Biodiversity Net Gain FAQs - Frequently Asked Questions

This page is part of a set of resources PAS is working on to help local authorities prepare for mandatory biodiversity net gain. You can find links to these resources via our front 'BNG for local authorities' page.

Biodiversity net gain (BNG) is an approach to development, and/or land management, that aims to leave the natural environment in a measurably better state than it was beforehand.

The National Planning Policy Framework (NPPF) states [our emphasis]:

174: Planning policies and decisions should contribute to and enhance the natural and local environment by: [...]

d. minimising impacts on and providing net gains for biodiversity, including by establishing coherent ecological networks that are more resilient to current and future pressures

179: Plans should:  [...]

b. promote the conservation, restoration and enhancement of priority habitats, ecological networks and the protection and recovery of priority species; and identify and pursue opportunities for securing measurable net gains for biodiversity and development whose primary objective is to conserve or enhance biodiversity should be supported; while opportunities to incorporate biodiversity improvements in and around developments should be encouraged, especially where this can secure measurable net gains for biodiversity.

180: When determining planning applications, local planning authorities should apply the following principles: [...]

d. development whose primary objective is to conserve or enhance biodiversity should be supported; while opportunities to improve biodiversity in and around developments should be integrated as part of their design, especially where this can secure measurable net gains for biodiversity or enhance public access to nature where this is appropriate.

The Environment Act sets out the following key components of mandatory biodiversity gain:

• Amends Town & Country Planning Act (TCPA);
• Minimum 10% gain required calculated using the Biodiversity Metric & approval of a biodiversity gain plan;
• Habitat secured for at least 30 years via planning obligations or conservation covenants;
• Delivered on-site, off-site or via a new statutory biodiversity credits scheme; and
• National register for net gain delivery sites.

It does not change existing legal protections for important habitats and wildlife species. It maintains the mitigation hierarchy of avoid impacts first, then mitigate and only compensate as a last resort. It will apply to Nationally Significant Infrastructure Projects (NSIPs) but not marine development.

We expect the mandatory requirement to come into place in January 2024 for all Town and Country Planning Act development but exemptions and small sites. The Government's response to the 2018 consultation on net gain set out that there would be a 2 year implementation period for mandatory BNG once the Environment Bill received Royal Assent and became the Act (which happened on 9 November 2021). The Act includes provision for secondary legislation to set a date for the requirement to come into force. This Government press release from 27 September 2023 outlines the timetable for mandatory BNG. It sets out that the relevant legislation will be laid in November 2023 and BNG will be required from January 2024. Implementation for Nationally Significant Infrastructure Projects is planned for 2025.

The Government’s 2023 response to the 2022 BNG consultation set out that the transition period for small sites will be extended to April 2024.  The delay to implementing BNG for small sites is to lessen initial burdens and allow a longer period for developers and local planning authorities to adapt and prepare for the high volume for minor applications.

Small sites are defined as:

(i) 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, a site area of less than 0.5 hectares.

(ii) For non-residential: where the floor space to be created is less than 1,000 square metres OR where the site area is less than one hectare.

This is covered in the Biodiversity Metric user guide:

• ‘On-site’ includes all land within the boundary of a project. In a planning context, this usually means within a red line boundary.
• ‘Off-site’ is all land outside of the on-site boundary, regardless of ownership.

Note that on-site does not include land within the ‘blue line’ boundary.

Demonstrating BNG requires an approach to measuring biodiversity. The Biodiversity Metric is a habitat based approach to determining a proxy biodiversity value developed by Natural England. The Biodiversity Metric is designed to provide ecologists, developers, planners and other interested parties with a means of assessing changes in biodiversity value (losses or gains) brought about by development or changes in land management. Mandatory BNG will require use of the latest version of the Biodiversity Metric. The current version is Biodiversity Metric 4.0, which was published in March 2023. Government anticipate that this will form the basis of the statutory metric, which will be laid before Parliament in November 2023. Further information on the latest on the Metric is available in the Government’s 2023 response to the 2022 Consultation on the Biodiversity Metric.

The biodiversity gain plan is a document which sets out how a development will deliver biodiversity net gain and allows the planning authority to check whether the proposals meet the biodiversity gain objective.

The Environment Act sets out that development subject to mandatory BNG will be required to submit a biodiversity gain plan for planning authority approval and the planning authority required to approve it prior to commencement. This is required under the 'General condition of planning permission' added as Schedule 7A to the Town and Country Planning Act 1990 (under Schedule 14 of the Environment Act). 

The Environment Act sets out that the biodiversity gain plan should cover:

• How adverse impacts on habitats have been minimised;
• The pre-development biodiversity value of the onsite habitat;
• The post-development biodiversity value of the onsite habitat;
• The biodiversity value of any offsite habitat provided in relation to the development;
• Any statutory biodiversity credits purchased; plus
• Any further requirements as set out in secondary legislation.

The Government's Consultation on Biodiversity Net Gain Regulations and Implementation of January 2022 set out further information about biodiversity gain plans (page 50 onwards), including that Government intends to publish a biodiversity gain plan template. A working draft of this template is included at Annex B of the consultation document. The Government’s response to this consultation provides some further information on what the template will look like at Section 5.1. It also indicates that biodiversity net gain information in the form of a BNG Statement will be required to be submitted at the planning application stage rather than a complete biodiversity gain plan. Further information on this core biodiversity gain information is set out from P.51 of the 2022 consultation document and we expect further details to be published in due course.

