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Biodiversity net gain

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The principle of seeking biodiversity net gain has been part of national and local planning policy for some years. However, the Environment Bill 2021 makes BNG a requirement of planning permissions in England, with a mandatory 10% net gain threshold due to come into force for most applications from January 2024.

Of course, delivering BNG is already a requirement in some adopted local plans and Supplementary Planning Documents. Local planning authorities are now routinely demanding the use of a metric to demonstrate the net gain position, as advocated under national Planning Policy Guidance.

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CSA have considerable experience with biodiversity net gain dating back to the original biodiversity offsetting pilot in 2012, through to the introduction of the Metric 4.0 in 2023. With ecology, landscape and masterplanning services in-house we are well-placed to assess BNG and advise on the best approach for your project. 

Biodiversity Gain Objective

Under the Environment Act, planning permission is subject to a condition to secure the ‘biodiversity gain objective’. This objective is met when the biodiversity value of the proposal exceeds the pre-development value of the site. This is currently set at 10%, but subject to review by the Secretary of State. This Biodiversity Value is calculated by adding together:

  • The post-development biodiversity value (in units) of the on-site habitats;
  • The biodiversity units arising from any registered off-site area being used to deliver a biodiversity gain for the development, and/or
  • The Government backed biodiversity credits purchased for the development (if required as a last resort)

A Biodiversity Metric is how biodiversity value, and any gains, are measured. Metric 4.0 is now the standard calculator used to assess BNG (although earlier metrics may still be used for continuity on existing projects).

A Biodiversity Gain Plan (BGP) will need to be approved by the Local Planning Authority. Importantly, the BGP will need to include information on steps to minimise adverse effects on biodiversity. This requirement reinforces the need for the Mitigation Hierarchy (Avoid, Minimise, Restore, Compensate) to be adopted and for good design.

How CSA can help:

  • At the due diligence stage CSA can provide you with an early feasibility appraisal to look at the implications of BNG.
  • We can provide expert advice for land promotion to help ensure schemes are deliverable.
  • At the application stage, we can ensure your proposal is compliant in legal and policy terms and help you to find the best solution.
  • We will help you optimise on-site design options: equally, we have a wealth of experience in securing the delivery of biodiversity offsets, when appropriate.
  • We can provide a ‘one-stop-shop’ to address BNG requirements:
    • Our Ecologists expert at managing the BNG process – surveying, establishing baselines, preparing Metric calculations and identifying solutions.
    • Our Masterplanning team can optimise your scheme to minimise biodiversity losses on-site, balancing this with other design influences.
    • Our Landscape Architects can draw up proposals that maximise the biodiversity value of new landscaping.

For more information contact one of our experienced ecologists in Hampshire, Hertfordshire, Worcestershire or Brighton.

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