Biodiversity Net Gain

Get ahead of the game and learn about the new Environment Act 2021. Find out how it requires developers to deliver at least 10% biodiversity net gain and what this means for landowners.

Under the Environment Act 2021, new developments will be required to deliver at least 10% biodiversity net gain (BNG) from November 2023. An ecological mitigation hierarchy will measure the impact of the development and must be secured for at least 30 years. 

This requirement will be phased between November 2023 and April 2024. The government has advised that a mandatory net gain will apply for most developments from November 2023, with smaller sites needing to demonstrate a Biodiversity Net Gain (BNG) from April 2024. 

So, what does this mean? We are here to explain the requirements for developers and landowners. 

What is Biodiversity Net Gain?

BNG is the concept that an area’s biodiversity is improved after the completion of development and to help reverse the country’s decline in nature. This development and land management approach aims to leave the natural environment in a measurably better state than before. Examples of achieving BNG can include new wildflower meadows, tree planting, hedgerows, ponds, native species-rich planting and so on. Achieving BNG can also have added environmental benefits for air quality and flood risk management.

What does this mean for developers and Land Owners?

In 2021, the government announced in the Environment Act 2021 that all development would be required to deliver a 10% BNG which should be maintained for at least 30 years. 

This Act makes BNG a condition of planning permission. It requires all developers to demonstrate how a 10% net gain will be achieved on-site unless it has been demonstrated during the planning application stage through submitting a biodiversity gain plan.

Achieving a BNG is a complex process that requires expert input from a suitably qualified ecologist. An ecologist will use the ‘Defra biodiversity metric’ to calculate the existing biodiversity value of habitats on a site before development and the proposed value following development. The site’s before and after biodiversity values then need to be measured to meet the required 10% increase. 

This process will soon become an integral part of the planning process for all projects.

What developments are required to demonstrate a BNG?

Whilst BNG is not mandatory until later this year, many local planning authorities are already requiring BNG. So it is already a familiar concept for some developers and landowners. For example, Cornwall Council have required a minimum biodiversity net gain of 10% on all major applications since March 2020.  

Under the Environment Act 2021, there will be certain exceptions from the BNG requirement, such as: 

  • Permitted development
  • Householder applications
  • Small-scale self-build / custom-build sites 
  • Developments impacting a habitat area below 25sqm or 5m for linear habitats
  • National significant infrastructure projects
  • Marine developments
  • Irreplaceable habitats. 

However, it should also be noted that local planning authorities can still require BNG on the above through local planning policies and supplementary planning documents.

Although, the government has advised that it would still like to see improvements in biodiversity, including on these ‘exempt’ developments, via imposed planning conditions. 

If you want to know whether BNG will affect your development and you are unsure of the process involved, please contact us today, and we would be happy to discuss.


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