Demystifying the UK’s mandatory Biodiversity Net Gain (BNG)

As of February 2024, it became mandatory for the majority of new developments in England to deliver a minimum 10% increase in Biodiversity Net Gain. However, achieving a 10% net gain in biodiversity is a challenging goal.

Mark Bentley, Landscape Architect at Encon Associates, explains, “in the majority of cases, a 10% net gain in biodiversity is not easy to achieve entirely within the confines of a site, and often off-site mitigation or the purchase of habitat units is the only option for developers to meet their obligations.” 

In today’s blog, we explore everything you need to know about the UK’s first mandatory Biodiversity Net Gain and share our top tips for compliance, allowing you to foster a more sustainable future for your upcoming development.

What is Biodiversity Net Gain?

The Biodiversity Net Gain (BNG) is a mandatory requirement for planning applications in England that is designed to improve biodiversity within development projects. It came into force for major developments on 12th February 2024, with minor projects following suit on 2nd April 2024. For Nationally Significant Infrastructure Projects (NSIPs), BNG is expected to become mandatory from late November 2025.

Natural England defines BNG as “an approach to development, land and marine management that leaves biodiversity in a measurably better state than before the development took place.” Put simply, it’s a measurable standard designed to create, improve, and protect our natural habitats. All new developments are required to deliver a minimum of 10% biodiversity compared to the baseline, which must be sustained for at least 30 years.

According to the guidelines, there are three ways to achieve BNG for new development projects. This is known as the biodiversity gain hierarchy and involves:

• Creating biodiversity on site through landscaping or green infrastructure.
• Creating biodiversity off-site on another piece of land owned by the same developer or through the purchase of off-site credits.
• Purchasing statutory biodiversity credits from the government if on-site or off-site BNG is not achievable. However, this option should be a last resort only.

How to measure Biodiversity Net Gain

It’s clear to see that there are a number of ways to achieve BNG for your new development project. But how is Biodiversity Net Gain measured?

The statutory Biodiversity Metric is used to calculate the biodiversity value of habitats. It involves converting the size, quality, location, and type of available habitats into ‘biodiversity units’, which are divided into area habitat units, hedgerow units, and watercourse units. These units are used as a currency to measure the overall BNG value. 

According to official Government guidelines, this tool should be carried out by “a competent person [that] has the knowledge and skills to perform specified tasks to complete and review biodiversity metric calculations.” Encon Associates is fully qualified to carry out the relevant biodiversity metric calculations on your development site – more on that below…

Our top tips for ensuring compliance with BNG standards

Incorporate BNG in the Early Design Stages

To comply with the stringent Biodiversity Net Gain regulations, Mark Bentley advises developers to, “engage with us as early as possible, because timely input into the design of the development can be the difference between hitting the 10% gain or missing the target altogether.” Our experienced ecological consultants and landscape designers can help you perform feasibility assessments to identify the value of your land’s existing habitats and ecological features, and use this information to develop clear Biodiversity Net Gain plans. 

If you have considered BNG at the early project design phase, you will be far more likely to gain planning permission from your local planning authority (LPA). Plus, it can also help you avoid costly delays and issues with compliance later down the line. 

Follow the Mitigation Hierarchy

According to Mark Bentley, “the best strategies [for achieving BNG] often centre around retaining and enhancing existing habitats rather than creating new ones from scratch,” which is why Encon Associates places great emphasis on the importance of the mitigation hierarchy. 

The mitigation hierarchy is a core component of Biodiversity Net Gain and involves aiming for the minimum amount of biodiversity loss possible. The four steps to the hierarchy are:

• Total avoidance of biodiversity loss
• Minimising biodiversity loss wherever possible
• Restoring biodiversity within specific project areas
• Offsetting the loss of biodiversity, either on-site or off-site

Depending on your budget, the overall land area, and the quality of habitats, your project may be able to avoid biodiversity loss completely. However, in worst case scenarios where biodiversity loss cannot be minimised, you will need to implement clear strategies to offset this loss. 

The mitigation hierarchy should be carefully considered throughout every stage of your project. Encon Associates can assist you in minimising biodiversity loss and developing clear offsetting strategies where required. 

Develop a Habitat Management & Monitoring Plan

A comprehensive Habitat Management & Monitoring Plan (HMMP) is a mandatory document that is required for compliance with Biodiversity Net Gain. It must outline a series of steps explaining how you will maintain and monitor your development’s biodiversity enhancements over the minimum 30-year period. 

Regular monitoring of your site’s habitats will need to be carried out by an experienced ecological consultancy, such as Encon Associates. We can take full ownership of your HMMP, ensuring that your BNG habitats continue to thrive. If necessary, we can help advise on further biodiversity enhancements if your habitats do not deliver as expected, ensuring total compliance with Biodiversity Net Gain legislation.

How Encon Associates can help your project achieve BNG excellence

The mandatory Biodiversity Net Gain is much more than just a regulatory standard; it offers a unique opportunity to contribute to a greener future for the construction industry. By understanding and implementing BNG measures, you can minimise the environmental impact of your project and avoid potential delays with obtaining planning permission.

Encon Associates is committed to helping your development achieve environmental excellence. We offer a wide spectrum of ecological services, including habitat surveys and ecological impact assessments, that are specifically designed to help you navigate the complex Biodiversity Net Gain regulations. 

If you need assistance with achieving Biodiversity Net Gain for your project, please don’t hesitate to get in touch with our expert team today.