Biodiversity Net Gain Mandatory from this Month

From 12 February 2024 biodiversity net gain, BNG, becomes mandatory.  Non-exempt major development (more than 10 homes or larger than 0.5 hectares) “will have to deliver net gains for biodiversity leading to positive outcomes for nature, better places for local communities and more consistent and transparent requirements for developers”[1].  The requirements will extend to small sites from April and Nationally Significant Infrastructure Projects from November 2025. Small sites will not include certain de minimis developments such as home extensions.

Biodiversity net gain is..?

An approach to development or land management intended to create an improved natural environment.  Developments will need to deliver a BNG of 10%, and such gains should be maintained for a minimum of 30 years.  The requirements stem from the Environment Act 2021, which imported changes into the Town and Country Planning Act 1990.

BNG is measured in units by reference to the Biodiversity Metric.  The metric will determine how many biodiversity units are present prior to development and how many need to be provided to replace lost units and achieve the 10% requirement.  This information will be included as part of a biodiversity plan that must be submitted to and approved by the Local Planning Authority before the commencement of development.

There are three ways in which the 10% can be achieved, which can be used in combination, but must be applied in hierarchical order.  The preference is for the BNG to be provided through on-site gains, ie, those within the red line of the planning application boundary.  Failing that some or all gains can be made up by off-site units registered to the development.  As a last resort biodiversity credits can be purchased for the development.

Good news for the environment.

The new requirements create opportunities for landowners to create and improve habitats on their land to be purchased as off-site BNG units.  They should push developers to consider biodiversity right from the site assembly stage of a development.  New developments will be pushed to try and deliver on site BNG, to be benefit of those to occupy the homes and workplaces created.  Ultimately BNG should mean widespread improved and new green spaces, benefitting nature, health and wellbeing.

If you'd like assistance in relation to the issues raised please do contact Janine Shaw at

[1] DEFRA Blog 18 January 2024

Posted on 01/31/2024 by Ortolan

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