Biodiversity net gain

• Advice for planning applicants
• Major or small development
• Biodiversity Net Gain exemptions
• Small Sites Metric (SSM) eligibility
• Statutory Biodiversity Metric requirements for small developments

Advice for planning applicants

Biodiversity Net Gain (BNG) (opens new window) is a new and mandatory approach to enhancing biodiversity in development. It makes sure that habitats for wildlife are left in a measurably better state than they were before the development. Most developers must deliver a gain of at least 10%. This means a development will result in bigger or better-quality natural habitat than there was before development. It does not replace the existing protection for species that may be present on the site.

Major or small development

If your proposal counts as a major development, you will need to employ an ecologist to deal with Biodiversity Net Gain. You will need to use a spread sheet called the Statutory Biodiversity Metric. You should aim to do this as early as possible in the development process. Do not carry out any clearance work on site until you have taken ecological advice, as this may make it difficult to achieve the mandatory requirements.

An application counts as a small development for Biodiversity Net Gain if it is either:

• A residential development where the number of dwellings is between 1 and 9 on a site of area 1 hectare or less. Or, if the number of dwellings is unknown, the site area is less than 0.5 hectares.
• A commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare. Additionally it is not a mineral working or waste development.

Biodiversity Net Gain exemptions

• A proposed development may be exempt from Biodiversity Net Gain for one or more of the following reasons:
• Householder development. This is defined within the Town and Country Planning (Development Management Procedure) (England) Order 2015 (opens new window).
• Development granted planning permission by a development order. This includes permitted development rights.
• Development subject to the de minimis exemption. These are developments that impact less than 25 square metres (e.g. 5m by 5m) of habitat, or less than 5 metres of linear habitats such as hedgerows. There must also be no impact on a priority habitat (opens new window).
• Self-build and custom build development - development which:
  • consists of no more than 9 dwellings, and;
  • is carried out on a site which has an area no larger than 0.5 hectares, and;
  • consists exclusively of dwellings which are self-build or custom housebuilding as defined in the Self-build and Custom Housebuilding Act 2015 (opens new window).
• Development of a biodiversity gain site - development which is undertaken solely or mainly for the purpose of fulfilling, in whole or in part, the biodiversity gain planning condition which applies in relation to another development.

You do not need to account for Biodiversity Net Gain in your planning application if the site chosen for development is:

• entirely hard standing;
• sealed surface, or;
• similar with absolutely no vegetation or water features within the red line boundary.

Include suitable images to support this with your application.

Small Sites Metric (SSM) eligibility

A small development that is not exempt because of any of the above criteria, would normally be eligible to use the simpler Small Sites Metric as part of your application.

https://www.gov.uk/government/publications/statutory-biodiversity-metric-tools-and-guides (opens new window).

If the proposed development is eligible to use the SSM you are not obliged to do so. The statutory biodiversity metric calculation tool can always be used in its place. In some cases, it may be easier to achieve 10% Biodiversity Net Gain with the statutory metric as it makes fewer constraints about habitat condition. However, the statutory metric does need to be completed by a qualified ecologist.

Statutory Biodiversity Metric requirements for small developments

You will need to employ an ecologist in order to complete the Statutory Biodiversity Metric if any of the following apply. If you are unsure, use of an ecologist is recommended.

• The site is within 10m of a river, stream or canal or 5m of a ditch.
• If priority habitats or irreplaceable habitats are present on site (opens new window).
• If statutory protected sites or European protected species are present on site.
• If any habitats are present on the site that are not listed on the Small Sites Metric calculation tool.

If statutory protected sites or priority habitats are located within 500m of the development site boundary, you should consider whether you need to contact an ecologist and use the statutory biodiversity metric calculation tool. If you choose to continue using the Small Site Metric (SSM), a section of the calculation tool must be filled in to reflect this.

In addition to Biodiversity Net Gain requirements, ecological surveys for protected species may also be required to be submitted at the validation stage.