10% Biodiversity Net Gain for Development

As it is now a part of UK legislation, Biodiversity Net Gain (BNG) is poised to become a compulsory consideration for all forthcoming development projects in England. BNG involves a systematic approach wherein a development project assesses its environmental impact with a specific focus on biodiversity. The main objective is to guarantee that the biodiversity is left in a better state than its pre-development state. This is achieved by mitigating biodiversity loss, preserving diverse habitat types, and protecting assets of strategic significance.

Local planning authorities are increasingly demanding Biodiversity Net Gain as part of the information required for a planning application. The intention is to show how the proposed development will contribute to biodiversity enhancement. BNG serves both as a planning condition and a mandatory policy for securing planning consent. Consequently, it holds considerable influence in the decision-making process of planning authorities as they deliberate on whether to approve or reject a planning application.

Local planning authorities are now requesting a minimum of 10% Biodiversity Net Gain for all future developments. Therefore, those in charge of planning projects will now need to factor in mandatory biodiversity net gain and recognise the importance of development biodiversity.

Biodiversity Net Gain Principles

According to the Chartered Institute of Ecology and Environmental Management (CIEEM), there are ten crucial good practice principles of biodiversity net gain. These should help to achieve BNG if they are followed accordingly. The mandatory BNG principles include the following:

  • Utilise the mitigation hierarchy to minimise the impact on biodiversity
  • Eliminate any negative impacts on biodiversity
  • Communicate each BNG outcome with complete transparency
  • Cover all areas of sustainability, including societal and economic factors
  • Involve any pre-development and post-development stakeholders in creating mandatory net gain solutions
  • Focus on producing long-term environmental benefits from BNG
  • Understand the variable factors and potential risks in order to deliver biodiversity net gain
  • Offer nature conservation that exceeds the stated BNG requirements
  • Determine a suitable method in order to secure measurable biodiversity net gains
  • Ensure the best possible results from biodiversity net gain

For case studies and a practical guide on BNG principles, visit the CIEEM website.

Our team has strong experience completing BNG and will provide guidance throughout the BNG planning system process. This applies from the initial land purchase agreements to monitoring assessments.

10% Biodiversity Net Gain: Calculating BNG

Metrics assign every habitat on a development site a ‘biodiversity unit value’ according to its relative importance for biodiversity. This enables comparison between the existing value of a site and what will be delivered through development or management and post development. This may include an increase in habitat creation or enhancement, which goes over and above the environmental habitat originally on site.

BNG can be calculated through the DEFRA biodiversity metric 4.0, which requires a limited number of factors. These factors include:

 The type of habitat (both on and off site)

  • Any locations (if they are local environment priorities)
  • The size of habitat parcels in kilometres or hectares
  • The condition of any habitat parcels

The government website also provides a biodiversity metric calculation tool which can help to determine your biodiversity unit score. This will then translate into the standards of your local planning authority.

The Environment Bill

The Environment Bill
 was passed this year as it received royal assent. Therefore, BNG will soon become mandatory through the forthcoming Environment Act in January 2024. BNG will be required for small sites in April 2024. However, the National Planning Policy Framework and Local Nature Recovery Strategies (LNRS) already require a net gain approach which should be achieved in a measurable way.

Within this Environment Bill, it aims to include the development of effective conservation covenants, 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 and use resources in an efficient manner.

As a result of this Act, BNG has been served as a core policy with numerous long term effects to ensure the preservation of habitat types is maintained for at least 30 years. The Act ensures that developers must deliver 10% Biodiversity Net Gain on all future projects.

Biodiversity Net Gain Plans

In order to obtain planning permission for a development from your local planning authority, you must be able to prove that you are taking the correct measures to increase biodiversity net gain. One of the first steps in this process is to book an experienced ecologist to create and develop a biodiversity gain plan.

Depending on the ecologist’s findings within a BNG assessment, the BNG plan will help to determine natural elements that could potentially be at risk as a result of the development project and any mitigation methods to prevent these outcomes from occurring.

How can Collington Winter assist you in achieving 10% Biodiversity Net Gain?

Our team of ecologists and land managers have helped numerous clients over the years to achieve 10% Biodiversity Net Gain for their projects. 

We can assist your development in achieving 10% biodiversity net gain by providing: 

Please get in touch if you would like further information about BNG. We can also develop land management plans. We are happy to offer free CPD sessions on the BNG principles and how we can help your schemes achieve this.

Our Ecology Director, Olivia Collington, holds a Natural England license. If you would like to find out more about the services we provide, feel free to contact us using the details below.

Contact Us

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23 Bark Street East, 1st Floor, Bolton, BL1 2BQ

Cambridge Office

Future Business Centre, Cambridge Campus, Kings Hedges Road, Cambridge, CB4 2HY


Head Office: 01204 939 608

Dumfries Office: 01387 378208

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