29/10/2026
As part of the Budget, the government has announced exemptions from Biodiversity Net Gain obligations for developments on brownfield sites, threatening to squeeze out nature from urban spaces and set back nature recovery targets.
As part of the ‘Biodiversity Net Gain’ (BNG) policy, developers in England were legally obliged to deliver an overall uplift to nature, with benefits to be as local to the site of development as possible. Now, developments on ‘brownfield sites’ (areas that have been previously built on - including derelict buildings and infrastructure) are exempt from this responsibility to nature.
⁉️ Improving biodiversity was considered a blocker to development, even though evidence shows brownfield developments generally find it easier and cheaper to deliver biodiversity net gains, compared to other development types.
🏗️ Nature-unfriendly development could squeeze out remaining nature in urban spaces, reducing connectivity for wildlife, and worsening nature poverty for local people.
🌱The poorest in society are likely to be most affected, since deprived neighbourhoods have more brownfield sites with housing potential. The most deprived fifth of neighbourhoods has around four times as much potential brownfield housing capacity as the most affluent fifth
🌱 3 in 4 people in England have a designated brownfield land in their immediate neighbourhood
People need more homes, but need development that benefits new and existing residents, strengthens community resilience, and fosters healthy ecosystems. The Mammal Society is disappointed with the government's choice to further overlook the importance of nature to human wellbeing. We believe that access to nature and thriving wildlife should be available to all.
References:
https://www.wcl.org.uk/docs/green_gap_report.pdf
https://verna.earth/news-item/brownfield-and-bng-what-the-data-shows-october-2026-update
