Biodiversity Net Gain Metric 3.1: Why is it important?

Biodiversity Net Gain (BNG) is an emerging metric that aims to measure biodiversity and improve the environmental outcomes of development projects. The concept of mandatory BNG is based on the idea that development projects should not only avoid causing harm to biodiversity but also deliver positive outcomes. This can be done by enhancing and increasing biodiversity within and around the project area.

inform a planning application. 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.

The Environment Act 2021 was passed in October 2021, and BNG will soon become legally binding in November 2023. As a result of this act, 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. 

Biodiversity net gain metric 3.1 refers to a specific measure used to assess the impact of development projects on biodiversity. It is part of the UK government’s response to declining environmental levels. This metric aims to ensure that new developments have a positive impact on biodiversity. The Small Sites Metric (SSM) can also be used for smaller development projects.

Biodiversity net gain metric 3.1 focuses on measuring the biodiversity value of the land before and after a development project. This is to ensure that the project delivers a net gain in biodiversity. This involves assessing the baseline biodiversity of the project area, calculating the biodiversity losses that will occur due to the project, and then designing and implementing measures to offset these losses and deliver a net gain in biodiversity.

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 by creating or enhancing habitats or by retaining existing habitats.

Biodiversity net gain metric 3.1 is a crucial component of the BNG framework. This is because it provides a clear and standardised methodology for assessing and improving biodiversity outcomes in development projects. By using this metric, developers and planners can ensure that their projects contribute to the conservation and enhancement of biodiversity. This will help to protect and restore our natural heritage for future generations.

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 BNG. One of the first steps in this process is to book an experienced ecologist to create and develop a BNG plan.

Depending on the ecologist’s findings within a BNG assessment and BNG metric 3.1, the BNG plan will help to determine natural elements that could potentially be at risk as a result of the development project. These findings can also identify any mitigation methods to prevent these outcomes from occurring.

Our team of ecologists and land managers have helped numerous clients over the years. This includes guidance for BNG metric 3.1 in England. 

We can assist with mandatory biodiversity net gain by providing: 

• BNG guidance
• Assessments
• On site and off-site Mitigation

Please get in touch if you would like a consultation on the biodiversity metric 3.1. 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.