Biodiversity Net Gain (BNG) was first introduced by the Environment Act 2021. Its overarching aim is to ensure habitats for wildlife are left in a measurably better state than they were in before the development was undertaken.
It is a term used to describe the process of increasing the biodiversity value of a site and is calculated by using the Biodiversity Metric.
You will need to understand the requirements of BNG if you’re a land manager, developer or LPA, as all planning permissions granted in England (with a few exemptions) will have to deliver at least 10% biodiversity net gain.
Although the mandatory requirements of BNG will not come into force until November 2023, many local planning authorities (LPAs) are already setting their own BNG targets within their local planning policy.
With this in mind, it is important to understand how it is calculated and how you can achieve the necessary BNG for your development, as Henry Bourne and Oliver Galliford, Planners at Vail Williams, explain.
Why is it being introduced?
Although certain sites are protected, there are limited mechanisms to value, maintain, enhance, or create wider habits.
As a result, habitats continue to be lost to development, thus reducing nature’s ability to connect and thrive.
What are the key components?
The National Planning Policy Framework (NPPF) includes provisions to enhance the natural and local environment and improving biodiversity in and around developments.
This additional legislation provides further clarity on how this can be successfully achieved.
The key components of mandatory biodiversity gain are:
- Amendments to Town & Country Planning Act (TCPA)
- Minimum 10% biodiversity net gain required. This is to be calculated using the Biodiversity Metric and included an approved biodiversity gain plan
- Habitat secured for at least 30 years via planning obligations or conservation covenants
- A new statutory biodiversity credits scheme
- National register for net gain delivery sites
How is BNG calculated?
Natural England’s Biodiversity Metric is used to calculate the biodiversity of both development and biodiversity uplift sites.
The metric is an accounting tool which assigns a measurable number of biodiversity units based on the type, extent and condition of habitats present or proposed on site.
It also takes into account how difficult the habitat is to create, the time taken to reach target condition and proximity to the development site.
This tool can be used by ecologists, developers, planners and other interested parties to assess the variations in biodiversity value (losses or gains) brought about by development or changes in land management.
An updated version (Biodiversity Metric 4.0) is expected to be launched later in 2023 and is expected to be the version in force when mandatory BNG launches this coming winter.
How can BNG be achieved?
The government has proposed a three-tier approach to addressing BNG requirements:
- The developer can demonstrate that they have produced a 10% BNG on the site itself
- The developer can deliver an offsite benefit of 10% BNG
- The developer can purchase statutory biodiversity credits through a section 106 agreement
Developers and land promoters will be required to provide a biodiversity gain plan which sets out how they will achieve the BNG requirements. This will include information on:
- The potential impacts of development on local habitats and how they have been minimised
- The site’s pre and post-development biodiversity value
- The biodiversity value of any offsite habitats provided in relation to the development proposed
- Any statutory biodiversity credits purchased