Environmental considerations are increasingly vital in construction following the introductions of mandatory Biodiversity Net Gain (BNG) requirements last year, with BNG and Nutrient Neutrality (NN) underpinning much of the shift.
In this briefing, senior associate Will Bond, associate Annabelle Lee and trainee Sophie Lindsay examine these changes, outlining their implications for landowners, developers and professional advisers.
Legislative changes introduce Biodiversity Net Gain requirements
BNG focuses on enhancing biodiversity through development, while NN aims to prevent nutrient pollution in water catchments. Together, these principles navigate construction projects towards minimizing environmental impact and promoting resilience, making them essential components of modern construction transactions.
Legislative changes to the Town and Country Planning Act 1990 with effect from February 2024 require developers to deliver a 10% gain in biodiversity (except in limited circumstances). Â The intent of the mandatory BNG provisions is to ensure that developments result in more or better quality habitat than there was before the development took place.
In terms of mechanics, if a proposal does engage the mandatory BNG requirement, a deemed condition of planning permission is imposed. Â This condition must be discharged before development can lawfully commence on site. Â In order to comply with the mandatory condition, an applicant must submit a BNG plan to the local planning authority (LPA) which demonstrates the delivery of 10% gain in biodiversity value and that it will be maintained for at least 30 years. Â The 10% gain can be provided on-site (inside a development area), off-site (outside a development area) and/or by way of biodiversity credits. Â
Before approving a BNG plan, the LPA will need to be satisfied that there are appropriate legal mechanisms in place to secure commitments from developers and/or landowners; typically, a section 106 planning agreement or a conservation covenant depending on the particular circumstances of a proposal. The simplest agreements may involve just a landowner and the local planning authority, but the developer will often need to join potentially together with a tenant, a funder and any broker who has brought the parties together. The LPA will be looking to secure the maintenance and monitoring of biodiversity post-construction in order to ensure BNG delivery for at least 30 years. Habitat Management and Monitoring Plans (HMMPs), which outline ongoing maintenance activities such as habitat restoration and monitoring, are critical to this.
The complexity, length and type of agreement that is appropriate for a particular proposal will depend on a range of factors such as the number of parties to the agreement and whether the BNG gain is to be provided on or off-site. The Russell-Cooke planning team is well-equipped to assist developers and landowners with the provision of BNG in the planning context.
Biodiversity Net Gain in construction
Early and ongoing engagement with ecological consultants is key to achieving BNG in construction projects. Â It is essential to conduct thorough site assessments at an early stage in order to identify existing biodiversity and any potential impacts of a proposed development. Input from an ecologist as early as possible will help developers and landowners to plan effective mitigation strategies and to integrate biodiversity considerations into a project from the outset. Â Ecologists also play an important role in producing a BNG plan and HMMP that is acceptable to the LPA, which is fundamental to the success of a project.
Integrating biodiversity into construction projects can be achieved through various innovative design solutions. Living walls and biodiverse roofs are excellent examples, providing habitats for plants, insects, and birds while improving air quality and insulation. Wildlife corridors within and around construction sites help maintain habitat connectivity, allowing species to move safely across urban areas. These design solutions not only support BNG but also enhance the aesthetic and functional value of buildings. Research has shown that green roofs in London have significantly improved the city’s urban biodiversity, hosting rare orchids, invertebrates and even attracting peregrine falcons to inner-city developments.
Nutrient neutrality in construction
NN is a critical environmental practice aimed at ensuring that new construction projects do not increase the levels of nutrients, such as nitrogen and phosphorus, in nearby water catchments. This is essential for preventing nutrient pollution, which can lead to eutrophication—a process that degrades water quality and harms aquatic ecosystems. By maintaining NN, construction projects help protect water bodies from excessive nutrient loads, preserving biodiversity and ultimately complying with the current planning regulations.
In the UK, NN is governed by regulations such as the Conservation of Habitats and Species Regulations 2017, which transposes the EU Habitats Directive into UK law. The Levelling Up and Regeneration Bill also plays a significant role by introducing measures to streamline planning processes while ensuring environmental protections. These regulations require developers to demonstrate that their projects will not increase nutrient levels in protected areas, often necessitating detailed assessments and mitigation strategies such as the purchase of off-site nutrient credits.
Implementing NN poses significant challenges for housing development, including increased costs and project delays. Developers must navigate complex regulatory requirements and often need to invest in mitigation measures such as creating wetlands or upgrading wastewater treatment facilities. Solutions include adopting best practices in sustainable construction, collaborating with environmental agencies, and utilising nutrient calculators to ensure compliance.
NN offset particular catchment can be a pecuniary planning, practical and financial obligation attaching to development. Russell-Cooke has recent advised a developer in respect of the granting of Option Agreements containing drainage easements to offset nutrient neutrality on a development site. Similarly, Russell-Cooke have advised rural land owners on an Option Agreement setting aside agriculture land for habitat creation, NN and for the prospective stacking of BNG.
Russell-Cooke’s rural and agribusiness team has experience in advising and negotiating the legal agreements that land owners considering natural capital projects would need to enter into to deliver BNG and NN schemes for sale by private treaty. In addition, we have experience of dealing with land owners and developers in respect of complex Option terms for NN offset.
The future of BNG and NN in construction
Evolving regulations in BNG and NN are set to significantly impact the construction industry. As environmental standards within construction and planning regulations improve, developers must adapt to new compliance requirements, which may increase costs and project timelines. However, these changes also present opportunities for innovation in sustainable construction practices. Staying ahead of regulatory updates and integrating ecological considerations early in the planning process will be crucial for developers. By embracing these evolving regulations, the construction industry can contribute to environmental protection while meeting both government criteria and wider development goals, ultimately leading to more resilient and sustainable communities.
If you are a landowner, developer or professional adviser, Russell-Cooke’s planning, rural and agribusiness and construction teams are well placed to work with you in respect of advising on and delivering natural capital schemes, particularly BNG and NN offset projects.
Russell-Cooke's real estate, planning and construction team acts for individuals, family businesses, investors, developers, charities, and for both landlords and tenants, on the full breadth of property transactions.Â
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