The principal of Biodiversity Net Gain (BNG) requires developments to provide or enhance habitats for wildlife such that the environment is left in a measurably better state than it was prior to the development taking place. Where a development has an impact on biodiversity, BNG requires developers to provide an increase in appropriate natural habitat over and above that being affected.

As a result of the Environment Act 2021, most planning applications will be required to provide a minimum of 10% Biodiversity Net Gain, contributing towards reducing the current loss of biodiversity through development and enhancing the restoration of ecological networks.

BNG will be a mandatory requirement, to be sequentially introduced as follows:

• Major development: 12 February 2024
• Small-scale development: 2 April 2024
• Nationally Significant Infrastructure Projects: November 2025.

Please note: the above date applies to the submission date of the application.

Developers must assess the pre- and post- development habitat value of their proposals to establish that a 10% gain can be achieved prior to submitting a planning application. The delivery of BNG will be monitored and enforced over a 30-year period.

A range of information provided by the government in relation to various aspects of the biodiversity net gain process can be accessed from the GOV.UK website:

GOV.UK - Biodiversity net gain (external website)

The council intends to produce a Supplementary Planning Document to provide guidance and confirm local policy requirements. In the meantime, additional information is outlined under specific questions below and any queries can be sent to nature.conservation@eastriding.gov.uk.

Most planning applications will be required to demonstrate a 10% Biodiversity Net Gain under the Environment Act 2021.

This will apply to major development submitted on/after 12 February 2024 and to minor development on/after 2 April 2024; with Nationally Significant Infrastructure Projects from November 2025.

Minor development means:

• For residential: where the number of dwellings to be provided is between one and nine inclusive on a site having an area of less than one hectare, OR where the number of dwellings to be provided is not known, on a site area of less than 0.5 hectares.
• For non-residential: where the floor space to be created is less than 1,000 m² OR where the site area is less than one hectare.

Exemptions will be confirmed by secondary legislation, but it is understood that this is likely to include the following:

• Permitted development
• Development impacting habitat of an area below a ‘de minimis’ threshold of 25 m², or 5m for linear habitats such as hedgerows
• Householder applications
• Planning permission for development which is part of the high speed railway transport network
• Biodiversity gain sites where the purpose of the development is to provide biodiversity gains in relation to another development proposal
• Self-build and custom housebuilding: consisting of no more than 9 dwellings or a site area of <0.5 hectares.

If your development falls into either the Custom and Self-build or De minimis exemption, please download and complete the relevant exemption form that will need to be accompanied with your planning application.

Custom and Self-build exemption form (word 75kb)

De minimis exemption form (word 70kb)

Biodiversity Net Gain is measured using a metric to measure the biodiversity value pre- and post- development. The Biodiversity Metrics are free biodiversity accounting tools published in Microsoft Excel format, which are used to calculate the change in biodiversity value caused by the change in land use and/or management included within a specific proposal. There are three types of biodiversity units, which are calculated in three separate ‘modules’ of the metrics (area units, hedgerow units and watercourse units). A 10% gain must be achieved for each unit type present on site pre-development.

The Biodiversity Metric tools and user guides can be accessed via the following link:

GOV.UK - Statutory biodiversity metric tools and guides (external website)

For major developments the Government’s Statutory Biodiversity Metric must be used to measure Biodiversity Net Gain. This should be completed by a ‘competent person’, suitably trained, qualified and experienced; generally considered to be an ecologist. Specific training is required to undertake river condition assessments, evidence of which should be provided.

For minor developments* the applicant may use the Small Sites Metric which should be completed by a ‘competent person’ although this does not need to be an ecologist. However, the Small Sites Metric cannot be used on sites where the following applies:

• the habitats on site are not included within the SSM (habitats of high distinctiveness and above).
• the habitats on site are not priority habitats (except for some hedgerows and arable filed margins).
• proposed habitats are not included within the SSM (habitats of high distinctiveness and above).
• the proposals result in watercourse encroachment.
• there are statutory protected sites or habitats present.
• there are European protected species present.

Where the above applies the Statutory Biodiversity Metric must be used and where statutory protected sites or priority habitats are located within 500m of the development it’s use should be considered.

