Biodiversity Net Gain (BNG) in Surrey

Planning-ready BNG assessments for Surrey — verified baselines, Metric 4.0 scoring and proportionate uplift strategies for a predictable planning route.

Do You Need a Biodiversity Net Gain Assessment in Surrey?

Most developments in Surrey 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. Surrey’s landscape includes extensive woodland, lowland heath, chalk slopes, river corridors and dense commuter settlements, all influencing how LPAs interpret BNG requirements. These factors strongly influence how LPAs interpret BNG.

Local landscape patterns affecting BNG expectations across Surrey include:

extensive woodland networks around Mole Valley, Guildford and Waverley

lowland heathland systems across Woking, Surrey Heath and the Thames Basin Heaths

chalk slopes and grassland along the North Downs

river corridors along the Wey, Mole and Thames

green belt edges and settlement boundaries with mixed farmland

These broader patterns shape how uplift opportunities and constraints are evaluated during planning.

We support projects across:
Guildford, Woking, Reigate, Redhill, Epsom, Ewell, Farnham, Godalming, Dorking, Camberley, Horley and all surrounding villages.

Why Surrey Planners Request BNG Evidence Early

Surrey LPAs request BNG evidence at an early stage because habitat distinctiveness and condition shift significantly in woodland-edge, heathland, chalk grassland and green belt transition zones. Even small design adjustments can alter metric outcomes or uplift feasibility.

Getting BNG right early prevents validation delays, redesign loops and late-stage uplift recalculation.

Early indicators your Surrey site may require BNG evidence

Common site-level triggers for BNG assessment in Surrey include:

proximity to woodland edges, mature trees or ancient woodland buffers

heathland fragments or acid grassland near the Thames Basin Heaths

semi-improved grassland or herb-rich margins

drainage channels, ditches or rivers (Mole, Wey, Thames) crossing or bordering the site

brownfield mosaics with early-successional or scrub habitats

PEA recommendations for botanical or condition-verification surveys

layout changes that affect habitat parcels or green belt boundaries

If these apply, early metric work keeps the planning route predictable and reduces programme risk.

Local Case Insight

BNG baseline work for a redevelopment site near Dorking identified higher-condition grassland along a woodland boundary than expected. By refining the layout and adjusting open-space connections, the scheme secured 10% net gain on-site, avoiding off-site units and clearing validation with no requests for metric revision.

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Our Approach

BNG must be practical, defensible and proportionate.
We align ecological evidence with real-world design constraints so your metric supports your planning route. We assess habitat condition, distinctiveness and connectivity to identify the most efficient uplift options, whether on-site, off-site or blended. For more detail on methodology, see our Biodiversity Net Gain Assessment service.

For schemes requiring integrated landscape design or planting plans, we work alongside our sister company Blue Iris Landscapes to keep proposals aligned with uplift feasibility and LPA expectations.

Every recommendation is shaped for validation, design iteration and planning negotiation.

BNG Requirements — Delivered in a Predictable Sequence

We produce planning-ready BNG Assessments aligned to Surrey’s policy expectations.

Key BNG Deliverables for Surrey's Projects

For Surrey’s schemes, every planning-ready BNG Assessment includes:

• verified UKHab baseline
• defensible Metric 4.0 calculation
• proportionate, locally-appropriate uplift strategy
• clear validation-ready reporting
• optional HMMP and Biodiversity Gain Plan integration

These deliverables are structured to satisfy Surrey’s LPAs while keeping your BNG route proportionate to the scale of development.

Step 1

Habitat baseline surveys

Year-round, with optimal survey seasons

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 Other Surveys

Only if needed. PEA, EIA, and Protected Species surveys

How this supports your project

These steps align with national requirements under NPPF Section 15 and ensure the BNG route remains defensible at planning. Early baseline clarity locks in feasible uplift routes, prevents late-stage reclassification, and keeps your planning programme on track.

Next Steps

0800 494 7479

[email protected]

FAQ - BNG in Surrey

Is a Biodiversity Net Gain assessment required for developments in Surrey?

Yes. Where a proposal falls within the statutory scope of Biodiversity Net Gain legislation, the applicant must demonstrate at least 10 percent measurable uplift using the statutory Biodiversity Metric as part of the planning submission.

How does the Thames Basin Heaths Special Protection Area affect BNG assessments?

Sites within or near the Thames Basin Heaths SPA may face additional ecological constraints. While the SPA relates to protected bird species, the Biodiversity Net Gain assessment must still accurately calculate baseline habitat units and demonstrate compliant uplift.

Are Green Belt sites in Surrey exempt from Biodiversity Net Gain?

No. Green Belt designation does not remove the statutory requirement for Biodiversity Net Gain. Any permitted development must still demonstrate measurable uplift in biodiversity units.

How are woodland and heathland habitats assessed under the Biodiversity Metric?

Woodland and heathland habitats often carry higher distinctiveness values within the Biodiversity Metric. Accurate classification and condition assessment are essential to avoid underestimating baseline habitat value.

Can small residential infill schemes achieve 10 percent uplift?

Yes, but feasibility depends on site constraints. On smaller plots, space for enhancement may be limited, making early stage modelling critical to confirm whether on site measures are sufficient.

How are river corridor sites, such as those near the River Thames, assessed?

Sites adjacent to rivers may include riparian habitats that must be properly classified and quantified. The assessment must ensure development proposals do not reduce ecological connectivity.

How long does a Surrey BNG assessment typically take?

Timescales vary depending on site size and habitat complexity. High value residential sites may require iterative modelling alongside design revisions to achieve compliant uplift.

What happens if a Surrey development cannot achieve enough uplift on site?

If the Biodiversity Metric identifies a shortfall in habitat units, the applicant may secure registered off site biodiversity units to meet the statutory 10 percent requirement.

Which authorities review BNG assessments in Surrey?

Biodiversity Net Gain assessments are reviewed by the relevant Local Planning Authority, such as Guildford Borough Council, Woking Borough Council, Elmbridge Borough Council or Reigate and Banstead Borough Council depending on site location.

Planning guidance for Guildford Borough Council can be accessed at:
https://www.guildford.gov.uk/planning

How can ProHort support Biodiversity Net Gain assessments in Surrey?

ProHort undertakes detailed habitat surveys and robust Biodiversity Metric modelling tailored to Surrey’s Green Belt and heathland context. We provide early feasibility advice, accurate unit calculations and clear planning documentation to minimise biodiversity compliance risk.

Biodiversity Net Gain Assessment in Surrey