Under the Environment Act, developers must achieve biodiversity net gain (BNG) on all qualifying development projects. This means delivering a 10% net gain in biodiversity value compared to the site’s baseline, using the statutory biodiversity metric or small sites metric.
This blog outlines practical biodiversity net gain examples: how developers are meeting the 10% requirement. Whether through on-site habitat improvements, off-site biodiversity units, or, in rare cases, statutory biodiversity credits, we explain how developers are aligning with the biodiversity net gain regulations and how Civity helps navigate the process.
Understanding the 10% Net Gain Requirement
To deliver biodiversity net gain, developers must:
- Assess the baseline biodiversity units using the statutory biodiversity metric tool or the small sites metric.
- Compare pre-development biodiversity value with the proposed post-development value (after habitat creation, enhancement, or retention).
- Achieve a minimum 10% uplift in units via a legally secured biodiversity gain plan.
- Off-site biodiversity gains must be secured through a legal agreement—either a Section 106 agreement with the Local Planning Authority or a Conservation Covenant with a Responsible Body. On-site gains do not require registration but may still require a legal agreement and must be delivered and maintained in line with the approved Biodiversity Gain Plan and local planning conditions.
- Ensure a minimum of 30 years of land management and monitoring to preserve those gains.
This process applies to the majority of full planning permissions granted after February 2024, including minor developments and small sites.
Example 1: On-Site Habitat Creation and Enhancement
Description
Some development sites are well-suited to achieve BNG entirely on site, especially where space, context, and habitat baseline allow. This is often the case for low-density housing schemes or brownfield sites with low existing biodiversity.
How Developers Achieve On-Site Gains
- Enhance existing features such modified grassland, ponds, or on-site linear habitats such as hedgerows
- Integrate tree planting, wildflower meadows, green infrastructure, and SuDS.
- Apply the mitigation hierarchy to retain irreplaceable or sensitive habitats and build around them.
Outcome
- 100% of the gain is delivered on the developer’s own land within the red line boundary.
- No need to source off-site compensation (i.e. biodiversity units)
- Full alignment with the biodiversity gain hierarchy, maximising the natural environment benefits at the site itself.
- A legal agreement may still be needed to secure on-site gains.
Good Practice Tip
Achieve on-site gains early by integrating biodiversity into design from the outset. Developers should coordinate ecological advice, drainage strategies and access public realm design to enhance the on-site habitat network.
Example 2: Combining On-Site and Off-Site Biodiversity Gains
Description
Where space is limited or development intensity is high, it’s not always possible to meet the full 10% on site. In these cases, developers often blend on-site biodiversity gains with off-site BNG purchases from third-party providers.
How Developers Balance the Requirement
- Deliver as much as possible on site, such as enhancing on-site habitats, creating small wildflower areas, planting trees and hedgerows or restoring existing biodiversity assets.
- Source the remaining units via off-site biodiversity gains from a registered gain site on the biodiversity gain site register.
Outcome
- A proportion of the gain is delivered on site, with the remaining delivered through purchase of off-site biodiversity units.
- The developer meets their mandatory biodiversity net gain obligation without compromising build density or viability.
- The off-site component aligns with wider national (ideally local) conservation efforts.
Good Practice Tip
Work with a specialist like Civity to secure units from registered gain sites. We ensure the off-site delivery is legitimate, auditable, and aligned with the developer’s biodiversity metric and gain plan.
Example 3: Using Statutory Biodiversity Credits (Last Resort)
Description
In exceptional cases, developers may be unable to meet BNG on or off site. This may occur where there are no suitable off-site BNG suppliers.
Statutory Credit Purchase: Requirements and Evidence
Before purchasing statutory biodiversity credits from the government, developers must first demonstrate that on-site and off-site options have been fully explored and are not deliverable.
This includes:
- A clear explanation of why delivering the full 10% Biodiversity Net Gain (BNG) requirement is not feasible within the boundary of the development site.
- Evidence that alternative off-site solutions have been sought and are unavailable.
To meet this requirement, the Biodiversity Gain Plan must include proof that the developer has approached at least three separate off-site unit providers – this may include habitat banks, specialist brokers, or national trading platforms.
Acceptable forms of evidence might include:
- Emails or letters showing engagement with unit providers.
- Screenshots from trading platforms demonstrating no matching units.
- Downloaded reports or search logs confirming no availability of required habitat types and locations.
Only once all reasonable efforts to secure on-site and off-site units have been documented can a developer proceed to purchase statutory biodiversity credits from Natural England to address any outstanding shortfall.
The use of statutory credits must be clearly recorded in the Biodiversity Gain Plan and will be subject to review and approval by the Local Planning Authority.
Outcome
- Statutory credits are used to reach the 10% uplift.
- Typically more expensive than other options and subject to scrutiny.
- Acceptable only if consistent with biodiversity net gain legislation and subject to the biodiversity gain condition in the planning permission.
Good Practice Tip
Statutory credits should only be used once off-site compensation and on-site enhancement options are proven infeasible. Planning authorities will require documentation to justify this route.
Supporting Developers to Achieve Biodiversity Net Gain
At Civity, we help developers meet their biodiversity net gain requirements in a compliant and efficient way. We:
- Review the submitted biodiversity metric calculations.
- Quote for the correct number and types of units – providing our most cost-effective option.
- Help quantify and allocate off-site biodiversity units from our registered habitat banks.
- Assist in completing the biodiversity net gain plan, including referencing relevant local planning authority, site location, unit breakdowns and legal agreements.
We work consultatively with your ecologist, planning consultant and legal advisor to ensure seamless integration of BNG into your wider development proposals.
Delivering BNG in Practice
These biodiversity net gain examples of how developers are meeting the 10% requirement demonstrate that BNG is achievable across a wide range of development sites.
Key takeaways:
- Create biodiversity on site wherever possible
- Source off-site biodiversity units responsibly.
- Only purchase biodiversity credits where no other option is feasible.
- Align with BNG on-site best practices and your relevant local planning authority’s expectations.
With the right technical input, legal oversight and delivery support, developers can consistently achieve biodiversity net gain.
To explore how Civity can support your planning application, secure off-site units, or assist with your biodiversity net gain plan, please get in touch.
