Concerns continue about the future of Biodiversity Net Gain (BNG), the pioneering policy designed to enable new developments to go ahead in a way that leave nature in a measurably better state.
BNG was introduced two years ago, as regulations to require new housing to produce a minimum 10% gain in biodiversity by the end of the development, intended to cover the vast majority of new developments. Welcomed across political parties, industry and civil society, the launch press release stated that ‘developers in England are now legally required to deliver at least a 10% increase in biodiversity when major building projects are undertaken’.
In practice, delivery has proved to be something of an optional extra for some developers. Analysis of BNG delivery by eftec, commissioned by The Lifescape Project and Wildlife & Countryside Link and drawing on Planning Portal data from BNG's entire first year, revealed that the BNG legal requirement has been wholly undermined by exemptions.
Of the 101,728 residential planning applications submitted between March 2024 and February 2025, an extraordinary 86% claimed some form of BNG exemption. This is very far from the intended majority coverage.
Notably more than half of all applications used the ‘de minimis’ exemption to avoid BNG. This exemption has been designed for very small-scale development, such as extensions to the entrance of an existing building. The eftec figures make it clear that this exemption is being abused; 35% of developments on sites larger than 0.5 hectares claimed the de minimis exemption to avoid BNG. An exemption meant for minor building work is being used for whole roads of new houses. As a result, an area the size of the city of Manchester, (< 14 000 ha) is being lost to development annually with no obligation to measure impacts, or to act to restore biodiversity.
Abuse of exemptions doesn’t get more glaring than this, but the Government has been slow to recognise the problem. In April, after months of concern from nature organisations, Ministry of Housing, Communities and Local Government (MHCLG) did commit to a review of evidence around use of the de-minimis exemption, but at the same time offered a defence of it in principle.
The defence included a number of examples of where the Government thought the de minimis exemption could still usefully apply, from roof extensions to electric vehicle charging points. There is however one problem – when you look at the examples closely, most of them wouldn't have to deliver BNG in the first place, with or without a de minimis threshold.
Wildlife and Countryside Link and The Wildlife Trusts have produced a new briefing which looks into detail, and debunks the wider myths around de minimis. We will continue to stress to the Government that this is an exemption that has failed, on such a scale as to undermine BNG as a whole, and to urge caution on new proposed exemptions, including on brownfield. BNG cannot function as a ‘win-win’ policy for nature and development if it is riddled with loopholes.
Read the Myth Busters briefing
We hope that Ministers are listening. Thanks to lots of advocacy, including 13,600 emails from Wildlife Trust supporters last year, some of the message about BNG needing to deliver as promised is cutting through.
In December, plans for a very damaging new 0.5 hectare exemption were watered down to 0.2 hectares. The April BNG announcements included confirmation BNG will now apply to major infrastructure from November, meaning energy and other large-scale projects must also contribute to restoring nature and strengthening vital natural infrastructure. Another easily abused exemption to BNG for residential development, concerning custom and self-build developments, has been scrapped altogether.
It is time for Ministers to continue this positive trajectory, act on the evidence and close the much-abused de minimis exemption.
BNG can unlock real benefits; new jobs, green spaces for residents to enjoy, environmental security for new homes, and urgently needed nature recovery. De minimis stands in the way – a blocker to nature-positive growth, ripe for removal.