NSIPs & Net Gain: An Opportunity to Contribute to Nature Restoration?
By Cameron Carmichael, Environmental Net Gain Lead at Biodiverse Consulting
After much delay, the government intends to implement mandatory Biodiversity Net Gain (BNG) for Nationally Significant Infrastructure Projects (NSIPs) in May 2026.
Following the broader rollout of BNG under the Town and Country Planning Act (TCPA), this announcement aims to ensure that major infrastructure developments leave nature in a measurably better state than before.
For those of us in the conservation, ecological and planning sectors, the scale and complexity of NSIPs will bring a host of opportunities and challenges.
With size comes opportunity
The government’s initial proposal suggests that BNG for NSIPs will follow a similar mechanism to projects under the Town and Country Planning Act. However, the sheer scale of nationally significant developments suggests that implementation will look and feel very different.
NSIPs often span vast areas, cross multiple local authority boundaries, and interact with a range of habitats and communities. This presents a powerful opportunity for large-scale habitat creation, particularly when BNG strategies are aligned with Local Nature Recovery Strategies (LNRSs). NSIPs often intersect with strategically important ecological corridors, making them well placed to deliver real and lasting benefits for nature at scale.
There is also greater potential to create quality biodiversity units, thanks to the space and funding mechanisms involved in NSIPs. However, with this opportunity comes numerous complexities, particularly with surveying and long-term monitoring and management.
The government proposes that the entire NSIP site be surveyed to establish its biodiversity baseline. This raises serious questions. With NSIPs often taking years to reach the submission stage, will surveys become outdated and need to be repeated?
Whilst not all NSIPs cover large tracts of land, most do, and the cost and resource implications of surveying them are significant. Based on our recent experience assessing BNG on a Solar NSIP, we at Biodiverse Consulting would advocate a sample-based approach, but phasing surveys may also be appropriate. The use of drones or satellite imagery would likely support a judicious approach to sampling, but accuracy and detail would inevitably be compromised.
Meanwhile, executing 30-year monitoring plans may require innovative methodologies to be developed, for example, a dependence on new technologies and AI. There is a strong case for clearer national guidance on what is acceptable and achievable for projects of this scale.
The rise of off-site gains?
One of the most notable proposed differences in the NSIP BNG consultation is that off-site and on-site gains will be treated equally, i.e. the Biodiversity Gain Hierarchy will not apply for NSIP projects. Given the landscape scale and opportunities for achieving gains, this seems logical. Although NSIPs often have access to powers of compulsory purchase, which make securing land for off-site mitigation more feasible, the government is clear in its consultation that this is not a route it wishes to pursue for this type of development.
This change could prove beneficial, stimulating the off-site habitat market by increasing demand and encouraging the development of more habitat banks. However, it also brings risks.
NSIPs could become dominant players in the biodiversity unit market, potentially outbidding smaller developers for locally available units. This could drive up prices or reduce access for projects with fewer resources and smaller requirements.
There is also a question about whether NSIPs themselves will become habitat banks. Given their scale, it is reasonable to assume that some will generate a surplus of biodiversity units to offset the costs of surveys and other ecology mitigation requirements. Could this negatively impact independent habitat bank suppliers?
These changes will need careful monitoring to ensure the emerging biodiversity-related nature markets remain equitable and that local nature priorities aren’t compromised.
The cornerstones of implementation
For BNG to work well on this larger scale, collaboration and communication will be crucial. Delivering BNG in a way that supports LNRSs and local policy objectives will require developers, ecologists, and planners to be in close dialogue from the outset.
The design of NSIP sites will benefit from tight coordination between ecologists, landscape architects, and engineers. Decisions about where to place habitats, which areas to buffer, and how to respect watercourses, priority, and irreplaceable habitats must be made early and informed by the right type and volume of data.
NSIPs often cross multiple Local Planning Authorities (LPAs), landowners, and communities. As such, developing strong relationships with LPAs will help ensure local priorities are considered. Engaging early with LNRS mapping will be key to ensuring the right interventions happen in the right places.
Success will also depend on our industry being prepared. That means upskilling in large-scale data interpretation, survey strategy, GIS tools, and remote surveying and monitoring techniques. It also means ensuring we have the ecological workforce capacity to meet this challenge without leaving gaps elsewhere in the system.
Final thoughts
Extending BNG to NSIPs could lead to some of the most significant biodiversity gains in decades. These projects have the scale, reach, and permanence to reshape habitats for generations. But the path to success is not linear, and the devil will be in the details.
Having learned from the rollout of BNG for TCPA developments, we now have a comprehensive understanding of the policies and methodologies that work well, and those that are impractical, insignificant or afford little lasting benefits for nature. Let’s support the government in applying these lessons to this next phase of the BNG rollout.
The consultation is open until 24th July, 2025. Now is the time for ecologists, planners, and environmental professionals to speak up and shape a policy that works for both development and nature’s recovery. Let’s make sure we get it right.
About the Author
Cameron Carmichael | Environmental Net Gain Lead | Biodiverse Consulting
Newcastle University graduate Cameron is an Ecologist and Nutrient Specialist at Biodiverse Consulting, an environmental consultancy based in Northumberland. Cameron has delivered sHRA and nutrient neutrality scoping for countless projects, ranging from change of use to 100+ unit developments. Experienced with BNG, he has also completed his MoRPH5 River Condition Assessment course.