Two major Mandatory Biodiversity Net Gain (BNG) requirements have been adopted by Cornwall Council. It has been a leader in implementing BNG, mandating a minimum of a 10% net gain for all major planning applications since 2020, ahead of the national requirement. This was extended to minor developments in 2024.
- Measurement: The change in biodiversity value is calculated using a metric, such as the latest version of the Defra Biodiversity Metric. This metric scores different habitat types based on their distinctiveness, condition, and size, both before and after development.
- Application Process: To secure planning permission, developers must submit a BNG statement or plan that demonstrates how their proposal will achieve the required net gain. This includes:
- The pre-development biodiversity value.
- The expected post-development value.
- A justification for any off-site gains needed.
- Proposals for significant on-site habitat enhancements.
- A draft Habitat Management and Monitoring Plan for long-term maintenance (at least 30 years).
- Mitigation Hierarchy: A key principle is the “mitigation hierarchy,” which prioritizes a step-by-step approach to achieving BNG. Developers must first try to avoid or minimize negative impacts on biodiversity. If that’s not possible, they must mitigate or restore habitats on-site. Only as a last resort are they allowed to use off-site gains or purchase statutory biodiversity credits.
- Enhancement Measures: The council encourages a range of enhancement measures, which can include:
- Retaining and enhancing existing habitats, such as Cornish hedgerows.
- Creating new habitats.
In 2023 The Climate Emergency Development Plan Document (DPD) which implements important measures for bio-diversity was adopted. These measures aim to restore natural habitat while addressing climate change and loss of ecology. This is a stand-alone adopted document and should be considered in planning decisions regardless of the out-of- date Local Plan. The document can be found on the Cornwall Council website under Climate Emergency Development Plan Document.
Conservation Measures:
Green Infrastructure Design and Maintenance (G1)
Local Nature Recovery Network (G4)
Tree Canopy (G3)
Sustainable Drainage Design (CC4)
Bio-diversity Measures
Biodiversity Net Gain (G2)
Natural Climate Solutions
Protection of Habitat
The Planning White Paper being brought to the House in September is raising concerns regarding BNG requirements being ‘watered down’ and developers being able to buy credit ‘off site’. How these would be promulgated and what measures would be in place to scrutinise and monitor raise serious questions.