Biodiversity Net Gain (BNG) will become a default component of the UK planning system. Major developments currently, from February 2024, will have to show how they will deliver at least a 10% gain in biodiversity through planning permission. This is a major change, under the Environment Act 2021, in how the effect of the development on the environment is determined—and mitigated.
For developers, BNG is becoming indispensable. It influences how projects are designed, valued, consented and built.
What Is Biodiversity Net Gain?
Biodiversity Net Gain is to leave the area they end up in measurably more beneficial for the natural world than it was when they first arrived. Developers must consider the baseline value for nature that the land has, and then show how they will add to it—by preserving existing elements, rehabilitating ecosystems, or adding new biodiversity value in green infrastructure.
- Legal and Policy Background
BNG was put on the statute book through the Environment Act 2021 and was to become fully operational for major developments from February 2024. The key requirements are:
- Minimum of 10% net biodiversity gain
- The benefits must be secured for a minimum of 30 years
- Delivery to be secured through planning conditions or Section 106 agreements
They apply to Town and Country Planning Act 1990 planning applications and are enforced by LPAs.
- What Schemes Will Be Impacted?
Most major schemes—residential, commercial, and infrastructure development schemes—will be subject to requiring BNG. Small householder schemes and some permitted development rights are exempted, although in most instances, planning applications will include BNG as a standard submission requirement.
- How Biodiversity Net Gain is calculated
Developers will be asked to use the Biodiversity Metric—a technique created by Natural England. It measures biodiversity in “units”, which differ by:
- Habitat type
- Area
- Condition
- Distinctiveness
At least a 10% improvement must be shown in a pre- and post-development investigation. The metric has to be supported with ecological survey data and included in the planning application.
- On-site vs Off-site Delivery
BNG can necessitate delivery:
- On-site – within red line boundary of development
- Off-site – on other land controlled or owned by the developer
- By utilizing biodiversity credits – bought from government, if this is the only alternative
On-site provision is to be preferred, but off-site benefits are permitted if sufficiently justified and legally tied to the required 30-year period.
- How BNG Affects Site Design
BNG is transforming site planning. Habitat and ecological value incorporation at an initial stage is now able to directly influence layout and land use. The traditional approach entails:
- Retention and enhancement of existing features
- Such as wildflower meadows, wetlands, or woodland planting
- Construction of wildlife green corridors
- Including SuDs that also enhance biodiversity
- Prioritizing native planting and multi-layer habitats
Working alongside ecologists and landscape architects is now inevitable.
- Planning and Budget Issues
BNG imposes cost and planning. Developers are required to:
- Budget for survey, ecological surveys, and design consultation
- Develop long-term habitat management plans
- Cover the cost of prices in law agreements, monitoring, and handover
- Consider land value effects where handing over off-site or crediting
Lack of proper planning can cause delays in checking or denial of planning consent.
- Long-Term Value and Strategic Advantage
BNG is not just a regulatory hurdle—it can generate value too:
- Improves site amenity and attractiveness
- Builds purchasing attractiveness, occupation, and investment attractiveness
- Increases green credentials and ESG commitments
- Minimizes local resident and stakeholder objection
- Improves working together with planning officers
Done well, BNG can be an asset—not a liability.
- Consequences of Non-Compliance
Non-compliance with BNG or the generation of lower-quality assessments has the following consequences:
- Planning rejection
- Invalidity and delay
- Judicial challenges or enforcement notices
- Damage to reputation with communities and councils
Preventing this requires developers to:
- Appoint experienced ecological consultants
- Kick-start BNG assessments as early as possible in design processes
- Use the appropriate metric measure and include complete supporting data
- Secure adequate legal agreements for delivery and monitoring
Last Word
Biodiversity Net Gain is now at the forefront of UK planning. It’s not necessarily about nature conservation but about advancing schemes that are future-proof on sustainability, climate resilience, and community benefit.
For developers, the challenge is to consider BNG part of the plan and design process, not a last-minute hurdle. They who do will not only be compliant, but they also gain an advantage in planning permission, site quality, and marketability. Contact Planning Consultants London for more information.