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Webinar: Mandatory Biodiversity Net Gain is imminent: Are you ready?

BNG becomes a legal requirement on new developments in November. It will be a powerful tool to promote smart and sustainable development design

Off-site habitat banks can help increase BNG, providing landscape-scale biodiversity.
Off-site habitat banks can help increase BNG, providing landscape-scale biodiversity.

The high level of interest in the RIBA Journal’s Designing for Biodiversity Net Gain webinar, which attracted more than 900 viewers, suggests a desire in the profession to get up to speed on mandatory BNG. The new regulations will require a minimum 10% uplift in the overall biodiversity value of a development site as part of planning. This becomes law in November for most developments in England under the Town and Country Planning Act 1990, with small sites following next April, and nationally strategic infrastructure projects in November 2025.

‘People are eager to know more,’ said RIBA Journal managing editor Isabelle Priest, who chaired speakers and panellists ranging from ecologists and architects to lawyers and local authorities.

First up was Ben Stansfield, a partner specialising in planning and environmental law at Gowling WLG. He set out the new requirements for a BNG plan to be approved by the Local Planning Authority as a pre-commencement condition before work can start on site. This improved biodiversity needs to be maintained for at least 30 years. Local planning authorities may require a greater uplift – some already ask for 20%.

Once the site’s baseline biodiversity level has been established, the proposed BNG Plan can be calculated using a Biodiversity Metric tool – templates for these plans will be available from Defra. The BNG Plan can comply using on-site or off-site methods, or both. For example, obligations can be met by on-structure, on-site, and/or adjacent to site measures on areas under the developer’s control. Off-site measures may include land controlled by the developer or offsite habitat banks. Statutory biodiversity credits will also, initially, be available to buy from the UK government, but at uncompetitive prices.

Stansfield had some concerns over potential delays while BNG plans were approved or decisions legally challenged, and how the required biodiversity uplift would be monitored and enforced over the 30-year duration. BNG works are to be secured via a Section 106 Agreement under the Town and Country Planning Act, or by conservation covenant with a responsible body. There were ‘lots of question marks’ over the enforcement of the latter, he said, as it was difficult to assess the long-term financial burden for many sites. Legal agreements will bind those with an interest in the land.

The Home of Gardening Science at RHS Wisley achieved more than 10% BNG.
The Home of Gardening Science at RHS Wisley achieved more than 10% BNG. Credit: Hufton + Crow

‘We’ll get there. It’ll all be fine. But we could have  a couple of tricky months ahead of November and then in December and January,’ he said.

Emma Toovey, ecology director at Environment Bank, struck a more optimistic note, preferring to see BNG not as another burden, but as ‘an amazing opportunity’ to address the decline in biodiversity, with the potential to be transformative. 

She advised getting baseline assessments done early, and working with a competent ecologist using the Biodiversity Metric tool to minimise the project’s biodiversity impact before considering BNG delivery.

‘It’s not a tool that you should be just applying right at the end of the process as some sort of scoring calculator. You’re missing a huge opportunity if you’re only using it for that purpose,’ she said.

After running through how BNG can drive high quality spaces (with potential for urban cooling, increased property value and much more) she set out potential challenges. On-structure greening, for example, can be costly and difficult to implement, with limited gain. She urged consideration of habitat banks, such as those from Environment Bank, as an alternative to compromised on-site options, which can be delivered within the local authority or national character area.

These have the advantage of being able to deliver at landscape-scale, creating the best outcomes for nature, and are managed by biodiversity experts with all funding for the full term secured. Off-site mitigation also leaves more space on-site for recreational green spaces and amenities. Statutory biodiversity credits should be considered the last resort.

Panellists from local authorities in Lichfield and Sutton described their own, already-established BNG policies, which have slightly different models and metrics. Lichfield has had a policy in its local plan for BNG since 2016 and also an SPG, and requires 20% BNG over the habitat that’s being lost. For off-site BNG, the first preference would be for this to remain in district.

Sutton’s Rosie Whicheloe said the borough has had a policy for no net loss in its local plan since 2018. Its own BNG metric will be updated from November, and it has a full-cost recovery approach to ensure the council doesn’t end up picking up related costs. She said it was keen to avoid BNG offset going outside the borough.

‘An amazing opportunity’ to address the decline in biodiversity, with potential to be transformative

Cobham Manor, designed by PRP, in east London, which has achieved more than 10% BNG.
Cobham Manor, designed by PRP, in east London, which has achieved more than 10% BNG.

Wilkinson Eyre head of sustainability Nuno Correia called for the industry to upskill itself in biodiversity to understand better how design decisions affect the new BNG metric, and said it is working with experts to prepare for the BNG. The practice achieved beyond 10% BNG at RHS Hilltop, its recent scheme at Wisley. Meanwhile at its recent Battersea Power Station restoration and repurposing, biodiversity measures included green roofs and a tower set apart from the main building for birds to nest in.

‘Everyone’s on that learning journey,’ said Derwent London head of sustainability John Davies, who added that it was critical that all members of the design team played their part to introduce meaningful and manageable habitats. He raised the difficulties of achieving BNG on highly constrained central London sites, and the question of whether local communities are losing out if this happens off-site instead. 

Viewers’ questions included how long ecology baseline assessments last (two years), and whether BNG banks were taking land from food production. Lichfield’s Kristie Charlesworth said farmers providing BNG sites may wish to diversify, or find new uses for land that didn’t affect food production. 

Perhaps the webinar’s most important message was the need for early engagement.

