Unlocking the potential of Biodiversity Net Gain for urban regeneration
- Joshua Gittins
- Jul 17, 2024
- 5 min read
Updated: Jul 19, 2024
A driver to ‘mainstream’ nature restoration
Traditionally, development in UK has struggled to balance the pressures of increasing development to promote socioeconomic success, with environmental conservation, and even more so ecosystem restoration. In England, The Environment Act (2021) recognises this challenge, and in an era of escalating biodiversity and climate crises, has looked to the planning system to support the conservation and restoration of the ecosystems which underpin our lives[1].
The broad principle of Biodiversity Net Gain (BNG) is to leave biodiversity in a measurably better state than before development
Since February 2024, BNG has become a mandatory requirement for developments requiring planning permission under the Town and Country Planning Act in England, with some specific exemptions. For Nationally significant Infrastructure Projects, the timeline for implementation is 2025 onwards.
Exemptions under the Environment Act 2021 requirement for mandatory BNG improvement of 10%[2] include:
Existing planning applications (prior to February 2024; April 2024 for ‘small sites’ threshold);
Variations of planning permission;
Developments below “small sites” threshold: If a development does not impact a priority habitat and impacts less than 25 m2 of on-site habitat, 5 m of linear habitats (e.g. hedgerow); and
Householder applications, self-build and custom build applications (no more than 9 dwellings, site below 0.5 ha, consists of self-build/custom house build).
Specifically, the Environment Act (2021) mandates that post-development habitats should be 10% higher than the pre-development baseline. This secures the position of measurable outcomes for nature conservation as an essential building block of development, rather than only requiring that biodiversity and green space losses are mitigated or off-set[3].
The multiple benefits of Nature recovery
The primary goal of the legislation is to halt biodiversity loss in England. This should not be seen as an additional burden but an opportunity to drive a trajectory of nature recovery to support sustainable development, despite early challenges associated with implementation. Planning how to manage BNG early is key for developers, whilst planning BNG delivery strategically is key for Local Planning Authorities (i.e. Local Nature Recovery Strategies[4]).
The Statutory Metric developed by DEFRA[5], which is used to calculate habitat units for the pre- and post-development scenarios for a site, puts an emphasis on BNG being delivered on-site. Where this is not possible, a weighting mechanism called the ‘Spatial Multiplier’ rewards habitat creation and enhancement located within the same Local Planning Authority area where the development occurs, opposed to outside the Local Planning Authority area. This promotes the coordination and delivery of a network of biodiversity enhancements close to where people live in towns and cities. Providing people with multiple benefits associated with nature.
Delivering BNG through utilising Nature-based Solutions, or landscape recovery at-scale, as part of urban development can provide multiple benefits which sit outside the traditional socioeconomic benefits seen to be associated with development. It is necessary to deploy the right expertise during project development phases, to enable the ‘value’ of these benefits to be captured, maximised, and realised. For example, the addition of ponds and wetland features to a green-space (where appropriate), can provide educational opportunities, aesthetic and public realm improvements to benefit physical and mental health and wellbeing, and flood risk and water quality benefits, in addition to the core biodiversity enhancements.
Creating more diverse green spaces rather than, for example, simply maintaining a low-quality amenity grassland, could be leveraged by the implementation of BNG. Providing a more nature-centred guide for urban placemaking and the design of our spaces, alongside the multiple localised benefits that Nature-based Solutions can provide (e.g. carbon sequestration, air quality betterment, temperature control, flood risk and water quality improvements). Urban focussed Nature-based Solutions are accounted for in the Statutory Metric (e.g., such as green walls, green roofs, and Sustainable urban Drainage Systems). This means that BNG can provide a funding mechanism to deliver nature-recovery in constrained urban areas.
Key considerations for developers to maximise BNG opportunities include:
Consider BNG strategy early on: the earlier a strategy is formed around BNG, the more opportunity to make decisions on strategic sites and habitat design;
Site selection: consider the baseline biodiversity on site, and whether there is opportunity to create nature-based solutions to deliver wider benefits beyond biodiversity; and
Consult with local stakeholders: to understand nature recovery priorities locally, for example linking habitat creation and enhancement with Local Nature Recovery Strategies.
Environmental Markets for Financing Nature
The implementation of BNG, similar to ‘nutrient neutrality’ and carbon emission reduction requirements, has led to the emergence of an Environmental Market to support the sale and purchase of ‘Biodiversity Units’ (BNG market credits). This may be especially key to support development in constrained urban environments where there is little current space to achieve a BNG improvement. Although, this should not discourage hyper-local efforts to incorporate creative BNG improvements on-site. Local Planning Authorities may wish to take a proactive, strategic approach to managing BNG within their area by establishing a ‘Habitat Bank’ – i.e. off-site areas utilised for restoration and habitat creation to generate Biodiversity Units for sale to developers facing a shortfall to achieve their 10% obligation.
Market analysis carried out for Defra in early 2021 estimated that the introduction of mandatory BNG could generate an annual demand for approximately 6,200 off-site biodiversity units per annum with a market value of £135,000,000[6]. Actual demand may be higher, as some Local Planning Authorities are mandating developers to achieve 20% BNG in line with their most recent Local Plans. This reflects the scale of the opportunity for all parties, and nature.
There is further opportunity to co-deliver BNG and other environmental requirements (e.g., nutrient neutrality, reductions in carbon emissions) through Environmental Markets. The principle of ‘Stacking’ credits to derive value from multiple environmental benefits is emerging and may accelerate a move to more sustainable development through providing a viable funding mechanism[7].
What is the future of sustainable development?
The introduction of mandatory BNG represents a fundamental shift in approach to achieving more sustainable development in England. Although there will likely be an inevitable steep learning curve for all parties involved, utilising multi-disciplinary teams to develop Nature-based Solutions early in project development phases should ease the transition.
The challenges are far outweighed by the wider benefits that habitat enhancements can provide, in terms of multiple benefits. It is an important step towards Environmental Net Gain, a fully integrated approach to balancing nature recovery and socioeconomic outcomes to benefit people and our environment in the long-term.
If you are interested in learning more about how to comply with BNG requirements or leverage these opportunities for more sustainable development in your projects, get in touch with your Delivery Associate or get in touch with the Delivery Associate Network to receive additional support.
Josh Gittins is a Senior Scientist, working for Arup’s Climate & Sustainability Services based in Bristol. He specialises in the restoration and recovery of the natural environment, and how we can implement nature-based solutions across the built environment to better facilitate sustainable development. Josh has a diverse background, having worked across academia, consultancy and the public sector on environmental consenting and urban planning challenges straddling England and Wales.
If you have any questions on this topic, or would like support, please contact your Delivery Associate, or email DeliveryAssociatesNetwork@Arup.com
References and footnotes
[1] ‘Net Benefit for Biodiversity’ in Wales, driven by Planning Policy Wales 12, the Wellbeing of Future Generation (Wales) Act 2015 and Environment (Wales) Act 2016, with a similar non-metric specific approach in Northern Ireland via the strategic Planning Policy statement for Northern Ireland. No plans for a comparable approach in Scotland at present.
[3] Biodiversity Gain Hierarchy
[6] Biodiversity Net Gain: Market analysis study, Economics for the Environment, February 2021. Available at: https://randd.defra.gov.uk/ProjectDetails?ProjectID=20608
[7] Combining environmental payments: biodiversity net gain (BNG) and nutrient mitigation - GOV.UK (www.gov.uk)
