Welcome to Field Notes, Gentian’s new monthly newsletter exploring everything from biodiversity policy developments to fascinating facts from the world of ecology. In our first issue, we unpack the UK’s new planning policy reshaping the built environment — and how our technology is helping tackle its challenges. We’re also celebrating Green Roof Day and spotlighting exciting work by our experts in the field of urban ecology.
Planning for Nature Recovery: The Challenges, Costs, and Opportunities
By Mana Starosta
Sustainable development amidst the global biodiversity crisis
As the global biodiversity crisis deepens, the built environment sector is under growing pressure to account for its ecological impact. In the UK, the government responded by introducing Biodiversity Net Gain (BNG), a policy requiring all new developments to deliver a 10% net gain in biodiversity, maintained for at least 30 years. This marks a significant shift in how property development is planned and executed across the country. Biodiversity is quantified using the Statutory Biodiversity Metric, originally developed by Natural England and formally implemented in February 2024. It has since found global significance with the metric being adapted to the US, the Netherlands, Saudi Arabia, and India.
Worldwide applications
In Sweden, a program offsetting the negative impacts of urban growth on biodiversity is being developed using Natural England’s biodiversity metric as a foundation. Meanwhile, in the Americas, Ramboll introduced a Global Biodiversity Metric (GBM) at COP16, reflecting the growing international movement toward standardised ecological accountability.
Incentivising nature recovery in the UK
For the UK - one of the world’s most nature-depleted countries - BNG represents a landmark shift with the potential to embed nature recovery into the planning process. While it imposes new responsibilities on developers, it also creates opportunities for nature-positive investment.
The Statutory Biodiversity Metric calculates “biodiversity units” present on a site based on the habitat type, condition, size, and strategic significance, among other factors. While developers are encouraged to enhance biodiversity on-site wherever possible, those who cannot must generate gains off-site or, as a last resort, purchase statutory biodiversity credits.
The cost of these credits has far exceeded initial estimates, with off-site units now averaging £30,000 and statutory credits exceeding £40,000. Some habitat types command even higher prices: watercourse units have reached £140,000, and neutral grassland-based habitats and hedge units can cost £20,000. These high costs are intentionally set to disincentivise the purchase of units from habitat banks - specialised land areas managed to generate biodiversity units - and instead encourage on-site ecological enhancement.
Since early 2025, habitat banks have seen a surge in demand as developers are turning to them to meet BNG requirements. In theory, this provides a powerful mechanism to restore degraded or underutilised land. However, practical challenges persist when it comes to enforcement and establishing trust.
Making BNG work
The overwhelming consensus from the government and industry experts is that considering BNG early in the development and design process is crucial to avoiding costly setbacks and delays.
Developers must submit a Biodiversity Gain Plan outlining how they will achieve a 10% net gain, which must be approved by the Local Planning Authority before work begins. Delaying BNG considerations until the application stage can derail entire projects.
In fact, according to Savills, “2024 saw a record-low number of permissions granted for new homes in England, with just over 30,000 projects approved” and they predict that “the amount of land estimated to be developed for housing in England each year, 20% will be required for BNG”.
For developers, this means strategic site selection, early baseline data collection, and integrating biodiversity uplift into design are now critical components of successful projects. Failing to do so can result in significant delays or high costs from having to alter designs or purchase expensive biodiversity units.
Challenges and Opportunities
While the need for baseline data and a method for regular monitoring throughout the 30 years of compulsory maintenance is evident, challenges remain in finding a reliable, standardised method of data collection.
Baseline habitat surveys must be conducted by a qualified ecologist with an exception for some small developments where the small sites metric can be used by a competent person. However, getting an ecologist to each site is expensive, time-consuming, and potentially problematic if the developer doesn’t have access to the site.
There is some habitat mapping data available online, such as the Living England Habitat Map, but this data is far too coarse to be useful for assessing specific sites for BNG. What developers need is a fast solution that gives them access to precise BNG data remotely, helping them make informed decisions early on.
Gentian True Sight - Instant Habitat Mapping for BNG
Gentian’s latest instantaneous habitat mapping tool, Gentian True Sight, enables developers to scope hundreds or even thousands of sites entirely remotely within days or minutes. Powered by our state of the art AI, True Sight analyses high-resolution aerial and satellite imagery to produce habitat surveys aligned with the statutory biodiversity metric. Our data is delivered at a fraction of the cost of manual surveys and eliminates the need for on-site visits during the site scoping and design phase.
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Our AI has been trained using on-the-ground ecologists’ surveys, which have also enabled independent validation. On one site, the ground survey found a total of 5.80 biodiversity units. Our instantly generated map for the same site: 5.81.
Gentian True Sight is available now and already supporting clients with BNG compliance. Simply upload your potential sites via our online platform or API, and within minutes you’ll receive a detailed habitat map and biodiversity unit calculation—ready to inform your planning process from day one.
Green Roof Day: Celebrating Urban Biodiversity from the Top Down
By Charles Bouqueuniaux
Marked on June 6, World Green Roof Day highlights the vital role green roofs play in supporting urban biodiversity. Far more than visual enhancements, these nature-based systems reduce urban heat, manage stormwater, and provide critical habitats. Inspired by natural landscapes like coastal shingle and gravel riverbeds, green roofs replicate rare ecosystems to host specialized species. This concept, pioneered in 1990s Switzerland and adopted in London in the 2000s, now shapes England’s Biodiversity Net Gain (BNG) requirements for new developments.
Globally, Japan’s Morigasaki Water Reclamation Centre transformed its rooftop into a nesting site for Little Terns. Professor Ayako Nagase has since championed “Harappa” green roofs—low-maintenance habitats that foster pollinators and birdlife for decades.
At Gentian, we support this movement through advanced habitat mapping tools that pinpoint rooftop biodiversity potential. As cities expand, green roofs offer a scalable, resilient solution to help urban ecosystems thrive—one roof at a time.
Gentian Supports Cross-University Workshop on Urban Environmental Challenges
By Charles Bouqueuniaux
From May 19–23, 2025, Gentian supported the Here and There, Now and Then workshop in London, uniting 34 students from CY Cergy Paris Université and UCL’s Connected Environments Lab. Focused on urban ecological issues, the event featured intensive fieldwork at Queen Elizabeth Olympic Park.
Gentian’s Remote Sensing Senior Expert, Olga Tutubalina, played a key role—presenting high-resolution satellite imagery and thermal time-series data during a preparatory seminar. These datasets, alongside contributions from partners like Bluesky International, enabled students to explore urban heat islands, biodiversity, and conservation strategies.
A park tour on May 18, led by Gentian advisor Gary Grant and Biodiversity Manager Tom Bellamy, offered valuable local insights. The week culminated in a showcase of innovative student solutions, including immersive visual tools and heatwave adaptation strategies.
Dr. Valerio Signorelli (UCL) praised Gentian’s contributions, highlighting the real-world exposure and cross-disciplinary collaboration the workshop enabled. Gentian remains committed to fostering future leaders in spatial and environmental analysis through meaningful, hands-on partnerships.
We invite you to join us as we navigate this critical space and share knowledge that empowers action. To receive Field Notes directly in your inbox, sign up via the form below:
