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Biodiversity Net Gain (BNG)

Use this page to understand the ideas behind BNG, who it affects, how we are involved as your Local Planning Authority, and how you can meet the requirements when submitting your planning application.

Understanding BNG

Biodiversity Net Gain (BNG) is a new process designed for the planning system to make sure new development delivers a net positive impact on the natural environment. It requires new developments to be designed and planned in ways that minimise any loss and damage to existing habitats, and then to compensate and off-set any damage caused.

See the section on how to deliver the BNG requirement, below, for more detailed information and guidance.

What is meant by Biodiversity Net Gain?

Biodiversity Net Gain is defined as the achievement of measurable gains for biodiversity through new development i.e., biodiversity is left in a measurably better state than before development commenced.

Select a topic below to read more about how the policy has evolved.

National Policy

The delivery of BNG is set to become a mandatory requirement of the planning system from January 2024 onwards. It directly affects people who need to secure planning permission for new projects above a certain size. It will be unlawful to issue a planning approval for any qualifying project that does not secure 10% BNG, with 30-year management and monitoring.

This will apply to small sites from April 2024, and implementation for Nationally Significant Infrastructure Projects is planned for 2025.

The National Planning Policy Framework (2019) sets out that planning policies and decisions ‘should contribute to and enhance the natural and local environment, by minimising impact on and providing net gains for biodiversity…’

The Environment Act (2021) contains a new BNG condition for planning permissions.

The Government will be providing secondary legislation, guidance, and tools to support its implementation of this policy.

B&NES Policy

In July 2020, we declared an Ecological Emergency, recognising the severity of the degradation of the natural environment and loss of wildlife, and the urgent need to act to restore nature.

Read more about what we are doing to address the Ecological Emergency

We committed to bringing forward the requirement to deliver BNG for local planning applications through our Local Plan Partial Update (LPPU). Policy NE3a (Biodiversity Net Gain) gained full statutory weight when we adopted the LPPU on 19 January 2023.

What BNG means for your planning application

Qualifying developments will have to demonstrate, and then deliver, measurable net gains for biodiversity which must be secured, managed, and monitored. The exact requirements, and methods are different for different categories of application.

Select a topic below, to understand in more detail what this may mean for your application.


Householder applications, changes of use, and permitted development are all exempt from the full BNG requirements of policy NE3a. However, we will still expect you to show that you have considered biodiversity, and to deliver habitat and species enhancements, as part of your planning application. These could include simple additions, such as the provision of integrated bird and bat boxes, or the use of native and nectar-rich species within landscaping schemes, for example.

Opportunities to secure Biodiversity Net Gain on householder developments.

Major applications

Major planning applications will be expected to deliver a minimum of 10% biodiversity gains, with habitat management and monitoring secured for at least 30 years. The gains must be calculated using the main government metric.

Minor applications

Minor planning applications are expected to demonstrate no net loss, and appropriate net gain, using the latest DEFRA Small Sites metric (or agreed equivalent.)

Delivering BNG

All planning projects subject to BNG requirements should consider BNG from the very outset, prior to site design, and ideally at site selection stage to help minimise the need for providing replacement habitats.

We have produced guidance to support the implementation of Local Plan Partial Update (LPPU) policy in this interim phase. This guidance reflects our best understanding of developing BNG practice.

For support on how to deliver BNG requirements for your development, see our list of guidance and resources.

The Mitigation Hierarchy

The mitigation hierarchy is a concept designed to help minimise the impacts of development and is a critical element of the BNG process. It can be used to help minimise the habitat off-setting and gains required.

The concept requires site planning and design to consider biodiversity from the outset. Harm to biodiversity must always first be avoided and then minimised. Where avoidance of harm is not possible, mitigation approaches should be used, and as a last resort, compensation, and off-setting.

On-site BNG provision

Biodiversity gains can often be achieved within a development site and can be linked to the provision of green spaces (such as community orchards and landscaped areas). These gains are usually referred to as on-site gains and will often be the preferred solution. These can help to achieve good placemaking, providing better places to live and work, and ensuring communities have good access to nature-rich sites.

Off-site BNG provision

There will be some circumstances when the full BNG requirement cannot be met on-site within the application site boundary. In these circumstances off-site BNG habitat will be required.

We recognise that we have an important role to play and are exploring ways that off-site habitat gains can be successfully achieved and delivered, including the role Council land could play.

For more information about our BNG off-site provision projects, please email us at

View BNG guidance and resources