The applicant should note that they may also choose to use the Statutory Biodiversity Metric irrespective of the application type, habitats or species present and that there may be advantages in doing so in respect to lower unit scores compared with the Small Sites Metric.

Please note: Minor developments are those which are not defined as major developments under the Town and Country Planning (Development Management Procedure (England) Order 2015. This means:

• Residential development where the number of dwellings to be provided is between one and nine inclusive on a site having an area of one hectare or less, OR where the number of dwellings to be provided is not known, on a site area of less than 0.5 hectares.
• Commercial development where the floor space to be created is less than 1,000 m2 OR where the site area is less than one 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.

The Metrics provide a measure of overall Biodiversity Value based on habitat type, area, distinctiveness, and condition, with an allowance to be made for strategic significance. The metrics are a tool that allows the biodiversity value of a site to be measured pre- and post-development. The change in Biodiversity Units indicates either a net loss or net gain in biodiversity.

• Habitat type: A habitat classification derived from multiple sources, principally the UK Habitat Classification System.
• Area: The size of the habitat parcel to be retained, enhanced, created, or lost. Within the main metric size is measured in hectares for area features, or in kilometres for linear features (this being m2 and linear m within the Small Sites Metric).
• Distinctiveness: A value for each habitat type which is pre-set within the metric. It is based on species richness, rarity, the extent to which the habitat is protected by designations and the degree to which a habitat supports species rarely found in other habitats.
• Condition: Condition is used as a measure of the quality of a habitat, since this can vary between areas of the same habitat type. Condition assessment can be undertaken by a suitably qualified ecologist in accordance with the methodology included within the Metric Guidance. It should be noted that condition is generally pre-set within the Small Sites Metric to enable it to be used by non-ecologists.
• Strategic significance*: Describes the local significance of the habitat based on its location and the habitat type.

*Note: the strategic significance of a habitat type will ultimately be defined on a local basis through Local Nature Recovery Strategies (LNRSs). The East Riding LNRS is currently being developed and is due to be completed in autumn 2024. In the meantime interim guidance is provided under a separate Q and A panel on this webpage.

The Biodiversity Metrics have been designed to follow the mitigation hierarchy and support the retention of valuable habitats. It disincentivises the loss of better-quality habitats by awarding them a higher unit value making them significantly more expensive to provide net gain for, compared to habitats of lower biodiversity value. The replacement of specific habitats of particularly high value, termed ‘irreplaceable’ habitats, is not to be incorporated within the metrics and may require that parts of the site are safeguarded from development. These habitats include blanket bog, lowland fens, limestone pavements, coastal sand dunes, ancient woodland, ancient and veteran trees, spartina saltmarsh swards, Mediterranean saltmarsh scrub.

Consequently, it is important to establish the baseline value of a site at as early a stage as possible when considering its development potential, as the loss of higher value habitats or presence of ‘irreplaceable’ habitats may make a scheme unviable.

Where the main Statutory Metric is to be used this work should be undertaken by a suitably qualified ecologist (relevant institute websites provide directories to identify suitably qualified ecologists including The Chartered Institute of Ecology and Environmental Management https://cieem.net/ and The Institute of Environmental Management and Assessment https://www.iema.net/). For minor developments, where the Small Sites Metric can be used, a suitably qualified ecologist may still be required in respect to the assessment of the site in respect to other wildlife legislation such as protected sites, species and/or habitats.

Strategic significance is one of the habitat characteristics which must be included within the Statutory Metric to calculate the biodiversity value of a site. It describes the local significance of the habitat based on its location and the habitat type.

The strategic significance of a habitat type will ultimately be defined on a local basis through Local Nature Recovery Strategies (LNRSs). The East Riding LNRS is currently being developed and is due to be completed in autumn 2024.

In the meantime, the following documents should be consulted in accordance with the Statutory Biodiversity Metric User Guide (page 25) to assist in allocating strategic significance on a site-specific basis, with justification provided by the assessor completing the Metric.

• Qualifying features associated with the National Habitat Network
• East Riding Local Plan (adopted April 2016, pdf 00kb)
  Particular reference should be made to Figure 12: Biodiversity priority areas and Figure 13: Green infrastructure corridors.

