Planning Conditions for Biodiversity Net Gain

In England, Biodiversity Net Gain (BNG) is an approach that has become an essential aspect of all future development projects as it is now a part of UK legislation. This involves considering the long term impact of a project on the environment, specifically in terms of biodiversity, with the ultimate aim of improving overall biodiversity. To achieve this, biodiversity loss is avoided, different habitats are preserved, and significant ecological assets are protected.

Local planning authorities require evidence of BNG to inform planning applications. This is to demonstrate how the proposed project will contribute to measurable improvements in biodiversity. BNG is now a policy requirement for planning consent and may also be a planning condition, significantly influencing planning authorities’ final decision.

Utility providers, transport companies, and other organisations are also adopting BNG into their internal policies. Some are even setting targets for a higher percentage gain than the mandatory minimum. This highlights the importance of recognising the significance of preserving biodiversity in development, and those in charge of planning projects must ensure that mandatory biodiversity net gain is incorporated.

Planning conditions for biodiversity net gain

As per the Environment Bill and in accordance with the national planning policy framework (nppf), most planning applications must adhere to a minimum of 10% BNG. This is measured by Defra’s biodiversity metric 3.1, with a requirement for habitats to be maintained for at least 30 years, except for certain exemptions. Alongside these requirements, further implementations were induced including:

  • A strengthened legal duty for public bodies to conserve and enhance biodiversity
  • New BNG reporting requirements for local planning authorities
  • Mandatory special strategies for nature described as “Local Nature Recovery Strategies (LNRS).

Further planning conditions may require a survey of the site’s existing biodiversity, including habitat types and species present. An assessment of the impact that the proposed project will have on surrounding biodiversity and monitoring of the site’s biodiversity over time may also be needed.

When will BNG become mandatory?

Most new projects in England will be required to incorporate BNG once the Environment Act is implemented. This Act has been approved by the UK Parliament and is expected to take effect in late 2023, subject to government approval.

The legislation will mandate a 10% net gain in biodiversity for all new projects in England that necessitate planning permission. The biodiversity metric specified in the legislation will be used to measure the net gain. BNG will be applicable to projects that impact habitats such as woodlands, wetlands, grasslands, and built environment. This will not include those exempt from planning permission or covered by specific exemptions.

The introduction of BNG represents a significant milestone in the conservation and enhancement of biodiversity in the UK. It will help to ensure that new projects contribute towards the overarching objective of halting biodiversity decline. The incorporation of BNG is a critical aspect of the UK government’s 25 Year Environment Plan.

Biodiversity net gain principles

According to the Chartered Institute of Ecology and Environmental Management (CIEEM), there are ten crucial good practice principles of BNG. 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 biodiversity net gain requirements
  • Determine a suitable method in order to secure measurable BNG
  • Ensure the best possible results from BNG

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 planning system process. This applies from the initial land purchase agreements to monitoring assessments.

Implementing BNG

If you are uncertain about the impact of mandatory BNG on your planning application, we recommend that you promptly contact your local planning authority for further information. They can offer in-depth advice on your plans and whether they comply with BNG regulations. If they advise you that your project may be affected, it is advisable to seek the assistance of an experienced ecologist without delay.

Our team of ecologists can assess your project proposals to determine whether they meet the requisite standards for BNG. They can also advise you on any steps you may need to take to achieve the biodiversity standards.

With a wealth of experience in BNG, our team can guide you through the planning process. We can arrange for one of our expert ecologists to visit your development site. They can help to create and enhance any necessary BNG plans and reports.

Our ecologists will perform a habitat classification assessment. This is then used to determine any changes to the natural environment before and after development using the current Defra Metric 3.1. Post-development biodiversity measures are informed by landscape planting plans and management plans.

How to calculate BNG

Metrics assign every habitat on a designated 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 habitat creation or enhancement, which goes over and above the environmental habitat originally on site.

BNG can be calculated through the DEFRA biodiversity metric 3.1, 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. This tool can help to determine your biodiversity unit score that translates into the standards of your local planning authority.

Why is BNG being required by local planning authorities?

BNG is significant for a variety of reasons and can help to positively affect the surrounding environment and wildlife. Some of the main benefits that BNG provides include:

  • It supplies water and improves air quality to the surrounding environment
  • Enhances the visual appearance of the environment
  • Facilitates a scientific understanding of the environment
  • Provides jobs for agricultural occupations
  • Helps to protect special scientific interest sites and irreplaceable habitats

The concept of mandatory planning conditions for biodiversity net gain is a structured method of ensuring that all of the factors listed above are encouraged and supported in the years ahead. As BNG applies to all planning projects, it causes a universal approach from governing bodies and local authorities. Therefore, due to the fact that BNG is a government policy, it prevents any potential issues with key stakeholders.

Biodiversity net gain plans

To secure planning permission from a local authority for a project, it is necessary for developers to demonstrate their commitment to enhancing BNG. One of the first essential steps is to engage an experienced ecologist who can create a BNG plan.

The BNG plan will be based on the ecologist’s assessment of the project. It will identify natural elements that could potentially be at risk due to the project. The plan will also outline any mitigation measures. This could include habitat recreation or conservation covenants to be implemented to prevent negative outcomes.

By incorporating biodiversity considerations into the initial planning and design stages, the goal is to avoid retrofitting. This can cause delays, unexpected financial costs, and complications with planning application determinations.

How can Collington Winter assist?

At Collington Winter, our team of ecologists and landscape architects have assisted numerous clients over the years to deliver biodiversity net gain on their projects. BNG is something that we are experienced and qualified in, and we can offer advice on your project. We are determined to offer you the support you need in order to reach the required mandatory biodiversity bracket.

Please get in touch if you would like consultation on planning conditions for biodiversity net gain or BNG plans. We also offer free CPD sessions on the BNG principles and how we can help your project to achieve them.

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

Contact Us

Registered Address

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

Get in touch
close slider
Please enable JavaScript in your browser to complete this form.