Biodiversity Net Gain

Biodiversity is the variety of all living things including species, habitats and ecosystems.

Biodiversity net gain (BNG) is an approach to planning and land management that leaves the natural environment in a better state than it was before. BNG will deliver measurable improvements for biodiversity by enhancing or creating new habitats in association with development.

The Council is committed to protecting, conserving and enhancing our natural environment and BNG will help to deliver the objective set out in the Sustainable Economy Strategy to improve, manage and promote biodiversity and nature recovery.

We are currently considering how best to implement BNG and we will be publishing guidance to help guide you through the process.

Government guidance on biodiversity net gain can be found on the GOV.UK website.

There has been and continues to be a significant decline in biodiversity in the UK. This is despite legislation and policy to protect biodiversity and wildlife. Whilst designated nature conservation sites and priority habitats are of significant value, the overall ecological network of habitats and species is important for biodiversity and nature recovery.

Measures to benefit nature including BNG can also have positive effects on other priorities and goals. For example, BNG will contribute to access to greenspace, place-making and improvements to air quality which are all important for health and wellbeing. It will also help to increase resilience to the effects of climate change.

The requirement for BNG does not alter the existing legal requirements and protections for the natural environment such as protecting important habitats and species.

From 12 February 2024, all major planning permissions granted in England will have to deliver a minimum of 10% BNG under the Environment Act 2021. BNG will be mandatory for small sites from 2 April 2024. Certain developments are exempt from BNG.

You will need to submit information on BNG with the planning application and, if granted planning permission, a Biodiversity Gain Plan showing how BNG will be achieved must be approved by us prior to commencement of development.

In addition to national requirements, there are also local requirements for the validation of planning applications. These are set out in the Local List.

The National Planning Policy Framework (paragraphs 180, 185 and 186) refers to net gains for biodiversity as do the site allocation policies in the Site Allocations DPD. Adopted District Plan Policy DP38: Biodiversity also refers to ensuring development contributes and takes opportunities to improve, enhance, manage and restore biodiversity and green infrastructure, so that there is a net gain in biodiversity.

BNG is calculated using the approved Biodiversity Metric which measures the biodiversity value of habitats in ‘biodiversity units’ as a proxy for nature. The Biodiversity Metric is used to assess how a development might change the biodiversity value of a site. It can help to inform the design, layout and management of a site to support biodiversity.

The application of BNG will require ecological expertise to interpret the inputs and outputs of the Biodiversity Metric.

Biodiversity net gain can be delivered on-site, off-site or through a combination of on-site and off‑site measures following the biodiversity gain hierarchy. It is also expected that the implementation of BNG should align with the local objectives and priorities for biodiversity improvements and nature recovery. Off-site BNG should also ideally be located in Mid Sussex District as close to the development site as possible so that local communities benefit from enhanced biodiversity and nature is given an opportunity to recover.

BNG should be meaningful; it should deliver demonstrable benefits for biodiversity both in the planning application process and in its ongoing implementation.

Appropriate funding, management and contingency arrangements will need to be in place to look after BNG for a minimum of 30 years.

BNG will be monitored by the Council and enforced if necessary. Failure to comply with the general biodiversity gain condition by commencing development without approval of the Biodiversity Gain Plan will be a breach of planning control. The initial delivery and ongoing management of BNG will also be monitored and enforced if necessary.

The Council will charge monitoring fees through a section 106 planning obligation to cover the cost of monitoring and reporting duties over the 30 years.  In addition to the monitoring fees, legal fees will also be levied.

The BNG monitoring fees will increase as the scale of development increases and the categories of development are the same as the categories used for pre-application advice.

The monitoring fees will be reviewed annually. The BNG monitoring fees for 2024/25 are as follows:

There will also be a £1,000 inspection fee for checking the initial BNG set-up in Year 0.

It is preferable to have a strategic approach for BNG so that BNG can be considered alongside wider priorities such as nature recovery, landscape, green infrastructure and resilience to the effects of climate change.

The mitigation hierarchy embedded in national policy should be followed and applied. This is where the impact on biodiversity should first be avoided, then minimised, then compensated as a last resort.

Higher levels of BNG (more than the minimum 10%) will be encouraged and developments should seek to maximise opportunities to deliver meaningful BNG.

Land managers may wish to consider using their land for biodiversity net gain. Identifying land for off-site biodiversity net gain provides an opportunity to enhance your land for nature and may be an income stream to help manage the land for biodiversity.

A habitat bank is a gain site which is not linked to a particular development and usually provides biodiversity units for more than one development.

Land will need to be registered as a biodiversity gain site using the Government’s online service

Land provided for off-site biodiversity net gain will need to be legally secured for this purpose for a minimum of 30 years.

A planning obligation (by way of a section 106 legal agreement) with the local planning authority or a conservation covenant with a responsible body will need to be used to secure the land.

An ecologist will need to calculate how many biodiversity units are available for the site and you will need to decide a price for each biodiversity unit.

The Council is keen that off-site biodiversity net gain sites contribute to the wider biodiversity, habitat and nature recovery priorities so you are encouraged to talk to us about your plans.

How much does it cost?

If the Council enters into a section 106 legal agreement with you, we will charge fees for:

• A set-up fee to cover the time we spend reviewing your proposal and drafting the legal agreement.
• An inspection fee in Year 0 to check the initial BNG set-up (e.g. habitat creation).
• A monitoring fee to cover the cost of monitoring and reporting duties over the 30 years.

Fees will be reviewed annually. The fees for 2024/25 are as follows:

Further information about off-site biodiversity net gain can be found on the GOV.UK website.

The Council is unable to recommend third party biodiversity gain sites, however, once we have a legal agreement to secure land as a biodiversity gain site (habitat bank), we intend to list them here as potential providers of biodiversity units. Please note the provision of biodiversity units is an open market and there may be other options available.

For information about the requirements for great crested newts, please see the Wildlife and Planning page.

For information about the requirements for planning applications within 7km of Ashdown Forest, please see the Protecting Ashdown Forest page.

Other biodiversity enhancements can also be important. Measures to help wildlife in your garden or development include:

• Bird boxes and roosts
• Bat boxes
• Swift bricks
• Bee bricks
• Insect hotels/ bug hotels
• Hedgehog highways
• Native wildflower planting with nectar- and pollen-rich flowers
• Rain gardens
• Adding water including a pond if you have space
• Keeping existing trees, hedgerows and streams
• Creating wildlife corridors and providing links to other areas of green space
• Lighting designed to avoid disturbing and harming wildlife