Guidance

Statutory biodiversity metric tools and guides: version history

Updated 3 July 2025

Applies to England

Statutory biodiversity metric calculation tool

Version 1.0.4 changes

• tab names – ‘Unit Shortfall’ changed to ‘Credits’
• formula correction in tab D2 – column V
• formula correction in headline results B19 and M7, correcting a typo in cell output
• corrections to UKHab codes in tab G1
• amended habitat definitions and codes in G1
• corrections to cell references in tab G2
• minor changes to the layout of ‘Area Habitat Trading Summary’
• corrections to the Credits tiers of Littoral Sea Grass and Lowland Beech and Yew
• minor formatting corrections
• change of ‘Habitats’ to ‘Area Habitats’ where appropriate
• change to enhancement rules for tab IH ‘Other Woodland’ with changes to formula in columns T and U of A3 and D3

Version 1.0.3 changes

• addition of hidden cells relating to credit calculations
• addition of ‘Version History’ and ‘Information’ tabs
• minor fix to incorrect formula associated with column ‘Final Time to Target – Years’ in tabs A2, A3, D2, D3, B2, B3, E2, E3
• minor fix to incorrect formula associated with column ‘Final Difficulty of Creation’ or ‘Final Difficulty of Enhancement’ in tabs B2, B3, E2, E3
• addition of missing flag to formula in tab A3 column AI
• minor fix to incorrect formula associated with flags of tab B1 column N
• minor fix to incorrect formula associated with flags of tab E1 column Q
• minor fix to incorrect formula of tab C3 column Y
• addition of some habitat notes to tab G1
• minor formatting fixes

Version 1.0.2 changes

• addition of symbols to warning flags where previously missing
• adjustment of column and row width to ensure text is visible
• additional minor formatting changes
• correction to how enhancements of watercourses are calculated for enhancement by re-meandering
• cell referencing area fixed on watercourse module
• error in formula in cell U12 of tab A3 amended to prevent a decrease in condition when enhancing

Version 1.0.1 changes

• ‘completed by’ and ‘date of completion’ are now compulsory information
• additional formatting and accessibility symbols have been added
• warning flags added to the headline results page
• enhancement tabs auto-fill function of ‘proposed habitat’ is now disabled
• trading rule error between hedgerow and area habitats (in certain scenarios) has been fixed
• new data entry cells and drop-down list
• fixed options for dropdown list
• restrictions on enhancements of irreplaceable habitats
• warning flags added to ensure data is captured
• changed to ‘same habitat required – bespoke compensation option’
• unit losses of very high distinctiveness habitats are ‘cancelled out’ where there is bespoke compensation agreed, retained and enhanced units still contribute to the calculation and 10% net gain is still required
• total off-site areas are shown on the start page
• error flag where off-site reference columns on all off-site data entry tabs (found on the far right of the page) have not been completed (required for accurate calculation of biodiversity unit change on a gain-site by gain-site basis)
• amendments to functions to ensure correct creation difficulty multipliers
• amendments to ensure SRM does not generate negative values
• amendments to apply the baseline SRM value to the corresponding habitat line in the enhancement tab
• the unit shortfall summary tab provides a breakdown of the requirements to meet the trading rules and net gain target if purchasing statutory credits
• the unit shortfall calculations tab displays the detailed calculations used to calculate the unit shortfall
• revision of tree size categories
• enhancement to ‘intertidal hard structures – integrated greening of grey infrastructure’ and ‘littoral seagrass’ from specific habitats is now permitted
• amendments to area calculations cross-check to facilitate changes to guidance on intertidal hard structures
• enhancement options for hedgerows have been amended
• formula and cell references to apply trading rules has been amended
• amendments to technical difficulty values for ditches and canals
• amendments to culvert encroachment multipliers
• strategic significance options are amended for culverts
• culverts removed from enhancement tab as an enhancement option
• correction to how enhancements of watercourses are calculated for enhancement by re-meandering
• cell referencing area fixed on watercourse module

Felled woodland split into 2 habitat types to support trading rules:

• ‘felled woodland’, at baseline
• ‘replacement for felled woodland’, at post intervention

Adjustments to enhancement times for following area habitats:

• blanket bog
• wet woodland
• coniferous woodland
• intertidal habitat group
• bioswale
• inland rock and scree

Small sites metric (statutory biodiversity metric): calculation tool

Version 1.2.3 changes

• correction of the difficulty of creation of actively worked sand pit or open cast mine
• correction to the retention formula for culverts to include encroachment
• change of ‘Habitats’ to ‘Area Habitats’ where appropriate
• further fix to area checker formula

Version 1.2.2 changes

• fix to area checker formula

Version 1.2.1 changes

• unlocked strategic significance cells for individual trees
• added reference to protected species to desktop assessment
• added tolerance to area checker to resolve floating point error
• altered wording in site details tab reflecting optional targets
• locked cells
• corrections to planning application type options

Version 1.2.0 changes

Corrections to difficulty multipliers for:

• ponds – non-priority
• actively worked sand pit or open cast mine
• developed land sealed surface

Version 1.0.1 changes

• error flag removed from tab D10 stating main metric must be used if targets not achieved on-site

