Biodiversity net gain

From 12 February 2024 a mandatory requirement came into force requiring delivery of 10% Biodiversity Net Gain (BNG) for all major developments, further to Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021).

Small sites remained exempt from statutory BNG until April 2024. Small sites include: residential development of between 1 and 9 units, or a site area <0.5 ha if the number of dwellings is unknown and commercial development with a floor space <1,000 sqm or site area <1 ha (plus certain other developments). Other exemptions include householder applications, self-build developments (<9 units and below 0.5 ha) and development that does not impact a priority habitat and falls below a threshold of 25 sqm of habitat affected.

CSA have considerable experience with biodiversity net gain dating back to the original biodiversity offsetting pilot in 2012, through all the iterations of the Biodiversity Metric leading up to the current Statutory Biodiversity Metric. With ecology, landscape and masterplanning services in-house we are well-placed to assess BNG and advise on the best approach for your project. Our integrated approach to scheme design from the start ensures that the implications of BNG can be full considered at an early stage.

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)

The Statutory Biodiversity Metric is used to calculate the baseline biodiversity value, and any gains post-development. Use of the Statutory Metric calculator is now mandatory to assess BNG on all major applications (subject to some limited exemptions) submitted on or after 12 February 2024. Earlier metrics may still be used for continuity on applications made prior to this date. BNG will become mandatory for some minor applications from 24 April 2024, with mandatory BNG coming into force for Nationally Significant Infrastructure projects (NSIPs) from April 2025.

At the planning application stage, as a minimum a Biodiversity Statement will need to be submitted which will need to include confirmation of whether the proposed development will be subject to BNG (or exempt), details of a baseline biodiversity report (including a baseline habitat survey and metric calculation), information about any degraded and/or irreplaceable habitats (e.g. Ancient Woodland) and an existing Habitats Plan. However, Local Planning Authorities may request a Draft Biodiversity Net Gain Plan setting out how BNG requirements intend to be met, and thinking about this from the outset is likely to be important in avoiding any significant delivery issues further down the line.

Post-consent BNG will be secured by way of a standard condition for a Biodiversity Gain Plan. This will need to be approved by the Local Planning Authority prior to commencement. The LPA will have 8 weeks to approve / refuse a BGP. The BGP will need to include a proposed habitats plan (on-site) and details of how any ‘significant’ on-site BNG will be secured, details of any off-site BNG land (including registration details on the Natural England BNG Off-Site Register) and a Habitat Management and Monitoring Plan (covering significant on-site / off-site BNG provision).

Importantly, the BGP will need to include information on steps to minimise adverse effects on biodiversity (in line with the ‘Mitigation Hierarchy applicable under the NPPF). Information will need to be supplied to show how the BNG Hierarchy (Avoid > Mitigate > Enhance / Create on-site > Registered off-site BNG Units > Purchase of Government BNG Credits) has been followed to demonstrate good BNG 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 Gloucestershire, Hampshire, Hertfordshire, and Sussex.