What is Biodiversity Net Gain?

Biodiversity Net Gain (BNG) is a term that is becoming commonplace in the wildlife conservation and planning and development sectors. Whilst the term "net gain in biodiversity" has been around for a while, when we speak about BNG, what is being referred to is the BNG requirement mandated by the Environment Act 2021. The Act introduces a legal requirement for development to achieve a 10% increase in biodiversity, measured using the Biodiversity Metric - a calculator tool developed by Natural England for the sole purpose of measuring BNG.

BNG is one of the tools to be used to deliver upon the Government's commitments to securing nature's recovery and protecting 30% of the UK's land and sea by 2030. In short, BNG is a mechanism which enables development to leave the environment in a measurably better state than it was before the development. The key is the inclusion of the term "measurably", as previous attempts to promote a consistent approach to development which delivered benefits for nature have fallen short of the mark, with enhancements taking the form of small wildlife strips or the addition of bat and bird boxes to developments.

Under the Environment Act 2021, all planning permissions granted in England (with a few exemptions) will have to deliver at least 10% biodiversity net gain. Through our work with the Kent Nature Partnership, Kent Wildlife Trust are advocating for Districts across Kent to adopt policies that go above the minimum requirement and secure 20% BNG. Kent is not alone in its aspiration to achieve higher gains for nature, and we can learn from those Districts that have recently adopted Local Plan Policies for 20% BNG, like Guildford.

Developer requirements under Biodiversity Net Gain

To achieve BNG, developers may need to implement a range of measures, such as creating new habitats, enhancing existing habitats either on or offsite, with these gains secured by a legal agreement for at least 30 years. Offsite BNG allows landowners the opportunity to put forward their land to create or enhance habitats, with funding for these works being linked to a specific development. This is something that local councils can explore on their own landholdings, and the Kent Wildlife Trust Consultancy Service would be pleased to explore opportunities with you.

A common misunderstanding of BNG is that it is a mechanism solely aimed at unlocking development - providing an excuse to destroy habitat in one place and off-set these losses somewhere “more convenient”. But, because BNG is an additional requirement, and does not replace existing obligations to avoid impacts to wildlife and enhance habitats for protected species, this should not be the case. At the core of delivering BNG is the mitigation hierarchy which requires that impacts to wildlife are first avoided, then mitigated and only as a last resort should their losses be compensated for. If done well, BNG presents the best opportunity that the sector has had to make a positive impact on tackling the ecological emergency and leave a positive legacy for both people and wildlife.

Making Biodiversity Net Gain measurable

One of the key features that sets mandatory BNG apart from any previous planning requirements for biodiversity is the fact that it is measurable. Whilst some concern will likely always remain in the sector regarding how values are attributed to different habitat types, providing this clear-cut assessment means that ecologists, developers and planning officers can all be on the same page and an objective assessment of biodiversity can be undertaken. There is however likely to be an ongoing challenge, particularly in the early days of BNG delivery, with the metric not being completed in line with guidance and best practice and not being supported by sufficient evidence. Kent Wildlife Trust’s Planning and Policy Team are already providing advice and comments to local planning officers to push for BNG assessments to be held to the highest standards, including the need for habitat creation and enhancement plans to be realistic and deliverable.

What are the principles of Biodiversity Net Gain?

The principles are as follows:

• Principle 1. Apply the Mitigation Hierarchy
• Principle 2. Avoid losing biodiversity that cannot be offset by gains elsewhere
• Principle 3. Be inclusive and equitable
• Principle 4. Address risks
• Principle 5. Make a measurable Net Gain contribution
• Principle 6. Achieve the best outcomes for biodiversity
• Principle 7. Be additional
• Principle 8. Create a Net Gain legacy
• Principle 9. Optimise sustainability
• Principle 10. Be transparent

These good practice principles are intended to guide developers, ecologists, planners, and other stakeholders in implementing BNG effectively in development projects in England, and to promote sustainable development that enhances biodiversity and contributes to nature conservation efforts. Local Planning Authorities should look to incorporate these best practice principles within planning policies and supporting documents, to ensure that the best outcome for people and wildlife is achieved.

Local development plans

At the heart of securing good quality BNG is embedding clear and ambitious policies within Local Development Plans. These Local Plans provide the framework for development in the local area and present an opportunity for Districts to set out how BNG should be used to support local nature recovery. Kent Wildlife Trust have been advocating for a commitment to deliver 20% BNG across Kent and are hugely supportive of the number of local authorities in Kent that are proposing a policy for 20% within their draft Local Plans. They will need to demonstrate that the need for the higher target is supported by evidence, and that it is both viable and deliverable within the local area.

Evidence for 20%

It is important to recognise that the figure of 10% has not been identified as the percentage of biodiversity gain required to halt the biodiversity crisis. Whilst 10% BNG is the minimum required by the Environment Act, its legislative status does not mean that this is all that is required to meet the UK’s commitments to natures recovery. This justification for the need to adopt a higher percentage of BNG has been used by local authorities in other counties who have successfully included a 20% BNG policy in their Local Plan.

Viability of 20%

There is a misconception that 20% BNG equates to double the area of land required and double the costs. A Kent wide assessment has demonstrated that this is not in fact the case and that the increase to 20% BNG is not as significant as many would expect, particularly when looking at provision of BNG entirely within the development site. Whilst each LPA will need to look at viability within their own district as local factors that influence viability will vary, the numerous Districts across the UK paving the way for securing more ambitious targets should provide confidence of its achievability.

Is 20% deliverable?

The deliverability of 20% BNG is going to be dependent on the availability of sufficient sites for delivering BNG to meet the demand generated by the Districts development allocations, effectively undertaking an assessment of supply and demand of BNG units across the county or district. Whist a proportion of BNG will be delivered within the boundary of development site, in instances where this is not possible nor achieves the best outcome for biodiversity then BNG can be delivered outside of the development site. The supply of these offsite units will soon be easily identifiable within the 'Kent BNG Sites Register'. This is a tool that Kent Wildlife Trust was commissioned to develop on behalf of the Kent LPAs. The Register effectively provides a catalogue of sites available to deliver off-site BNG and can be used by landowners to advertise their BNG sites, by developers to identify suitable sites and for LPAs to support their decision making and evidence requirements.

So, what can Parish and Town Councils do to support BNG in your area which delivers the best outcomes for local residents and wildlife alike?

• Advocate for, and work with, District Councils to embed strong Local Plan policies for BNG which seek to deliver above the statutory minimum 10% and integrate good practice principles.
• Include a BNG policy with Neighbourhood Plans which supports the Local Plan Policy whilst defining principles of what good BNG looks like in your local area, looking at creating wildlife corridors locally and delivering benefits that support and engage the local community.
• Engage in proactive conversations with developers in your area about BNG delivery.
• Explore opportunities for delivering offsite BNG within council owned land holdings to support local priorities.

For support on any of the above steps, you can contact our Planning and Policy team.

The success of BNG is going to be contingent on having strong local policies and clear national legislation, policy and guidance. There is time for the former to be developed and implemented, but the clock is ticking for the latter. There remains significant uncertainty for developers and local planning authorities given the lack of national legislation or guidance. Following delays to the start of mandatory BNG until January 2024 (previously November 2023) we now have a clear timetable from Defra and Natural England on when this information is expected. Whilst the delay came as a disappointment, we are hopeful that the delay will be used as an opportunity for the Government to support local planning authorities to prepare for the start date of mandatory BNG and to support its continued success.

References

• Environment Act 2021
• Biodiversity Metric 4.0
• Biodiversity Net Gain: Good Practice Principles for Development