Biodiversity Net Gain, guidance for developers and ecological consultants

Biodiversity net gain (BNG) (opens new window)is a way of making sure development has a measurably positive impact ('net gain') on biodiversity, compared to what was there before development.

BNG is becoming mandatory under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021) (opens new window). Developments must deliver a BNG of at least 10%.

This compliments and adds to existing local policy requirements in Gateshead. Policy MSGP37 of the Local Development Plan (LDP) states: "Where appropriate, development proposals must demonstrate how they will:

• avoid/minimise adverse impacts on biodiversity and geodiversity in accordance with the mitigation hierarchy; and
• provide net gains in biodiversity."

The introduction of mandatory biodiversity net gain marks a significant change in the way in which ecological matters are addressed through the planning process, and it is recommended the provision of BNG is given due regard as early in the process as possible to achieve the best results for developers and biodiversity.

A range of guidance concerning biodiversity net gain has been provided by government; it is not the intention of this guidance to replicate or replace that but to highlight key issues and set out local information requirements for planning submissions. 

This guidance may be periodically updated to reflect changes in government guidance. Please check this page for updates to make sure you are referring to the current version. 

The following types of development are exempt from the BNG requirement (opens new window):

• Householder development.
• Permitted development.
• Development subject to the de minimis exemption - defined as development that does not impact a priority habitat and impacts less than: 
  • 25m2 (5m by 5m) of habitat
  • 5m of linear habitat such as hedgerows. 
• Self-build and custom build development when all the following conditions apply:
  • it consists of no more than 9 dwellings
  • it's on a site which has an area no larger than 0.5ha 
  • it consists exclusively of dwellings which are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015. (opens new window)
• Development of a biodiversity net gain site, where that requires planning permission.

Variations and reserved matters are exempt from mandatory net gain if the original or outline application was submitted prior to the 12th February 2024.

Exemption statement 

The Tyneside Validation checklist 2024 (PDF, 1 MB)(opens new window) requires that where an exemption is being claimed (other than householder development or changes of use where no groundworks are proposed), that a statement setting out why the proposed development is exempt must be submitted with a planning application.  

National validation requirements also require that the reason suggested for exemption be listed on the planning application form. 

De Minimis exemption 

Consistent with Paragraph 004 Reference ID: 74-004-20240214 of Planning Practice Guidance on Biodiversity Net Gain (GOV.UK: Biodiversity net gain (opens new window)). 

In cases where the development would be smaller than 25 square metres, the description of development, existing and proposed site plans, and the development's area size (in square metres) may be sufficient evidence.   

Where it cannot be clearly demonstrated through site plans and descriptions, applicants should provide a completed metric for the pre-development and post-development value for the onsite habitat and clear plans identifying the nature and size of this pre-development onsite habitat and how much of it will be impacted by the development.

The Town and Country Planning Act has been amended to make every grant of planning permission deemed to have been granted subject to the following planning condition:

The development may not be begun unless:

• a biodiversity gain plan has been submitted to the planning authority, and 
• the planning authority has approved the plan.

The purpose of the condition is to secure the biodiversity objective, which is that the biodiversity value attributable to the development exceeds the pre-development biodiversity value of the onsite habitat by at least 10%. 

There are different options which can be utilised and combined to achieve net gain. They must be considered in the following order, known as the biodiversity gain hierarchy. 

1. habitat creation or enhancement onsite (within the red line boundary of a development site)

2. making off-site biodiversity gains on their own land outside the development site or buying biodiversity units from a habitat bank

3. or as a last resort buy statutory credits

Although final details may only be required through the discharge of the pre-commencement Biodiversity Gain Plan condition, BNG is often a material consideration when determining applications and Paragraph: 002 Reference ID: 74-002-20240214 of Planning Practice Guidance on Biodiversity Net Gain (GOV.UK: Biodiversity net gain (opens new window)) makes it clear that the Local Planning Authority (LPA) needs to understand how the BNG requirement is to be met prior to determining the application, so that necessary planning conditions can be imposed and/or S.106 Agreements signed. Accordingly, sufficient information is still required at the application stage.

