In one of the largest environmental policy changes in decades, most planning permissions granted in England will be required to deliver a minimum of 10% biodiversity net gain (BNG) as of 12 February 2024.
Under the Environment Act 2021 via secondary legislation in the Town and Country Planning Act 1990, small sites are obligated to demonstrate a BNG of 10% as of 2 April 2024 (November 2025 for NSIP’s), and new habitats must be secured for at least 30 years.
This applies to applications submitted on or after 12 February 2024, and yet, there’s still a lot of confusion about BNG legislation. So, what do these changes mean? Here are the key points you need to understand.
Biodiversity Net Gain Exemptions
First, here are the exemptions to these new policy changes.
- Permitted Development and Crown Development (excluding sites in conservation areas);
- Land with habitats below the ‘de minimis’ threshold (under 25 square metres of habitats or under 5 m of hedgerow/watercourse) and do not impact a ‘priority habitat’;
- Off-site gain developments (such as habitat banks);
- Certain self-build and custom build developments;
- Change of use applications;
- High-speed railway networks;
- Householder applications.
BNG: The Planning Process
To offset the environmental impact of a development, there are 5 steps to follow during planning
1. Check Local Plans
Some LPAs will have specific BNG requirements. Assessing the Local Plan is vital, as 10% net gain is the bare minimum, and some sites may need to achieve a higher percentage.
2. Pre-Application Advice
Developers can query local requirements and consider a mitigating hierarchy application (if feasible). For a mutually beneficial outcome for BNG requirements and the functionality of the site, involve an ecologist as soon as possible.
3. Planning Application
A Biodiversity Gain Statement must be submitted during the planning application. Providing as much information as possible here will reduce future requirements, and the time between determination/commencement of work.
What should be included?
- the pre-development biodiversity value;
- steps taken to minimise adverse biodiversity impacts;
- the proposed approach to enhancing biodiversity on-site;
- any proposed off-site biodiversity enhancements (including the use of credits) for the development.
4. Off-Site BNG
If an application can’t deliver 10% (or as per Local Plan) BNG on site, developers must show off-site BNG improvements through a S106 agreement or conservation covenant. Developers with large land portfolios can use this land as off-site BNG, but the further the off-site land is from the application site, the fewer units it will contribute to the BNG.
If developments can’t show a 10% net gain on or off-site, Local Authorities may use their own land as off-site biodiversity units to developers in their Local Plans.
Locating off-site land is the responsibility of the developer and must be registered on Natural England’s off-site register.
5. Discharge BNG Conditions
When planning permission is granted, schemes are subject to the submission of a biodiversity gain plan. DEFRA have a template available for this, which must be sent for approval to the LPA.
Be sure to include:
- a completed statutory biodiversity metric calculation;
- pre and post-development plans (showing the location of on-site habitat, the direction of north and drawn to an identified scale);
- a compensation plan if the development impacts irreplaceable habitats;
- biodiversity net gain register reference numbers if you’re buying off-site units;
- proof of purchase if you’re buying statutory biodiversity credits;
- a habitat management and monitoring plan.
Trading Rules: Don’t Get Caught Out
The Environment Act has strict trading rules on habitat creation and enhancement to compensate for habitat losses. The table below shows examples of habitats that fall under the medium distinctiveness category.
As you can see, a habitat creation of low distinctiveness wouldn’t meet BNG requirements in this example. But a habitat creation of the same group (medium) or high/very high habitat creation would.
Where possible, explore areas of existing ecology and landscaping that can be retained, rather than removing or replacing them.
What Happens if You Have a Net Loss?
If developers are at a biodiversity net loss, it’s likely that penalties will be implemented to offset those losses.
Many off-site providers will transfer the loss of a habitat area (ha) into units based on distinctiveness, condition, and habitat type before settling on a price per unit. Conservation groups, wildlife trusts, or Local Planning Authorities may then use these units to fund areas to achieve the 10% increase in biodiversity.
If BNG can’t be achieved on or off-site, the Government’s Statutory Credit scheme is available. However, credit prices can range drastically depending on the habitat. In many cases, 2 credits will be equal to 1 unit, and the cost of that unit can reach upwards of £125,000 depending on the type.
In other words, purchasing credits should be a last resort.
UPDATE: As of April 2, 2024, BNG is now mandatory for all ‘small’ developments.
What is a ‘Small Development’?
A small development doesn’t fall into the category of a major development, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
A small development could include a:
- Residential development where the number of dwellings is between 1 and 9 on a site of an area 1 hectare or less, or if the number of dwellings is unknown, the site area is less than 0.5 hectares.
- Commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare.
- Development that is not the winning and working of minerals or the use of land for mineral-working deposits.
- Development that is not waste development.
What is the ‘Small Sites Metric’ (SSM)?
It’s essentially a simplified version of the Statutory Biodiversity Metric, with a reduced number of habitat types and simplified condition assessment methodology.
Some key differences include how and when the SSM can be used. In summary, the SSM can only be used when:
- The development falls under the definition of a ‘small development’.
- There are no priority habitats present on site.
- Only the habitats available in the SSM are present on site.
- There are no statutory protected sites or habitats present on site (such as SSSIs).
- There are no European protected species present on site (such as bats, great crested newts, or otters).
Like the Statutory Biodiversity Metric, the requirement is to deliver 10% BNG, and meet the trading rules for all habitats on site. If you have a small development, the SSM doesn’t necessarily need to be used, and the Statutory Biodiversity Metric can be used in its place.
Achieving BNG on a Small Site
Even with limited space on a small site, several BNG solutions can be implemented.
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Collaborate on BNG at the earliest opportunity of the design process
Early consideration of BNG at the design stage will help you understand the constraints and opportunities from the get-go, reducing issues later in the planning process. Collaboration between your design team, ecologist, landscape architects, and drainage designers will maximise biodiversity opportunities on site.
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Implement Sustainable Urban Drainage (SUDs) and Green Infrastructure (GI)
Several GI solutions can be incorporated into a small development, including the provision of green roofs and green walls on buildings, which help incorporate biodiversity units without taking away development space (these will need to be designed in the early stages due to potential additional structural costs).
Suitably designed and managed SUDs can also deliver both urban drainage and biodiversity solutions to small developments.
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Maximise floral diversity and native planting on site
Work with our native species to create a botanically diverse planting scheme on site, including the provision of native tree and shrub species. Look at utilising wildflower rich grassland instead of standard amenity grassland to increase the diversity of the site and implement a relaxed mowing regime to allow wildflowers to flower all year round.
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Look to utilise a Habitat Bank
Habitat banks are also available to provide off-site biodiversity units to offset any losses that are on-site. Tetra Tech is working in strategic partnerships with leading habitat banks to support clients in achieving effective management of their BNG requirements.
The requirements for BNG for small site developments is a large step away from what was previously required. Early engagement with planners, ecologists, arborists, and landscape architects is key to achieving BNG in a cost-effective way.
Potential Future Changes
All planning applications require foresight, attention to detail, and guidance to prevent potential issues.
But when you also factor in environmental policy changes (which can be subject to unexpected revisions and alterations), it can feel like an insurmountable road to site commencement.
We’ll continue to update this page to ensure you’ve got the most recent news and insights on any potential changes to BNG legislation. And if you’re concerned or confused about how to navigate this new policy, don’t hesitate to: