Biodiversity Net Gain

Biodiversity Net Gain (BNG) is a simple concept, meaning that development sites leave wildlife in a better state than it was found in, whereby developments result in a quantifiable net gain of typically 10%. This gain can be achieved through a number of ways, including enhancing biodiversity on-site alongside appropriate mitigation for any unavoidable losses. Where on-site enhancement may not be feasible, net gains can also be attained off-site.

To quantify gains and losses, the DEFRA Biodiversity Metric 3.0 can be utilised, whereby existing and proposed post-development habitats, with their associated area and condition can be inputted. A percentage denoting overall net loss of gain is then contained within the output (see below).


With the up and coming Environment Bill, BNG is anticipated to be mandated for most developments in the near future, whilst local authorities are requesting net gain assessments more regularly, which is also in line with their legislative and policy-related obligations to biodiversity.

Tyrer Ecological Consultants Ltd are fully trained in using the Biodiversity Metric 3.0 and the Small Sites Metric, including MoRPH appraisal for riverine habitats and are happy to offer this service to all clients who are in need of a BNG assessment!


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Tyrer Ecological Consultants
Formby Business Centre
42 Duke Street, Formby
Liverpool, L37 4AT