BNG for NSIPs: what delivery teams need to be thinking about now

Biodiversity Net Gain (BNG) is moving from policy discussion into practical delivery planning for Nationally Significant Infrastructure Projects (NSIPs), and the questions being asked by promoters, advisers, habitat providers and landowners are becoming more detailed as the regime develops. 

Last month, Ardent welcomed guests to Panshanger Park, for a roundtable hosted by Tarmac and Maydencroft to discuss how the emerging regime is likely to affect project strategy, compulsory acquisition, species mitigation, procurement, landowner engagement and long-term delivery. The discussion reflected a market that is still maturing, but one where the practical challenges are becoming much clearer.  

A consistent theme was the need to bring BNG into project thinking much earlier. Where decisions on habitat design, delivery route, land requirements, procurement or long-term management are left too late, projects risk creating avoidable cost, programme and compliance issues that could have been identified earlier through more joined-up planning. 

1. BNG needs to sit closer to core project strategy 

One of the strongest messages from the discussion was that BNG should not be treated as a self-contained environmental workstream. Although the technical requirements are specific, the delivery implications cut across land, legal powers, stakeholder engagement, procurement, construction sequencing, ecological design and long-term asset management. Critically, BNG needs to be considered as part of habitat and species mitigation strategies as a whole. This is for ecological design but will also be crucial for determining the best approach to land (or biodiversity unit) assembly.   

Where BNG is considered late, project teams may find that preferred habitat solutions are not deliverable, landowner agreements are not sufficiently mature, procurement routes do not reflect whole-life risk or environmental commitments are difficult to reconcile with species mitigation and habitat compensation requirements. 

Earlier involvement from habitat banks, land managers, landowners, environmental advisers and delivery contractors can help test whether proposed strategies are realistic before they become embedded in project assumptions. It also allows promoters to understand cost, risk, market capacity and long-term management requirements before options narrow. 

1. Compulsory acquisition remains a nuanced area 

The discussion around compulsory acquisition and reasonable alternatives highlighted the need for careful project-specific judgement. Participants noted that promoters now need to demonstrate that there are no reasonable alternatives, bringing BNG closer to the wider compulsory purchase framework, while also recognising that BNG may involve more potential alternatives than some infrastructure requirements because off-site habitat banks, local landowner agreements and statutory credits may be available. 

That creates a more complex assessment for promoters. Where suitable off-site options exist, or where statutory credits remain available as a last resort, the case for compulsory acquisition will need to be carefully considered against the specific facts of the project, including spatial requirements, habitat type, mitigation needs and the availability of credible alternatives. 

The discussion did not suggest a single answer, but it did point to the importance of building a clear evidential trail around the options considered, the reasons alternatives may or may not be suitable and the relationship between BNG delivery and the wider purpose of the scheme. 

1. BNG, species mitigation and compensation need clear boundaries 

A significant part of the roundtable discussion focused on the interaction between BNG, species mitigation and habitat compensation. Participants highlighted the risk of overlap, double counting or uncertainty where the same land, habitat or ecological intervention may be relevant to more than one requirement. 

Project teams will need to be clear about the distinction between baseline requirements, mitigation or compensation obligations and additional biodiversity gains that may be capable of being commercialised or stacked.  

Those boundaries are likely to vary by project, shaped by ecological connectivity, local populations, licence requirements, habitat type and stakeholder expectations. 

Where those questions are not resolved early, they can create issues for land requirements, DCO strategy, procurement, cost planning and compliance. A clearer approach at the outset can help avoid assumptions that later prove difficult to defend or deliver. 

1. On-site and off-site delivery both need whole-life scrutiny 

On-site delivery may appear attractive where land is already being acquired or where habitat compensation is already required. However, participants raised concerns about long-term management, operational constraints, whole-life costs and whether infrastructure promoters have the in-house capability to manage complex habitats over a 30-year period. For private sector promoters looking to dispose of infrastructure assets following consent, on-site obligations may also be a concern for buyers. 