The Environment Act makes provision for the Secretary of State to set up a system of statutory biodiversity credits that will be invested in habitat creation. The biodiversity credits scheme allows the UK government to sell biodiversity credits to developers if the required biodiversity net gains cannot be achieved on-site or through the off-site market. The price of biodiversity credits will be set higher than prices for equivalent biodiversity gain on the market and Defra published indicative credit prices on 27 July 2023. Natural England will sell statutory biodiversity credits on behalf of the Secretary of State. An accessible and user-friendly digital sales platform is currently being developed and tested. 

The Environment Act includes provision to exempt irreplaceable habitats from the mandatory BNG requirement.  Secondary legislation will set out a clear definition of irreplaceable habitat and list of habitat types to be considered irreplaceable. Government will be consulting on this definition and seeking views on the proposed list. Further information is available in Section 3.3 of the Government’s 2023 BNG consultation response.

The Environment Act has an 'extent' section which sets out which parts of the Act apply across Britain. The BNG provisions only apply to England via Schedule 14. CIEEM have just published a briefing note for Scotland see: Biodiversity Net Gain in Scotland: Briefing Note for Local Planning Authorities.

The approach and metric for marine habitats and environments is not as developed as the terrestrial version. Defra published its consultation on the Principles of Marine Net Gain in June 2022.

The Government has committed to funding all new burdens on local authorities arising from the Environment Act and Defra is working with DLUHC on the new burdens process. Government has provided transitional funding for LPAs to prepare for mandatory net gain up to the end of the 2023/24 financial year. Further funding beyond the current grant period will be confirmed in due course. The figure outlined in the 2019 net gain impact assessment is being revisited by Defra in recognition that things have changed since 2019. The funding has been estimated based on the additional burden from mandatory biodiversity net gain. 

PAS has published a short guide on resourcing BNG to help local authorities understand the skills and expertise they are likely to need to meet the requirements of mandatory BNG. It also provides examples of how local authorities can best secure natural environment skills and expertise. It has been developed with our BNG local authority officer advisory group and the Association of Local Government Ecologists (ALGE) and is available here. PAS has been funded by Defra to provide guidance and training for LPAs to enable them to be 'day 1 ready for mandatory BNG'.

Conditions relating to the grant are set out in the section 31 letter which was sent to most LPAs on 1 March 23. For National Park Authorities and Development Corporations, alternative grant arrangements are in place. In relation to the Section 31 grant, unspent funds can be carried over in a ring-fenced reserve but must be held for use in line with the same conditions. Defra will consider future reductions where there are large underspends.

Essentially the 10% set out in legislation is mandatory and therefore there is no scope for LPAs to reduce the requirement based on viability or other issues.

Once the mandatory requirement for BNG is in place (in January 2024) for all but small sites (which will be required from April 2024), it will be a legislative requirement, so there is no need to repeat the legal requirements in local policy. However, we would encourage LPAs to develop a locally specific BNG policy for the following reasons:

• A locally-specific policy allows the local authority to set what strategies they require developers to take into account in delivering BNG, e.g. Green Infrastructure strategies, Local Nature Recovery Strategies (LNRS), for example in targeting offsite BNG delivery and to determine the ‘strategic significance’ score that is part of the Biodiversity Metric. This means that BNG can contribute to wider nature recovery plans in addition to local objectives. It can help ensure that the right habitats are provided in the right places.
• Including BNG in the Local Plan can link biodiversity to other strategic objectives and the overall place-making strategy for an authority, enabling a more holistic approach.

We have posted some good examples of locally-specific policies and the evidence base used to develop policy on our Biodiversity Net Gain in Local Plans and Strategic Planning webpage. We will also have examples of developer guidance and advice notes that some LPAs are using where their current Local Plan does not cover net gain on our Biodiversity Net Gain in Development Management webpage. In addition, Section 4.2 of the CIEEM/IEMA/CIRIA Biodiversity net gain good practice principles for development covers evidence gathering and provides further detail on types of evidence and links to good practice, whilst Sections 4.6 and 4.7 cover policy development.

If this is set out in policy in the Local Plan and the Local Plan is deemed sound, i.e. viability has been tested and the BNG target checked against other policies in the plan, it will be difficult for a developer to challenge it. The Government's BNG consultation of 2022 states: 'It remains the UK Government’s intention to continue to allow higher percentage targets to be set by planning authorities at a local or site level. Any higher target should be made clear at an early stage in the planning or development process and careful consideration should be given to the feasibility and achievability of any requirements above 10%, which can have significant impacts on the costs of developing a site.'

See our Biodiversity Net Gain in Local Plans and Strategic Planning webpage for more information on assessing plan viability for BNG above 10%.

Mandatory net gain, informed by the Biodiversity Metric, will be a minimum requirement for applicable development types. Any local policy will need to achieve this minimum but can work alongside the mandatory requirement. The mandatory requirement will also be in addition to the London Plan policies. It will be necessary for applicants to provide a Biodiversity Metric score and a UGF (Urban Greening Factor) score when applicable.

See the Greater London Authority’s Urban greening and BNG design guide for further information on how this can work.

For the same reasons why it is helpful to have a BNG policy in your Local Plan, it is also good practice to include neighbourhood plans, but no further guidance on this is available at present.

 Government aims to confirm the exact date in January shortly.

Section 3.1 of the Government’s 2023 consultation response sets out exemptions from mandatory BNG, which will be implemented via secondary legislation:

• development impacting habitat of an area below a ‘de minimis’ threshold of 25 metres squared, or 5m for linear habitats such as hedgerows and watercourses [NOTE Defra have confirmed (9 August 2023) that this is 25 square metres (5m x 5m = 25 sqm)]
• householder applications
• biodiversity gain sites (where habitats are being enhanced for wildlife)
• small scale self-build and custom housebuilding.

