A biodiversity net gain consultant is a MCIEEM-qualified ecologist who specialises in calculating biodiversity net gain (BNG) using the DEFRA biodiversity metric. Mandatory BNG became a legal requirement for most planning applications in England from February 2024 under Schedule 7A of the Town and Country Planning Act 1990 (inserted by the Environment Act 2021). Developments must deliver a minimum 10% net gain in biodiversity value above the pre-development baseline, measured using the DEFRA biodiversity metric, and secured for a minimum of 30 years.
What they do
- Carry out baseline habitat surveys using the DEFRA biodiversity metric methodology
- Complete DEFRA biodiversity metric calculations (pre and post-development)
- Identify on-site habitat creation and enhancement opportunities
- Prepare Biodiversity Gain Plans for submission with planning applications
- Prepare Habitat Management and Monitoring Plans (30-year management)
- Source and procure off-site biodiversity units where required
- Advise on conservation covenants and section 106 BNG obligations
- Carry out annual BNG monitoring surveys
When you need one
A BNG consultant is required for most planning applications submitted in England from February 2024 onwards. Check the exemptions list with your planning consultant before proceeding.
Typical costs (UK, 2025)
| Service | Typical cost |
|---|---|
| BNG assessment (DEFRA metric calculation) | £800 - £2,500 |
| Habitat Management and Monitoring Plan (30 years) | £600 - £2,000 |
| Off-site BNG unit procurement (varies by habitat and location) | £5,000 - £50,000+ |
| Conservation covenant legal advice | £1,000 - £3,000 |
| BNG annual monitoring survey | £300 - £600 / year |
| Hourly rate | £65 - £110 / hr |
Off-site BNG unit costs vary enormously depending on local supply, habitat type and whether statutory biodiversity credits are required. Engage a consultant early to assess on-site delivery potential before committing to expensive off-site routes.
Qualifications to look for
The primary qualification for BNG consultants. CIEEM has developed a BNG practitioner pathway to demonstrate competence in biodiversity net gain assessment. Check membership at cieem.net.
Consultants should have formal training in the application of the DEFRA biodiversity metric 4.0. CIEEM and Natural England both offer training. Confirm the consultant is familiar with the current metric version and local authority requirements.
How to find a reputable BNG consultant
Frequently asked questions
What is Biodiversity Net Gain?
A requirement under the Environment Act 2021 that most new development in England must provide a 10% net gain in biodiversity value above the pre-development baseline. It became mandatory for major planning applications from February 2024 and for minor applications from April 2024 (with some exemptions for householder applications, small sites and certain other development types). The gain is measured using the DEFRA biodiversity metric and must be maintained for at least 30 years.
How is biodiversity net gain calculated?
The DEFRA biodiversity metric 4.0 assigns unit values to different habitat types based on their area, condition and strategic significance. Losses from development are subtracted from gains created through habitat creation or enhancement. A net gain of at least 10% over a minimum 30-year period is required. The calculation must be carried out using the official DEFRA biodiversity metric tool and submitted as a biodiversity metric calculation with the planning application.
What happens if I cannot achieve BNG on site?
You can purchase biodiversity units off-site from a registered BNG provider or landowner - prices vary significantly by location, habitat type and demand. As a last resort, statutory biodiversity credits can be purchased from Natural England but this route is deliberately priced to be expensive to incentivise on-site and local off-site delivery. Off-site units must be secured by a conservation covenant or section 106 agreement for a minimum of 30 years.