Biodiversity Net Gain: statutory must-haves, plus the delivery model that de-risks planning

Biodiversity Net Gain (BNG) is now a statutory planning condition in England. Under Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021, permissions are deemed subject to a biodiversity gain condition requiring a minimum 10% uplift measured with the statutory biodiversity metric. For major development, this has applied since 12 February 2024, and for small sites since 2 April 2024 (subject to limited exemptions and transitional provisions). Treat the 10% as your compliance floor, not your design ceiling.

What the planning authority will look for

Before starting works, you must have an approved Biodiversity Gain Plan showing: firstly, the measured baseline and post-development outcomes using the statutory metric; secondly, how you follow the mitigation hierarchy (avoid - minimise - compensate) in the design; and thirdly, how on-site 'significant enhancements' and any off-site units are secured and managed for at least 30 years. Off-site land must appear on the Biodiversity Gain Site Register and be locked in via s106 obligation or conservation covenant. Sequence legal drafting and registration early to avoid programme risk.

A repeatable delivery model (Work Stage-aligned)

• Stages 0-1 (Mobilise): Set ambition beyond 10% where feasible and align with local Nature Recovery priorities. Comission the ecological baseline; agree data standards for the metric and monitoring.
• Stage 2 (Concept): Masterplan around highest-value habitats and connectivity (hedgerows, dark corridors, green roofs/walls as stepping stones). Embed BNG targets in the brief, risk register, and outline cost plan.
• Stages 3-4 (Spatial/Technical): Produce the BNG Delivery Plan to include habitat drawings and schedules, soil and substrate specs, lighting controls, SuDS for biodiversity, phasing, and a 30-year management and monitoring plan. Integrate into specs, prelims and Employer’s Requirements so contractors' price the ecological intent. Reference BS 8683:2021 for process discipline.
• Stage 5 (Construction): Use ecological hold-points, site inductions and protection zones; maintain the auditable trail (photos, as-builts, planting certificates, lighting commissioning records).
• Stages 6-7 (Handover/Use):  Activate the long-term management plan; set adaptive-management triggers linked to habitat condition scores.

How to professionalise at practice level

BNG is the project-level 'what'; pair it with organisational 'how' so outcomes scale. As highlighted in Martin Brown’s Regen Note (A Regenerative Imperative: Biodiversity, Net Gain, ISO & Biophilia), the emerging BS ISO 17298 (strategy: integrating biodiversity into governance, dependencies/impacts, and value chains) and BS ISO 17620 (process for designing and implementing BNG) create a complementary toolkit with BNG- project obligations + organisational standards, to drive consistent, auditable results. Use them to hard-wire roles (RACI), templates, KPIs, and supplier expectations into your QMS.

From compliance to regeneration. The profession’s opportunity is to treat 10% as a minimum and design for nature-positive outcomes but 20%, 50%, even 100%+, where context allows, prioritising connectivity, soil health, structural diversity, and long-term stewardship aligned to Nature Recovery Strategies. This is the 'regenerative imperative': bending the curve from loss to gain.

Make gains visible and valued. Biophilic design translates technical uplift into human experience, building user stewardship and lowering lifecycle risk. Shade, water, micro-topography, and species-appropriate lighting make the gains legible, loved and therefore maintained. Think of biophilia as the 'secret sauce' that keeps BNG working on the ground.

This week’s actions for ATs: 

• Pre-screen live schemes for BNG applicability and exemptions. 

• Lock a Stage-2 internal gateway for metric assumptions. 

• Instruct legal on s106 or conservation covenant paths for any off-site units. 

• Align construction information and contracts to the approved Gain Plan to avoid compliance drift. 

Deliver the letter of the law, and the spirit of regeneration, with a process clients can trust and planning can approve, first time.