Understanding Biodiversity Net Gain 

Biodiversity Net Gain

What Architects and Planners Must Know about BNG

Biodiversity Net Gain (BNG) is now a legal requirement under the Environment Act 2021. It mandates that developments must leave the natural environment in a better state than before. This means achieving a measurable improvement in biodiversity, with local planning authorities expecting a minimum 10% net gain.

Key Landscape Features for Biodiversity

1. Native Planting Schemes: Support local wildlife with native plants that require less maintenance and provide year-round habitat value.
2. Green Roofs and Living Walls: Enhance urban biodiversity and improve stormwater management.
3. Sustainable Drainage Systems (SuDS): Create wetland habitats that also mitigate flooding and improve water quality.
4. Species-Rich Grasslands: Opt for wildflower meadows over traditional lawns to attract pollinators and small mammals.
5. Trees and Hedgerows: Retain and supplement with native species to provide critical nesting and foraging areas.
6. Deadwood and Log Piles: Integrate these features to support invertebrates, fungi, and small mammals.
7. Artificial Wildlife Habitats: Use bat boxes, bird nesting sites, and insect hotels to compensate for habitat loss.

Aligning BNG with Site Constraints

• Baseline Ecological Assessment: Conduct assessments to understand the current ecological value of the site.
• Work with Existing Features: Retain mature trees, hedgerows, and water bodies for instant habitat value.
• Optimise Underutilised Spaces: Transform small or overlooked areas into ecological assets.
• Balance Biodiversity with Usability: Design plazas, pathways, and recreational spaces with biodiversity in mind.
• Use Biodiversity Metrics: Ensure proposed enhancements meet planning requirements.
• Collaborate with Ecologists: Integrate biodiversity planning early to prevent costly redesigns.

Practical Strategies for BNG

• Green Infrastructure: Embed ecology into your site with permeable surfaces, green roofs, and living walls.
• Planting for Biodiversity: Select native species to support local ecosystems and attract pollinators.
• Creating Wildlife Corridors: Link isolated green spaces to allow species to move freely.
• Lighting Considerations: Use low-level, directional lighting to minimize impact on nocturnal wildlife.
• Deadwood Habitats: Retain tree stumps and create log piles to support insects and fungi.

Using Biodiversity Metrics

• Early Engagement: Integrate biodiversity metric calculations during the site feasibility stage.
• High-Value Habitats: Prioritize native woodland, species-rich grassland, and wetlands.
• Align with Local Policies: Tailor proposals to meet local biodiversity goals.

Securing Planning Approval

• Review Local Policies: Understand local biodiversity action plans and green infrastructure strategies.
• Pre-Application Discussions: Engage with local planning authorities early to identify potential roadblocks.
• On-Site Solutions: Design landscapes to retain and enhance existing habitats.
• Detailed Documentation: Provide clear, evidence-backed justifications in your biodiversity net gain plan.

Maintaining and Monitoring Biodiverse Landscapes

• Biodiversity Management Plan: Ensure habitats remain functional and continue delivering net gain.
• Measurable Targets: Set specific goals for survival rates, canopy cover, and habitat condition improvements.
• Regular Monitoring: Schedule assessments every five years to ensure compliance.
• Maintenance Strategies: Align maintenance with biodiversity goals, such as rotational cutting regimes for wildflower meadows.
• Funding Long-Term Maintenance: Factor in financial commitments for ongoing management.
• Leveraging Technology: Use remote sensing, drone surveys, and AI-powered habitat analysis for accurate tracking.

By embedding biodiversity net gain principles into your landscape planning from the start, you can reduce planning risks, streamline approvals, and create resilient, ecologically rich developments.