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Biodiversity Metric 3.0

This online resource paper provides information about Natural England's free accounting tool for calculating biodiversity net gain

Definition and purpose

Biodiversity Metric 3.0 is a biodiversity accounting tool designed by Natural England that can be used for the purposes of calculating biodiversity net gain. The metric includes both intertidal and terrestrial habitats. The Biodiversity Metric 3.0 was released in July 2021 and updates and replaces the beta Biodiversity Metric 2.0 which was published in 2019.  

Biodiversity Metric 3.0 can be used or specified by any development project, consenting body or landowner that needs to calculate biodiversity losses and gains for terrestrial and/or intertidal habitats. It will be this metric that underpins the Environment Act’s (2021) provisions for mandatory biodiversity net gain in England, subject to any necessary adjustments for application to major infrastructure projects (see the Environment Act 2021 resource paper).

The NPPF 2021 sets out that development should deliver measurable net gains in biodiversity. Paragraph 174 (d) states that developments should minimise impacts on and provide net gains for biodiversity, including by establishing coherent ecological networks that are more resilient to current and future pressures. Craven Local Plan policy ENV4: Biodiversity also sets out that developments should make a positive contribution towards achieving a net gain in biodiversity wherever possible. Hence, the Biodiversity Metric 3.0 is a tool for applicants to use in this regard.

Natural England state that Biodiversity Metric 3.0 has been extensively tested. However, they also say that they will continue to listen to feedback and will aim to address any errors or problems identified in the materials or function of the Metric 3.0 before the Town and Country Planning Act is amended to take account of the Environment Act’s mandatory biodiversity net gain provisions, currently estimated to be in 2023.

Key points to consider

  • The metric does not change the protection afforded to biodiversity. Biodiversity metric calculations can inform decision-making where application of the mitigation hierarchy and good practice principles conclude that compensation for habitat losses is justified. The metric’s biodiversity units are only a proxy for biodiversity and should be treated as relative values;
  • The metric focuses on typical habitats and widespread species. Important or protected habitats and features should be given broader consideration. The metric design aims to encourage enhancement, not transformation, of the natural environment. The metric is designed to inform decisions, not to override expert opinion;
  • Information about a habitat, such as its type, size and condition, is fed into an algorithm, which then gives a number defining how valuable it is for biodiversity;
  • This version differs from Biodiversity Metric 2.0, with changes in how woodland is assessed in terms of distinctiveness and to recognise the role of urban trees. The ecological connectivity tool has also been removed amongst other changes.

What this means for spatial planning and development management

Biodiversity Metric 3.0 is to become the industry standard biodiversity metric for all on-land and intertidal development types in England, becoming a requirement for ecological consultants, developers, local planning authorities, landowners and other interested parties to use, through the Environment Act 2021. Use of the metric will be a requirement once BNG is mandatory, at a yet unspecified date in 2023. Use of the metric is encouraged as a tool to show how the requirements of adopted local plan policy ENV4 are met, in terms of achieving a net gain in biodiversity wherever possible.

Biodiversity unit values need to be calculated prior to intervention, and then again post-intervention, for all parcels of land / linear features affected. Compensation for habitat losses can be provided by creating new habitats, or by restoring or enhancing existing habitats. Losses of irreplaceable or very high distinctiveness habitat cannot adequately be accounted for through the metric. Policy ENV4 of the Craven Local Plan sets out provisions for applicants so that irreplaceable habitats can be protected when planning proposals are being designed.

Biodiversity unit values generated by biodiversity metric 3.0 are unique to this metric and cannot be compared to unit outputs from version 2.0, the original Defra metric or any other biodiversity metric. Furthermore, the three types of biodiversity units generated by this metric (for area, hedgerow and river habitats) are unique and cannot be summed. 

It is not the area/length of habitat created that determines whether ecological equivalence or better has been achieved but the net change in biodiversity units. Deviations from the published methodology of Biodiversity Metric 3.0 need to be ecologically justified and agreed with relevant decision makers.

The Biodiversity Metric 3.0 is expected to be used and applied by ecologists and the Small Sites Metric can be used by non-ecological professionals.

Relevant Craven Local Plan policies

Relevant Craven Local Plan policy guidance


March 2022. This webpage provides general information about relevant planning topics and we hope you find it helpful. Please be aware that it is not a statement of Council policy and does not provide formal policy guidance. For those things, please refer to the Craven Local Plan and supplementary planning documents.