What is Biodiversity Net Gain (BNG)?  

BNG looks to ensure that habitats for wildlife are left in a measurably better state than they were before the development.

In England, BNG is mandatory under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021).

Developers must deliver a BNG of 10%. This means a development will result in more or better quality natural habitat than there was before development. 

Find out more about BNG in:

• step by step guidance for developers 

• step by step guidance for land managers

Measuring biodiversity  

For the purposes of BNG, biodiversity value is measured in standardised biodiversity units. 

A habitat will contain a number of biodiversity units, depending on things like its size, quality, location and type.  

Biodiversity units can be lost through development or generated through work to create and enhance habitats. 

Measuring biodiversity value

An ecologist will:  

• measure the biodiversity value of your existing habitat  

• advise on suitable habitat creation or enhancement for the land

Calculating the units

There is a statutory (official) biodiversity metric, which you must use to measure how many units:

• a habitat contains before development  

• are needed to replace the units of habitat lost and to achieve 10% BNG

Exempt developments 

Some developments are exempt from BNG requirements. 

Find out what types of development are exempt.

Ways to achieve BNG: on-site units, off-site units and statutory biodiversity credits 

Through site selection and layout, developers should avoid or reduce any negative impact on biodiversity. They must deliver at least 10% BNG, as measured by the statutory biodiversity metric.

There are three ways a developer can achieve BNG:

1. They can create biodiversity on-site (within the red line boundary of a development site). 

2. If developers cannot achieve all of their BNG on-site, they can deliver through a mixture of on-site and off-site. Developers can either make off-site biodiversity gains on their own land outside the development site, or buy off-site biodiversity units on the market.

3. If developers cannot achieve on-site or off-site BNG, they must buy statutory biodiversity credits. This should be a last resort.

Developers can combine all three options, but must follow the steps in order. This order of steps is called the biodiversity gain hierarchy. 

BiOME are highly experienced in BNG so please contact us to help with your project.