BNG Rollback: What is at Stake for Planning and Nature?

The UK Government has launched a consultation on proposals to significantly relax Biodiversity Net Gain (BNG) requirements for small to medium-sized developments. The eight-week consultation, running until 24 July 2025, has drawn sharp criticism from environmental groups including the Berkshire, Buckinghamshire & Oxfordshire Wildlife Trust (BBOWT).

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What is BNG?

Under the Environment Act 2021, BNG was introduced and became mandatory for new major development in November 2023, with requirements extended to small sites in April 2024. This means that proposed developments must deliver at least a 10% increase in biodiversity compared to the state of the site prior to development. This gain can be delivered on-site or off-site, ensuring that completed developments leave nature in a better condition than before.

What is Proposed?

The government is currently consulting on proposed changes to BNG requirements, specifically considering whether more types of development should be exempt from these obligations.

These proposals form part of broader government measures announced in May 2025 to help small and medium enterprises (SMEs) deliver accelerated housebuilding, such as £100m in SME 'accelerator loans' and £10m for councils to fund specialists to speed up environmental assessments. The government argues that current planning rules impose similar hurdles on small sites of around 10 homes as on much larger developments, deterring smaller firms from starting projects.

Current Situation

• Small or Minor Developments: Currently defined as residential developments of 9 or fewer units.

• These developments are already subject to reduced BNG requirements.

Proposed Changes Under Consultation

New Development Categories:

• Introduction of a new "medium development" category for residential schemes with 10–49 units.

• This new category could also benefit from BNG exemptions.

Extended Exemptions:

• Expanding exemptions to include both small and medium developments.

• All single dwellings may be fully exempt from BNG.

Threshold Adjustments:

• Raising the de minimis threshold (the minimum area triggering BNG requirements) from the current 25 square metres to potentially 50, 100 or even 250 square metres.

Process Improvements:

• Simplifying the small sites metric to reduce administrative burden.

• Enhancing access to the off-site market for meeting BNG obligations.

BBOWT Raises Serious Concerns

BBOWT has issued a strong warning about the potential consequences of the government’s proposal to broaden exemptions from BNG requirements.

According to BBOWT, approximately 70% of residential planning applications in England currently fall under the small development category. Exempting such a significant portion of developments from BNG could have serious and far-reaching impacts, including:

• Loss of local wildlife habitats.

• Degradation of green spaces.

• Detrimental effects on public and community health.

Estelle Bailey MBE, Chief Executive of BBOWT, described the proposals as "alarming and shortsighted", stating:

"Here in Berkshire, Buckinghamshire & Oxfordshire, smaller housing developments often take place in or near treasured wild spaces that are home to declining species like hedgehogs, bats and wild bees. Removing BNG requirements would not only jeopardise the survival of these habitats, without any obligation to restore or replace them, but it would also see generations to come living in dwellings devoid of nature”.

Matthew Stanton, BBOWT’s Director of External Affairs and Land Recovery, echoed these concerns:

"Letting some developers off the hook now punishes those who've done the right thing. It undermines the trust and momentum we've been building locally. It tells communities that nature doesn't matter unless it's big or easy to quantify, which is the opposite of what we need during a nature and climate crisis. BNG isn't just about numbers, it's about making sure that new homes are good places to live".

BBOWT is urging members of the public, local authorities, MPs and other decision-makers to oppose the proposed exemptions during the current consultation period. The Trust emphasises the need to defend planning policies that support nature’s recovery in both urban areas and the wider countryside.

Environmental Sector Response

The Chartered Institute of Ecology and Environmental Management (CIEEM) has issued strong criticism of the government’s proposal to broaden BNG exemptions.

CIEEM highlighted that the Small Sites BNG policy was only introduced in April 2024, stating:

"The policy for Small Sites BNG has only been in place since April 2024, so it has been barely a year from introducing it to considering getting rid of it".

CIEEM described the proposal as

"Another example of the Government talking about supporting nature recovery but acting to undermine it".

Implications for the Planning System

The potential expansion of BNG exemptions presents a mixed picture for the planning system, with both possible benefits and significant risks:

1. Reduces cost and complexity for small and medium-scale developments: could lead to widespread habitat loss due to the increased number of exempt developments.

2. Speeds up delivery of smaller housing schemes: developers might game the system by dividing large projects into multiple smaller, exempt sites.

3. May stimulate economic activity by lowering barriers for development: undermines the core objective of BNG - to protect and enhance biodiversity.

4. Could reduce administrative burden on local planning authorities: risks eroding public trust in the planning system and in the Government’s commitment to nature recovery.

   
   

What Happens Next?

The consultation runs until 24 July 2025, providing an opportunity for developers, environmental groups, planners, local authorities and the public to influence the final policy. Those concerned about the environmental implications are encouraged to respond to the consultation before the deadline.

Why It Matters

Any policy changes resulting from this consultation could have far-reaching consequences, potentially weakening environmental protections and impacting thousands of small and medium developments across England. The future of local wildlife habitats, biodiversity and pro-nature planning efforts may hinge on the decisions made following this consultation.

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The proposed changes to BNG requirements represent a significant shift in planning policy that could fundamentally alter project viability, timelines and costs for developers across the size spectrum.

At Bluestone Planning, we are closely monitoring this consultation and will be tracking all developments as the government refines its approach. The complexity of BNG requirements, and their potential changes, underscores the importance of expert planning advice, particularly during this transitional period.

Whether you are currently submitting applications or planning future developments, we can guide you through how these changes may affect your strategy and help you prepare for a smoother, more efficient process.

Contact us at Bluestone Planning by calling +44 1235 766825 or emailing admin@bluestoneplanning.co.uk.