The de minimis threshold applies to the area or length of habitat within a development, not the total development footprint, and the same exemption will apply for small sites. If a development contains less than 25m² of non-priority habitat but 5m or more of linear habitat, or vice-versa, then the exemption will not apply and all habitats would be subject to BNG. If the exemption does apply then there is no requirement to deliver BNG on that site.

The BNG requirement will apply only to those applications submitted after BNG takes effect in January 2024 (or April 2024 for small sites), as confirmed in this July 2023 Defra blog post. This includes applications made under s73 of the Town and Country Planning Act 1990 where the earlier permission was submitted or granted before the relevant January date. There are a couple of reasons for this:

1. BNG information will need to be provided at the applications stage to support an LPA to determine whether or not the BNG objective will be met. Accordingly, if this applied to all applications determined after January/April 2024, there will be thousands of applications that would not include this information as it wouldn’t have been required beforehand.
2. While BNG is dealt with as a post-permission matter through the mandatory condition, LPAs need to have clarity on the BNG position prior to granting permission so that they can put in place necessary planning conditions and obligations to secure it (the aforementioned information will support with this).

Primary legislation provides for transitional or saving provisions under Section 148 of the Environment Act 2021. Secondary legislation will come forward which sets out how we transition to the new framework (and which applications will be captured). Government intends to give further clarity when they publish the draft regulations and policy summaries.

DLUHC intends to amend the national validation requirements in the DMPO so that applications for BNG-eligible development proposals are accompanied by a certain level of BNG information (e.g. the pre-development biodiversity value). The precise form and contents of this information is to be decided, though is likely to be broadly in line with what was set out in the consultation.

The Government's BNG consultation recognises that it is important for planning authorities to know what is being proposed for BNG early in the planning process. It is expected that the secondary legislation will require developers to provide certain biodiversity gain information as a BNG Statement alongside the application for planning permission. This information will likely include:

• the pre-development biodiversity value,
• steps taken to minimise adverse biodiversity impacts
• the proposed approach to enhancing biodiversity on-site, and
• any proposed off-site biodiversity enhancements (including the use of credits) that have been planned or arranged for the development.

The full biodiversity gain plan will be submitted either with the planning application or after the permission is granted, but before development has commenced. Further information on how BNG plans fit within the planning process can be found on pages 51-54 of the consultation. PAS has worked with the Future Homes Hub to draft a BNG development process flow.

Defra are producing a standardised template for the biodiversity gain plan that will also be in a digitised form - a working draft is available in Annex B of the 2022 BNG consultation.

Schedule 14 of the Environment Act sets out that a general condition will be applied to every planning permission (except those exempt from BNG requirements) that a biodiversity gain plan should be submitted and approved by the planning authority before commencement of development, specifically:

Every planning permission granted for the development of land in England shall be... subject to the [following] 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...

This means that a complete biodiversity gain plan will be required for all relevant development, but that this can be approved after the grant of planning permission, as long as this happens prior to commencement of development. 

BNG does not change existing protections, so current legal and policy provisions relating to development impacts on the natural environment, including protected sites and species, and priority species and habitats, all need to be considered in relation to habitat loss. A development cannot avoid this requirement by virtue of delivering a net gain. If there are protected species on-site then these should be approached and managed in the same way as they are currently. BNG and the Biodiversity Metric calculations would then be additional to this.

BNG just ensures that habitat is ‘valued’ in a way that it may not have been and that is at least replaced with a 10% extra. Assuming the habitat lost is not irreplaceable and the project is otherwise permissible, a LPA could not refuse planning permission based solely on the lifespan of a replacement habitat. Ultimately it is the LPA’s decision whether the biodiversity net gain information accompanying an application is acceptable and whether to refuse or not on this basis, using the evidence submitted by the applicant, including on any locally distinctive habitats, to inform that decision.  The Biodiversity Metric also takes into account the risk of delay to the creation/ enhancement of habitat; so where a habitat is being lost and new habitat being created to replace it, this is more costly in terms of biodiversity units (and harder to reach 10%) than enhancement.  The LPA will need to be satisfied that the Biodiversity Metric has been used appropriately.

The Biodiversity Metric is a habitat-based approach, using habitat as a proxy for biodiversity. Species-based features such as bird and bat boxes are not included within the metric, instead it focuses on the habitats such species need to forage and complete their life cycles. The provision of such species features within developments should still be encouraged and LPAs can promote their usage through design guides and codes.

In relation to BNG, the Environment Act states that habitats should be secured for a minimum of 30 years: ‘habitat enhancement… will… be maintained for at least 30 years after the development is completed’. The 30 year term for biodiversity net gain isn’t meant to be regarded as in perpetuity – it was what was regarded as reasonable to ask for.

In some other cases, for example mitigation provided for sites or species protected under the Habitats Regulations, the requirement may be for management and maintenance of habitats ‘in perpetuity’. It will be up to the planning authority to determine the length of time that it is appropriate and reasonable to require ongoing management and maintenance of habitats as part of the grant of planning permission, taking into account the range of policy and legislative requirements, but the legal requirement for biodiversity gain habitats is 30 years as a minimum.

