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Biodiversity Net Gain

Biodiversity Net Gain is now a statutory requirement for most planning applications in England. We deliver baseline habitat assessments, metric calculations and BNG strategies that demonstrate the mandatory 10% uplift — and hold up under LPA scrutiny.

Mandatory sinceFeb 2024 (major)
Uplift required10% minimum
MetricDefra Statutory Metric
Management plan30 years

Overview

The Environment Act 2021 made Biodiversity Net Gain a mandatory condition for most planning permissions in England. Major developments have been required to demonstrate a measurable 10% biodiversity uplift since February 2024, with small sites following from April 2024. The requirement applies to the overall biodiversity value of the site, measured in habitat units and hedgerow units using the Defra Statutory Biodiversity Metric.

A BNG assessment starts with a baseline survey of the site — mapping and classifying all habitats using UKHab, recording their condition, and running the metric to quantify the site's pre-development biodiversity value. The post-development design is then modelled through the same metric to demonstrate that the 10% uplift has been achieved, either on-site, off-site, or through statutory biodiversity credits.

The metric calculation alone is not enough. LPAs expect a clear BNG strategy explaining how uplift will be delivered, a habitat management and monitoring plan covering a minimum of 30 years, and evidence that the gains are additional and secured through planning condition or conservation covenant. We deliver the full package — from baseline through to the management plan.

When you need this

  • You are submitting a planning application for any development in England (with limited exemptions)
  • The LPA requests a Biodiversity Net Gain assessment or metric calculation
  • You are preparing a major development and need a BNG strategy to accompany the planning submission
  • You want to explore off-site BNG delivery or biodiversity credit options
  • You need a 30-year habitat management and monitoring plan to discharge a BNG condition

Our approach

  1. 01
    Baseline habitat survey

    A UKHab-compliant habitat survey of the site, classifying all habitat parcels and linear features (hedgerows, watercourses) and recording their condition against the published criteria.

  2. 02
    Metric calculation (pre-development)

    All habitats are entered into the Defra Statutory Biodiversity Metric to produce the site's baseline biodiversity value in habitat units and hedgerow units.

  3. 03
    Post-development metric modelling

    The proposed development layout is modelled through the metric, accounting for habitat retention, enhancement and creation, to demonstrate the 10% uplift is achieved.

  4. 04
    BNG strategy & management plan

    A planning-ready strategy document sets out how net gain will be delivered, secured and maintained for a minimum of 30 years, including monitoring schedules and remedial measures.

Frequently asked questions

01Is BNG mandatory for all developments?+
Most planning applications in England are now subject to mandatory BNG. Limited exemptions apply, including householder applications, self-build, some permitted development and developments below a de minimis habitat threshold. Your LPA can confirm whether your specific application is exempt.
02What happens if I can't achieve 10% on-site?+
If on-site habitat creation or enhancement cannot deliver the full 10% uplift, the shortfall can be made up through off-site habitat delivery (on land you control or via a registered habitat bank) or, as a last resort, by purchasing statutory biodiversity credits from the government.
03How long does a BNG assessment take?+
The baseline field survey typically takes one to two days depending on site size. The metric calculation and BNG strategy report are normally delivered within two to three weeks of the survey. The 30-year management plan can be prepared in parallel with the planning submission.
04Do I need a separate BNG survey or can it be combined with a PEA?+
In many cases the UKHab baseline survey for BNG can be carried out at the same time as your Preliminary Ecological Appraisal, saving time and cost. We'll advise on the most efficient approach for your site when scoping the work.
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