The following national validation requirements have been imposed:

• a statement as to whether the applicant believes the development is subject to the biodiversity gain condition (on application form)
• where the applicant believes that planning permission, if granted, would not be subject to the biodiversity gain condition, the reasons for that belief (within the statement on the application form)
• where planning permission would be subject to the biodiversity gain condition:
                 

The completed biodiversity metric showing the calculation of the biodiversity value of the onsite habitat, on

• the date of the application; or
• an earlier date proposed by the applicant

With the date being immediately before any activities of the type mentioned in paragraph 6 or 6A of Schedule 7A to the 1990 Act having been carried out on the land.

• Where any of the above activities to degrade the land have been undertaken, submit:
  • a statement that such activities have been carried out
  • confirmation of the date immediately before those activities were carried out; and
  • any available supporting evidence
  • a description of any irreplaceable habitat on the land (on the application date or earlier date proposed by the applicant); and
• a plan showing onsite habitat existing on the date of application, including any irreplaceable habitat that matches the red line boundary of the application site

If this information has not been provided, the local planning authority must refuse to validate the application.  

Submitting the BNG Metric  

Please note that Section 9 of the Metric User Guide states that the metric should be submitted as a macro disabled Excel file. This is because the Planning Portal cannot handle macro-enabled files. 

What is required for validation

See the Tyneside Validation checklist 2024 (PDF, 1 MB)(opens new window).

• title includes that the document is/includes a Biodiversity Net Gain assessment and report
• must include a fully completed DEFRA Biodiversity Metric Calculation Tool (in Excel format). The statutory version of the tool must be used for the assessment.

Further information/guidance - Information to be submitted to support a planning application (see the Tyneside Validation checklist 2024 (PDF, 1 MB)(opens new window)) 

A Biodiversity Net Gain Assessment must be provided outlining how the Biodiversity Gain Objective will be met. This must be prepared by a professional ecologist with suitable qualifications and experience and be in accordance with the British Standard BS8683 'Process for designing and implementing biodiversity net gain - specification'. Biodiversity net gain must always follow the principles outlined in 'Biodiversity Net Gain - Good Practice Principles for Development'  

The assessment should include details of: 

• information required as set out in the Biodiversity Net Gain Planning Practice Guidance (opens new window)
• the proposed methods of delivery of the biodiversity gain objective including onsite gains, off-site gains and the use of statutory biodiversity credits
• how the biodiversity gain hierarchy (opens new window) has been considered and adhered to
• information about any potential planning obligations required to deliver the biodiversity gain objective connected to the planning application (e.g. should a S106 agreement be required to secure significant areas of onsite habitat). 

A draft version of the Statutory Biodiversity Metric Calculation Tool (in Excel format) must be submitted. This should be completed in accordance with the Biodiversity Metric Principles included in 'The Statutory Biodiversity Metric User Guide' published by DEFRA. As a minimum this should include completed sections for onsite pre-and post-development habitat delivery. 

The following supporting information must be submitted alongside the metric:

• completed statutory biodiversity metric condition assessments for baseline habitats, including supporting information i.e. species lists and quadrat locations
• predicted habitat condition assessments of created/enhanced post-development habitats and details of the realistic and appropriate interventions/management regimes which are being suggested to achieve the stated condition/s and secure the biodiversity enhancements for a minimum 30 years post enhancement/creation
• pre- and post- development site plans clearly showing polygons and areas for each habitat used to populate the statutory metric calculation tool using UK Habitat Classification symbology (shapefiles in GIS or AutoCAD may be requested). The plans must be drawn to an identified scale and show the direction of north. Plans using Phase 1 symbology are not acceptable
• polygons within pre- and post-development plans should be labelled with a Habitat Reference Number which should also be noted within the associated column within the Statutory Metric Tool

Where it is suspected the baseline value of a site has been affected negatively prior to assessment the LPA may require an assessment of the site based on its condition before such an occurrence. This may need to be based on aerial photos and/or historic information held by the Council and if there is any doubt regarding the Distinctiveness or Condition of habitats/features it will be assumed that the highest likely value will apply. 

