The Main Biodiversity Metric

Biodiversity net gain will be measured using the ‘Biodiversity Metric’. The most current statutory Defra Biodiversity metric must be used. The metric and additional guidance on how to use it can be found on the Gov.uk website.

A Biodiversity Gain Statement including the statutory Defra metric will be required to be submitted with all applicable planning applications.

There are three modules within the biodiversity metric – area, hedgerow, and watercourse. In the framework of BNG, habitats can be either retained, enhance, lost or created. 10% uplift is required for each module separately, the units delivered cannot be summed, traded, or converted between modules.

Developers must enter the size and condition of each habitat type on their site, and the proposed habitats post-development both on-site and off-site, the metric then calculates the units lost and gained, and the overall net gain. Trading rules also apply, whereby habitats have different ‘distinctiveness’ and certain habitats may only be replaced like-for-like or better; see the Statutory Biodiversity Metric User Guide

Condition assessment details of each habitat parcel  should to be submitted within a supporting BNG report, including the overall condition assessment score and details of which criteria have passed/failed. Condition assessments should also be provided for newly created/enhanced habitat, detailing which conditions the interventions aim to meet.

Landscape plans should highlight habitats that are proposed for retention, enhancement and creation. Only habitats within Public Open Space (not privately owned areas) should be included within the post-development sheets of the metric calculation. Any planting, including individual trees, within private gardens should be inputted as the habitat type ‘Urban – Vegetated garden’.

Key Considerations

  • Validation checklist: developers should submit several items alongside the metric in order for the application to be validated by the LPA. There is now a national validation checklist, however the LCR will produce a local validation checklist which aims to streamline the application process.
  • Offsite: If a 10% net gain cannot be met onsite, the developer must seek suitable offsite compensation, this may be from a habitat bank, privately arranged with a landowner, or via a broker. The Developer must obtain all relevant BNG data from the offsite provider in order to complete their application.
  • Biodiversity Gain Plan- this must be submitted after Planning Permission is granted and must be approved in order to discharge the statutory BNG condition and commence the development. More information on what the BGP should contain can be found on the Gov.uk website

 

 

 

The Small Sites Metric

Small developments may be eligible for a less onerous approach to BNG, via use of the Small Sites Metric. This is a simplified version of the Biodiversity Metric and may be completed by a ‘competent person’ in lieu of a qualified and certified ecologist. The requirement to deliver 10% net gain on small site developments is mandatory from April 2024.

The SSM can only be used on residential developments:

  • Where there are 1-9 dwellings on site area of less than 1 ha site
  • OR if the number of dwellings is unknown the site area mut be less than 0.5 ha.

For non-residential or mixed developments:

  • The floor space created is less than 1000 m2.
  • OR the development site is less than 1 ha.

However, it is not appropriate to use the SSM on all small site developments. If any of the following points apply to the development, the main metric must be used instead:

  • Habitats that are not available in the SSM are present on the development site, including riparian zones where relevant.
  • Priority habitats are present within the development site.
  • Statutory protected sites habitats are within the development site.
  • European protected species are present on the development site.
  • Any off-site compensation is required.

If statutory protected sites or priority habitats are located within 500m of the development boundary, consideration should be given to contracting an ecologist and using the main metric.

If the developer cannot meet the 10% net gain on-site (and therefore requires off-site mitigation), the main metric must be used instead.

Small Sites Metric does not become mandatory until April 2024, so there is expected to be some revisions of the legislation and the metric- watch this space!

SSM- what needs to be submitted?

Along with the Small Sites Metric, the applicant should submit the landscape plans, photographs of all the habitats onsite, HMMMP if  enhancements are significant, and any accompanying ecological data

What is a competent Person?

A ‘competent’  person is someone who is confident in identifying the habitats present on site (pre-development),  and understanding the management requirements for habitats to be created or enhanced within the landscape design (post-development).

A competent person is someone who can demonstrate they have acquired through training, qualifications or experience, or a combination of these, the knowledge and skills enabling that person to perform specified tasks in completing and reviewing metric calculations.

Competency is aligned with the British Standard ‘Process for designing and implementing biodiversity net gain: BS 8683:2021’.

The developer is responsible for selecting the competent person, it is not required that the LPA verify this, however they should check the evidence provided.