Are You Exempt from Biodiversity Net Gain Requirements?
Introduction
Since February 2024, Biodiversity Net Gain (BNG) has required most developments in England to deliver a 10% biodiversity improvement. However, several important exemptions exist. This guide will help you quickly determine whether your project needs to comply with BNG requirements.
Key BNG Exemptions
1. Permitted Development
If your project can be carried out under permitted development rights, it does not require BNG. This includes many:
Household extensions and outbuildings
Certain agricultural buildings
Some changes of use
Specific industrial and commercial developments
However, if your development exceeds permitted development limits and requires planning permission, BNG requirements will typically apply unless another exemption applies.
2. Small Residential Sites
Your development is exempt if it:
Is smaller than one hectare in size, AND
Will create fewer than 10 dwelling houses
Important notes:
If either threshold is exceeded (size OR dwellings), BNG applies
The exemption applies to the whole development, not individual phases
Local authorities may still impose BNG through their own policies
3. Householder Applications
Planning applications for works to existing individual dwellings are exempt, including:
Extensions
Conservatories
Loft conversions
Outbuildings
This exemption applies only if the work relates to a single household and doesn't create separate residential units.
4. Biodiversity-Focused Development
Projects where the primary objective is biodiversity enhancement are exempt, such as:
Habitat creation or restoration projects
Nature reserves
Wildlife ponds and wetlands
To qualify, the primary purpose must be biodiversity improvement rather than other forms of development with biodiversity elements.
5. Urgent Crown Development
Certain Crown developments may be exempt if required urgently for national security, defense, or emergency response purposes.
Temporary Transition Exemptions
Existing Planning Permissions
Developments with planning permission granted before February 12, 2024
Developments with outline planning permission granted before February 12, 2024
Reserved matters applications where outline permission was granted before February 12, 2024
Brownfield Sites (until April 2, 2026)
Sites that:
Are on the brownfield land register
Have not been in active use for at least 10 years
Have significant structures requiring demolition
Can demonstrate BNG would make redevelopment economically unviable
Small Development Transition (until April 2, 2026)
Residential development of fewer than 10 dwellings on sites of any size
Development on sites smaller than 1 hectare (non-residential)
Local Authority Variations
Always check your local planning authority's specific requirements, as some have:
Higher BNG percentages (15% or 20%)
Broader application than national requirements
Different implementation timelines
Common Misunderstandings
Low ecological value sites still require BNG
Sustainable features don't automatically exempt a development
Change of use requiring planning permission typically needs BNG compliance
Statutory biodiversity credits are available as a last resort, not an automatic alternative
Still Unsure? Use Our BNG Exemption Calculator
Not sure if your development is exempt? Use our simple calculator here to find out.
Conclusion
Understanding BNG exemptions is crucial for effective project planning. For developments that do require compliance, early engagement with ecological professionals remains the most effective strategy for achieving cost-effective solutions.
References
Department for Environment, Food & Rural Affairs. (2024). Biodiversity Net Gain: Statutory Guidance for Development. https://www.gov.uk/government/publications/biodiversity-net-gain
Town and Country Planning (Biodiversity Net Gain) (England) Regulations 2023. https://www.legislation.gov.uk/uksi/2023/1378/contents/made
Planning Advisory Service. (2024). Biodiversity Net Gain: Advice for Local Authorities. https://www.local.gov.uk/pas/topics/environment/biodiversity-net-gain
