The Small Sites Metric (JP040)

The Small Sites Metric is a simplified version of the Biodiversity Metric 3.1. It has been specifically been designed for use on small development sites where the project chooses to do so. Such sites are defined (for the purposes of this Small Sites Metric) as small sites where BOTH of the following criteria are met:

1) Development sites where;

- For residential developments the number of dwellings to be provided is between one and nine inclusive on a site having an area of less than one hectare

- Where the number of dwellings to be provided is not known the site area is less than 0.5 hectares

- For all other development types where the site area is less than 0.5hectares or less than 5,000sqm

2) Where there is no priority habitat present within the development area (excluding hedgerows and arable margins)

It is not appropriate to use the Small Sites Metric to calculate offsite losses and gains
The Small Sites Metric is being published with user guidance and an accompanying calculation tool. We have made some minor updates to the Small Sites Metric to reflect the newly released biodiversity metric 3.1 (published 22.04.2022)
This is a simplified version of the Biodiversity Metric 3.1. It is still under development. The Small Sites Metric can be used now but users should be aware of its beta test status.
02/08/2022 – Ahead of the commencement of mandatory biodiversity net gain the Secretary of State is now running a technical consultation on Biodiversity Metric 3.1 and the Small Sites Metric (SSM). This is a requirement of the Environment Act 2021. The consultation runs for 8 weeks and closes on the 27th September 2022.

To view and comment on the consultation please visit the Technical Consultation on the Biodiversity Metric

18/05/2022 – An error was fixed that prevented unit calculations for green roofs, hedgerows and active sand pits. – The net change formula for watercourses has been corrected. – Scrub habitat types with no condition assessment required can now be enhanced by distinctiveness to all other scrub habitat types. – An error has been corrected to allow for enhancements to cropland habitats. – Additional symbology has been added to the headline results and detailed results tabs. – An additional error check has been added to flag when lengths of hedgerows and watercourses exceed the length permitted through the SSM.
28/04/2022 – An issue where data was unable to be input into the Small Sites Metric (Beta) has been resolved. – An issue with the ‘Headline Results’ incorrectly flagging offset requirements has also been resolved
26/04/2022 – Updated to fix an error which was resulting in an incorrect user flag for residential developments & a correction to permissions (Tab 5, Area Habitats) to allow data input
To access Biodiversity Metric 3.1 please go to Biodiversity Metric 3.1 page

Downloads available for this record

File Uploaded
Small Sites Metric Calculation Tool (updated to reflect metric 3.1) - beta test, XLSX, 1.5 MB 2022/05/18
Small Sites Metric - summary of changes compared to 2021 published version, PDF, 153.2 KB 2022/04/21
Small Sites Metric Calculation Tool - User Guidance, PDF, 978.5 KB 2022/04/21

Related Access to Evidence records

The Biodiversity Metric 3.1 (JP039)