Figure 12 - Biodiversity priority areas

Figure 13 - Green infrastructure corridors

• The East Riding of Yorkshire Landscape Character Assessment
• Lower Derwent Supplementary Planning Document (Adopted January 2018)
• Catchment Management Plans
  Hull and East Riding Catchment Partnership
  Humber Management Scheme

Schedule 14 of the Environment Act includes measures that allow the Local Planning Authority to take account of any habitat degradation or destruction undertaken on a site since January 2020. If a site has been cleared or degraded the baseline for the purposes of Biodiversity Net Gain is taken to be that before the clearance or degradation has taken place.

Aerial or other photographs may be used to evidence the habitat types formerly present on site and, in the absence of any other information, the habitat should be allocated a condition score of ‘good’ on a precautionary basis.

This is to deter intentional degradation/destruction prior to planning applications being submitted, by ensuring that there is no advantage to be gained by the deliberate clearance of land to achieve a lower baseline value for BNG with potential penalties where a higher value habitat or condition has to be assumed in the absence of evidence to the contrary.

The Environment Act requires proposals to provide a minimum 10% gain compared with the pre-development biodiversity value of the site. Achieving 10% net gain means fully compensating for losses of habitat on a development site, but then going further so that overall, there is a gain in biodiversity value of at least 10% as a result of the development process. The gain can be provided on site, off site or through a combination of the two. As a last resort Statutory Biodiversity Credits, a national credits purchase system will be available for purchase from Natural England.

The 10% net gain in biodiversity value should, where possible, be provided on the development site itself. However, where space and circumstances do not allow this, provision of biodiversity gain on land off-site, or a combination of on- and off-site provision, would be considered. Off-site habitat creation can be undertaken on land owned by the developer, or on third party land where the landowner is willing to undertake such work and maintain it for at least 30 years in return for a payment from the developer.

As an Authority East Riding of Yorkshire Council will encourage the provision of habitat on-site as a priority with off-site habitat creation/enhancement as a secondary option once appropriate on-site measures have been provided. The Statutory Biodiversity Credit scheme is seen as a last resort option, use of which must be justified by the applicant, and has been priced accordingly to deter use and encourage the development of a local off-site BNG markets.

The ultimate BNG will be secured by a pre-commencement condition. However, at the point of application, sufficient information will need to be submitted to allow the Authority to be satisfied that an appropriate level of net gain can be provided by the development either utilising on-site land, a combination of on-site and off-site (either developer owned or third party land) or as a last resort, where on-site and off-site provision is unable to provide a 10% net gain, the purchase of Statutory Biodiversity Credits, is being proposed to deliver the outstanding units.

Government legislation and guidance have confirmed the minimum information requirement for an application, which the Authority will require for validation, as follows:

• a statement as to whether the biodiversity condition would be relevant to the application if permitted
• the baseline metric calculation (Excel spreadsheet format) using the Statutory Metric
• confirmation of the date the metric calculation was undertaken
• confirmation of whether any degradation has taken place and how this has been considered within the metric
• a description of irreplaceable habitats if relevant
• a scaled plan of existing habitats
• completion of a custom and self-build or de minimis exemption form if applying either of these exemptions.

However, to ensure the biodiversity gain objective can be met and the condition discharged successfully, it is important biodiversity net gain is considered at the very start of the development process, factored into site selection and considered throughout the design stage. This is to ensure that appropriate decisions can be made in respect to habitat retention, creation, and enhancement to maximise biodiversity benefits and minimise financial costs.

Dependant on the development and the site selected we would therefore anticipate that the following information will have been prepared and should be submitted to support the application.

• A statement outlining how the development will achieve a minimum 10% net gain, including details of the existing baseline onsite habitats, and the anticipated post development habitats retained, created or enhanced to achieve net gain. The statement should include an indication of whether BNG will be delivered onsite or whether additional offsite units or the purchase of statutory credits will be required, explaining how this will comply with the biodiversity gain hierarchy. If offsite provision is proposed an indication of where and how it is intended that these will be secured should be provided.
• A complete (as far as possible) Statutory Metric, including post development onsite habitats and proposed use of offsite units, if use is anticipated.
• Pre- and post-development habitat plans (GIS format preferred with pdf versions).
• A draft/interim Habitat Management and Monitoring Plan (HMMP) based upon the Natural England template.

