What is BNG?

Biodiversity Net Gain (BNG) is an approach to development that measures the impact on habitats and wildlife, and ensures that any losses are more than compensated for through habitat creation or enhancement, resulting in a net positive outcome for nature.

This policy shift has already transformed how biodiversity is considered in planning. Ecologists are now integrated from the earliest design stages, working alongside landscape architects, planners and other stakeholders to shape development layouts. This collaboration not only enhances ecological outcomes but also improves quality of life for future occupants through increased access to green space and enhanced visual amenity.

Lessons from the first year

While the new approach has brought many successes, there are also lessons learned and ongoing challenges.

Urban developments, for example, often face constraints such as limited space for habitat creation and high land values, making on-site biodiversity interventions difficult to deliver. One particularly complex issue is the presence of open mosaic habitats on previously developed land. These habitats – often found in urban areas – can form relatively quickly and are ecologically rich, scoring highly under the BNG metric. Yet they are extremely difficult to recreate or offset

In contrast, rural locations may offer greater space and ecological potential, but they bring their own complexities. A high biodiversity baseline can make it harder to deliver a 10% uplift, while the presence of protected species or sensitive habitats often requires extensive surveys and mitigation strategies.

Additionally, the River Condition Assessment (RCA) – required under the BNG framework for developments near watercourses – is a critical yet sometimes overlooked element. Its findings can significantly influence both the baseline value and the feasibility of proposed interventions.

Moving beyond the metric

While urban and rural sites present different ecological contexts, both highlight a broader challenge: the BNG metric, though valuable, has a limited scope. It focuses primarily on measurable habitat units and does not account for the wider ecosystem services that many sites provide, such as carbon sequestration, nutrient neutrality, flood resilience or the social and health benefits associated with access to nature.

As environmental challenges become increasingly interconnected, there is growing recognition that BNG must evolve to integrate with wider sustainability metrics. A more holistic approach would enable developments to deliver co-benefits across climate adaptation, water management and community wellbeing – making them more resilient and future-proof.

Hilson Moran’s approach

At Hilson Moran, we support clients in navigating these complexities. Our interdisciplinary environmental team provides strategic advice that goes beyond the BNG metric.

We tailor our advice to the unique challenges of each site, ensuring that biodiversity goals are achievable and aligned with broader sustainability ambitions. By embedding ecological thinking into every stage of the design and planning process, we help create developments that deliver lasting value for nature, people, and the planet.