More than 12 months since the statutory roll-out of Biodiversity Net Gain (BNG) in planning policy, the construction sector is still adjusting to its new normal. While the policy was introduced with bold intentions – to halt biodiversity loss and embed ecological thinking into development – is it working? Megan Russell, quality assurance and compliance lead at leading BNG and carbon unit provider CSX, assesses its impact.

While the BNG policy has created a wave of learning and recalibration, it has also produced a raft of challenges across the planning and development ecosystem. Indeed, its implementation has revealed a landscape as uneven as the one its creators hope to restore.

From large-scale housebuilders to single-plot developers, the question isn’t whether BNG applies but whether it’s being approached as an environmental strategy of significance, or just another regulatory checkbox.

The compliance ‘minefield’ is still evolving

Local planning authorities (LPAs) have needed to get to grips with  the concept of BNG compliance in an iterative and developmental way, with arguably less resources available to them than they would ideally have at their disposal. The biodiversity regulations, requiring developers to achieve at least a 10% net gain in biodiversity, came into effect for developments in February 2024. Major infrastructure projects are expected to comply by 2025.

It has been an unsettling time for planners and developers as they navigate this regulatory minefield, but with people becoming more fluent in ‘BNG-speak’, we have certainly seen confidence growing and more harmonised processes.

However, while the core policy requirements and DEFRA’s metric are clear, many LPAs have been going beyond simple measurements of biodiversity units, often requiring developers and BNG unit providers to demonstrate financial feasibility modelling, additional survey requirements, and the rationale behind broader environmental considerations.

This push for a more holistic approach has expanded the compliance burden, particularly for smaller developers with less capacity or in-house expertise.

At the same time, LPAs are at different stages of readiness. A growing number are beginning to refine their processes, streamlining legal agreements and increasing the number of biodiversity units brought to market. Yet others remain under-resourced and uncertain, lacking clear internal frameworks for reviewing and approving BNG proposals. This variation continues to cause delays and confusion.

Small developers feel the squeeze

One of the more unexpected outcomes of BNG’s roll-out has been the discrepancy in how different types of developers have responded. While large-scale developers have generally been able to adapt, often by delivering their biodiversity gains on site, smaller developers have found the process steeper to navigate. A lack of spare land and internal expertise has left many exposed to compliance risks.

In many cases, smaller operators delayed engaging with BNG in the hope that requirements would be eased or enforcement would be slow to take effect. That time has passed. In the last few months, there has been a noticeable increase in reactive inquiries as developers receive pushback from LPAs and scramble to find viable off-site solutions.

It’s interesting to see some developers starting to recognise a strategic opportunity. By exceeding the minimum 10% requirement, such as offering a 30% gain, they can strengthen their case for approval, particularly when planning proposals face other obstacles. It’s an early indicator that BNG might become not just a hurdle, but a lever.

LPAs are catching up – but slowly

There’s a clear divide between LPAs that are actively engaging with localised BNG unit creation and supply, and those still finding their footing. Those further ahead tend to have dedicated staff who know what a strong BNG proposal looks like, making for clearer communication and faster approvals.

We have realised that some remain rather underprepared, and CSX has often been able to provide feedback to help guide the authority through the creation of their BNG processes, rather than the other way around.

That said, change is happening. Slower LPAs are increasingly now establishing their own internal BNG procedures, often upon realising that a lack of unit supply could hold up the planning process.

Many now recognise the long-term value of having in-house ecological expertise not just to ensure compliance, but to create a potential revenue stream through fees and to reduce the risk of flawed applications.

Deserted chances for collaboration?

Despite common goals, collaboration between developers and LPAs remains patchy. Frustrations run high on both sides as developers see delays and shifting goalposts, while LPAs juggle underfunded departments and rising expectations.

What’s clear is that early engagement makes a measurable difference. Developers who bring BNG into the conversation from day one are more likely to secure efficient approvals and avoid costly redesigns.

Meanwhile, consultants who can translate LPA expectations into actionable steps have become invaluable go-betweens, especially for smaller developers.

Some planning authorities are also beginning to understand how BNG can support broader environmental and community objectives, moving from a purely technical requirement to a more strategic asset. But this shift requires cultural change as much as policy alignment, and that’s still a work in progress.

Lessons from the first year

The first year of BNG implementation has been a steep learning curve. From legal mechanisms to ecological baselining, every aspect of the policy has raised new complexities. But it has also driven innovation and encouraged earlier, more strategic thinking, particularly around land use, community benefit, and development viability.

Consultancies working in this space are now positioned not just as compliance specialists, but as early-stage advisors helping developers assess viability, mitigate risk, and plan for long-term biodiversity success. We urge developers to engage early to save them time, money and stress.

As the market matures, the expectation is that BNG will become less reactive and more embedded in standard planning practice. The next 12 months will likely see faster approvals, more units entering the market, more robust collaboration between stakeholders – and hopefully a greener outcome for our natural habitats.