The delayed government consultation providing more detail on the introduction of the mandatory minimum 10% biodiversity net gain (BNG) requirements for Nationally Significant Infrastructure Projects (NSIPs) under powers in the Environment Act 2021, was published on 28 May (ending on 24 July). 

Originally consulted on in broad terms in 2022 and expected to be introduced by November 2025, this consultation clarifies key aspects of the new NSIP BNG regime and provides more (but not all) detail on how it will apply to NSIPS from the new date of May 2026.  But it also raises concerns.

Whilst many NSIPs in the pipeline are already incorporating biodiversity gains into scheme design in anticipation of the new rules coming into force, this consultation is helpful in confirming the broad framework and direction of travel, though it raises questions as to whether this approach will work in practice for all schemes.  In some areas, the door remains open to the adoption of an alterative approach not yet considered, depending on the consultation outcome, so scheme promoters need to be alive this. 

Whilst detailed guidance will be published at a future date, for example on how BNG will apply to schemes crossing multiple boundaries, the use of CPO (or not) and how specific issues such as aerodrome safeguarding should be accounted for, the proposal to apply the same core approach to calculating and delivering BNG for all NSIP types is unlikely to workable in all cases without some in built flexibilities.  Long linear schemes in particular may well find a standard approach to be challenging due to the size and nature of these schemes and the variations in habitats and scheme impacts. 

So whilst this consultation can be seen as a step forward for scheme promoters in some respects as it outlines more detail, because elements of the regime may still change, preparing applications, scheme design and programmes in anticipation of what is to come will present its challenges.  And if the proposed approach ultimately adopted has little or no flexibility built in, this will present ongoing challenges for some NSIP types in meeting the BNG objective.  

In summary, and broadly following the approach consulted on in 2022, this consultation anticipates:

• A ‘core’ (rather than bespoke) approach to BNG  will apply to all onshore NSIPs, including temporary, permanent, and associated development included within the ‘order limits’ (although, the door remains open on a bespoke approach for land temporarily used for construction depending on the consultation outcome);
• Model text is included for a core Biodiversity Gain Statement to be applied to each NSIP sector to have the same effect as if they were in the NPS once published. But again, depending on the consultation outcome, bespoke arrangements for certain NSIP types could ultimately be introduced;
• The same statutory biodiversity metric to be used as for TCPA BNG to calculate biodiversity values (which incentivises local enhancements) but with amendments to the user guide to confirm off-site BNG can be delivered in any of the relevant LPAs for schemes that cross multiple LPA boundaries without incurring a spatial risk multiplier penalty, and that relate to associated development;  
• Applicants can deliver either or both BNG on-site or off-site in the first instance, or purchase statutory biodiversity credits as a last resort. This differs from BNG from TCPA schemes where BNG on-site must be prioritised before off-site gains considered, to disincentives expansion of scheme boundaries (and the CPO of land) to deliver BNG entirely on-site;
• Onsite pre-development biodiversity value to include all habitats within the order limits, unless an alternative approach emerges through the consultation, as development boundaries may be much larger than actual construction areas so this may not be the best approach for all schemes;
• Securing and maintaining enhancements for 30 years  through DCO requirements, planning obligations or conservation covenants; 
• DCO applications will be required to include a biodiversity gain plan with their applications, possibly based on a template, along with a completed biodiversity metric calculation (this contrasts with TCPA schemes where biodiversity gain plans are submitted after planning approval, though draft plans can be submitted with applications);
• Requirements will be drafted on a case-by-case basis for each DCO to require approval of an updated biodiversity gain plan and metric calculation post consent, with biodiversity units to be secured before commencement of development (or a phase) and any shortfall secured before completion of construction or operation or once the final impact on habitats is known.

BNG on brownfield land

A separate consultation, running simultaneously, relates to improving the implementation of BNG for minor developments. Most of this consultation is not applicable to NSIPs, except for the section on brownfield development with open mosaic habitat (OMH) which is relevant for all development types with a BNG requirement.  

Brownfield sites with OMH presents challenges because of its a high distinctiveness for the purposes of the BNG statutory metric, meaning that it must be compensated for on a ‘like for like’ basis, and the difficultly in recreating this type of habitat onsite, or locating it off-site.  Options to overcome this are proposed, with updates to the metric definitions, guidance and condition assessment to support ecologists in the identification of OMH or alternatively when no OMH habitat is available off-site, allowing compensation for the loss of such habitats with an alternative habitat mosaic with similar ecological benefits.