Biodiversity Net Gain (BNG): Requirements, Biodiversity Metrics and Planning Support

Biodiversity Net Gain (BNG) in England

Biodiversity Net Gain (BNG) is now a mandatory planning requirement for most developments in England. Introduced under the Environment Act 2021, BNG became a legal requirement for major developments on 12 February 2024 and was extended to small sites from 2 April 2024.

Under Schedule 7A of the Town and Country Planning Act 1990, developers must demonstrate that their project will deliver at least a 10% increase in biodiversity value compared with the site's pre-development baseline.

This requirement ensures that new developments contribute to nature recovery and environmental improvement by creating, enhancing or securing habitats that provide measurable biodiversity benefits.
​What is Biodiversity Net Gain (BNG)?

​Biodiversity Net Gain is a planning approach that requires development to leave the natural environment in a better condition than it was before development began.

Rather than simply mitigating ecological impacts, BNG requires developers to achieve a measurable increase in biodiversity through:
  • On-site habitat creation and enhancement
  • Off-site biodiversity units and habitat improvements
  • Statutory biodiversity credits, where other options are not available

The objective is to ensure that development contributes positively to wildlife, habitats and wider ecosystem recovery while supporting sustainable growth.
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Why is Biodiversity Net Gain Important?

Biodiversity is the variety of life on Earth, including plants, animals, insects, fungi, microorganisms and the ecosystems they form.

Across the UK, biodiversity has declined significantly due to habitat loss, fragmentation and environmental pressures. Biodiversity Net Gain is designed to reverse this trend by ensuring that development projects actively contribute to habitat restoration and ecological resilience.

The benefits of Biodiversity Net Gain include:
  • Creating and enhancing wildlife habitats
  • Supporting local and national nature recovery strategies
  • Improving ecosystem services such as flood mitigation and carbon storage
  • Increasing environmental sustainability within new developments
  • Delivering long-term ecological improvements for future generations
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How is Biodiversity Net Gain Measured?

BNG is assessed by comparing the biodiversity value of a site before development with its biodiversity value after development.

To achieve compliance, developers must demonstrate a minimum 10% net gain in biodiversity value. This calculation takes account of:
  • Existing habitats on the site
  • Habitat losses resulting from development
  • Proposed habitat creation and enhancement measures
  • Off-site biodiversity gains
  • Statutory biodiversity credits where applicable

The assessment provides a transparent and measurable framework for evaluating ecological impacts and biodiversity improvements.
What is the Biodiversity Metric?

The Biodiversity Metric is the statutory tool developed by Natural England to calculate biodiversity value and measure Biodiversity Net Gain.
The metric converts habitat data into biodiversity units using a standardised methodology. It considers several factors, including:
  • Habitat type
  • Habitat size and extent
  • Habitat condition
  • Strategic significance and location
  • Difficulty and time required for habitat creation

The Biodiversity Metric provides a consistent approach for local planning authorities, developers and ecological consultants to assess biodiversity losses and gains associated with development proposals.

All developments subject to mandatory BNG requirements must use the statutory Biodiversity Metric when demonstrating compliance.
Biodiversity Gain Plans and Planning Requirements

Before development can commence, developers must submit a Biodiversity Gain Plan to the Local Planning Authority (LPA) for approval.

The Biodiversity Gain Plan typically demonstrates:
  • The site's baseline biodiversity value
  • Predicted biodiversity impacts
  • Proposed habitat creation and enhancement measures
  • Biodiversity Metric calculations
  • How the required 10% Biodiversity Net Gain will be achieved and maintained

Where off-site biodiversity units are used, the land delivering those gains must be registered on Natural England's Biodiversity Gain Site Register.
Biodiversity Net Gain Consultancy and Planning Support

Achieving Biodiversity Net Gain requires early ecological input and strategic planning. Identifying opportunities for habitat enhancement at the outset of a project can help minimise costs, reduce planning risks and improve development outcomes.

Our experienced consultants provide specialist support for:
  • Biodiversity Net Gain assessments
  • Biodiversity Metric calculations
  • Baseline habitat surveys
  • Habitat creation and enhancement strategies
  • Biodiversity Gain Plans
  • Off-site biodiversity unit solutions
  • Planning application support
  • BNG compliance advice for developers, landowners and planning professionals.
​​Need Help with Biodiversity Net Gain?
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Whether you are planning a residential, commercial or infrastructure development, we can help you navigate Biodiversity Net Gain requirements and achieve compliance efficiently.
Contact our team today to discuss your project and receive expert advice on Biodiversity Net Gain assessments, Biodiversity Metrics and planning support services.

For more information about how we can assist with your project, please complete our contact form and one of our consultants will be in touch.