Angeli Ganoo-Fletcher, director of landscape at PRP, described the practice’s approach of ‘preserve, protect and then enhance’, with BNG added to a set of standards to follow at each RIBA project stage. On one recent project in Tunbridge Wells, it achieved a 20% BNG.

‘BNG can’t be an afterthought anymore.’ she added. ‘It needs to be part and parcel of that inception meeting where we’re all around the table with the architectural client, because we’ll have to target that 10% – and sometimes more than that.’ 


 Speakers include:  

Ben Stansfield, partner, Gowling WLG  
Emma Toovey, ecology director, Environment Bank  
Nuno Correia, head of sustainability, WilkinsonEyre  
Angeli Ganoo-Fletcher, director, landscape, PRP  
Rosie Whicheloe, biodiversity net gain officer, London Borough of Sutton 
John Davies, head of sustainability, Derwent London 
Kristie Charlesworth, ecology and climate change manager, Lichfield District Council


Speaker biographies

Isabelle Priest, managing editor, RIBA Journal

Isabelle joined RIBA Journal in 2015. She had previously worked at Architecture Today, The Architects’ Journal, The Modern House and a10 New European Architecture in Amsterdam. She studied architecture at The Bartlett (UCL) and later graduated from there with distinction in MA architectural history.
Isabelle has been shortlisted for multiple International Building Press awards and won the Architecture Writer category in 2016 and 2019. 

Ben Stansfield, partner, Gowling WLG 

Ben Stansfield is one the UK's leading lawyers practising planning and environmental law. Ben is based in our London office and brings with him a wealth of experience advising clients on the consenting and regulation of their projects and their compliance with environmental regulations and reporting standards.

In addition to his advisory and transactional practices, a substantial part of Ben's work is contentious and he has enjoyed a number of successes, both bringing and defending challenges to planning permissions and environmental consents.

Ben is highly regarded for his straightforward approach and clients appreciate his ability to break down complex regulations into user-friendly practical advice that they can action. Ben is a former Vice Chair of the United Kingdom Environmental Law Association (UKELA) and was a Trustee of UKELA for eight years.

Ben speaks internationally on UK and European environmental law issues and represents a number of overseas law firms with specialist elements of their transactions.

Ben is recommended for both planning and environmental law in both Legal 500 and chambers and partners and also features in Who's Who Environmental Law.

Emma Toovey, ecology director, Environment Bank 

Emma has more than 18 years of ecological consultancy experience across diverse industries, specifically the development sector, working with landowners, developers, planning authorities and a range of stakeholders in the development consenting process. She ensures sound ecological principles and technical integrity underpin every decision the business makes.

Kristie Charlesworth, ecology and climate change manager, Lichfield District Council

Kristie has worked in wildlife conservation and ecology for Local Planning Authorities for the last 7 years, providing guidance and ecological advice to the council and its customers, and contributing to writing policy. As planning consultee, Kristie responds to applications relating to species, habitats, Habitat Regulations Assessment (HRA), and Biodiversity Net Gain (BNG). She leads and coordinates on the council's response to BNG, Climate Change, and emerging Local Nature Recovery Strategy (LNRS). Kristie is a habitat manager of council owned wildlife sites, delivering numerous countryside management projects to achieve the aspirations of the Nature Recovery Network. Kristie has recently won the LGC Rising Star award 2023.

Nuno Correia, head of sustainability, WilkinsonEyre 

Nuno is the Head of Sustainability at WilkinsonEyre and has over thirteen years of cross sector experience in sustainability in the built environment. Nuno specialises in environmental design, building performance and net zero carbon, and plays a key role in the development of our evolving sustainability strategy to enable integrated design across the practice.

He is an active member of industry groups, part of the Low Energy Transformation Initiative (LETI) steering committee, and a co-author of the Climate Emergency Design Guide. He is also a contributor to the Net Zero Carbon Building Standard and a design tutor at University College London.

Rosie Whicheloe, biodiversity net gain officer, London Borough of Sutton

Advocate for sharing knowledge, connecting people and breaking down barriers. Qualifications, appointments, paid and voluntary experience that cross between arts, science and communications, planning, design and management. Rosie currently works for the London Borough of Sutton as their Biodiversity Net Gain Officer, where she supports the four-strong ecology team to embed biodiversity through the planning process, habitat management, outreach and internal collaboration. Previous appointments included London Wildlife Trust where she co-produced the GLA Urban Greening for Biodiversity Net Gain -  a design guide. In her spare time she loves cycling and is a volunteer/ treasurer of Manor Park Community Garden in Newham.  

Angeli Ganoo-Fletcher, director, landscape, PRP

Angeli is a director who heads up PRP's landscape team. She is responsible for delivering large-scale estate regeneration projects, residential developments, as well as master planning and is an expert in the field of design for older people, dementia and those with physical, cognitive or learning disabilities. She has over 25 years’ experience in all aspects of landscape procurement from feasibility stages to design development, implementation and delivery of large-scale residential and commercial landscapes. As a chartered landscape architect, Angeli applies environmental and social values through external spatial design and arrangement, an approach that enhances people’s lives and the environments that they live in.

John Davies, head of sustainability, Derwent London

John Davies is Head of Sustainability at Derwent London and on the Executive Committee. He is responsible for leading the company wide sustainability and responsibility agendas. John is a recognised sustainability expert in the commercial property sector and has been instrumental in creating a number of industry leading sustainability programmes and strategies. Prior to joining Derwent London John was Head of Sustainability at Davis Langdon LLP where was responsible for developing and delivering its range of sustainability services.

Topics of expertise: Real estate ESG strategy, climate risk, net zero carbon by 2030, prioritising reducing carbon emissions, long-term approach, responsible business, collaborative solutions.



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