We would note that it is accepted that post-development habitat plans may be indicative at this stage with some of these documents in draft format, particularly for offsite BNG provision and with respect to outline applications. However, sufficient detail should be provided to enable the Authority to have confidence that the level of BNG proposed is realistically achievable; that the application will be able to meet its biodiversity net gain obligation and that the applicant is aware of the potential costs associated with the plan proposed to achieve it.

During the determination of a planning application, biodiversity net gain will be a material consideration, and the Authority will need to consider, where relevant, whether the general biodiversity gain condition is capable of being discharged successfully through the imposition of conditions and agreement of section 106 planning obligations to secure significant onsite biodiversity gains and registered offsite biodiversity gains.

This work should be undertaken by a suitably qualified Ecologist (relevant institute websites provide directories to identify suitably qualified ecologists including The Chartered Institute of Ecology and Environmental Management (external website) and The Institute of Environmental Management and Assessment (external website).

Biodiversity Net Gain monitoring fee

The Environment Act 2021 has introduced a mandatory 10% Biodiversity Net Gain (BNG) for new development, and this became a statutory requirement for major developments on 12 February 2024 and for minor developments from the 2 April 2024.

It is a new statutory requirement to ensure that developments deliver measurable improvements to biodiversity through enhancing existing habitats or by creating new ones. Effective monitoring is therefore essential to the robust implementation of BNG and is a statutory duty for Local Planning Authorities.

For the Local Planning Authority to audit the delivery of Biodiversity Units (BUs) approved within the Biodiversity Gain Plan and check that the management plan is being complied with, monitoring reports will be required for all on-site significant net gain and all off-site net gain.

A monitoring fee will be taken, to cover the long-term costs of the LPA to review these monitoring reports and undertake site visits over the 30-year period. The fees will be proportional depending on the scale of the site and the complexity of the habitats to be delivered. Any non-significant on-site gains will not incur a monitoring fee. These fees will be secured through S106 agreements.

The fees are set out are as follows:

Under the Environment Act 2021, new development in England must deliver at least 10% Biodiversity Net Gain.

A metric must be used to assess the value of the habitat, pre and post development. This calculates how much habitat is lost through development and provides a numerical value as to how much needs to be provided to achieve the required net gain.

The council is offering a new service to allow applicants and ecologists to request confirmation that they are assessing their sites appropriately using the correct metric. It is anticipated that this assessment will assist developers in determining the correct metric to use for their site, which will assist in the overall consideration of the planning application.

A new statutory pre-commencement planning condition will be used to secure BNG. The condition is deemed to apply to every planning permission granted for the development of land unless exemptions or transitional provisions apply and will not be included in the list of conditions imposed in the written notice when granting planning permission.

Condition wording: ...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 statutory condition will require the submission of a Biodiversity Gain Plan, a template for which has been published by Natural England. Additional conditions will be used to secure implementation, management and monitoring in accordance with the proposals outlined within the Biodiversity Gain Plan.

The plan will confirm how the minimum 10% net gain will be provided. A Habitat management and Monitoring Plan (HMMP) is likely to be required including details of the habitat management to be undertaken to ensure achievement, monitoring and measures to be implemented if the BNG anticipated is not being achieved. Regular monitoring of the habitats will be required, anticipated at years 1, 2 ,3 ,5, 10, 15, 20, 25 and 30, at which points the developer will be required to submit Monitoring Reports to the LPA which identify whether the intended habitat types and conditions are being achieved and outlining the actions to be undertaken in the next management period in order to rectify any failings. This is to ensure that the Biodiversity Gains proposed with the development are achieved in the long term.

The point of completion from which the period of at least 30 years begins will be based upon the completion of any onsite habitat enhancements rather than the completion of the buildings related to the development. The creation/enhancement of on-site habitats should start as soon as possible or at least within 12 months. Where delays of over 12 months in habitat creation/enhancement are expected these should be factored into the metric calculation tool at condition discharge stage.

