What this means for you is simple:
If you're working on a development project, it's not just about reducing the harm your project might cause to biodiversity. You are now required to go further by ensuring that biodiversity is thriving once your project is complete more than before you started.
Who does BNG affect?
Like biodiversity, BNG policies impact many stakeholders, such as:
Local planning authorities
Communities
Government bodies
NGOs
Professional consultants.
Part of what makes BNG such an exciting progression for nature is the scale and breadth of involvement of different stakeholders to ensure we make meaningful impacts for nature.
Regarding developments subject to mandatory BNG under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021), the picture becomes more nuanced. BNG Applies to:
"Major developments" from the 12th of February 2024
"Small sites" from the 2nd of April 2024
Nationally significant infrastructure projects from late November 2025
Some examples of major developments include:
For residential developments where there are ten or more dwellings on a site of an area above 1 hectare in size
For commercial development, the floor space created should be more than 1,000 square metres, or the total site area should be 1 hectare and above.
Some examples of small developments which fall under mandatory BNG from the 2nd of April 2024:
For residential developments where there are one to nine dwellings on a site of an area up to 1 hectare.
For commercial development, the floor space created should be less than 1,000 square metres, or the total site area should be below 1 hectare.
Who is exempt from BNG?
Here is a summary of crucial exemptions to mandatory BNG:
Existing Planning Applications: Developments with planning applications submitted before the 12th of February 2024 are exempt from BNG requirements.
Variations of Planning Permission: Changes to existing planning permissions fall under transitional arrangements, detailed in the planning practice guidance.
Small Developments (Exempt until the 2nd of April 2024): As described above.
Developments Below the Threshold: Impacting less than 25 square metres of on-site habitat or 5 metres of linear habitats (e.g., hedgerows) without decreasing biodiversity value.
Householder Applications: Small projects by householders, such as extensions or loft conversions.
Biodiversity Gain Site: Developments for fulfilling BNG conditions for another project are exempt.
High-Speed Rail Transport Network: Any development part of or ancillary to the high-speed railway network as defined in the High-Speed Rail (Preparation) Act 2013.
Other Exemptions: As outlined by the Environment Act 2021, include urgent crown developments and those granted permission by a development order.
Self-build and Custom Build Applications are also exempt if the development:
Consists of no more than nine dwellings.
On a site ≤0.5 hectares.
Exclusively comprises self-build or custom housebuilding.
How long have I got to become compliant?
The best time to become BNG compliant was before the 12th of February 2024 implementation date for major developments; the next best time is today.
There are numerous reasons to begin incorporating BNG considerations into the development pipeline and planning process ahead of mandatory BNG requirements - especially from a portfolio perspective, where numerous assets in the development pipeline could become financially unviable when considering the subsequent BNG impact.
Getting a grasp of your exposure as a developer to BNG across your pipeline is prudent and can lead to significant savings in the long run.
Outside of the implementation dates that we have verified for major developments, small developments and NSIPs, there are currently instances of developers being asked to incorporate BNG into their planning application to meet a "no net loss".
This means that even when mandatory BNG is not required, the metric and subsequent on and off-site provision is being applied as a mechanism to measure and meet local planning biodiversity policy.
Ultimately, there is much more to BNG than compliance with the regulations, as duties of care and delivery of on and off-site BNG require considerable planning, stakeholder engagement and expertise.
With no current accreditation or mark of excellence in the industry, it is vital to ensure that BNG unit providers are contacted well ahead of immediate need and questions on delivery, viability and financial mechanisms.
How do I become compliant?
You must provide a minimum net gain of 10% to meet your Biodiversity Net Gain obligations. The 10% net gain is measured using the most current Defra BNG Metric (the statutory metric at the date of this article).
What does this mean? A straightforward way to look at it is:
If your development would remove 10 BNG Units, you would need to ensure that 11 BNG Units are delivered.
These units can be delivered utilising any combination of the below options while following the "Biodiversity Gain Hierarchy", which does not apply to irreplaceable habitats.
For guidance on calculating BNG units read or handy how to.
10 Principles for Effective Biodiversity Net Gain
CIRIA, CIEEM and IEMA have generated a comprehensive guide to help developers and stakeholders implement best practices that not only comply with regulations but also promote meaningful, lasting ecological benefits.
Apply the Mitigation Hierarchy
Prioritise avoiding impacts on biodiversity, minimising them where avoidance isn’t feasible, and only as a last measure, compensate for unavoidable losses. Compensation should be strategically placed if on-site actions are inadequate.
Avoid Irreplaceable Biodiversity Loss
Ensure that development avoids impacts on unique or critical biodiversity that cannot be replaced or offset, thus maintaining net ecological balance.
