellings within section 1(A1) of the Self-build and Custom Housebuilding Act 2015. Note that self and custom build sites which are in excess of the thresholds set out will be required to deliver BNG because of the impact that they have on habitat.
   5. The High Speed Railway Transport Network.

Along with the finer details we’ve learned over the last few days, there are a number of concepts and procedures which we’ve known for some time with which local planning authorities will need to be familiar. As a reminder:

1. The details of BNG are a post-permission matter – they require the submission of a BNG plan no earlier than the grant of permission and before commencement of the development. The plan will need to explain how the developer has applied the required biodiversity gain hierarchy; the biodiversity unit values before and after the development is carried out; and how the developer will deliver the 10% BNG mandated by the deemed condition.
2. Whilst it will usually be inappropriate to refuse a planning application solely based on BNG non-compliance, whether the condition can be discharged successfully will be a material consideration at the determination stage.
3. Ensuring compliance with the mandatory condition (i.e. the delivery of the 10% net gain) will need to be achieved in practice through conditions, section 106 agreements and/or conservation covenants. Furthermore, any mitigations and enhancements required to achieve the 10% BNG must be maintained for at least 30 years after the development is completed. We suspect that maintenance, and funding and monitoring obligations are most likely to be secured through section 106 agreements, but it will be interesting to see the take up in use of conservation covenants.

Mandatory BNG represents a big change for planning professionals and for many planning applications made after 11 February. Now we have the final details of the new regime, local planning authorities and developers can invest the time and resources in familiarising themselves with it, what they are likely to need to provide by way of BNG, and whether it can be secured in a Biodiversity Gain Plan.

Sharpe Pritchard’s planning team can advise as to whether mandatory BNG applies to your development and can assist in securing the necessary mitigation required to satisfy the BNG condition. We can also help planning authorities in implementing the condition, and land owners who are interested in making land available for BNG.

Sharpe Pritchard are ready for mandatory BNG: are you?

Alastair Lewis is a Partner and Parliamentary Agent and Emily Knowles is a Senior Associate at Sharpe Pritchard LLP.