Off-site and significant on-site gains must be secured by legal agreement for a minimum period of 30 years. Section 106 agreements are anticipated to be the primary method for securing BNG off-site and potentially significant on-site gains, although unilateral undertakings may be considered in respect to the later. Conditions may be used to ensure the implementation of on-site gains which are not considered significant. Conservation covenants, a new form of legal agreement specifically designed for BNG between a landowner and a responsible body, may become more widely used as the system develops and responsible bodies become available.

Once off-site units have been legally secured, they must be registered on a National Register which will be run by Natural England prior to being allocated to a specific development. In order for the Local Authority to approve the Biodiversity Gain Plan any off-site biodiversity units being used must be registered.

Significant on-site habitat enhancements must be legally secured in the same way as off-site provision of biodiversity units. Some guidance with respect to what is considered significant has been provided by government. It is acknowledged that it will vary depending on the scale of development and existing habitat, but may include:

• habitats of medium or higher distinctiveness in the biodiversity metric
• habitats of low distinctiveness where they provide 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.

It is anticipated that decisions will be made on a case by case basis taking into consideration a combination of site location, baseline value and proposed habitat types, extents and condition.

Significant onsite habitat enhancements are likely to form an integral part of the development, such that the applicant would be expected to include detailed proposals for these habitat enhancements as part of the original application including landscape proposal plans and full metric calculations.

Where developers are unable to provide a 10 per cent Biodiversity Net Gain on-site, they can purchase off-site units from third parties either through brokers, habitat bank operators or direct from land owners or land managers.

Information on selling biodiversity units as a landowner or land manager can be found on government websites.

The council is currently considering its potential role in the off-site BNG Market. Current plans include the compilation of a list of landowners and land managers with a potential interest in providing off-site BNG. This list would be made available to applicants in need of securing off-site BNG for their proposed developments. If you are a landowner or land manager with a potential interest in providing off-site BNG and would like to be included on this list, please contact nature.conservation@eastriding.gov.uk.

No, the metric does not change existing biodiversity protections, statutory obligations, or policy requirements; BNG is in addition to existing wildlife legislation and policy.

BNG introduces a quantitative measure to demonstrate a net gain in biodiversity and a framework to secure its implementation. It does not replace the requirement to carry out other assessments of impacts on biodiversity including protected species (e.g. bat and great crested newt surveys) or protected habitats (e.g Habitat Regulations Assessments in respect to European Sites). Appropriate licences in respect to derogation of the legal protection given to specific species or sites will still be required where unavoidable impacts are identified.

Compliance with other environmental planning policies will still need to be demonstrated by the developer; these include requirements relating to:

• protected or important nature conservation sites
• protected or important species
• irreplaceable habitats.

BNG maintains the mitigation hierarchy with the principles having been built into the technical guidance that accompanies the Metric. In this process adverse impacts on biodiversity should in the first instance be avoided, then minimised or mitigated and, only as a last resort, compensated as follows:

• Avoidance - actions taken to avoid causing impacts to the environment prior to beginning development (for example, moving the development to a different location, retaining habitats of importance within the design)
• Minimisation - measures taken to reduce the duration, intensity, extent and/or likelihood of the unavoidable environmental impacts caused by development (for example, adapting the development design to minimise impacts via timing, utilising precautionary working methods)
• Mitigation/remediation - actions taken to repair environmental degradation or damage following unavoidable impacts caused by development; and
• Compensation - measures taken to compensate for any adverse environmental impacts caused by development which cannot be avoided, minimised and/or mitigated (e.g. including habitat creation to offset losses).

Further resources, information and guidance can be found at the organisation website listed below:

Natural England Biodiversity Net Gain Brochure (external pdf)

BS 8683 Process for Designing and Implementing Biodiversity Net Gain

Biodiversity Net Gain: Good Practice Principles for Development – a Practical Guide (CIEEM, IEMA and CIRIA)

Future Homes Hub: Biodiversity Net Gain Project

Biodiversity Net Gain Metric and User Guide

Current Government guidance

GOV.UK - Collections: Biodiversity Net Gain