Understanding Biodiversity Net Gain (BNG)
Since 2024, legislation has required development projects to deliver Biodiversity Net Gain (BNG). The aim is to leave a site with measurably better habitats for wildlife than before development, helping to create environments where nature can thrive. We have explored this topic in previous blogs:
Biodiversity Net Gain, a handy guide and Rewilding, a Holistic Approach to Biodiversity Net Gain in your Project
In those articles, we focused on embracing the principles behind the legislation to create better habitats for wildlife to thrive, and on how this can benefit both the project and nature.
Defra is now updating the policy in response to consultation on the implementation of BNG, with the changes expected to come into force by the end of July 2026.
What Biodiversity Net Gain (BNG) will developers have to deliver?
These changes are intended to reduce the burden on smaller developers, while focusing on larger developments that have greater potential to deliver meaningful biodiversity gains. The main changes are:
- Exemption for projects up to 0.2 hectares unless priority habitats (eg. hedgerows) are impacted. This simplifies previous rules in which a de minimis exemption had to be proven
- Removal of exemption for self and custom build projects – these are new developments eg new build, or conversion of building from another use to residential
- Exemption for temporary planning permissions up to 5 years
- Amendments to the BNG hierarchy for minor development, giving more flexibility for BNG to be gained off site.
The current householder exemption will remain in place. In practice this means, planning applications relating to an existing house, eg. an extension or building within curtilage does not have to deliver BNG.
Defra is also planning further changes later in the year, including exemptions for developments:
- Whose aim is to conserve or enhance biodiversity
- Which enhance parks, playing fields and public gardens
There may also be an exemption for brownfield residential development, along with changes to the de minimis threshold, although these proposals are still under consultation.
These changes are designed to reduce confusion for small projects applying for the de minimis exemption. Householder applications, such as extensions, were already exempt, and this change is designed to extend this exemption to other projects, such as change of use on small sites.
How will these changes to Biodiversity Net Gain affect you and your project?
Projects with BNG conditions already in place will continue under the current legislation, so the changes won’t affect projects which have already received planning permission. Any projects currently going through the planning process will remain subject to the existing rules.
For more details, please see the government website.
If you are unsure how these updates may affect your project, please get in touch and we would be happy to discuss your options.