Biodiversity Net Gain (BNG)

Biodiversity net gain (BNG) is now a legal requirement to deliver enhancements to the natural environment through the development process. BNG makes sure development has a positive and measurable impact ('net gain') on the biodiversity present on site before development. It does this by requiring developers to increase biodiversity by a minimum of 10%. This reflects and reinforces our adopted local plan policy ENV1 c(v).

It is in addition to existing legislation for protected habitats and species, but is now a statutory requirement in the Environment Act 2021.

How is this measured?

Natural England has published a biodiversity metric tool, which uses biodiversity units to measure the value of a habitat. It calculates units based on the size, distinctiveness, condition and strategic significance of the habitat. In addition to following the mitigation hierarchy (avoid, mitigate, compensate), a biodiversity net gain of at least 10% must be achieved from the baseline value of the site.

It is the Council's preference that developers should look to provide BNG on-site in the first instance. You can gain on-site units by improving the habitat on-site through new landscaping and green infrastructure. You can gain on-site units by improving the habitat on-site through new landscaping and green infrastructure. If you are unable to improve biodiversity directly on-site, you can do it on other land you already own, or in partnership with public or private landowners, to gain off-site units.

You could seek a hybrid solution with a combination of providing both onsite and offsite units where the whole of the BNG cannot be secured on site. This will both reduce costs and maximise outcomes for biodiversity gain onsite.

In exceptional circumstances, if you are unable to deliver gain on-site or via off-site units, then you need to buy statutory biodiversity credits from the government. This must be used only as a last resort.

The government will use the revenue to invest in habitat creation in England.  

How will this affect your planning application?

The BNG requirements are introduced on a phased basis:

  • major developments and Priority Habitat Sites from Monday 12 February 2024
  • small sites from Tuesday 2 April 2024

An application will be exempt if it is:

  • permitted development
  • a householder application
  • a development impacting habitat of an area below a threshold of 25m2, or 5m for linear habitats (De Minimis)
  • a biodiversity gain site
  • a small-scale self-build and custom housebuilding

How will Planning secure BNG

We will use planning conditions or a legal agreement to secure on-site habitat enhancements. You will need to secure and maintain the enhancements for at least 30 years. Other potential conditions may include monitoring and reporting arrangements. We are likely to use a legal agreement ( Section 106 agreement) to secure any off-site enhancements, including their management and monitoring.

What you need to submit as part of your application

All developers must submit a:

  • Biodiversity Net Gain Statement
  • site plan, drawn to an identified scale marked with the direction of north, showing on-site habitat existing on the date of application (or an earlier date), including any irreplaceable habitat
  • completed biodiversity metric (as an Excel-file type), for both pre-development and post-development
  • a draft BNG plan

You have to submit a final Biodiversity Gain Plan, which we must approve, before you start work. You need to provide us with a draft version of the plan with your application.

You also need to submit a Habitat Management and Monitoring Plan (HMMP), to show how you will manage and monitor the biodiversity enhancements for at least 30 years.

You can download a:

which you need to complete and submit as part of your application.

You must submit both plans through the CCC Discharge of Conditions process

Further guidance
You can find more details about BNG on GOV.UK.

Page last reviewed: 5 March 2024


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