Information about biodiversity net gain for developers
Through the Environment Act (2021), all developments covered by the Town and Country Planning Act have to demonstrate a minimum measurable Biodiversity Net Gain (BNG) of 10%. This means that the biodiversity value of a development must exceed the predevelopment biodiversity value of the site by a minimum of 10%.
Biodiversity value is measured using a metric produced by DEFRA based on the condition of the site before any development has occurred.
Meeting BNG requirements
BNG habitats can be delivered on site and developers must try to meet the requirements on site if possible. If this is not possible they can be met off-site or by buying biodiversity credits from approved sites.
Where requirements are met off site, they must be consistent with our Local Plan and conform to the BNG Good Practice Principles for Development in the Environment Act. Habitats must be secured and managed for a minimum of 30 years.
Information needed to validate a planning application subject to BNG
The following minimum information set out in Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015 is required for validation:
- 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.
If this information has not been provided, the local planning authority will refuse to validate the application.
Statutory biodiversity metric tools and guides are available from the government webpage Statutory biodiversity metric tools and guides.
Planning Validation Supporting Statement for Biodiversity Net Gain can be downloaded below.
Download planning validation support statement document
The Statutory Metric must be undertaken by an ecologist or, in the case of small sites, by a competent person
Pre-development biodiversity value must be calculated before any site clearance or other habitat management work has been undertaken, by applicants or anybody else. The baseline date for habitats on any site proposed for development will be taken as 30 January 2020, (as set out in the UK Environment Act 2021), or the nearest (in time) prior aerial photographic evidence or survey.
Any scheme of Biodiversity Net Gain must include a mechanism for delivery of the target habitats, management, and monitoring of their condition, and an approach to remediation in the event of targets not being met.
Applicants should refer to the Chartered Institute of Ecology and Environmental Management and Construction Industry Research and Information Association Biodiversity Net Gain Good Practice Principles documents for information on the standards that will be expected.
Final Metric calculations and other documents must be constant with final project masterplans and landscaping schemes.
Templates and guidance for these documents are available from DEFRA.
Planning permission
Planning permissions may have additional conditions attached to them to secure the creation and long-term management of habitats.
What will be exempted?
Draft regulations have been published in The Biodiversity Gain Requirements (Exemptions) Regulations 2024.
Details are also provided in the Draft Biodiversity Net Gain Planning Practice Guidance.
Where applicants consider that the development would not be subject to the general biodiversity gain condition, Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015 provides that the applicant must provide a statement as part of the planning application setting out why they believe this is the case.
Small sites
For minor developments (fewer than 10 residential units or an area of less than 0.5 hectares) and householder applications, biodiversity net gain measures should be clearly identified in supporting information and illustrated on the relevant plans.
Measures should be appropriate to the site’s location and surroundings and should be focussed on supporting recognised nature conservation priorities. The DEFRA ‘small sites’ Biodiversity Metric should be used to demonstrate net gain in these circumstances. Small sites should also include integrated bird, bat or insect box provision, and hedgehog-friendly fencing.
Delivering BNG (onsite / offsite)
BNG can be achieved either onsite; registered offsite; through the purchase of statutory biodiversity credits or a combination of the three options.
BNG should ideally be delivered onsite or locally with statutory credits the last resort.
Where measures cannot be delivered onsite, secondary conditions will likely be required.
A register of offsite providers is available from us on request. Developers will need to contact providers directly to agree biodiversity unit provision.
Offsite BNG must be registered via the biodiversity gain site register.