Understanding The Spatial Risk Multiplier: Balancing Local and Practical BNG Solutions
The spatial risk multiplier is one of the most commercially important and often misunderstood parts of the biodiversity metric. It directly affects how many off-site biodiversity units a developer needs to secure, and ultimately the cost and deliverability of a BNG strategy. Understanding how it works in the planning process can help developers reduce procurement risk, avoid unnecessary cost increases and make more informed decisions about off-site unit sourcing.
Under Biodiversity Net Gain (BNG) regulations, developers are encouraged to deliver compensation as close as possible to the development site. When off-site units are sourced further away, the spatial risk multiplier reduces their effective value within the metric - meaning more units are needed to achieve the same outcome.
With the spatial risk framework now confirmed to be moving from LPA/NCA boundaries to Local Nature Recovery Strategy (LNRS) areas, understanding how this multiplier works and planning accordingly has never been more important.
Key Takeaways
The spatial risk multiplier reduces the effective value of off-site biodiversity units the further they are from the development site - increasing the number of units required
Under the current framework, units within the same LPA or NCA attract no penalty, while units outside neighbouring areas may require up to twice as many to achieve the same outcome
The framework is confirmed to be moving to LNRS boundaries, which will change how spatial alignment is assessed
Assessing local unit availability early in the planning process is one of the most effective ways to reduce spatial risk, procurement delays and unexpected cost increases
What is the Spatial Risk Multiplier in BNG?
The spatial risk multiplier is part of the statutory biodiversity metric used to assess off-site habitat delivery under the biodiversity gain hierarchy.
It’s purpose is to encourage biodiversity enhancements to be delivered close to the development site wherever possible, helping ensure ecological benefits remain locally relevant. In practical terms, the further away an off-site biodiversity gain site is from the development, the lower its biodiversity value contribution becomes within the metric.
This can significantly increase the number of units required to achieve compliance
How the Spatial Risk Multiplier currently works
For area habitats under the current framework, the multiplier is applied based on the relationship between the developmetn site and the biodiversity gain site:
Within the same LPA or NCA (multiplier of 1.0): No penalty. Units contribute their full value within the metric.
Neighbouring LPA or NCA (multiplier of 0.75): Units contribute 75% of their value, meaning roughly a third more units are needed to achieve the same outcome.
Outside neighbouring areas (multiplier of 0.5): Units contribute only 50% of their value, effectively doubling the number of units required.
The principle is straightforward, but the commercial implications can become significant - particularly where local unit availability is limited or sourcing begins late in the planning process.
Important note: The Government has confirmed that the spatial risk multiplier assessment for area-based habitats will be moving from LPA/NCA boundaries to Local Nature Recovery Strategy (LNRS) boundaries. The specific multiplier values described above reflect the current framework and may change as the transition to LNRS takes effect. For watercourse units, the spatial risk multiplier will continue to be assessed by catchment area.
How the Spatial Risk Multiplier affects BNG costs
The spatial risk multiplier is not simply an ecological consideration. It can have a direct impact on project cost, programme certainty and off-site unit availability.
Developments that leave BNG planning until late in the application process may discover that:
local unit supply is limited or already allocated
the most suitable habitats are no longer available nearby
multiplier penalties reduce the effectiveness of available units from other areas
sourcing options become more constrained, reducing negotiating flexibility
This can result in developers needing to secure additional units to achieve the same biodiversity outcome - increasing procurement costs and limiting delivery flexibility.
In practice, early visibility of available habitat banks and registered sites can make a significant difference to procurement flexibility and overall delivery strategy. This is particularly relevant for larger-scale projects including NSIPs, where the volume of units required means even small multiplier differences translate into meaningful cost and delivery implications.
The importance of planning early
One of the most effective ways to reduce spatial risk issues to assess off-site availability as early as possible in the planning process. Understanding what habitats are available, where sites are located, which LPAs and NCAs they site within, and how those locations relate to the development site can help developers build more realistic BNG strategies before planning applications are submitted.
This becomes particularly important on schemes where onsite delivery is constrained and off-site solutions are likely to form a significant part of the overall biodiversity gain plan.
Early planning also gives developers greater flexibility around habitat type selection, unit pricing and long-term delivery confidence. Leaving unit procurement until discharge stage (when options may be more limited and timelines are tighter) is where spatial risk costs tend to escalate.
Preparing for LNRS and future spatial changes
Spatial planning within BNG is continuing to evolve. The Government confirmed in its April 2026 consultation response that the spatial risk multiplier assessment for area-based habitats will move to using LNRS boundaries. This is a significant change to how spatial alignment is assessed, and it will affect how developers and consultants evaluate the suitability of off-site units going forward.
LNRS areas are expected to create broader spatial groupings than the current LPA-based approach, which in many cases should mean that more habitat banks fall within the ‘local’ category for a given development - potentially reducing multiplier penalties. For developers who have previously struggled to find suitable units within their LPA or NCA, this could open up options that were previously subject to higher spatial costs.
However, the transition also introduces uncertainty. Teams with live projects who have already identified or reserved units will need to consider whether those units will still align favourably under LNRS boundaries.
To help developers plan ahead, ILM has updated its BNG Sites Directory to include LNRS filtering alongside existing LPA, NCA, and habitat type filters. This allows users to explore available sites not only based on current spatial requirements, but also with future regional prioritisation in mind.
Exploring Off-Site Units with the BNG Sites Directory
ILM’s BNG Sites Directory has been designed to help developers and consultants assess off-site unit availability earlier in the planning process. Users can filter sites by:
Local Planning Authority (LPA)
National Character Area (NCA)
LNRS area
Habitat type
This helps provide greater visibility of what is realistically available within relevant geographies before procurement pressures arise later in the project lifecycle.
Understanding spatial alignment early - before planning applications are submitted - is one of the most practical steps developers can take to reduce spatial risk multiplier costs and avoid procurement delays.
Need help understanding spatial risk and off-site unit availability?
Understanding the spatial risk multiplier is only one part of building a successful BNG strategy. Equally important is understanding what habitat banks are actually available, how trading rules apply and what delivery routes remain realistic within project timelines.
ILM works with developers, planners and landowners across the BNG process to help identify practical off-site solutions and reduce procurement uncertainty early in the planning journey.
If you would like support understanding local availability or sourcing off-site units, get in touch with the team.
Related Articles
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The spatial risk multiplier is part of the statutory biodiversity metric. It reduces the effective value of off-site biodiversity units the further they are located from the development site, incentivising developers to source units locally wherever possible.
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Units sourced from outside the development's LPA or NCA currently attract a reduced multiplier, meaning more units are needed to achieve the same biodiversity outcome. This can significantly increase procurement costs, particularly when sourcing begins late in the planning process.
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The Government has confirmed that the spatial risk multiplier assessment for area-based habitats will move from LPA/NCA boundaries to LNRS boundaries. LNRS areas are generally larger, which may provide more local options for some developments. The specific multiplier values may also change under the new framework.
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The most effective approach is to assess off-site unit availability early in the planning process. Understanding what habitat banks are available locally — and how they align with the development site's LPA, NCA and LNRS area — helps developers build more realistic BNG strategies before procurement pressures arise.