Off-site delivery may provide advantages where specialist habitat bank can take on long-term delivery and risk, although availability, price, spatial multipliers, procurement routes and assurance around quality remain important considerations.  

Another model discussed was the creation of bespoke habitat banks, local to the project, through agreements with local landowners. The legal infrastructure of conservation covenants (Environment Act 2021) means long term agreements that ‘run with the land’ could be an attractive option for local habitat creation can be agreed which take the 30-year management obligation away from the promoter. This model could also potentially deliver habitat and species compensation requirements. The emphasis is the right type of agreement with the right landowners, with agreements concluded well in advance to avoid programme risk if deals fall through.   

The question isn’t about whether on-site or off-site delivery is cheaper, it’s ultimately about considering deliverability, management responsibility, long-term risk, ecological quality, spatial relevance, landowner appetite and the credibility of the delivery model. 

1. Procurement needs to recognise long-term value 

Procurement was identified as a major challenge, particularly where public sector promoters are working within frameworks that may not fully capture the value of BNG delivery.  

Participants raised concerns that procurement exercises can focus too heavily on price, or bundle BNG into broader packages in ways that make it difficult for specialist suppliers or landowner-led portfolios to participate. 

For BNG, lowest cost and best value may not always point in the same direction. A strategy that appears competitive at procurement stage may carry future risk if it does not properly account for long-term management, monitoring, enforcement, land access, replacement capital costs or practical delivery capability. 

Habitat management plans also need enough practical detail to allow proper pricing. Without clarity on access, quantities, operational constraints and future maintenance requirements, delivery contractors and land managers may struggle to price the work accurately, increasing the risk of underestimation and later challenge. 

1. Landowner engagement should start earlier and go deeper 

Landowners will play an important role in many BNG delivery strategies, particularly where promoters are seeking local off-site solutions or exploring agreements outside the immediate project boundary.  

Participants stressed the importance of engaging landowners early and respectfully, with proper attention to business models, appetite for 30-year commitments, succession considerations, practical land management capability and expectations around payment or revenue share. 

Where proposals align with farming or estate operations, landowners may be willing to participate, particularly where they receive fair support, advice and clarity on long-term obligations. Landowner-led habitat bank proposals are unlikely to emerge quickly where baseline surveys, design, legal agreements and registration are required, which reinforces the need for early engagement rather than late-stage negotiation. 

Covering adviser costs, giving landowners time to understand the implications and recognising the operational realities of long-term land management can all help create more credible delivery options. 

1. Monitoring, enforcement and risk transfer need to be understood from the outset 

The roundtable also explored what happens if habitat delivery fails. Conservation covenants, financial reserves, enforcement rights and monitoring arrangements were discussed as mechanisms for securing delivery, but participants also recognised the potential complexity of drawing promoters into off-site management disputes or enforcement processes. 

Promoters want assurance that promised outcomes will be delivered. Habitat providers and land managers need clarity on responsibility, intervention rights, reporting and financial provision. Local planning authorities and statutory bodies need confidence that commitments are robust enough to withstand scrutiny over time. 

Responsibility, risk transfer, enforcement and monitoring need to be understood before commitments are made, particularly where a project’s compliance position depends on outcomes being maintained over decades. 

1. A maturing market, but not yet a settled one 

The discussion suggested that the BNG market is moving quickly, with guidance, practical examples and shared learning beginning to clarify expectations.  

Uncertainty remains around policy interpretation, spatial flexibility, procurement models, the relationship between BNG and other ecological obligations, monitoring and enforcement. 

For promoters and delivery partners, the practical message is to avoid treating that uncertainty as a reason to delay.  

Project teams should use the current period to test assumptions, engage the market, understand landowner appetite, refine procurement routes and bring delivery expertise into the strategy before key decisions become difficult to change. 

BNG will require environmental expertise, but successful delivery will also depend on land, legal, procurement, engagement and project delivery disciplines working together earlier and more consistently. 

Treating BNG as a critical project activity from the outset, with enough practical detail to move from policy intention to long-term delivery confidence is ultimately the key to success.