We are providing a number of data layers to assist clients with the Biodiversity Net Gain (BNG) requirements. The data we provide is not intended to be a substitute for a full formal BNG assessment through the BNG metric.
Our aim is to provide users with two things:
Indications of high value or irreplaceable habitats at a site which may result in a development being unviable, particularly complex, or requiring bespoke negotiation and compensation
Provide information to assist clients in determining more suitable areas to search for offsite BNG mitigation
Developers should be mindful of the biodiversity gain hierarchy of BNG mitigation, as the further down the hierarchy a development goes, the greater the cost. Well managed on-site mitigation will often be the most financially and legally efficient option, and must be considered as part of any development.
Biodiversity gain hierarchy
Create biodiversity gains within the red line boundary of the site
If full gains on site are not possible, developers can achieve this through a mixture of on-site and off-site gain, or purely through off-site gains. This can be achieved by making gains on land the developer owns, or buying off-site biodiversity units on the market.
If a developer cannot achieve on-site or off-site mitigation, they must buy statutory credits from the government. This will be a highly expensive way of mitigating BNG requirements and should only be considered as a last resort.
Significant on site gains and all off-site gains must be maintained for a minimum of 30 years.
How to use the data
Initial searching for a development opportunity
Suggested data layers
Irreplaceable Habitats
Irreplaceable Ancient Woodland
Other Protected Habitats
Other Protected Areas
These data layers will allow users to to flag higher biodiversity value sites which could have a significant impact on the viability of a site for development. Additionally, if a priority or protected habitat is located on site, the small sites metric (to be introduced from 2nd April 2024) cannot be used. Using the small sites metric means that you do not require a condition assessment or a qualified ecologist to complete the metric, leading to much greater efficiency for small developments i.e. those with fewer than 10 dwellings. See Data layers: detailed description below for further details on the habitats included in the data bundle.
Searching for off-site mitigation sites
Suggested data layers
BNG Spatial Risk Multipliers
Biodiversity Improvement Areas
Allocations
Land Availability Assessments
Planning development constraints
Local Planning Authority
Agricultural Land Classification
BNG Spatial Risk Multipliers and the Local Planning Authority layers will allow users to identify sites within the same area as their development (from a BNG metric perspective), leading to lower BNG requirements for off-site mitigation.
Biodiversity Improvement Areas will allow users to identify land which has been identified as being in need of biodiversity improvements. This indicates that both the initial baseline of these sites may be lower than desired (and hence offers scope for uplift), and that the land may be considered more suitable for such schemes.
Allocations. Any site which is allocated for development is unlikely to be suitable for use as a BNG offset site
Land Availability Assessments. These could represent constraints or opportunities for offsetting, depending on the outcome of the assessment. A SHLAA-positive site is unlikely to be suitable for use as a BNG offset site, but a SHLAA-negative site may show land that has had development ruled out due to other constraints, and hence be a suitable candidate of BNG offsetting
Planning development constraints
At present this is restricted to Green Belt and Flood Zones, both of which are significant constraints for general construction projects, so can highlight areas that are more suitable for BNG offsetting, as they are less likely to be earmarked for development.
Agricultural Land Classification. Best and Most Versatile (BMV) agricultural land (Grades 1-3a) is unlikely to be taken out of production and therefore is less suitable for use as a BNG offset site. Any land classed as Grade 3b or lower may be more suitable.
Data layers: detailed description
BNG Spatial Risk Multipliers
The spatial risk multiplier within the BNG metric reflects the relationship between the location of on-site biodiversity loss and the location of off-site habitat compensation. It affects the number of biodiversity units provided to a project by penalising proposals where offsite habitat is located at distance from the impact site. The lower the score, the more units will be required to offset. Clients should be sourcing offset sites as close as possible to the development site from a financial and ecological value perspective, and only sourcing offset sites if on-site mitigation is not possible.
National Character Areas
Applicable to: Development that affects land-based habitats
Description: National Character Areas (NCAs) in the UK refer to distinct geographic regions characterised by their unique landscapes, ecosystems, and cultural heritage. By considering NCAs in the context of BNG, planners and developers can tailor conservation efforts to the specific characteristics and needs of each region, contributing to the preservation and restoration of the UK's diverse natural heritage.
Impact: Offsite mitigation within the same NCA as the development will result in a spatial multiplier value of 1. Mitigation within a neighbouring NCA will result in a spatial multiplier value of 0.75, and mitigation outside the same or neighbouring NCA will result in a multiplier value of 0.5. This can lead to a significant increase in the number of units required for offsetting.
