Guidance

Irreplaceable habitat

How biodiversity net gain (BNG) applies to irreplaceable habitat.

Applies to England

Biodiversity net gain (BNG) is mandatory from 12 February 2024.

You can view all of the BNG guidance in the BNG collection.

What irreplaceable habitat is

Irreplaceable habitat is very difficult (or takes a very long time) to restore, create or replace once it has been destroyed. This may be due to its: 

  • age 

  • uniqueness 

  • species diversity 

  • rarity 

Irreplaceable habitat includes some of England’s most ecologically valuable terrestrial and intertidal habitat.  For example: 

  • ancient woodland 

  • ancient and veteran trees 

  • blanket bog 

  • limestone pavements 

  • coastal sand dunes 

  • spartina saltmarsh swards 

  • mediterranean saltmarsh scrub 

  • lowland fens 

See the definition and full list of irreplaceable habitat for BNG in the Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024.

Development on irreplaceable habitat 

You will only get planning permission for development that results in loss of irreplaceable habitat in exceptional circumstances. 

The 10% BNG requirement does not apply when there is loss of irreplaceable habitat because it would be impossible to achieve. 

Instead, you need to minimise adverse impacts and agree a compensation strategy with the planning authority.

Read the national planning policy framework on irreplaceable habitat.

Compensation rules for irreplaceable habitat 

Special compensation rules apply to irreplaceable habitat. 

If planning permission is given you will need to agree a compensation strategy with the LPA

Compensation for irreplaceable habitat needs to be relative to the baseline habitat type. The LPA  will agree compensation as part of the determination of the planning application, on a case-by-case basis. 

Read more in the biodiversity net gain planning practice guidance

What developers need to do 

1. Consider irreplaceable habitat from the start 

Think about irreplaceable habitat at the design and planning stage, and look at how to avoid any adverse impacts. 

At the planning application stage, you will need to satisfy the  minimum information requirements. 

You will need to provide: 

  • a description of any irreplaceable habitat on site at the date of the planning application 

  • a plan of existing irreplaceable habitat on site at the date of the planning application 

Your local planning authority may ask you for more information related to biodiversity net gain and wider planning policies designed to protect the environment.  

Find out more in the biodiversity net gain planning practice guidance.

2. Record irreplaceable habitat in your BNG calculation 

You must record all irreplaceable habitat on your site in the metric calculation tool, regardless of whether they will be affected by the proposed development. 

When there are adverse impacts to irreplaceable habitat   

Impacts to irreplaceable habitat cannot be measured by the biodiversity metric and are automatically removed from the baseline calculation in the tool.   

Do not record any bespoke compensation action for losses of irreplaceable habitat within the enhancement or creation sheets of the biodiversity metric. 

Find out more in the statutory biodiversity metric user guide

When irreplaceable habitat is enhanced 

Where there are no losses or deterioration of irreplaceable habitat, you must record enhancements in the metric calculation tool and include them in the baseline calculations. 

Enhancement works may contribute towards the calculation of post-development biodiversity units. 

Enhancement works must be ecologically appropriate and not have any adverse impacts on irreplaceable habitat. 

When the development site includes irreplaceable and non-irreplaceable habitat 

You must achieve at least 10% BNG  on non-irreplaceable habitat on your development site.  

This is in addition to agreeing bespoke compensation for impacts on irreplaceable habitat, which cannot count towards your BNG requirement.  

3. Record irreplaceable habitat in the biodiversity gain plan 

If planning permission has been granted for development on a site that includes irreplaceable habitat, you will need to provide details in the biodiversity gain plan for the development.

This should include: 

  • type, extent and condition of any irreplaceable habitat there is before development 

  • any expected changes in irreplaceable habitat type, extent and condition as a result of development 

  • actions taken to minimise adverse impacts to irreplaceable habitat 

  • compensation plan 

Special arrangements apply for the treatment of irreplaceable habitat for phased development and permissions granted under section 73.  

Find out more in the biodiversity net gain planning practice guidance.

You can give feedback on this guidance by completing a short survey.

Updates to this page

Published 22 February 2024
Last updated 4 September 2024 + show all updates
  1. Updated to make it clearer how irreplaceable habitat is dealt with under biodiversity net gain, and to explain what information is needed at planning application stage. The policy around irreplaceable habitat and biodiversity net gain remains unchanged.

  2. First published.

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