Biodiversity Net Gain: Developing a future for habitats & homes

Biodiversity Net Gain was introduced through the world-leading Environment Act and is a fundamental step in helping the UK reduce environmental decline by 2030

February 12, 2024

What is Biodiversity Net Gain?

At its core, Biodiversity Net Gain (BNG) is about enhancing the natural environment during the development process, and ensuring that developers leave wildlife habitats in a better state than they were before they started.

Biodiversity Net Gain is mandatory

From 12 February 2024 BNG is mandatory for most new major developments - with small developments (between 1 and 9 dwellings) following from 2 April 2024 and nationally significant infrastructure projects from late November 2025

The aim? A legally binding commitment to deliver a 10% positive impact on local environments. This can be achieved through creating new habitats, green spaces, or any means that boost the local ecology. 

Guidelines for developers: How can BDN be achieved?

There are 3 ways a developer can achieve BNG.

  • Create habitat on-site: This refers to the actual land earmarked for development.
  • Improve off-site habitats: Either on a different land owned by the developer or by purchasing units from a land manager.
  • Buy statutory credits from the government: This is the last resort, where the government then invests in habitat creation elsewhere in England.

Developers can combine all 3 options, but must follow the steps in order of the hierarchy above. In addition, they must commit to maintain the habitats created for a minimum of 30 years - which applies to off-site gains or significant on-site gains.

Measuring biodiversity: the biodiversity net gain metric

Biodiversity is made up of all of the natural life you might find in an area - including plants, animals, insects and even microorganisms. To quantify the significance of these factors, biodiversity metrics provide a unit of measurement determined by the natural features that could act as habitats for local wildlife. This includes:

  • grassland
  • hedgerows
  • lakes  
  • woodland
  • watercourses such as rivers and streams

The statutory biodiversity metric (used to measure BNG) measures the biodiversity value of habitats by calculating biodiversity units. This includes:

  • how many units a habitat contains before development takes place
  • how many units are needed to replace the units of habitat lost and to achieve 10% BNG, through the creation or enhancement of habitat  

The formula takes different factors including the habitat’s:

  • size
  • condition
  • strategic significance
  • type

For created or enhanced habitats, the formula also calculates:  

  • difficulty of creation or enhancement
  • the time it takes a habitat to reach its target condition
  • distance from the habitat loss  

The statutory (official) biodiversity metric calculation tool must be used in order to demonstrate that you have calculated the number of biodiversity units for existing habitat or habitat enhancements by the statutory biodiversity metric.

What do developers have to do to achieve BDN?

If your development has to meet mandatory biodiversity net gain (BNG) requirements, you will need to use the statutory metric tool and consult an ecologist to help measure the biodiversity value of the existing habitat and explore ways to achieve BNG.

As a developer, you can use the metric tool to assess:

  • the number of biodiversity units your proposed development site has – its biodiversity value
  • how this value could be lost through development  
  • what you need to do to achieve BNG

You should enter details of your development site into the metric tool, and if you haven’t achieved the 10% BNG, you will have to change the site design or consider off-site gains.

For small projects, hiring an ecologist isn't required but you can use the small sites biodiversity metric tool yourself, or have someone who knows the site well, like a project manager, gardener, or landscape architect, do the survey and calculations for you.

A small development means: 

  • residential development where the number of dwellings is between 1 and 9 on a site of an area 1 hectare or less, or if the number of dwellings is unknown, the site area is less than 0.5 hectares
  • commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare
  • development that is not the winning and working of minerals or the use of land for mineral-working deposits
  • development that is not waste development

Biodiversity Net Gain is England's commitment to a brighter, greener future. It is a testament to the belief that nature and development can not only co-exist but can also mutually benefit from one another. As developers and landowners, embracing BNG is not just about compliance; it's about paving the way for sustainable growth and a lasting legacy.

May 9, 2024

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