Mandatory BNG for NSIPs: what changes from 2nd November 2026?
By Jon Collins, Head of Consultancy at Maydencroft, leading a multidisciplinary team of specialists in ecology, arboriculture, forestry and nature recovery.
On Monday 2nd November 2026, another significant Biodiversity Net Gain (BNG) milestone will be reached, with mandatory requirements applying to Nationally Significant Infrastructure Projects (NSIPs) where a Development Consent Order (DCO) application is made on or after this date.
Established in the Environment Act 2021 and originally planned for implementation by ‘no later than November 2025’, the landing date has been pushed back on several occasions in response to industry-led concerns regarding the complexity of building BNG into the DCO process.
Whilst fully appreciating the scale of challenges faced, even more so since having the opportunity to share in-depth discussions with industry-leaders delivering NSIP projects, I can’t deny having been a nervous wreck with each postponement that we would at some point lose this opportunity altogether. To have reached this point is something to celebrate.
Ever since Maydencroft Limited began to deliver BNG work with Metric 2.0 back in 2019, the destination I have been anticipating most has been the mandatory requirement for NSIPs. Required use of the Statutory Metric to fully quantify pre- and post-development baselines will be a giant leap forward in helping to understand the true impact of these major projects and given their significant scale will have the potential to secure the most exciting and meaningful benefits for nature recovery.
So, what will this mean for ecological consultants in practice? On the face of it, quite a different experience and process compared to what we have been delivering in recent years, albeit with much the same principles.
Defining the worst-case RLB
One point that jumps out is the importance of a firm Red Line Boundary (RLB) as early as possible. Even with the smallest of development schemes, every tweak and adjustment (which can be painfully frequent) requires our consultants to update all BNG documentation and GIS mapping at every twist and turn. This means from an advisory perspective, whilst we are recommending capturing baseline data as early as possible in the process, we are having to be tactically slow in proceeding to finalisation if we anticipate a likelihood of RLB shift.
The DCO process for NSIPs requires an Outline Biodiversity Gain Plan at submission stage with a credible strategy for delivering 10% gain, which means that BNG consultancy work will need to be heavily front-loaded, with subsequent allowance for updating through the lifespan of the project. Having a confirmed RLB early in the process will be vital to support this work and, in accordance with government guidance, where there is design uncertainty the RLB will need to be a realistic worst-case approach. This could significantly increase the scope and scale of initial BNG baseline work for consultants.
Developing adaptive HMMPs
It is also notable that where units are being secured through the DCO, a draft Habitat Management and Monitoring Plan (HMMP) will need to form part of the Outline Biodiversity Gain Plan. Given that currently this document tends to only be produced once there is absolute certainty over the scheme design and associated metrics, there is an interesting challenge in writing fluid and flexible HMMPs that can accommodate and respond to changes in design.
Does the industry have the ecological capacity?
It has been encouraging to see how the level of scrutiny on both planning and habitat bank BNG projects has increased over the last few years, with the need for evidencing competency, such as with the Field Identification Skills Certificate (FISC) accreditation for botanical surveys becoming the recognised standard. This has led to consultancies such as ours investing a great deal to ensure all our people meet the requirements, and one hopes influencing a wider lifting of standards throughout the industry. However, this isn’t necessarily enough to address the widely recognised skills and capacity shortage with ecologists, particularly at a more technical level, and therefore a risk with regards to both the delivery and scrutiny of very large, complex NSIP schemes.
Avoiding 'design by metric'
Alongside the positivity and excitement I feel for the arrival of mandatory BNG for NSIPs, I do have an overriding concern about the impact it may have on other project outcomes.
Through the delivery of numerous planning applications for housing, renewables and small-medium water-industry infrastructure developments over the last few years, we have seen how the need to cost-effectively achieve 10% gain in biodiversity has become the primary focus, often at the expense of a more holistic approach to post-project enhancement that would previously have considered protected species, arboriculture, landscape character, heritage, and so forth. This is an approach we have been able to take on projects such as Chaul End Reservoir, where BNG formed part of a wider package of ecological, arboricultural and landscape mitigation. That’s not to say that BNG hasn’t been a significant and very welcome leap forward, but it is essential that professionals and project managers are not viewing BNG in isolation and are able to avoid the dreaded ‘design by metric’.
It is perhaps a cliched point to make, but anyone who has driven past the HS2 depot at West Hyde can’t help but wonder at the scale of ecological and landscape change resulting from NSIPs and how such loss can ever be truly mitigated. Here’s hoping that in future with the addition of mandatory 10% BNG to our arsenal, we’ll be able to drive past these in-progress projects with greater feelings of hope and confidence.
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About the author:
Jon Collins is Head of Consultancy at Maydencroft, leading a multidisciplinary team of specialists in ecology, arboriculture, forestry and nature recovery. A Chartered Member of the Landscape Institute and Full Member of CIEEM, Jon has over 20 years of experience across the public and private sectors, specialising in landscape management, biodiversity net gain (BNG), habitat management and monitoring plans, landscape planning, and the delivery of complex environmental projects.