Lewisham Council Homepage Skip navigation

Biodiversity net gain

Find information on the national validation requirements for biodiversity net gain (BNG).
Biodiversity net gain

From 2 April 2024, biodiversity net gain is mandatory for both major and small site development proposals.

Find further information and details of national validation requirements.

From 2 February 2024, you must demonstrate how your development site meets the minimum mandatory requirement of 10% biodiversity net gain over the pre-development value of the site. The minimum information that you must submit is set out in paragraph 11 of the Biodiversity Net Gain (BNG) Planning Practice Guidance.

Some of these requirements are included in the standard application form available on the Planning Portal. With your application, you must include a completed statutory biodiversity metric and a scaled plan.

The metric should be completed by a competent person with specialist knowledge of habitat types and conditions, such as an Ecologist, who is a registered member of the Chartered Institute of Ecology and Environmental Management (CIEEM) and can advise on the calculations.

You must also explain how a biodiversity net gain approach has been taken at the development site. This must be carried out in line with the ecological mitigation hierarchy of avoiding and minimising impacts first before BNG is applied. 

Extra information on the proposed BNG strategy is needed for schemes that are proposing significant biodiversity and/ or the use of offsite biodiversity gains. 

The government has advice on exemptions from the BNG requirement.  If you think your site is exempt, you should submit a statement with your application explaining why. You might need to submit evidence with this statement. 

Make sure you:

  • use the statutory metric as early as possible in the site design process to help avoid biodiversity loss
  • follow the biodiversity gain hierarchy which prioritises onsite BNG first
  • consider how BNG and the London Plan’s Urban Greening Factor policy G5 can be optimised at design stage. Meeting UGF can contribute towards the achievement of BNG
  • consider how the location of onsite biodiversity relates to adjoining habitats, green corridors or existing green space within the site and beyond the red line boundary
  • consider how suitable multi-functional biodiversity enhancements can form part of the site’s landscaping and amenity space strategy
  • check whether your site is in or close to a designated park, open space or Site of Importance for Nature Conservation (SINCs)