This won’t be set in legislation and will need to be assessed by LPAs as part of their planning approval process. The minimum viable area for particular habitats will vary depending on the habitats in question. Guidance available on delivering viable biodiversity improvements, including CIEEM’s Biodiversity Net Gain: Good Practice Principles for Development, A Practical Guide.

The biodiversity net gain approach embeds a fundamental principle for spatial hierarchy of habitat delivery, where there is a preference for onsite or local enhancements.  The Environment Act requires that ‘information about the steps taken or to be taken to minimise the adverse effect of the development on the biodiversity of the onsite habitat and any other habitat’ is included in the biodiversity gain plan.  

Onsite and local offsite units must be the first option explored and the Government’s 2023 BNG consultation response confirms this position: ‘Government will continue to incentivise a preference for on-site gains over off-site gains’ with the exception of ‘intertidal developments, for which small on-site enhancements are often inappropriate’. The 2022 consultation sets out that: ‘Where the available local opportunities for off-site habitat creation or enhancement are insufficient for developers to meet their net gain requirements, off-site delivery outside of their local area will be allowed'. More guidance is expected to be published to support decision making.

Biodiversity Metric 4.0 incentivises habitat delivery on or close to the development site through a ‘Spatial Risk Multiplier’, which reduces the biodiversity value of habitats delivered further away from the development. It is recommended that the onsite first, then local offsite hierarchy is also included in local plan policy.

Where a development cannot achieve BNG either wholly or partly onsite, then the developer can secure the unit shortfall by securing a bespoke site for net gain, or from appropriate sites on the local net gain habitat market from other landowners. These sites will need to meet the criteria of the biodiversity gain sites register (when available - see National biodiversity gain sites register below). If a shortfall in units required to achieve BNG remains, having explored the onsite and local offsite options, a developer can purchase statutory biodiversity credits from government as a last resort. 

PAS has some examples of conditions and S106s currently used by local authorities to secure BNG on our Biodiversity Net Gain in Development Management page. Furthermore, PAS hosts a BNG Practitioner Network for LPA officers, which acts as a group to discuss and share documents and templates on BNG. If you wish to join this network, please fill out this Microsoft Form. For more information on securing off-site BNG, see Off-site BNG, BNG markets and habitat banks below.

Permitted development will not be required to deliver BNG under the Environment Act. However, the metric can still be used to quantify the losses and gains of habitat associated with the development activity and this is already being done by a number of developers for permitted development.

Mandatory BNG is not yet a legal requirement. It will only start to become one from January 2024 onwards, and not for small sites until April 2024 onwards and cannot be applied retrospectively. However, BNG is required in planning policy terms through the NPPF.

Householder applications will be exempt from mandatory BNG. There will be a less onerous process for applying BNG to small sites, including use of the Small Sites Biodiversity Metric, which is available now for use on smaller sites, and the BNG requirement will not be implemented until April 2024 for small sites. Small sites are defined (see Section 4.2 of the Government’s 2023 BNG consultation response) for the purpose of the BNG exemption as:

(i) 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, a site area of less than 0.5 hectares.

(ii) For non-residential: where the floor space to be created is less than 1,000 square metres OR where the site area is less than one hectare.

You may also want to watch the recording of our ‘BNG: the essentials’ event held in November 2022, where David Warburton from London Borough of Sutton outlined how they are currently delivering BNG on small urban sites: Biodiversity Net Gain and Nature Recovery Autumn 2022 events | Local Government Association

Additional biodiversity gain information that sets out how biodiversity gain will be achieved across the whole site on a phase-by-phase basis will be required for outline planning permissions and phased development. Such development will also be required to be subject to a condition which requires approval of a biodiversity gain plan prior to commencement of each phase. Government will set out details about this process through secondary legislation and accompanying guidance and states in the 2023 BNG consultation response that “it will be important to leave room for discretion for local planning authorities when it comes to deciding this”.

Reserved matters will not be required to fulfil mandatory BNG if the outline was approved prior to mandatory BNG; it will only apply to new full and outline applications submitted once BNG is mandated (from January 2024). You can also see the slides and recording from our Spring 2022 deep-dive session on the BNG process for TCPA development for further information.

Government is working on guidance and policy informed by further engagement with relevant sectors. You can also see the slides and recording from our Spring 2022 deep-dive session on the BNG process for TCPA development, which covered minerals development.

 As set out in the response to the BNG policy and legislation consultation, Government intends to exempt small scale self-build and custom house building from the BNG requirement to ensure small and custom builders are not placed under undue burden by BNG. This will be set out in the BNG Exemptions regulations. Defra and DLUHC are working together to define this exemption in a way that addresses the risks of exempting large sites made up of many custom plots and will keep this under review. 

Within Schedule 14 of the Environment Act, which sets out the biodiversity gain condition for development, measures are included that allow planning authorities to recognise any habitat degradation since 30th January 2020 and to take the earlier habitat state as the baseline for the purposes of biodiversity net gain. In order to ascertain the habitats present and their condition on 30th January 2020, aerial imagery or data sets from that time could be used. 30th January 2020 is the relevant date as it was the day the Bill entered Parliament.

For example, if a grassland site were strimmed or ploughed in July, the planning authority would be able to seek compensation for the habitat as it was in June, rather than the degraded habitat present in July. This system will take effect when the biodiversity gain requirement in the Environment Act is commenced.

Natural England and Defra intend to produce guidance on how this will work and which data sources may be of assistance in demonstrating the former value of any degraded or destroyed habitats. The 2022 consultation document sets out that further guidance within the Biodiversity Gain Plan will make provision for an earlier habitat value to be applied as the baseline where the value of habitats has been recently degraded.

