BNG: Big news for small sites

Joseph Lewis is Policy Lead at the Institution of Environmental Sciences, working to promote the use of the environmental sciences in decision making. Joseph leads the delivery of the IES Policy Programme, standing up for the voice of science, scientists, and the natural world in policy.

Joseph has ten years of experience in public policy, including in Parliament and the charity sector. He is particularly passionate about science communication and the role it can play in shaping environmental decisions.

In big news for small sites, the Government has announced the latest of its proposals for the future of mandatory Biodiversity Net Gain (BNG).

Still subject to consultation, the proposals offer a mixture of good news, unsurprising delays, and troubling prospects for the future of a policy that has been commended as potentially world leading.

What are the latest announcements?

Last week, the Government announced four planning consultations covering the implementation of the Planning and Infrastructure Bill, including two which will directly shape the future of BNG: one on ‘improving the implementation of biodiversity net gain for minor, medium and brownfield development’ and one considering biodiversity net gain for nationally significant infrastructure projects (NSIP).

The latter came alongside an announcement that BNG will come into force for NSIP in May 2026, six months later than the previously expected date of November 2025.

These consultations have come alongside a lot of media attention and commentary from various Ministers, once again emphasising their view that current environmental regulations are blocking progress on infrastructure and housing development.

Reconsidering the implementation of BNG is critical to ensuring the policy’s success, particularly given the evidence that it is not yet performing as intended. To that end, some of the options outlined in the consultations could help to materially improve BNG’s implementation and get closer to an actual ‘win-win’ for nature and development.

However, change also comes with risks, including the possibility of throwing away meaningful progress because of an imperfect policy. The better option, sensible and evidence-led reform, will only be possible if the environment sector speaks with a shared and constructive voice, and if the Government is ready to listen to a different approach.

Highlights: The good

Some of the options discussed (but not necessarily proposed) in the consultations include:

The removal of the custom and self-build exemption, which the IES called for earlier this year, following evidence that the exemption is being used inappropriately. The consultation proposes that this is replaced with an exemption for a single dwelling house.
Delivering biodiversity net gain for nationally-significant infrastructure, which will be an important part of ensuring nature protections apply more universally, as long as progress on smaller sites is not sacrificed.
More guidance on using the small sites metric and the definition of a competent person, which the sector has long been calling for. The consultation also discusses digitalisation of the metric tools, which if done well would make them much easier to use.

Highlights: The bad

Other options raised in the consultations would be less positive. These include:

Scrapping BNG for small sites altogether, which would be a significant backwards step, and which currently seems to be the Government’s intended course of action.
Expanding the use of the small sites metric to medium habitats. The small sites metric is less robust than the statutory biodiversity metric and the use of it is already causing difficulties in practice.
Proposals that where no offsite Open Mosaic Habitat (OMH) is available to compensate the loss of OMH due to a development, it could instead by compensated for with “alternative habitat mosaic with similar ecological benefits”, which in practice could mean risking a significant loss of OMH.

Highlights: The unknown

Some proposals also pose serious risks, but the overall costs and opportunities may depend on how the proposal would be implemented in practice. Examples include:

Simplifying and streamlining the small sites metric: there have been challenges with the implementation of the small sites metric, and reform to make it easier for both those completing and receiving it to use is welcome, but changes to the trading rules will need to be approached with caution to ensure that safeguards for nature are not lost.
Relaxing the Biodiversity Gain Hierarchy for small sites to put offsite gains on the same standing as onsite gains. If safeguards and monitoring are not in place, this could make the most nature-friendly options less likely to happen in practice. If they are, it could simplify the process for the projects where onsite gain was never possible or likely to be meaningful.

For full details on the consultations and what they cover, see:

What do the experts say?

"This is a dangerous moment for BNG. The scrapping of BNG for small sites would weaken this world-leading legislation beyond recognition, and could open to door to further backsliding on biodiversity and nature.

But this consultation is also an opportunity to sort out the implementation challenges that our members are facing. The IES is already working with others in the sector to send the Government a clear, strong and cohesive message about how to strengthen BNG so it works better for environmental professionals, and delivers better for the economy, communities and our natural world."

