11.02.2026
As Biodiversity Net Gain (BNG) continues to embed itself within the planning system as a statutory requirement under the Environment Act 2021, Government signals suggest that further refinements may be on the horizon. A number of potential policy updates—currently under discussion—could reshape how BNG is applied across different development types and scales.
DHA Planning has reviewed the emerging themes and considered the likely implications for our clients and the wider development sector below.
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Brownfield development plays a vital role in regeneration; however, brownfield sites can support high-distinctiveness habitats, such as open mosaic habitat often because the sites have not been managed for some time These environments are often costly and complex to replace, frequently triggering significant off-site compensation requirements. The targeted exemption for small scale residential brownfield development (potentially ≤2.5 ha) would therefore be welcomed.
However, the issue of habitat loss on larger sites will remain a significant constraint where high distinctiveness habitats exist.
For modest developments, where BNG cannot delivered on-site , the transaction costs associated with purchasing off-site units can be disproportionately high. This can have a particular impact on SMEs and small developers operating within tight viability margins.
A small site exemption could reduce unnecessary financial burden while allowing local planning authorities to focus BNG delivery where it can deliver the greatest ecological benefit. The current proposed small site exemption is <0.2ha.
Arguably this should be higher but it is much more generous than the existing 25sqm threshold.
Some adopted and emerging Local Plans currently seek BNG targets above the statutory 10%.
Proposed changes could restrict the circumstances in which higher thresholds can be applied. Clear guidance will be essential to ensure a balance between national consistency and local environmental priorities.
A new medium-sized category—potentially covering sites of 10–49 dwellings or up to 2.5 ha—could introduce more proportionate requirements. This would address long-standing concerns that the current framework does not sufficiently differentiate between development scales.
The Government is expected to respond to its NSIP consultation later in 2026, with early indications suggesting that BNG will become mandatory for major infrastructure projects.
Many infrastructure providers already voluntarily deliver 10% or more BNG, placing the sector in a strong position to adapt. DHA’s own experience with NSIPs shows that BNG is increasingly being considered at the earliest stages of project design and land strategy.
While the detail of potential reforms is still emerging, several themes are clear:
Through our work on a wide range of schemes—from strategic renewables and education projects to brownfield regeneration — DHA continues to support clients in navigating BNG requirements and managing the impact on developments.
The direction of travel is clear: BNG will become increasingly embedded in early design thinking, viability testing, and land strategy. Ensuring that ecology, landscape and masterplanning inputs are joined‑up from the outset will remain essential.
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