If a site has a baseline biodiversity unit value of zero, then it would be exempt from mandatory BNG, but planning policy requirements for net gain would still apply. It would be advisable to calculate any biodiversity unit gains as a numerical unit value as opposed to a percentage. It will be at the discretion of the LPA to agree an appropriate number of biodiversity units to be delivered for the site in question on a site-by-site basis. Where a local authority knows that a number of development sites are likely to have very little to no biodiversity value or of a major allocation that fits this bill, e.g. urban, recently-previously developed land, they could consider setting expected unit gain values for these sites in Local Plan policy.  

It cannot be assumed that just because a site is small it has no baseline value. The baseline value reflects the ecological value of the pre-development site, not its size. Defra has committed to work with DLUHC to develop planning policy for minor development such as householder and de-minimis development, to seek to secure proportionate on-site biodiversity enhancements where possible.

This is provided for in the Environment Act, Schedule 14: Schedule 7A to the TCPA paragraph 5:

Pre-development biodiversity value

5(1) In relation to any development for which planning permission is granted, the pre-development biodiversity value of the onsite habitat is the biodiversity value of the onsite habitat on the relevant date.

(2)The relevant date is—

(a) in a case in which planning permission is granted on application, the date of the application, and

(b) in any other case, the date on which the planning permission is granted.

(3) But the person submitting the biodiversity gain plan for approval and the planning authority may agree that the relevant date is to be a date earlier than that specified in sub-paragraph (2)(a) or (b) (but not a date which is before the day on which this Schedule comes into force in relation to the development)

Circumstances under (2)(b) include things like Local Development Orders, Neighbourhood Development Order, Simplified Planning Zones, Enterprise Zones etc. BNG won’t be commenced for these routes in January. Everything else is (2)(a), so baseline date is the date of application (not planning permission). 

Green Infrastructure (GI) can form part of BNG and pretty much all the most common GI features are captured within the metric and can contribute towards a BNG outcome. It is for the consenting body (LPA) to determine whether or not the proposal is appropriate (ecologically) or not. Horsham District Council have produced a Biodiversity and Green Infrastructure Planning Advice Note setting out how they consider BNG and GI in planning decisions.

BNG can be a sustainable, long-term funding stream for parks and greenspaces. GI strategies if published and agreed by the LPA can inform strategic significance scores in the Biodiversity Metric. See London’s Urban greening and BNG design guide for more information.

The Government’s 2023 BNG consultation response states that they will not make an exemption for development on statutory sites designated for nature conservation from the BNG requirement. They intend to use policy and guidance to prevent BNG being used as a justification for otherwise unacceptable development on such sites. See under ‘Additionality and stacking’ below for how SSSI enhancement can be counted for BNG.

Yes. Private gardens can make positive contributions to biodiversity, but appropriate planting and ongoing management can not be secured in the long-term. The Biodiversity Metric recognises this in its scoring of the value of gardens. See the Biodiversity Metric section for more information on this aspect.

Yes. See the Greater London Authority’s Urban greening and BNG design guide for further information on how this can work. Both scores will need to be submitted where applicable. One cannot be used as a proxy for the other policy.

It is expected that land used for off-site BNG delivery will be secured for the length of the net gain agreement, either via Section 106 agreements, or a conservation covenant. You will not need to have both in place to secure a site – just one of those two options. A conservation covenant is a private voluntary legal agreement, made in writing, between a Responsible Body and a landowner which establishes that land will be used for a conservation purpose. See Conservation Covenants below for more information. Further information on off-site BNG is available from our deep-dive session in Spring 2022.

The Government's response to the BNG consultation stated “the planning enforcement regime will be the principal way of enforcing delivery of BNG”. We expect further guidance to be published on enforcement, as well as on the use of conditions and S106 to secure BNG. For gains that are secured with conservation covenants, Government expects costs for monitoring and enforcement activities to be reflected in the price of biodiversity units. The responsible body for the conservation covenant will have responsibility for the enforcement.

Yes, BNG can be used to enhance local wildlife sites and local nature reserves. Defra will be providing guidance on the circumstances in which statutory protected sites can be enhanced for BNG.

Under the mandatory BNG approach, biodiversity units refer to the output of the biodiversity metric. The metric uses habitats and ‘biodiversity units’ as a proxy to describe biodiversity. These biodiversity units are the ‘currency’ of the metric. There are three types of biodiversity units, which are calculated in three separate ‘modules’ of the metric (area units, hedgerow units and watercourse units). Off-site biodiversity units can be sold, i.e. ‘1 unit of modified grassland costs £xx', but should not be referred to as credits to avoid confusion with statutory credits. Statutory credits are the last resort option for developers, if they can’t deliver the BNG they need onsite or via purchasing off-site biodiversity units. See Statutory credits scheme below for more information.

Habitat banking is an approach where investors pay landowners to increase the biodiversity value of their land and this uplift is then sold as units to those that need off-site biodiversity net gain. Often habitat is created in advance of units being sold meaning this is an ecologically beneficial approach. In practice, the term ‘habitat bank’ can either be used to describe:

• The parcel or parcels of land where the value of biodiversity is uplifted to provide off-site biodiversity units.
• The green finance approach where investors finance habitat restoration and creation and are rewarded with both monetary interest and environmental returns. See the Future Parks Accelerator resource for more information.

Under mandatory BNG, habitat created or enhanced after 30 January 2020 will be eligible for registration and sale of the associated biodiversity gains, provided it meets the other criteria of the biodiversity gain site register. Further information on habitat banking and BNG is provided in section 5.4 of the Government’s 2023 BNG consultation response.

