Despite a temporary Government stall on the roll out of the requirement for Biodiversity Net Gain (BNG) with new development, it’s almost inevitably coming at us in one form or another. In a bid to get our heads around what it means for our clients and projects, we recently caught up with Sarah Curnow of Planning, Environment and Landscape consultants Stephenson Halliday/RSK, following her research for Leicestershire County Council into the implications of BNG for its constituent Local Planning Authorities. Sarah generously shared her findings and gave us the heads-up on the BNG basics for parties on both sides of the planning fence. Whilst its pretty complex and much of the detailed guidance is still awaited from DLUCH, here’s our key takeaways on the issue just now:

  • The Legals – the requirement for BNG to be provided as a condition of planning permission comes from the Environment Act 2021, Schedule 14. This compels the use of a biodiversity metric to calculate existing/proposed biodiversity levels associated with development in a uniform way. It’s a mandatory legal requirement which involves an amendment to the TCPA 1990, and applies regardless of whatever adopted development plan policies are in place. It’s only a requirement in England as yet, with Wales and Scotland considering their own metric regimes;
  • Existing Protections – the BNG requirement does not change existing legal protections for important habitats and wildlife species. It maintains the mitigation hierarchy of i) avoid impacts; ii) mitigate; and, only as a last resort, compensate;
  • How much, where and how long? – the requirement is to provide a minimum of 10% gain in biodiversity on any development site (although apparently LPA’s can actually ask for more). In the first instance the preference is for gain to be delivered on-site, then failing that off-site (either within ‘blue line land’ belonging to the applicant, or on land within the LPA boundary held by a private ‘Habitat Bank’). As a last resort, gain can be delivered through a new statutory government-run biodiversity credits scheme (Natural England will hold a national BNG Site register). Any habitat provided must be secured, managed and monitored for a period of 30 years, so it’s a long-haul commitment whichever route you opt for;
  • Quantity and Quality matter – any BNG delivered must be measurable and equivalent or additional to the habitat lost through any development, and must be relatable to the individual site. Habitat is measured in 3 forms – habitat area, terrestrial linear (hedges) and aquatic linear (rivers) and you must compensate with similar (ie. you can’t replace woodland with a pond). Essentially, the further away from a site, the less relatable local ‘value’ the BNG will deliver;
  • Exemptions – the 10% requirement is not universal to all developments. Exemptions include Permitted Development, householder applications, self-build schemes and interestingly ‘Sites which are entirely buildings or sealed surfaces’ (ie. with de minimis biodiversity from the outset), which surely rules out a significant quantum of urban brownfield land?. Biodiversity gain sites in themselves are also exempt, as are currently Nationally Significant Infrastructure Projects and Marine Development, although further guidance over NSIPS is coming in 2025;
  • Documentation and validation – the Act also stipulates the use and approval of a Biodiversity Gain Plan (BGP) which will ultimately take the form of a templated report and set out how the gain will be achieved, managed and monitored etc. The metric calculation will form part of planning application validation requirements, whilst the BGP may be covered by planning condition (although this is still to be decided). The BGP will be a specialist document, so our Ecologist consultant colleagues are going to be busy; 
  • Securing delivery  – once your application is up and running and the BNG quantum calculated and agreed, delivery will either be secured by planning condition (for on-site delivery within the red-line) of by means of a S106 agreement or Conservation Covenant (for off-site delivery within the blue line or within the LPA boundary), or by S106 agreement for the statutory credit route. Conservation Covenants are private voluntary agreements which seek to conserve the natural or heritage features of the land (so, interestingly they could potentially be used for heritage applications), but must only be used for the public good, and must have a conservation purpose. They differ from S106’s in that the responsible body has to sign the covenant (this must be before the decision notice is issued), and all parties can decide if they wish to allow public access to the BNG land involved. Some LPA’s may be happy to defer a certain amount of information to pre-commencement conditions, but it’s likely that many will want details up-front;
  • LPA duties – whilst the metric and BGP responsibilities lie firmly with an applicant, the LPA role in the process will be equally significant, with pretty onerous implications for the public purse. In addition to integrating BNG requirements into strategy, policy and plan delivery, LPA’s will also need to register as an ‘Off setting body’, as well as dedicating legal/other resources to monitoring, management and reporting. BNG plans/delivery are to be monitored by LPA’s at 1,2,5,10, 20, and 30 year intervals (so the volume of reports involved could potentially run to 1000’s) and reported to central government. Natural England and DEFRA are due to release a monitoring template to assist LPA’s with this, who will also need some mechanism for triggering enforcement action where delivery is failing;
  • Interface with Development Plans/Other Strategies  – another requirement of the Act (and task for LPA’s) is for the production of Local Nature Recovery Strategies. These will involve a unitary/combined authority effort to assess and identify strategically significant areas for biodiversity gain, on a broadly county-wide basis. Local plan policies will feed into such strategies, and designated areas of strategic significance will in turn feed into metric scores (rating locally important habitats). Your BGP should reference the relevant local nature recovery strategy for your area to demonstrate how the ‘gain’ you are offering will contribute to these wider biodiversity needs;
  • Timings from hereon – the secondary legislation is now due out this month (November), which should trigger the mandatory requirement for BNG delivery on large sites from January 2024. Smaller sites will not be obligated until April 2024, with these being defined as: between 1 and 9 dwellings on a site of less than one hectare (or less than 0.5 hectares where the number of dwellings is unknown); or, less than 1,000sqm of commercial floorspace or where the site area is less than one hectare; 
  • Available guidance – DEFRA already has a biodiversity metric in place (which may well be rolled out as the statutory metric in due course), and which will apparently be reviewed on a 3-5 year basis. A national model of BNG conditions is also anticipated, along with further guidance on the use of Section 106 legal agreements, all of which will hopefully provide some much-needed structure to the process. In the meantime, check out the Planning Advisory Service collection of guidance which includes a useful flow map (developed with Future Homes Hub) illustrating how BNG requirements and responsibilities will impact on the planning application process;
  • Current figures – and finally, whilst private ‘habitat banks’ have already started to mobilise, current DEFRA figures for the statutory credit system range from £42,000 per unit of low habitat distinction (eg heathland or scrub), up to to £650,000 per unit of high value habitat (peat/marl environments). So there are potentially some big figures involved, which you absolutely need to be programming in now. Will be interesting to see how the impacts on viability unfold – it’s not just LPA’s who will be taking a hit on resources. 

So, a brief summary of what we know about BNG so far. Still so much more detail awaited  – and it’s possible that the entire can could get kicked even further down the road – but it’s clear we need to be teeing up urgently for this and to better understand how our projects/developments can deliver on biodiversity that is proportionate, local and genuinely valuable. We’re learning on the hoof here, and would be so interested to hear your BNG experiences. And big thanks again to Sarah Curnow for sharing her knowledge thus far.