Biodiversity Net Gain (BNG) in Sussex
Planning-ready BNG assessments for Sussex — clear metrics, proportionate uplift strategies and predictable progress through planning.
BNG Requirements in Sussex
Most developments in Sussex now require a mandatory 10% biodiversity net gain under the Environment Act 2021.
Local planning authorities expect clear baseline data, a defensible Metric 4.0 calculation and a proportionate uplift strategy before your application can progress.
Across Sussex, planning authorities frequently tailor evidence requirements based on prevailing landscape patterns:
river valleys and wet grassland associated with the Arun, Adur and Ouse
former industrial and coastal regeneration sites
intensively managed farmland with historic hedgerow networks
woodland and downland mosaics near the South Downs
linear habitat corridors following railways and waterways
greenfield growth areas around Crawley, Horsham and Lewes
Establishing baseline constraints and achievable enhancement early helps avoid uncertainty later in the application process.
Our services cover locations across Sussex, supporting schemes in Crawley, Horsham, Lewes, Worthing and surrounding communities.
Why planning officers in Sussex request BNG Assessments
Sussex LPAs request BNG evidence early because many developments sit close to watercourses, settlement edges or regeneration land, where small layout changes can noticeably affect habitat value and connectivity.
Officers want verified baseline habitats and clear Metric 4.0 scoring before designs progress, so uplift options can be understood without late-stage compromise. The county’s focus on canal corridors, historic field patterns and woodland-edge mosaics also means uplift feasibility needs to be established upfront.
Early Indicators Your Sussex Site May Need BNG Evidence
On the ground, site-level features signal when BNG evidence will be needed:
- semi-improved grassland or species-rich margins
- hedgerows that link into wider networks
- wet ditches, streams or floodplain edges
- brownfield mosaics with herb-rich patches
- woodland edges or scattered trees
- PEA recommendations for botanical verification
- layout changes affecting habitat parcels
Providing this clarity early prevents validation queries, redesign instructions and delays during casework.
BNG Requirements — Delivered in a Predictable Sequence
We produce planning-ready BNG Assessments aligned to Sussex’s policy expectations.
Case Insight
What We Deliver for Sussex Projects
Every report includes:
verified UKHab habitat mapping
defensible condition and distinctiveness scoring
full DEFRA Metric 4.0 calculation
uplift strategy shaped around LPA priorities
integration with layout, drainage and protected species
clear, structured reporting for validation and negotiation
Step 1
Habitat baseline surveys
Year-round, with botanical elements best May–September.
Step 2
Metric 4.0 calculations
Completed once habitat data is verified.
Step 3
Uplift strategy development
Aligned with design progression and layout refinement.
Step 4
Integration with PEA, EIA or protected species
Used where additional clarity is needed around baseline or constraints.
Our approach keeps evidence proportionate, technically robust and predictable through the full planning sequence.
Next Steps
Contact us and we’ll confirm exactly what your site requires and support a planning-ready, proportionate route forward.
FAQ - BNG in Sussex
Why do planning authorities in Sussex require Biodiversity Net Gain assessments?
In Sussex, BNG assessments are required due to the sensitivity of downland, river valleys and coastal habitats affected by development.
You can check local planning guidance here:
East Sussex County Council – https://www.eastsussex.gov.uk/
West Sussex County Council – https://www.westsussex.gov.uk/
When is Biodiversity Net Gain required for development in Sussex?
Most new developments in Sussex that result in habitat loss or alteration must demonstrate at least 10% BNG.
Which habitats most affect Biodiversity Net Gain outcomes in Sussex?
Grassland, hedgerows, woodland edges and wetland habitats commonly influence BNG calculations in Sussex.
Is on-site Biodiversity Net Gain achievable in Sussex?
On-site BNG delivery is often possible through integrated landscape design, particularly on edge-of-settlement sites.
How does a Biodiversity Net Gain assessment help Sussex planning decisions?
It provides evidence that biodiversity impacts have been quantified and addressed in line with policy.
Who prepares Biodiversity Net Gain assessments in Sussex?
BNG assessments in Sussex should be completed by qualified ecologists familiar with local habitat character.