Local authorities will be able to use their own land to offer offsite biodiversity units to developers or act as a broker for third party units. When the mandatory BNG requirement comes into effect, this will need to be subject to the same confirmed rules and requirements for BNG as for other biodiversity unit providers, including registration on the Biodiversity Gain Sites Register. Local authorities will need to calculate appropriate biodiversity unit prices for offsite gains delivered on their land, or sold by them on behalf of a third party.  The prices will need to be sufficient to cover the costs of creating or enhancing the habitat and maintaining it for a minimum of 30 years.

Local authorities will not be able to direct developers to purchase biodiversity units from them in preference to other ecologically equivalent suppliers, and will be expected to manage any associated conflicts of interest.

Freeths have written an article in Practical Law on how local authorities can create habitat banking mechanisms for BNG.

When mandatory BNG comes into force (in January 2024 for all but small sites), any approach to the delivery of BNG will need to meet the minimum requirements as set out in the legislation (primary and secondary). This means that LPAs will not be able to levy a tariff system (i.e. a general fee) to then pool money for investment in nature elsewhere at some future point.  Offsite lands used for BNG must be registered on the biodiversity gain sites register, measured using a standardised biodiversity metric and legally secured for at least 30 years.

There is, however, scope to encourage the development of a local habitat bank (on LPA or other third party land) from which multiple developments could secure BNG through a single site through the sale of smaller parcels of biodiversity unit uplift (see above re schemes for local offsite delivery).

Yes. This is where having a Local Plan policy that links BNG to delivery of local strategic priorities is really helpful. See our Biodiversity Net Gain in Local Plans and Strategic Planning webpage for further information. See below for further questions on the national credit scheme.

This would be reliant on the LPA having a locally-specific policy that allows them to set what strategies they require developers to take into account in delivering BNG, e.g. Green Infrastructure strategies, Local Nature Recovery Strategies.

No, this is not currently under consideration by Natural England or Defra.

Sellers will need to commit to managing the habitat for at least 30 years. They will need a planning obligation (section 106) with an LPA or a conservation covenant with a responsible body and will need to agree an achievable habitat management and monitoring plan (HMMP) with them.

Government expect to put in guidance that when securing gain sites, those involved should make sure that appropriate funding is in place for the duration of the agreement. Funds should be held for the duration of the agreement, should be held independently for large schemes and an appropriate payment schedule should be in place.

If a habitat bank provider can’t secure finance for the whole bank, they can still have plans in place for what they intend to do with the land but should only be entering land into conservation covenants/planning obligations if they have funding secured.

Defra can’t advise on specific financial arrangements but would suggest seeking independent advice. Government is also looking into options for a BNG assurance scheme.

Yes, it will be the developer’s responsibility to find a suitable location for off-site BNG delivery. This land will need to be legally secured and managed for the duration of the BNG period. We expect more information on the planning application process, including what the requirements for biodiversity net gain information will be at planning application stage, to be set out in the forthcoming additional guidance. 

There is no requirement to hold a local register, although you may find it useful to do so. Some LPAs are setting their own requirements for landowners that want to feature on the ‘local register’.

Developers can only sell units if that 'excess' is registered on the national register and would need to be subject to all the usual off-site requirements, i.e. legally secured via either s106 or a conservation covenant for at least 30 years and subject to any minimum reporting requirements for offsite delivery established via secondary legislation.

If a Local Plan specifies a higher percentage than 10% then the LPA would need to consider whether the proposed approach is acceptable to them, as for any other local policy, through the planning application process for the later development(s).

Where units are being created in advance, they can be legally secured at the point of creation. The clock starts ticking for the 30 years once the habitat works have completed.  If these units are registered on the BNG register, this will provide assurance that the site is secured for 30 years following completion of the works. There will be no requirement to re-secure the units for another 30 years with another legal obligation when they are sold – the original creation date will apply. To approve the gain plan, the units must be registered on the offsite register.  The gain site must be registered, and the units allocated to the relevant planning permission prior to gain plan approval.

 Ideally they would have been created for BNG. They would need to meet with the combining payments guidance that ensures, for example, that they have not been paid for by a public grant and the land manager guidance which sets out additionality requirements, for example. that you cannot sell a woodland that has been required by a restocking notice.

 It’s important to be aware that there are two different kinds of monitoring: habitat monitoring (the actual delivery of the habitat) which sits with the developer or the person securing the habitat. Monitoring delivery of BNG sits with the LPA. Some information on monitoring requirements is set out in the 2022 BNG consultation from Page 80 and Section 5.8 of the consultation response. You can also see the slides and recording from our Spring 2022 deep-dive session on BNG monitoring, evaluation and enforcement. Further guidance on monitoring will be published by Government. 

Habitat monitoring is the responsibility of the developer and should be set out in the biodiversity gain plan. Defra are looking at standardised reporting requirements over the 30 years for developers with a draft template and digital capability. Natural England have developed and have been testing a Habitat Management and Monitoring Plan template.  All this will help with consistency and remove some of the need for specialist input to every application. Planning authorities will be required to set any specific and proportionate monitoring requirements as part of planning conditions and obligations used to secure off-site or significant on-site habitat enhancements. 

The planning practice guidance states that LPAs can charge a monitoring fee for s106 obligations now. BNG can pay for itself over time so LPAs can generate income through monitoring and pre-application fees. We have an online forum for the PAS BNG practitioner network, where officers are sharing how they are doing this, including costing monitoring. LPA officers can join by filling out this Microsoft Form. For conservation covenants, the price agreed for the units should include monitoring arrangements.

