Streamlining Biodiversity Net Gain: The Library Extension at a London Primary School
Planning a school expansion in a busy urban area like Greater London (NW9) often brings concerns about complex environmental regulations. However, a recent Biodiversity Net Gain (BNG) assessment for a library extension project demonstrates how ecological compliance can be handled efficiently when the baseline impact is minimal.
The project involves a modest 6m extension to an existing school library. By identifying the ecological value of the land early, the development team has established a clear, low-friction path to meeting statutory requirements.
Assessing the Baseline: Minimal Ecological Constraints
The initial site survey, conducted in February 2026, confirmed that the proposed construction area holds very little botanical or habitat value. This is a best-case scenario for developers, as it simplifies the mitigation process.
The site currently consists of:
-
Modified Grassland: Regularly mowed lawn area with high foot traffic.
-
Sealed Surfaces: Existing concrete hardstanding.
Because these are categorized as low-value habitats, the “biodiversity cost” of the project is extremely low. The survey concluded that the site has no regional importance and does not serve as a vital corridor for protected species, meaning no complex or expensive wildlife relocation strategies are required.
Former City of London School (Example Photo: This is not the school where we carried out the BNG assessment)
Meeting the 10% Mandate with Ease
Under current UK planning laws, most developments must demonstrate a 10% Biodiversity Net Gain. For this specific project, the “baseline” value was calculated at a mere 0.0122 units. To hit the 10% target, the site only needs to reach 0.0134 units.
The proposed landscape plan doesn’t just meet this target; it far exceeds it, achieving a 104% gain through very simple, low-maintenance additions:
-
Native Tree Planting: The core of the strategy involves planting just two small native trees. Species like Elder, Blackthorn, or Hawthorn are recommended because they are hardy, require minimal upkeep once established, and provide immediate value to local birds and insects.
-
Simple Habitat Enhancements: To further support the “Green Infrastructure” of the school, the plan incorporates bird and bat boxes. These are cost-effective additions that can be installed on existing buildings or new structures to satisfy local authority biodiversity checklists.
Professional Compliance Without the Headache
For the school and the developers, this ecological report provides a “ready-to-go” roadmap for planning approval. By choosing native species that are well-suited to the local soil and drainage, the project avoids the need for specialized irrigation or high-intensity gardening in the future.
Furthermore, the report provides clear, practical guidance on lighting design to ensure the new extension doesn’t interfere with nocturnal wildlife, as well as simple instructions for creating invertebrate habitats (like log piles) that cost nothing but provide significant ecological “points” in the BNG matrix.
Conclusion
This project serves as a prime example of how urban development can proceed smoothly by addressing ecology early. With a baseline of low-value grassland, the library extension can move forward with minimal environmental overhead, delivering a modern educational space while contributing a measurable, 100%+ improvement to the local London ecosystem.