Collington Winter Environmental

Biodiversity Net Gain Planning Law: What you need to know

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Biodiversity net gain planning law is the requirement for all development projects in England and Wales to adhere to principles surrounding biodiversity net gain (BNG), which ultimately means all development projects and development consent orders must consider their impact on the environment.

BNG will become a legal requirement in November 2023, though many local planning authorities have been asking developers to adhere to the principles prior to this. The aim is to demonstrate how the proposed development will be of benefit to biodiversity in a measurable manner. BNG also acts as a planning condition as well as a policy requirement for planning consent. It can therefore have a significant impact during the decision making process of planning authorities when they debate whether to grant or refuse a planning application.

Our team of experts at Collington Winter Environmental can assist clients all across the country with their queries surrounding Biodiversity Net Gain planning law, helping to see through the planning process and development consent with local authorities.

What is Biodiversity Net Gain?

Biodiversity net gain plans ultimately ensure developers have to consider the impact their project or development has on the local environment and surrounding irreplaceable habitats. As such, developers must change and adapt their planning processes to safeguard the local ecosystems and encourage habitat enhancements to ensure no damage is caused.

Leaving an environment in a better condition than it was prior to development is the ultimate aim of biodiversity net gain, and it can be accomplished by creating or enhancing a habitat surrounding and within the development itself.

To obtain planning permission for projects and developments, local planning authorities are commonly asking developers to meet the biodiversity net gain requirements before it becomes mandatory. This is ultimately in hopes that the developers can demonstrate how their project will benefit the environment around them. Complying with biodiversity net gain is a significant factor in whether planning permission is granted or denied.

Implementing BNG

To meet the required biodiversity standards for your local planning authority it is recommended to consult an experienced Ecologist to ensure you are complying to the correct guidance, as guidance varies around the authorities.

Our team of expert Ecologists can visit your development site to provide individualised guidance on how to follow biodiversity net gain planning law. We can also create and provide relevant BNG reports and plans.

Calculating Biodiversity Net Gain

To calculate biodiversity net gain, a pre development biodiversity metric score will be given to the land or area to be developed. This score, developed by Natural England, will enable Ecologists to calculate the the existing value of the site in biodiversity units and what BNG will be delivered when the land is developed.

The current version of the metric system is 4.0, and factors that go into the metric include:

  • The type of habitat (both on and off site)
  • Any locations (if they are local environment priorities)
  • The size of habitat parcels in kilometers or hectares
  • The condition of any habitat parcels

If biodiversity cannot be improved on the land in question then developers can use biodiversity offsetting to improve another area of land as compensation for their development, this is done by the purchase of biodiversity credits.

Biodiversity net gain offsetting is essentially an act that ensures conservation measures are taken to further habitats and environments when biodiversity net gain is unable to take place elsewhere, ultimately compensating for what is lost in a measurable way. Developers will have to ensure that biodiversity is maintained for at least 30 years via conservation covenants or planning obligations.

The Environment Act 2021

The Environment Act 2021 brought in the requirement of biodiversity net gain planning laws under the Town and Country Planning Act.

Within this Environment Bill, it aims to include the development of effective conservation, increase the use of recycling, improve air and water quality, recall products that violate environmental standards, protect local wildlife species, regulate chemicals that may harm the environment, reduce plastic waste, introduce local nature recovery strategies and provides guidance surrounding planning consent for nationally significant infrastructure projects (NSIPs).

How can CWE assist?

At Collington Winter, our team of ecologists are experts in the field of biodiversity net gain planning law and can keep you up to date with new and changing legislation. As regulations can vary across local authorities it is important to instruct a qualified ecologist to ensure you are following the correct rules.

Our team’s experience and qualifications in BNG means we can support our clients pre and post development in order to reach the required mandatory biodiversity net gain bracket that is becoming law in autumn 2023. We are well versed with current and upcoming legislation including the Environment Bill, Town and Country Planning Act and Natural Environment and Rural Communities Act to name a few.

To find out more you can contact our Ecology Director, Olivia Collington, via email at or use the form below and a member of our team will be in touch with you.

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23 Bark Street East, 1st Floor, Bolton



01204 939 608


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