LPAs will have duties to report on BNG delivery under the Natural Environment and Rural Communities (NERC) Act. Government has published guidance on complying with the NERC duty and reporting on actions, including BNG:

'As a local planning authority, you must include:

• a summary of the actions you’ve carried out to meet biodiversity net gain obligations
• details of biodiversity gains resulting, or expected to result, from biodiversity gain plans you’ve approved
• a summary of how you plan to meet biodiversity net gain obligations in the next reporting period

You can include quantitative data in this section of your report. It is optional, but it can add useful detail to your report.

In 2023, Defra will provide a suggested format for tabulating any quantitative data on biodiversity net gains you choose to include.'

In relation to BNG, the Environment Act states that habitats should be secured for a minimum of 30 years: ‘habitat enhancement… will… be maintained for at least 30 years after the development is completed’. The 30 year term for biodiversity net gain isn’t meant to be regarded as in perpetuity – it was what was regarded as reasonable to ask for.

In some other cases, for example mitigation provided for sites or species protected under the Habitats Regulations, the requirement may be for management and maintenance of habitats ‘in perpetuity’. It will be up to the planning authority to determine the length of time that it is appropriate and reasonable to require ongoing management and maintenance of habitats as part of the grant of planning permission, taking into account the range of policy and legislative requirements, but the legal requirement for biodiversity gain habitats is 30 years as a minimum. The Government’s 2023 consultation response sets out some more information on ‘Securing sites for more than 30 years’.

The Environment Act states that significant increases from the on-site pre-development biodiversity value should be secured for at least 30 years. The legislation does not define ‘significant’. Government will define the threshold for significant on-site gains in guidance and the application of this guidance will be a matter for the LPA to consider. These gains will need to be secured through planning conditions, planning obligations or conservation covenants (or a combination of these methods). Defra are currently minded to set a definition according to habitat area and distinctiveness. As set out in the 2022 BNG consultation, the expectation is that suitable arrangements for ongoing management should be made for all proposed gains, including those deemed ‘not significant’, as is normal practice. In all cases, the LPA should be satisfied that the net gain condition to achieve a 10% gain will be met.

The Government's response to the BNG consultation stated “the planning enforcement regime will be the principal way of enforcing delivery of BNG”. Defra is working with DLUHC on enforcement guidance and will also publish guidance on the use of conditions and S106 to secure BNG. For gains that are secured with conservation covenants, Government expects costs for monitoring and enforcement activities to be reflected in the price of biodiversity units. The responsible body for the conservation covenant will have responsibility for the enforcement.

Incentives in the metric encourage gains to be located closer to the original impact location and the developer should demonstrate in the gain plan how they have applied the mitigation hierarchy, i.e. avoid losses, if not possible mitigate and as a last resort compensate.

In these circumstances, it may be preferable to use a conservation covenant but it would depend on the specific nature of individual cases.

The 2023 consultation response states that Natural England will be the Biodiversity Gain Site Register Operator, responsible for establishing and maintaining the register. The core purpose of the biodiversity gain site register is to record allocations of off-site biodiversity gains to developments and make this information publicly available. The register will not act as a marketplace platform for buying or selling units, nor will it assess the ecological suitability or additionality of proposals. Government  will set an achievable determination time for applications to the register in consultation with Natural England. This is likely to be around 6 weeks.

The 2022 BNG consultation states that a publicly available register of off-site gains will allow local communities to view an up-to-date record of biodiversity gains across the country and access information on the delivery and monitoring of habitat sites. Developers who deliver net gains off-site will need to register these gains on the register. They will need to be verified to ensure they are legitimate, accountable, and transparent. There will be a fee, expected by Government to be ‘between £100 and £1,000’, charged to process register applications. 

Natural England are currently developing the digital Biodiversity Gain Site Register. Natural England's Biodiversity Net Gain digital services blog provides updates on this work and the digital credit sales service.

Further information on the register, including the information that will be required from developers, can be found on page 63 onwards of the 2022 BNG consultation and section 5.5 of the 2023 consultation response. Further information will be available in the forthcoming secondary legislation and associated guidance, expected in November 2023.

PAS has worked with Future Homes Hub on a BNG process flow showing the process through from pre-application to 30 years post-commencement and including the register.

The 2023 BNG consultation response confirms that net gains delivered on site will not be required to be recorded on the national biodiversity gain sites register. Any off-site land used for the purposes of achieving BNG will need to be registered. Further guidance on how information on on-site gains in biodiversity gain plans can be recorded is expected to be published in Government guidance. The long-term ambition is to include on-site as well as off-site BNG delivery on the national biodiversity gain sites register, but there is no mandate for this under the Environment Act. 

There will be no need to register off-site gains that have been sold prior to commencement of mandatory BNG in January.  

Natural England fully intends for the register to be up-and-running when BNG becomes mandatory. Defra is preparing a policy summary which will set out the intent of the register regulations. This will include information to be provided in an application to register land.

The consultation response recognises that the consultation proposal that “on-site biodiversity gains should be secured for delivery within 12 months of the development being commenced or, where not possible, before occupation” wasn’t always reasonable and Government ‘will take these observations into account as we draft final guidance wording’.

The national credit scheme will not allow for funds to be earmarked for a particular region.

This has not yet been decided and will depend on data received through our monitoring and evaluation programme. There may be some types of habitat that will always require statutory credits.

