CIEEM responds to Government update on Biodiversity Net Gain exemptions
CIEEM cautiously welcomes the Government’s confirmation – announced by Housing Minister Matthew Pennycook MP in Parliament today – that it will introduce an area-based exemption from mandatory Biodiversity Net Gain (BNG) for smaller sites up to 0.2 hectares, rather than the previously rumoured 0.5 hectare threshold.
Whilst this still falls disappointingly short of the 0.1 hectare exemption that much of the sector has consistently called for, and which the evidence supports, it represents a significant improvement on earlier rumoured proposals and reflects the extensive efforts of environmental organisations, businesses, practitioners and investors to highlight the serious risks that a 0.5 hectare exemption would have posed to nature recovery and to the emerging private finance market for nature.
However, CIEEM notes that no evidence has yet been published by Government to explain how the 0.2 hectare threshold was selected. Independent analysis by eftec suggests that around 82% of all planning applications would still be exempt from BNG under a 0.2 hectare scenario, and that this would result in a loss of approximately 2.4% of the overall Biodiversity Unit market. While significantly less damaging than a 0.5 hectare exemption, this is still four times larger than environmental experts have proposed. It will therefore weaken cumulative biodiversity outcomes and reduce investment flowing into nature recovery.
We remain concerned for urban communities where nature is already scarce and people most depend on access to green space. CIEEM therefore strongly encourages Government to publish its evidence and modelling as soon as possible.
Sally Hayns, Chief Executive of CIEEM, said:
“Reducing the proposed exemption threshold from the rumoured 0.5 hectares to 0.2 hectares is a welcome step and avoids what would have gutted the BNG approach and been a serious setback for nature recovery and private nature investment. However, independent analysis suggests that more than four in five planning applications would still fall outside BNG under this approach, and without Government’s own published evidence and impact assessments it remains difficult to fully assess the implications. We urge Government to be transparent and continue working with the sector on genuinely pragmatic, evidence-based solutions.”
CIEEM remains very concerned that Government is still considering a broad exemption for brownfield sites, with testing reportedly extending to sites of up to 2.5 hectares. While we are pleased that Government intends to consult on this proposal rather than introduce it outright, such an exemption could significantly undermine biodiversity outcomes. CIEEM will engage fully with the consultation process and urges Government to proceed with caution.
CIEEM also notes the Government’s intention to introduce measures to make it easier, quicker and cheaper to deliver BNG offsite, particularly for medium-sized developments. In principle, improving the efficiency of offsite delivery could support both development and nature recovery, but further detail is urgently needed to understand how these measures will operate in practice and how environmental integrity will be safeguarded.
We welcome confirmation that a full consultation response and implementation timeline is expected to be published in the new year for Nationally Significant Infrastructure Projects (NSIPs), which is due to go live in May 2026. Clear timelines and policy certainty will be essential for ecologists, local authorities, developers and investors preparing to deliver BNG for NSIPs effectively.
CIEEM is also very pleased to see Government support requirements for new developments to include nature-friendly features, such as swift bricks, which can deliver tangible benefits for wildlife and help embed biodiversity considerations into everyday development practice. However, building features such as swift bricks must be in addition to, and not an alternative to, the habitat-based delivery of BNG.
BNG remains one of the most important mechanisms that England has to deliver nature recovery, mobilise private finance and support the delivery of Local Nature Recovery Strategies. It is vital that any changes to its scope or operation are evidence-led, proportionate and designed to strengthen, not dilute, outcomes for nature.
As always, CIEEM is willing to continue working constructively with Government to refine these proposals and to help deliver a BNG framework that removes unnecessary burdens for the smallest developments, supports a credible and functioning nature market, and crucially delivers the economic growth and nature recovery that the country so urgently needs.