The general biodiversity gain plan condition has a separate statutory basis to other planning conditions and is deemed to apply to all planning permissions other than specifically exempted ones.  

Gateshead has taken the decision to list the biodiversity gain plan condition on the decision notice for clarity, along with additional conditions to secure biodiversity net gain as required. The decision notice will also include information about BNG, in accordance with model paragraphs provided by Defra. 

Development cannot be commenced until the mandatory BGP condition has been discharged.  

An application to discharge this condition can only be made on the day after planning permission is granted and there is an 8 week determination period. It is therefore recommended that developers wishing to start on site as soon as possible after being granted planning permission have their Biodiversity Gain Plan drafted in advance. 

To discharge the condition, the following information must be submitted:

• a completed biodiversity metric
• a Biodiversity Gain Plan setting out how the biodiversity gain objective of at least a 10% gain will be met for the development
• for habitat being created on the development site, a Habitat Management and Monitoring Plan setting out how the habitat will be managed for at least 30 years, and how this will be monitored
• pre-development and post-development plans showing the location of on-site habitat
• if the developer is purchasing units from a Habitat Bank - the reference number from the Biodiversity Gain Sites Register
• if the developer is purchasing statutory credits - proof that they need them and proof of purchase

Templates for the Biodiversity Gain Plan (opens new window) and for the Habitat Management and Monitoring Plan (opens new window) have been created by Natural England and these must be used unless otherwise agreed with the LPA.  

The Biodiversity Gain (Town and Country Planning) (Modifications and Amendments) (England) Regulations 2024 modify the general biodiversity condition for planning permissions which are phased development. Instead of the standard approach for the Biodiversity Gain Plan:

• an Overall Biodiversity Gain Plan must be submitted to and approved by Gateshead Council as LPA before any development can begin
• a Phase Biodiversity Gain Plan for each phase must be submitted to and approved by Gateshead Council as LPA  before the development of that phase can be begun

In recognition that phased development can often be implemented over a long period of time, the purpose of the Overall Biodiversity Gain Plan is to set a clear upfront framework for how the biodiversity gain objective of at least a 10% gain is expected to be met across the entire development.

Each Phase Biodiversity Gain Plan will subsequently set out a phase's contribution to biodiversity net gain and track progress towards the overall biodiversity gain objective for the development once clear proposals for each phase have been developed.

It is envisaged that, for an outline planning permission for phased development, the Phase Biodiversity Gain Plan would be prepared alongside the application for reserve matters approvals for a phase. Further details can be found in Paragraph 053 Reference ID: 74-053-20240214 to Paragraph: 063 Reference ID: 74-063-20240214 of the Planning Practice Guidance for Biodiversity Net Gain (opens new window). 

Important issues to consider when planning how to meet your BNG requirements.

Mitigation hierarchy 

While the introduction of a metric that generates numerical values to quantify losses and gains of habitats is one of the most striking aspects of Biodiversity Net Gain, the metric is only a tool to help to estimate the value of what is being proposed. The purpose of Biodiversity Net Gain is to require development to have a positive impact on biodiversity overall through the creation and enhancement of habitats, and so at every stage of the process it is essential that ecological principles are being followed and the process is being considered in terms of how to achieve best outcomes for nature rather than just best numbers in the metric.  

Importantly, the mitigation hierarchy set out in paragraph 193a of the NPPF remains paramount - harmful impacts must first be avoided. Where they are unavoidable, they must be adequately mitigated, with compensation being a last resort. 

Enhancement should then be secured over and above that. Accordingly, the net gain process can be seen to apply right at the end of that process - to the compensatory and enhancement stages. It does not remove the need to avoid impacts as the first priority.  

