Biodiversity Net Gain Assessment : Mandatory Planning Compliance.
Delivering mandatory 10% biodiversity net gain through robust metric calculations and habitat management plans to secure your project’s planning approval.
E3 Ecology.
Expert BNG metrics for planning success.
Biodiversity Net Gain (BNG) is a mandatory requirement for most planning applications in England. If your proposal involves development, land use change, or results in the loss or change of habitats, you will usually need to demonstrate how the scheme will deliver at least a 10% net gain for biodiversity. A BNG assessment measures the biodiversity value of a site before and after development using Defra’s Statutory Biodiversity Metric.
In many cases, this assessment is required to support a planning application with the BNG assessment informing the Biodiversity Gain Plan (BGP) that is typically secured as a planning condition by the Local Planning Authority. Early assessment is recommended to allow you to influence site design to retain or enhance valuable habitats, reduce the need for costly off-site compensation, plan realistic habitat creation, and ensure your proposals remain compliant with evolving policy.
It should be noted that there are some exemptions to BNG requirements, with details of the latest exemptions provided on the relevant Government web page.
Alternatively, you may be looking to enhance your own land to generate biodiversity units and create a “habitat bank”. These units can then be sold to developers to help them achieve a 10% net gain for their development. This process is similar and starts at the same point – a BNG assessment to explore the baseline value and how this can be enhanced to maximise gains. We can also assist with this process.
What do BNG assessments involve?
A BNG assessment usually starts with a desk study to review aerial imagery, development plans, and landscape plans, followed by a site visit to map existing (baseline) habitats and assess their condition. This can typically be conducted at the same time as the Preliminary Ecological Appraisal (PEA) or Ecological Impact Assessment (EcIA) if we are aware that the development will require a BNG assessment. From this information, we get a baseline value for the site.
We then collaborate with you or your landscape team to work out the anticipated post-development biodiversity value and thereby identify the development’s net change in value. We can work closely with the design team to maximise BNG scores and identify whether the site design should be modified to achieve higher values, or whether off-site measures are required to achieve a 10% net gain, such as habitat creation and enhancements or purchasing of biodiversity units from third-party providers. Sometimes this is an iterative process requiring multiple revisions and recalculations using the Metric.
Once a strategy is confirmed, a BNG assessment report, supporting Biodiversity Metric spreadsheet, and a Habitat Management and Monitoring Plan (HMMP) will be prepared to demonstrate how the project will achieve a 10% net gain and meet planning requirements. A BGP, updated Biodiversity Metric and updated HMMP are also usually required to discharge a mandatory BNG planning condition, prior to the commencement of works.
If looking to create a habitat bank, a similar process to above would take place and the resulting BNG assessment and HMMP could be used to reach an agreement with a “Responsible Body” in order to register the site and sell the biodiversity units.
When can BNG surveys be carried out?
BNG surveys can be conducted throughout the year, but the best time is spring through to autumn when habitats and plant species are most easily identifiable.
How Can E3 Ecology Help?
All of our ecologists are experienced in delivering BNG assessments across a wide range of projects, from complex, large-scale quarry restoration and housing developments to habitat banking schemes. A number of the team are also qualified to undertake Modular River Physical (MoRPH) surveys to assess watercourse units at a site, as part of a River Condition Assessment.
We stay fully up to date with evolving BNG policies and planning guidance, ensuring your assessment is robust, evidence-based, and aligned with current requirements.
If you think you require or have been asked for a BNG assessment, please don’t hesitate to get in touch and we will be happy to help.