– Ellie Savage, IES Policy Officer, recently recognised in the ENDS Power List 2025

As part of a statement by the IES and the Association of Local Government Ecologists (ALGE), Dr Iain Boulton, Vice-Chair of ALGE said “This is removing a problem that needs fixing, rather than actually fixing it, which is not the way a credible government should act.”

What does it mean for you?

As environmental professionals, IES members have been at the front lines of delivering BNG in practice. The challenges have been clear for over a year, which is why the IES and ALGE have been producing evidence on the need for reform. It is a good sign that the Government has heard the call for action, but it needs to ensure that the consultation leads to the right action to solve these challenges, rather than environmental decline.

We urgently need the expert voices of environmental professionals and ecologists - those ‘in the roots’ of environmental policy - to ensure that these consultations are an opportunity to improve the way that BNG is delivered, rather than weakening environmental protections or developing regulations that are incoherent with other policies and legal commitments.

The IES will be gathering member views to shape our response to the consultation. If you want to be a part of the IES response, or want support in putting together an individual response, please contact Ellie Savage, IES Policy Officer (ellie@the-ies.org).

In practice, if the Government introduces more exceptions and exempts small sites from BNG entirely, the sector will be left with major uncertainties for how projects will meet their broader sustainability commitments. Equally, with the right advice and the courage to make a sensible but uninteresting decision, the Government could produce a better system that speeds up good developments while protecting and enhancing biodiversity and habitats.

It all depends on the consultation, so the importance of speaking up has never been so critical.

Lessons to learn: Environmental communication

If there’s one clear message from the latest announcements, it’s that we have been playing the communications game wrong.

A policy academic might take the opportunity to talk about Sabatier’s Advocacy Coalition Framework, which tells us that when coalitions come together to effect change, they unite around core values on which they will not compromise but may be willing to negotiate their secondary values, or how those values are implemented in practice, in order to move forward with change.

It makes sense that an uncompromising approach has not worked: if the other coalition we are trying to persuade values rapid infrastructure development more than protecting and enhancing nature, then we have done a poor job of articulating why the things we value are so important that the Government should be willing to compromise on the specifics of their proposed implementation.

BNG is not currently working the way it should be, so some kind of reform is needed. If we aren’t willing to find a better system for small sites, we risk losing it altogether. To that end, the environment sector needs to be willing to genuinely consider the Government’s proposals and not dismiss out-of-hand anything that deviates from the way BNG works now. A bad compromise could lead to less legal protections for the environment, but a good one could lead to a better implementation of BNG than what we have today.

The IES Environmental Policy Implementation Community (EPIC) is working with partners to build a coalition around a practical approach to mandatory BNG, so that the best parts of the policy can be retained while finding an approach to implementation that works for people, the economy, and the environment. To find out more about how EPIC is engaging with the BNG consultation, contact Ellie Savage, IES Policy Officer (ellie@the-ies.org).

What are we doing about it?

The IES provides training and resources to help members engage with environmental policy, including our introduction to environmental policy briefing series and our collection of case studies on effective engagement with environmental policy.

Our Environmental Policy Implementation Community (EPIC) plays a key role in supporting the effective implementation of environmental policies. It brings together members from across the environmental sciences to share their experiences and call for ambitious and deliverable policy, as well as providing members with the knowledge, insights and tools to help them deliver on the ground. Join EPIC today to help shape the future of BNG and similar policies.

EPIC has already been shaping the future of BNG:

Read the report from EPIC and the Association of Local Government Ecologists (ALGE), which includes evidence of what is going right and wrong with the implementation of BNG so far
Catch up with EPIC’s BNG in Practice event series
Read the statement from EPIC and ALGE responding to the consultation

The IES is also holding a discussion event on policy priorities for nature and biodiversity, including the future of BNG. The event is free, and you can sign up now on the IES website.

Get involved: if you want to support the work of the IES to stand up for science and nature, become an affiliate, or if you’re an environmental professional, join the IES.

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