To help ensure that good ecological outcomes are secured through the Biodiversity Net Gain process, a series of nine metric principles are set out in section 3 of the Statutory Biodiversity Metric user guide (opens new window), in addition to the four metric rules that must be adhered to in all circumstances. The principles exist to ensure that expert ecological advice and established ecological principles are always used throughout the BNG process. A guide called Biodiversity Net Gain: Good Practice Principles for Development (opens new window) has also been produced by CIEEM, IEMA and CIRIA, which provides extensive advice to ensure that best ecological outcomes can be secured through the BNG process.  

The use of the biodiversity metric does not override existing biodiversity protections, statutory obligations, policy requirements, ecological mitigation hierarchy or any other requirements. 

Interim arrangements for the Strategic Significance Section of the Metric until the South of Tyne Local Nature Recovery Strategy is published 

Strategic significance describes the local significance of the habitat based on its location and the habitat type. 

All habitat parcels (both baseline and post-development) must be assigned a strategic significance score; it should be considered separately for each individual habitat parcel in the metric and not on a site-wide basis.  

On an interim basis, until the South of Tyne Local Nature Recovery Strategy (LNRS) is published, strategic significance categories should be based on: 

• Mapping of the Gateshead Wildlife Corridors as shown on the policies map (opens new window) ; and
• Habitats listed as Priority Habitats for Durham Vice County 66 in Appendix 16 of Making Spaces for Growing Places (MSGP) (PDF, 8 MB) Local Plan Document for Gateshead (Gateshead Council February 2021).

High: Where the project delivers a local priority habitat within a Wildlife Corridor: 

• Record the strategic significance as low in the baseline tab
• Record strategic significance as high in post-development tab  
• Record the documents used in the user comments 

Medium: Cannot be applied given that the habitats and locations to be considered have been specified by the local planning authority (as above).(See table 7 of Statutory Metric User Guidelines) 

Low: Where the definitions for high strategic significance are not met. Even if your project is within a Wildlife Corridor, if it does not deliver a local priority habitat you should: 

• Record strategic significance as low in the baseline
• Record strategic significance as low in in post-intervention sheet

Provision of BNG on the development site

In principle, the development site itself is the preferred location for the created or enhanced habitats that will satisfy the BNG requirement, so that there isn't a spatial separation between where habitats are being lost and where they are being established, and to ensure that local communities benefit from a nature-rich environment. However, there are significant issues to be considered when determining whether this is realistic, especially on residential sites where open space is going to be used by local residents for a range of uses such as informal play and exercise, including dog-walking. 

This imposes some extra considerations on top of the normal considerations such as soil nutrient status in determining what habitats could realistically be sustained and managed, and what condition could realistically be achieved for those habitats.  

Disturbance levels and lighting must also be considered when determining whether habitat types/conditions can be deemed realistically representative of targeted habitats. 

Once they have been created, significant on-site habitats will need to be managed and monitored for a 30-year period, , to determine if the required gains are being achieved and to identify remedial measures if not. It is therefore in everyone's interests to ensure that BNG proposals are realistic and achievable. 

Significant onsite enhancements

Significant on-site enhancements are areas of habitat enhancement which contribute significantly to the proposed development's BNG, relative to the biodiversity value before development. 

Retention of existing habitat does not count as an on-site enhancement. 

What counts as a significant enhancement will vary depending on the scale of development and existing habitat, but these would normally be:  

• habitats of medium or higher distinctiveness in the biodiversity metric 
• habitats of low distinctiveness which create a large number of biodiversity units relative to the biodiversity value of the site before development
• habitat creation or enhancement where distinctiveness is increased relative to the distinctiveness of the habitat before development 
• areas of habitat creation or enhancement which are significant in area relative to the size of the development   
• enhancements to habitat condition, for example from poor or moderate to good 

View further guidance on significant enhancements on the GOV.UK website (opens new window)

Meeting the BNG requirement through the purchase of biodiversity units

Habitat Banks - areas of land where habitat is created or enhanced to sell the resulting biodiversity units to developers - may be established in Gateshead.  

In order to do this, landowners will need to conclude legal agreements with the Council and then register the sites on the Biodiversity Gain Site Register. More information can be found on the DEFRA website (opens new window).