BNG Units for Planning and Development

What are BNG units?

Biodiversity net gain involves quantifying the change in biodiversity value resulting from development projects. Biodiversity net gain units refer to the standardised measurements used to assess biodiversity, such as the number of species, habitat area, ecological functionality, etc. These biodiversity net gain units can then be used to assess whether any mitigation measures may need to be used to meet planning obligations.

To calculate the uplift, the number of units is increased by a minimum of 10%. This value is the number that will be required to be delivered in order to obtain development planning permission.

Biodiversity net gain can be implemented on-site and should be maintained for a minimum of 30 years. If net gain of 10% or more cannot be completed and maintained on-site, or can only be partially completed on-site, the remainder can also be accommodated off site using biodiversity banking.

Calculating BNG units

Metrics assign every habitat on a 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 natural habitats through retention and when habitats are created or enhanced, as this goes over and above the environmental habitat originally on site.

BNG units can be calculated using the 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 3.1 calculation tool which can help to determine your biodiversity unit score. This will then translate into the standards of your local planning authority.

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 achieve biodiversity and deliver 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.

Biodiversity net gain is especially important for nationally significant infrastructure projects and sites of special scientific interest. Our team has strong experience completing BNG and will provide guidance throughout the planning system process. This applies from the initial land purchase agreements to monitoring assessments. 

The importance of biodiversity net gain

BNG is significant for a variety of reasons and can help to positively affect the environment almost anywhere. Some of the key benefits that biodiversity net gain provides include:

• Enables the production of raw materials
• Supplies water and oxygen to surrounding ecosystems
• Enhances the environment’s visual appearance
• Provides jobs for local farmers and other agricultural occupations
• Facilitates a scientific understanding of the natural environment
• Offers recreational activities such as fishing, camping and hiking
• Enhances habitat creation and retention

The idea of mandatory BNG is a structured and regulated method of prioritising and ensuring that all of the factors listed above are supported and encouraged in the years ahead. As BNG applies to all development projects, it causes a universal approach from governing bodies. Therefore, as BNG is a government policy, it prevents any potential issues with key stakeholders.

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 November 2023. However, the National Planning Policy Framework (NPPF) also requires 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 Bill, BNG has been served as a core policy with numerous long term effects on ensuring the preservation of habitat types for a minimum of three decades. 

Implementing BNG

If you are unsure of how mandatory BNG may affect your planning application, you should contact your local planning authority immediately. They can discuss your development plans in detail and whether they align with BNG.

If they indicate that your development could be significantly impacted, we recommend that you contact an experienced ecologist as soon as possible. Our ecologists can discuss whether your development plans meet the required standards. They can also recommend any measures you may need to take in order to meet the biodiversity standards.

At Collington Winter, our team has strong experience completing BNG and will provide guidance throughout the planning process. We can ensure that one of our experienced biodiversity ecologists visits your development site to create and develop any necessary BNG plans and any required BNG reports.

Our ecologists will complete a habitat classification assessment, and the data is entered into a metric to measure changes to the natural environment, post and pre development. This metric is currently Defra Metric 3.1. Landscape planting plans and management plans are used to inform post development measures.

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 net 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?

Our team of ecologists and land managers have helped numerous clients over the years, including policy guidance for BNG in England.

We can assist with biodiversity net gain by providing: 

• BNG guidance
• Assessments
• Mitigation

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.