Challenges

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Delivering Biodiversity Net Gain on constrained urban land presented several challenges. The development was required to achieve at least a 10% BNG uplift under statutory requirements and to respond to Enfield Council’s emerging 20% biodiversity target. Limited available space, existing infrastructure constraints, and the need to maximise housing density significantly reduced opportunities for large-scale habitat creation.

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The most significant issue arose on the Enfield site, which initially recorded a shortfall of 0.25 biodiversity units. Meeting policy targets without compromising housing provision or relying on off-site biodiversity credits required a carefully considered and innovative approach. Tight programme timelines and budget constraints typical of large-scale housing projects further increased complexity.

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Our Approach

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TMA carried out detailed baseline ecological surveys and arboricultural assessments to establish habitat condition and tree value across both sites. Retention of existing trees and enhancement of valuable habitats such as grassland and scrub formed the foundation of the strategy. Protecting canopy cover and preserving established ecological features ensured that biodiversity gains were built upon a strong baseline.

 

Working collaboratively with architects and the landscape team, new green infrastructure was integrated throughout the scheme. This included native tree planting, species-rich shrub beds, rain gardens, bioswales, ponds, allotments and biodiverse green roofs. Sustainable drainage features were designed to provide both stormwater management and habitat value, maximising multifunctional benefits within a compact footprint.

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A key innovation was the use of inter-site biodiversity unit trading between the Enfield and Haringey parcels. Surplus units generated on the Haringey site were allocated to offset the minor shortfall on the Enfield site, avoiding the need for off-site credits and aligning with the BNG hierarchy.