Be Inclusive and Equitable
Engage stakeholders early and inclusively during project design, implementation, and evaluation. Foster partnerships and distribute biodiversity benefits fairly among all involved parties.
Address Risks
Proactively mitigate risks related to biodiversity losses and gains. Utilise accepted practices to add contingencies that offset uncertainties and bridge the gap between biodiversity loss and full realisation of gains.
Ensure Measurable Contributions
Make tangible, quantifiable improvements to biodiversity and ecosystem services. Align these efforts with local, regional, and national conservation priorities to enhance accountability.
Achieve Optimal Outcomes
Use solid evidence and local expertise to guide decisions. Aim for compensation that matches or exceeds ecological equivalency, enhances connectivity, and delivers broader biodiversity benefits.
Provide Additionality
Go beyond pre-existing obligations to achieve conservation gains. Net Gain efforts should represent contributions that would not have occurred without the specific project initiatives.
Create a Lasting Legacy
Embed long-term strategies by collaborating with stakeholders, ensuring continuous management, securing funding, and adapting to changes such as climate impacts to sustain biodiversity gains.
Optimise Sustainability
Integrate biodiversity net gain with broader environmental goals to promote sustainable development that benefits society and the economy.
Maintain Transparency
Clearly document and communicate net gain processes, including methodologies and outcomes, in a timely manner. Share insights to foster knowledge and collaboration.
By following these principles, projects can balance progress with nature conservation, achieving gains that align with both local and global priorities for biodiversity.
How do I follow the Biodiversity Gain Hierarchy?
For on-site habitats with medium to very high distinctiveness (scoring four or above on the biodiversity metric), developers should first aim to prevent any adverse effects of their project.
If prevention is not feasible, they need to minimise these effects. In cases where development harms on-site habitats, the damage should be counterbalanced by improving current on-site habitats, creating new on-site habitats, using off-site provision, and, as an absolute last resort, buying statutory biodiversity credits.
By following the Biodiversity Gain Hierarchy and utilising on-site efforts, off-site units, or, as a last resort, statutory biodiversity credits, developers can meet their obligations while contributing to the health and vitality of England's natural habitats. The journey to compliance is not just about adhering to regulations; it's about fostering a sustainable future where development and nature thrive together.
The likely outcome is that for most planning applications, a considered mix of avoidance, mitigation, on-site and off-site BNG Unit provision will be needed to achieve a 10% biodiversity net gain while ensuring that the development remains viable financially and for the intended end user.
Three ways to become compliant
In practice, there are three avenues that developers can utilise to achieve BNG compliance once avoidance of on-site impact has been maximised, and they can use any combination of the three solutions as long as they follow the Biodiversity Gain Hierarchy:
On-site Units
Through conscious design, developers should first attempt to provide up to 100% of their required Biodiversity Net Gain within the development boundaries.
Off-site Units
Developers can enhance biodiversity on land they own outside the development area or purchase off-site BNG Units on the market.
Statutory Biodiversity Credits
If developers cannot secure their biodiversity net gain requirements via on-site or off-site BNG provision, they must purchase government-issued biodiversity credits as a final option. The Government will use the funds from these credits to create habitat projects in England.
Biodiversity net gain is a transformative approach to development that minimises harm to biodiversity and actively enhances it. This approach, mandatory for various development projects in England, reaches across a broad spectrum of stakeholders and requires careful planning and engagement.
On-site and Off-site Units - What does it mean?
On-site Biodiversity Net Gain refers to actions taken directly within the development site to improve biodiversity.
This involves enhancing the quality or quantity of natural habitats and ecosystems where the development occurs. The goal is to leave biodiversity in a better state than before development.
Off-site Biodiversity Net Gain is when improvements to biodiversity are made at a different location from where the development is happening.
This can be necessary when there needs to be more than on-site improvements. It may involve investing in or creating habitats elsewhere or supporting projects that improve biodiversity outside the development area.
The primary difference between on-site and off-site Biodiversity Net Gain is where biodiversity improvements are made.
On-site measures are implemented within the boundaries of the development project, aiming to integrate conservation with development.
Off-site measures are taken elsewhere, usually when on-site improvements can't fully address the biodiversity losses caused by the development.
Another critical difference between the two types of BNG provision is the varying risks and implementation difficulties.
For example, on-site provision of BNG can be exposed to additional stakeholders, such as the residents who purchase and live in the development area and their perception of biodiversity and its aesthetic impact compared to their use of the areas.
Get your planning application approved with a Biodiversity Gain Plan.
Developers who fail to submit a Biodiversity Gain Plan will not get their planning application approved by LPAs.
That’s more delays and resources needed before you can start.
A Biodiversity Gain Plan done by ecology experts helps you meet stipulated deadlines, avoid potential financial pitfalls and ensures environmental stewardship.
