BIODIVERSITY NET GAIN Biodiversity reforms – a (small?) step in the right direction?
 | Richard is a chartered town planner and Managing Director at Planning & Design Practice, based in Derby. He has been working in the planning system for over 22 years (15 years private sector, 7 years public sector) and is highly experienced in a diverse range and scale of cases, including large scale residential and commercial schemes and bespoke rural developments. |
Richard gives a practical perspective of BNG from the viewpoint of other professions. He concludes: “However, the wider question of whether the reforms will ultimately deliver better outcomes for nature remains unresolved.” |
The government has made a raft of recent changes to the BNG regime in order to reduce the cost burden and simplify the process for small and temporary developments (which have been disproportionately affected), as well as a reduced administrative burden for local planning authorities (LPAs). This article looks at the changes from the perspective of a SME developer and two ecologists, to shed some light on what is working and where there remain significant question marks about the system.
As trailed by David Alborough in the 2026 Summer Terrier, a number of significant changes came into effect for planning applications submitted on or after 6 August 2026:
introduction of the new 0.2ha exemption, which means that the smallest developments will not be required to do mandatory BNG (unless onsite priority habitat is negatively impacted)
introduction of a new temporary development exemption, for land which is to be reinstated within a period of 5 years or less (unless onsite priority habitat is negatively impacted)
modification of the biodiversity gain hierarchy for minor development, meaning that minor sites which aren’t exempt from BNG (e.g. over 0.2ha) can choose to go straight to offsite in the first instance
removal of the existing exemption for self and custom build development
(Defra blog post 14/7/26, https://defraenvironment.blog.gov.uk/2026/07/14/biodiversity-net-gain-amendments-and-transitional-arrangements-published/) .
The primary intention of these changes, according to Defra’s Explanatory Memorandum, is summarised as follows: “The Government considers that these changes will help to reduce the burdens on the smallest developers and local authorities. This will benefit the whole BNG system by focusing resources on larger development, which has the greatest impact, and therefore the potential to deliver the greatest benefits to nature.”
SME developer
In order to get a developer’s take on these changes, I spoke to Clayton Penny, Land & Planning Director at Derby-based Chevin Homes. Established in 2002, Chevin builds out approximately 25 homes per year and, one would assume, are exactly the type of developer that the government is looking towards to assist them in achieving the highly ambitious (some would say ludicrous) target of 1.5 million homes by the end of this parliament.
However, his take on the changes is somewhat mixed. He is keen to point out that he supports the principle and overall objectives of the BNG regime, but is not convinced that the current set of rules is the right way to achieve it. He sees both on-site and off-site BNG as presenting challenges, but for different reasons. Off-site provision is generally viewed as the simpler and lower-risk option from a delivery perspective, particularly following the recent relaxation of the biodiversity gain hierarchy. However, it requires substantial up-front expenditure, can create cash flow pressures, and remains expensive, particularly for SME developers. Penny also sees it as slightly perverse that off-site habitat creation may be located a considerable distance from the development itself.
On-site delivery can avoid the cost of purchasing off-site units, but introduces greater complexity and uncertainty. Biodiversity calculations can change as landscape proposals evolve, potentially delaying planning and development programmes. There are also concerns over the long-term management obligations associated with BNG, particularly if management companies were to fail during the 30-year maintenance period, meaning responsibility for habitat management becomes unclear.
But ultimately, for a developer, it’s just another tax on development and a significant additional layer of red tape, which all adds time and cost to development, at a time when costs have risen significantly. The Home Builders Federation reported in May 2026 that cumulative taxes, regulatory changes and inflation have added c.£76,000 to the cost of building an average new home in England since 2020. This is broken down as:
£37,000 due to material and labour cost increases
Over £23,000 in regulatory costs, including £5,700 for BNG
Over £7,000 in taxes and levies
£7,000 in additional potential site-specific costs such as nutrient mitigation requirements.
While, clearly, the increased cost burden is primarily due to other factors, Penny concludes that “BNG is a factor and another cost that developers are required to pay which, when viewed in the context of the various other costs, does impact on viability.”
Ecologist
But what about the ecologist’s perspective? In order to get a first-hand view on whether BNG is actually working, I spoke to two ecologists who own ecological consultancies and have first-hand experience of the system in practice.
On the question of whether the recent BNG changes are a sensible move overall, Tim Elton from Elton Ecology, supports the principle of making BNG more proportionate and reducing costs for developments with limited ecological impacts, although he does point out that “small sites are not necessarily ecologically unimportant. Their cumulative loss matters, particularly in urban areas where gardens, trees and smaller green spaces provide connections between larger habitats.” He also feels that a simple site-size threshold may exempt sites that are small but ecologically important, and he would prefer a system that is based more on ecological impact than site area alone.
Another owner of a Derbyshire based ecological consultancy, who preferred not to be named so we will refer to him as ‘Ecologist A’, strongly supports the changes and considers the 0.2ha exemption to be broadly the right threshold, opining that the previous requirements were unfair on homeowners and small developers bringing forward single plots or very small schemes. He also supports retaining protection for priority habitats regardless of site size.
When asked whether BNG will achieve what it sets out to achieve, particularly on smaller sites, Elton believes that BNG has the potential to deliver substantial biodiversity benefits because it requires biodiversity to be explicitly considered within development decisions. However, he feels that it is still too early to judge the success or otherwise of the system, and cautions that achieving a metric score does not necessarily equate to genuine biodiversity gains, and that success should be judged by the long-term condition of habitats.
Ecologist A was less convinced by the overall success of the system. While he feels that the BNG system is "better than doing nothing" and that larger sites are likely delivering some biodiversity benefits, he is less convinced about the effectiveness of delivery on smaller sites because funding and local authority capacity for monitoring and follow-up appear limited. For this reason, he believes that biodiversity outcomes could potentially be improved through a more centralised approach, focused on larger habitat areas and ecological corridors connecting them.
So, what are the main risks with the 30-year management and monitoring requirement? Elton identifies a broad range of ecological and management risks, including unrealistic habitat targets, inadequate long-term funding, changes in ownership or responsibility, competing land uses, and environmental pressures such as climate change or disease. His primary concern is that habitats promised at planning stage may prove impractical or unaffordable to manage over a 30-year period.
Ecologist A questioned what happens if a management plan is not achieved, and suggests enforcement remains largely untested as it is barely 2 years since the first mandatory BNG schemes were approved. For these reasons, he agreed with Clayton Penny that off-site provision can reduce risk for developers because the responsibility for long-term management transfers to the habitat provider once the credits are purchased.
Conclusion
So, do the recent biodiversity reforms achieve what they set out to? The answer is yes, but only in part. The changes introduced in August 2026 appear to have succeeded in their immediate objective of reducing the burden on the smallest developments and providing greater flexibility for developers and LPAs. There is broad support for this increased proportionality, particularly where the costs and administrative requirements of BNG were previously difficult to justify on very small schemes. However, BNG still adds a not insubstantial cost to development at a time when developers are struggling to make schemes stack up from a viability perspective.
However, the wider question of whether the reforms will ultimately deliver better outcomes for nature remains unresolved. While BNG has undoubtedly elevated biodiversity as a material consideration in the development process, there is still limited evidence that metric gains are translating into long-term ecological success. Concerns remain over monitoring, enforcement, funding and the practicalities of managing habitats over a 30-year period.
Ultimately, the reforms may improve the efficiency of the system, but their true success will be judged not by the number of exempt sites or completed calculations, but by whether meaningful and enduring biodiversity gains are still being delivered decades from now.
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