The UK Government recently confirmed plans to dilute Biodiversity Net Gain (BNG) requirements for housing developments, announcing full exemptions for the smallest sites and reduced obligations for medium-sized schemes.
The BNG mandate, introduced in early 2024 under the Environment Act 2021, requires housing developments in England to deliver a minimum 10% increase in biodiversity on-site. Where this is not feasible, developers can instead contribute financially to off-site nature restoration by purchasing accredited biodiversity credits. The policy was designed to tackle the UK’s accelerating nature loss, enhance public access to green spaces and support sustainable housebuilding.
In May, the Ministry of Housing, Communities and Local Development voiced its intention to radically change the level of BNG requirements for smaller developments. Ministers initially proposed defining “small sites” as schemes delivering fewer than ten homes, a category that makes up around 70% of England’s housing pipeline.
The Government has now confirmed that exemptions for small sites will proceed, although the definition has been revised. Developments occupying less than 0.2 hectares will be fully exempt from BNG requirements. Furthermore, a new “medium site” category will be introduced for developments of between 10 and 49 homes delivered by small and medium-sized enterprises (SMEs). The specific requirements for this category will be shaped through further consultation.
A full response to the Government’s spring consultation on BNG is expected in early 2026.
Environmental organisations have welcomed the narrower scope of the exemptions, while warning that the changes still undermine progress on nature recovery. One sector representative said the revised proposals amount to “damage limitation rather than positive leadership for nature,” arguing that the Government should be strengthening, not weakening, green economy rules if it is serious about halting wildlife decline.
Another expert warned that exempting sites under 0.2 hectares represents a missed opportunity to drive private investment into nature recovery. They added that efforts to simplify the process for smaller developers must be approached carefully, as excessive streamlining could erode essential safeguards and allow biodiversity outcomes to be compromised
The Labour-led Government has committed to delivering 1.5 million new homes during this Parliament, a target critics argue is increasingly being pursued at the expense of environmental protections.
Alongside changes to the BNG framework, ministers are introducing measures aimed at accelerating development, including the creation of a new “grey belt” land category. This would apply to low-quality land within the green belt, such as disused car parks, making it easier to redevelop. Planning authorities have also been instructed to prioritise faster approvals for housing near transport hubs, including train stations.
Further guidance on how BNG will apply to Nationally Significant Infrastructure Projects (NSIPs) is expected in early 2026.
Campaigners have criticised the direction of travel, arguing that weakening environmental protections in one of the most nature-depleted countries in the world risks repeating the short-term political thinking that contributed to the current crisis. They have called on the Government to treat nature as a foundation for long-term economic and community resilience rather than an obstacle to development.