Statutory biodiversity metric condition assessments

Version 1.0.3 changes

• formatting correction to sheet 8B – Hedges
• reformatting of Instructions and Habitat Definitions sheets
• clarification of information in Habitat Definitions sheet
• addition of river condition assessment (RCA) form to condition assessments
• amended references in habitat definition sheet

Version 1.0.1 changes

• ‘Individual trees’ tab – added wording to say ‘Please see the separate Line of Trees condition sheet for rural trees. You should only use the Line of Trees condition assessment and record that habitat type in rural locations.’
• ‘Individual trees’ tab – changed ‘Canopies must overlap continuously’ to ‘Canopies should predominantly overlap continuously’
• ‘Coastal’ tab – wording added to the list of ‘General coastal species indicative of suboptimal condition’ to say ‘sea buckthorn (only outside its restricted native range)’
• ‘Scrub’ tab – wording added to Criterion A to say sea buckthorn can be 100% cover ‘(only in its restricted native range)’
• ‘Instructions’ tab – changed date at top of sheet from ‘November 2023’ to ‘February 2024’
• ‘Habitat definitions’ tab – removed reference to ‘see Technical Annex 2’ from the table – cells C11, C131 – C140
• ‘Hedgerow’ tab – ‘See the Statutory Biodiversity Metric Technical Annex 2 and UK Habitat Classification’ removed, leaving just the UKHab link
• ‘Intertidal biogenic reefs’ tab – changed ‘see the Statutory Biodiversity Metric Technical Annex 2’ to say ‘see tab G1 of the Statutory Biodiversity Metric’
• ‘Intertidal hard structures’ tab – changed ‘see the Statutory Biodiversity Metric Technical Annex 2’ to say ‘see tab G1 of the Statutory Biodiversity Metric’
• ‘Intertidal seagrass’ tab – changed ‘see the Statutory Biodiversity Metric Technical Annex 2’ to say ‘see tab G1 of the Statutory Biodiversity Metric’
• ‘Intertidal sediment’ tab – changed ‘see the Statutory Biodiversity Metric Technical Annex 2’ to say ‘see tab G1 of the Statutory Biodiversity Metric’
• ‘Pond tab’ – removed ‘For ponds (non-priority) – see the Statutory Biodiversity Metric Technical Annex 2’
• ‘Habitat Definitions’ tab – cell E48 – removed reference to ‘<2ha’ for Ornamental lake or pond
• ‘Habitat Definitions’ tab – cell E54, E55 – changed ‘<=2ha’, from Ponds (priority) and Ponds (non-priority) to ‘<2ha’
• ‘Habitat Definitions’ tab – row 55 – removed references to Ponds (non-priority) having a definition different to that in UKHab

Statutory biodiversity metric: user guide

July 2025

• definition updates – commercial building and private gardens
• minor updates to compensation for loss of watercourses and removal of stream order
• replacement of felled woodland – minor updates for clarification
• applying rule 4 – inclusion of ‘other mosaic habitats’
• calculating a statutory credit requirement – credit calculations tab renamed
• strategic significance – clarification to cover use of multiplier when an LNRS has been published
• habitat retention – clarification that retained habitats do contribute towards post-development habitat units
• canals – clarification on definition of canals
• riparian zone encroachment – change of wording from exemptions to exceptions for feature that should not be recorded at baseline
• additional information on ditches - new table added to inform habitat classification for rivers and streams and ditches
• watercourses – clarification to define the riparian zone, works within a riparian zone, encroachment of watercourses and riparian zones, watercourse enhancement and watercourse creation
• new section on technical fish passes
• habitats with a land use function – addition of ‘urban -actively worked sand pit quarry or open cast mine’
• additional clarity on assessing habitat changes within a private garden
• new section on green roofs and walls
• clarity on recording post development tree size classes

July 2024

• document history table added 
• added biodiversity metric tool definition for private gardens in table 1 
• new section on private gardens  
• re-ordering and formatting of guidance  
• expanding guidance on recording individual trees  
• expanding guidance on rural lines of trees

February 2024

• draft status removed 
• detail and clarification added for the assessment of strategic significance  
• addition to recording individual trees

Small sites metric (statutory biodiversity metric): user guide

July 2025

• addition within competency requirements of ‘no requirement for the LPA reviewer to be a qualified ecologist’
• definition updates – commercial building and private gardens
• strategic significance – clarification to cover use of multiplier when an LNRS has been published
• updated definition of canals and ditches
• additional information on ditches - new table added to inform habitat classification for rivers and streams and ditches
• additional clarity on assessing habitat changes within a private garden
• new section on green roofs and walls
• further clarity on recording post development tree size classes
• calculating statutory credit requirements - further details on the calculation of credits using SRM
• site walkovers – reference to valid until date as indicative for LPAs

July 2024

• document history table added 
• amendments to appendix 2 relating to list of hedgerow habitats 
• clarifications on private gardens provided 
• restructured sections on urban trees found in lines and rural lines of trees and strategic significance

February 2024

• draft status removed 
• detail and clarification added for the assessment of strategic significance  
• addition to recording individual trees