Watercourse catchments and operational catchments
Applicable to: Development that affects watercourse-based habitats
Description: Hydrological units delineated by the drainage areas of rivers and streams. A waterbody catchment refers to individual waterbody catchments, whereas operational catchments are a larger grouping of individual waterbody catchments.
Impact: Offsite mitigation within the same waterbody catchment as the development will result in a spatial multiplier value of 1. Mitigation within an operational catchment will result in a spatial multiplier value of 0.75, and mitigation outside operational catchment will result in a multiplier value of 0.5. This can lead to a significant increase in the number of units required for offsetting.
Irreplaceable Habitats
Irreplaceable habitats are those which should not be built on due to their inherent value. As such they are exempt from the 10% BNG uplift calculations as they are so valuable that they cannot easily be recreated. Any impacts to irreplaceable habitats will be automatically flagged as ‘unacceptable’ within the BNG metric and will require bespoke compensation agreements with the planning authority.
Current list of irreplaceable habitats (it is expected this will evolve over time)
Ancient woodland
Ancient and veteran trees
Blanket bog
Limestone pavements
Coastal sand dunes
Spartina saltmarsh swards
Mediterranean saltmarsh scrub
Lowland fens
Other Protected Habitats
If any of these are on site, the small sites metric cannot be used. The presence of any protected habitats in this list will likely be indicative of high existing biodiversity value at the site, making on-site uplift more difficult to achieve, and may restrict the developable area of the site. They are also likely to add to the ‘strategic significance’ multiplier in the BNG metric, increasing the BNG uplift required.
Open mosaic habitats are found on larger previously developed brownfield land and can support a large variety of often rare plant and animal life. They are considered a Priority Habitat but are currently categorised separately.
Priority Habitat Inventory
The Priority Habitat Inventory contains details of 56 habitat types identified as ‘priority habitats’ in the UK Biodiversity Action Plan (UK BAP). These habitats do not receive statutory protection, but are protected by planning policy in the National Planning Policy Framework (NPPF), in addition to their value with BNG assessments.
Other Protected Areas
Internationally Protected Sites
Special Areas of Conservation (SACs)
Special Protected Areas (SPAs)
Ramsar sites
Nationally Designated Sites
Sites of Special Scientific Interest (SSSIs)
National Nature Reserves
Locally Protected Sites
Local Nature Reserves
Wildlife Corridors
Site of Local Importance for Nature Conservation (SINC)
Site of Borough Importance for Nature Conservation (BINC)
Biodiversity Improvement Areas
Habitat Networks (Improvement Areas)
These are areas around protected and priority habitats that have been assessed as having a high potential value and desirability for biodiversity uplift by Natural England. Note that there is the potential for projects to already be underway in these areas.
Types of habitat networks included
Restorable Habitat
Areas of land, predominantly composed of existing semi-natural habitat where the primary habitat is present in a degraded or fragmented form and which are likely to be suitable for restoration
Network Enhancement Zone 1
Land connecting existing patches of primary and associated habitats which is likely to be suitable for creation of the primary habitat. Action in this zone to expand and join up existing habitat patches and improve the connections between them can be targeted here
Network Enhancement Zone 2
Land connecting existing patches of primary and associated habitats which is less likely to be suitable for creation of the primary habitat. Action in this zone that improves the biodiversity value through land management changes and/or green infrastructure provision can be targeted here.
Fragmentation Action Zone
Land within Enhancement Zone 1 that connects existing patches of primary and associated habitats which are currently highly fragmented and where fragmentation could be reduced by habitat creation. Action in this zone to address the most fragmented areas of habitat can be targeted here.
Network Expansion Zone
Land beyond the Network Enhancement Zones with potential for expanding, linking/joining networks across the landscape i.e. conditions such as soils are potentially suitable for habitat creation for the specific habitat in addition to Enhancement Zone 1. Action in this zone to improve connections between existing habitat networks can be targeted here.
Habitat Restoration-Creation
Areas where work is underway to either create or restore the primary habitat. These areas may therefore likely be less suitable for BNG offsetting as there may not be room for new projects. However, there may still be the potential for developers to contribute to existing schemes, or work in parallel to these schemes.
Nature Recovery Projects
Areas within the Nature Recovery Network where Nature Recovery Projects have been defined. These areas are likely to be considered favourably for BNG enhancement projects. Note that there is the potential for projects to already be underway in these areas.