ACP Consultants
Based in London · Covers UK-wide Accreditation stated by provider: CIEEMOwn websiteUK-wide
01 · Planning stage · BNG
Biodiversity net gain assessment
Most planning permissions in England must now deliver a measurable 10% improvement in biodiversity compared with what was there before, known as biodiversity net gain. An ecologist surveys the site, runs it through the statutory metric, and sets out how the gain will be achieved and maintained for 30 years.
DWGuide by Dan Wallis · Updated 4 October 2026
This guide covers the rules in England. See Wales, Scotland and Northern Ireland.
Who needs oneMost applicants for new development in England, with some exemptions for small sites and householder applications
Who can do itAn ecologist experienced with the statutory biodiversity metric
WhenSurvey at the pre-application or application stage, metric calculation before submission
17 ecologists listed across the UK
Featured (paid) listings first, then A–Z · How we check listings
Find ecologists by region
South East (3) South West (3) Yorkshire and the Humber (3) North West (3)
National providers (11)
Arbtech Consulting Ltd
Based in Chester · Covers UK-wide (England and Wales) Accreditation stated by provider: Not statedOwn websiteUK-wide
Crossman Ecology
Based in Oakhill, Somerset · Covers South West and UK-wide Accreditation stated by provider: Not statedOwn websiteUK-wide
Ecus Ltd
Based in Sheffield, South Yorkshire · Covers Nationwide Accreditation stated by provider: Not statedOwn websiteUK-wide
Green Shoots Ecology
Based in Woodford Green, London · Covers Nationwide Accreditation stated by provider: Not statedOwn websiteUK-wide
Phlorum
Based in Brighton, East Sussex · Covers National team; air quality work focused on southern England Accreditation stated by provider: PCA accredited, ISO 9001, ISO 14001, ISO 45001, Expert Witness Institute member, Trustmark registered, River Restoration Centre memberOwn websiteUK-wide
Richard Green Ecology
Based in Woodbury Salterton, Devon · Covers South West England and nationwide Accreditation stated by provider: Not statedOwn websiteUK-wide
Sweco UK
Based in Leeds, West Yorkshire · Covers Nationwide Accreditation stated by provider: Not statedOwn websiteUK-wide
The Ecology Partnership
Based in Leatherhead, Surrey · Covers Surrey, the South East, and projects across England Accreditation stated by provider: CIEEM Registered Practice, BREEAM, SSIP Acclaim, CHASOwn websiteUK-wide
Thomson Environmental Consultants
Based in Guildford · Covers UK-wide Accreditation stated by provider: CIEEMOwn websiteUK-wide
Tyrer Ecological Consultants Ltd
Based in Formby, Merseyside · Covers North West and UK-wide Accreditation stated by provider: Not statedOwn websiteUK-wide
Regional providers (check they cover your area) (1)
Midland Ecology
Based in Birmingham · Covers Midlands Accreditation stated by provider: CIEEMOwn website
How it works
- A habitat survey records what’s on site now and gives it a baseline biodiversity value
- The statutory metric calculates the value of the proposed scheme, including any habitat created or enhanced
- Where the 10% gain can’t be met on site, it’s bought off-site or through statutory biodiversity credits
- A habitat management and monitoring plan sets out how the gain is kept up for 30 years
What’s exempt
Householder applications (like most extensions and loft conversions), small sites below the minor development threshold in some cases, and a handful of other categories are currently exempt. Check with your planning consultant or the council if you’re not sure your project needs it.
In Wales, Scotland and Northern Ireland
This guide describes the rules in England. Building regulations are devolved, so here is how biodiversity net gain assessment works in the rest of the UK.
Wales
Wales is developing its own biodiversity net gain approach rather than using England’s exact scheme; check the current Welsh Government position before applying.
Scotland
Scotland doesn’t currently mandate the same statutory biodiversity net gain scheme as England, though positive effects for biodiversity are often expected through planning policy.
Northern Ireland
Northern Ireland doesn’t currently mandate England’s statutory biodiversity net gain scheme, though some councils encourage biodiversity enhancement as part of applications.
Common questions
Does my extension need a BNG assessment?
No. Householder applications are exempt from the biodiversity net gain requirement.
What counts as the 10% gain?
The improvement is measured against a baseline biodiversity value calculated by the statutory metric, not just a rough estimate of greenery.
What if I can’t fit the gain on site?
You can buy off-site biodiversity units from a registered site, or as a last resort buy statutory credits from the government.
Who runs the metric calculation?
An ecologist experienced with the statutory biodiversity metric tool, usually the same firm that did your habitat survey.
New to the jargon? See our glossary of terms, from air permeability to TrustMark.