Pond - Sam Hanks
What is Biodiversity Net Gain?
Biodiversity Net Gain (known as BNG) is a new planning requirement designed to leave biodiversity in a measurably better state after development, such as housebuilding.
While development is not the only cause of our ongoing biodiversity crisis, BNG seeks to ensure that each development increases biodiversity and plays a part in nature recovery. Biodiversity Net Gain became mandatory for most development in England from 12th Feburary 2024.
What is Suffolk Wildlife Trust's position on Biodiversity Net Gain?
We believe that, done well, BNG could and should help to make development better for wildlife – and for people and businesses who benefit in so many ways from more and better nature-rich spaces. Done badly though, there is a risk that it may not improve ecological outcomes or aid nature recovery. In the worst cases, it could see development continue to result in biodiversity loss.
We want to ensure BNG is done well - that all development delivers genuine and meaningful biodiversity gains and helps to reverse biodiversity declines and to create a wilder Suffolk.
How will Biodiversity Net Gain be measured?
Natural England and the Department for the Environment, Food & Rural Affairs (Defra) have developed a tool, known as the Defra Metric, which uses information on the type, size, condition, and location of habitats to calculate their biodiversity value. This is measured in ‘Biodiversity Units’. The Metric is used to calculate the change in the biodiversity value, measured as an increase or decrease in Biodiversity Units, between pre- and post-development habitats. This will then tell developers if they need to do more to increase biodiversity as part of a proposed development.
How can developers achieve a gain in Biodiversity Units?
By creating new habitats or improving the condition of habitats that already exist on the development site (on-site) or away from the development site (off-site), developers will be able to increase the number of Biodiversity Units compared with pre-development levels. The starting point though should always be to avoid loss in the first place by retaining existing habitats.
Developers are encouraged to deliver BNG on-site if possible. If off-site Biodiversity Units are required, developers will have the option to buy the Units they need from a registered provider, or ‘habitat bank’, where habitats have been created or enhanced in advance. Alternatively, off-site BNG habitats might be created ‘to order’ based on the specific needs of a development.
Off-site BNG should be delivered in strategic locations to provide the greatest value for biodiversity, and sites will have to be registered with Natural England and submit regular reports on the condition of habitats.
Species enhancements, such as bat boxes or bird boxes, are still required in new developments but are not included in BNG calculations.
Do you need a Biodiversity Net Gain Assessment? Our Wilder Ecology team can help.
Do you need to buy off-site Biodiversity Units? Find out more about purchasing Biodiversity Units from Suffolk Wildlife Trust:
Who will check that biodiversity gains are being delivered?
Local planning authorities will be responsible for monitoring and enforcement, but the cost of this should be paid by the developer, who is ultimately accountable for BNG delivery.
BNG habitats must be maintained for a minimum of 30 years, but should ideally be retained in perpetuity.
You can find out more about BNG, and the role of local authorities, on the Local Government Association’s Planning Advisory Service website.
How does Biodiversity Net Gain affect other wildlife protections and planning requirements?
BNG is additional to, and does not remove or replace, other legal and planning policy protections and requirements such as those set out in the Wildlife and Countryside Act 1981 and national and local planning policy.
Development requiring planning permission will still have to assess the potential for impacts to designated wildlife sites, such as Sites of Special Scientific Interest (SSSI), and protected species like bats and hazel dormice. Any such impacts will still need to be addressed according to the mitigation hierarchy – 1) avoid, 2) mitigate, 3) compensate – separately from BNG, and may require a Natural England licence.
Will Biodiversity Net Gain mean Irreplaceable Habitats are lost?
No. Irreplaceable habitats are habitats that take a very long time to develop or are very technically difficult to recreate and have significant protection in national planning policy. Development that would result in loss or damage to irreplaceable habitats will not normally be permitted. BNG will not change this.
Biodiversity Net Gain and Nature Recovery
BNG could help to reverse biodiversity declines and increase nature in Suffolk by creating and restoring priority wildlife habitats where they will become part of a Nature Recovery Network, working at a local, county, and national scale.
To achieve this, it is essential that we have ambitious local BNG policies and frameworks that ensure development delivers significant and meaningful increases in biodiversity and the right habitats are created in the right places and retained and managed in perpetuity.
We are encouraging local authorities in Suffolk to help ensure BNG supports nature recovery by:
- requiring new development to deliver at least a 20% increase in biodiversity,
- delivering a proportion of BNG for every development through off-site measures that support wildlife recovery in the wider landscape,
- preventing a ‘race to the bottom’ that could result from developers selling ‘excess’ biodiversity increases to offset biodiversity losses elsewhere.
You can read our policy advocacy briefing and recommendations for Suffolk local authorities, and the evidence we have gathered to support ambitious local policies:
Why we advocate a minimum 20% Biodiversity Net Gain
Suffolk’s wildlife is rich and varied, with most of our coastline and many of our remnant wetlands, meadows and ancient woodlands protected as nationally or internationally important for wildlife. These places face significant development pressures, both from new housing to meet the needs of a growing population and from the new energy infrastructure needed to reach UK Government net zero targets and bring offshore wind power into the national grid.
The UK Government has set the minimum level of BNG development in England must achieve at 10% – this is within the typical range of statistical uncertainty of most ecological studies and is the lowest level of gain needed to be reasonably confident that development will not result in a loss of biodiversity. But no loss is not the same as increasing biodiversity and a 10% minimum is simply too low to ensure genuine biodiversity gains.
To help protect and restore nature across our county, we believe all development should be achieving at least 20% BNG. Suffolk County Council has already adopted it own policy aim to achieve a 20% BNG within its own housing programme, and we want other local authorities and all new development in Suffolk to follow suit.
Read more about our recommendations and the evidence we have gathered to support more ambitious BNG policies in Suffolk: