Biodiversity Net Gain

Biodiversity Net Gain (BNG) in Summary

The principle of seeking biodiversity net gain has been part of national and local planning policy for some years. However, the new Environment Bill 2021 makes BNG a requirement of planning permissions in England; a mandatory 10% net gain threshold is included. However, with a two-year implementation period (and various secondary legislation still to be passed) mandatory BNG won’t actually come into force around the end of 2023.

Of course the requirement to deliver BNG is already present in many emerging and adopted local plans and local planning authorities are now routinely demanding the use of a metric to demonstrate the net gain position. The metric often presents a very different picture to previously unquantified statements that “biodiversity net gains are provided”. With all of this unfolding quite quickly, developers are still getting used to the implications of delivering net gain and how this can affect developable area and viability.

CSA have considerable experience with biodiversity net gain dating back to the original biodiversity offsetting pilot, the first Defra Metric, the Warwickshire Metric, Beta Metric 2.0 and now Metric 3.0. With ecology, landscape and urban design services in-house we are extremely well-placed to assess BNG and advise on the best approach, something we have been extremely busy doing for many clients throughout the last year or so. 

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 of the onsite habitats;
  • The biodiversity value of any registered offsite biodiversity gain allocated to the development, and/or
  • The biodiversity credits purchased for the development (something still ‘ in development’!)

A Biodiversity Metric is how biodiversity value, and any gains, will be measured. Natural England’s Metric 3.0 is now the standard calculator used to assess BNG (although earlier metrics may still be used for now for continuity, or where agreed).

A Biodiversity Gain Plan will need to be approved by the Local Planning Authority. Importantly, a Biodiversity Gain Plan will need to include information on how steps will be taken to minimise the adverse effect of the development on the biodiversity of the onsite habitat and any other habitat. This requirement reinforces the need for good design and adoption of the Mitigation Hierarchy – Avoid, Minimise, Restore/Compensate.

How CSA can help:

  • At the Due Diligence stage CSA can provide you with an early feasibility assessment to look at the likely implications of BNG requirements.
  • We can provide expert advice for Land Promotion to help guide your site through the development plan process, ensuring allocations are robust and deliverable in respect of BNG.
  • At the application stage, we can ensure your application is legislatively and policy compliant and help you to find the best solution in each individual situation.
  • Whilst our Ecologists are very happy to work with any other consultants involved, we can also provide a ‘one-stop-shop’ to address BNG requirements:
    • Our Ecologists have the expertise and experience to manage the BNG process – surveying, mapping and establishing baselines, running biodiversity metric calculations, advising on scheme design and identifying on and off-site solutions.
    • Our Urban Design team can optimise your scheme to minimise biodiversity losses on-site alongside other design considerations.
    • Our Landscape Architects can draw up proposals that maximise the biodiversity value of new landscaping on-site.

For more information contact our dedicated teams in Hampshire, Hertfordshire, Worcestershire or Brighton.

For our thoughts on the current DEFRA consultation and some key details around the emerging legislation see our February 2022 opinion piece here.