The credit price will be set to be intentionally uncompetitive with the market. Defra published indicative statutory biodiversity credit prices on 27 July 2023.

Credit sales revenue will be received by Natural England and invested in habitat creation projects. Natural England will be providing detail on the eligibility criteria of projects later in the year.

Revenue from credit sales will be invested in strategic habitat creation and enhancement which delivers long-term environmental benefits and is aligned with local nature recovery priorities

Government published guidance on combining environmental payments with BNG in February 2023. They also provided information on combining BNG with mitigation for protected species and protected sites in their 2023 BNG consultation response under Section 5.6 Additionality. You can also view the slides and recording from our deep-dive session on BNG and additionality in Spring 2022.

The current Natural England position is that it is possible to use sites delivering nutrient neutrality/SANG/GCN habitat to also deliver biodiversity net gain, on the basis that:

• Delivery of the non-BNG outcomes via habitat creation/enhancement could contribute up to a point equivalent to no net loss of BNG (as calculated by the Biodiversity Metric) but not beyond  – assuming they meet any other BNG requirements e.g. agreement type/duration etc.
• Additional habitat features created or enhanced on that same land beyond those delivered for the purpose of non-BNG outcomes could take you into positive BNG territory (again if measured and demonstrated using the metric) – assuming they meet any other BNG requirements e.g. agreement type/duration etc
• Good practice would be to illustrate BNG contributions derived from the above using a separate accounting line for transparency reasons. It is intended for this to be required in the biodiversity gain plan. Further details on this will be provided in the forthcoming BNG consultation.

So, habitats created for, and fulfilling the minimum requirements of, District Level Licensing for Great Crested Newts (DLL) could never get a project beyond a point of no net loss. The contribution to BNG through measures required as part of DLL is capped at a point equivalent to no net loss irrespective of the actual delivery outcome, as measured by the Biodiversity Metric 4. To achieve the required biodiversity unit uplift beyond no net loss to meet the BNG requirement, there must be habitat provision or enhancement beyond the minimum requirements of DLL.

Government will be providing guidance on the circumstances in which statutory protected sites can be enhanced for BNG and will keep this position under review through policy evaluation.

The current Natural England position on this is:

• Biodiversity net gains cannot be delivered on the designated features of protected sites. This is because biodiversity gains through the net gain policy need to be additional to those measures that should be in place already (i.e. required through the relevant SSSI legislation).
• However, technically you could deliver biodiversity gains within the ‘fabric’ of a designated site, i.e. there may be areas of a designated site that don't include habitats listed as ‘features’, and a net gain plan might be able to provide benefits to those undesignated habitats within the boundary of the protected site (as long as this didn’t impact the conservation objectives already in place and went through the relevant assessments etc).

Government will state that all habitats in the intertidal zone, including designated features of protected sites, or a short distance (to be confirmed, but no more than 2 kilometres) above the high-water mark, would be eligible for enhancement for BNG. Any compensation that a development is delivering in meeting wider statutory protections may be counted towards that development’s BNG. This would be subject to any relevant approvals for the enhancement and only permitted where the proposals do not risk harming designated species or features.

The UK Land Carbon Registry is the database that stores and publicly displays data about the status of Woodland Carbon Code and Peatland Code projects and ownership and use of carbon units. You cannot stack carbon and BNG on the same land for the same activity (i.e. planting a woodland). You can only stack on top of carbon if you can further enhance the habitat and it does not affect the carbon value.

No, in accordance with the combining payments guidance, you can't sell biodiversity units where they have already been funded through public grant

Natural England’s recommendation would be that a separate accounting line is used, to ensure transparency and a clear audit trail in terms of evidencing the uplift in biodiversity unit value, i.e. The mitigation measures and the habitat delivering BNG is accounted for separately in the metric and any reporting.

Habitat works for mitigation purposes can count towards a no net loss, but could never on their own deliver a net gain. There would need to be habitat delivery over and above that required by the mitigation measures in order to count towards a net gain. 

Biodiversity Metric4.0 has been designed to work alongside the Environmental Benefits from Nature Tool (EBNT). EBNT provides developers, planners and other interested parties with a means of enabling wider benefits for people and nature from biodiversity net gain. The tool uses a habitat-based approach to provide a common and consistent means of considering the direct impact of land use change across 18 ecosystem service services.

For example, a user can run habitat data through the Biodiversity Metric in order to quantify any losses or gains in biodiversity unit value. They could then use that same data in the EBNT to calculate the wider ecosystem service benefits associated with the habitats (such as, carbon sequestration, recreational value and air quality benefits). 

We have hosted introductory and intermediate training sessions on the Biodiversity Metric from Natural England and you can access the recordings and slides from these events for more information on the Biodiversity Metric. The following questions and answers are taken from a Natural England training session we hosted in October 2021 on Biodiversity Metric 3 with some updates to reflect more recent information in June 2023.

Working with colleagues in the Environment Agency, we hosted some training events on the watercourse elements of the biodiversity metric in March 2023. Based on this and the guidance to Biodiversity Metric 4.0, the EA have just shared a set of Frequently Asked Questions which are now available on our website alongside a copy of the slides and recording of one of the events.

Natural England encourages local authority officers making decisions on BNG to read the Biodiversity Metric user guide, in particular the first three chapters including the ‘Rules and Principles’ on pages 12-16. They welcome feedback with suggestions for improvement from those that have familiarised themselves with the guidance: [email protected].

Currently, and for the immediate future, the Biodiversity Metric is a Microsoft Excel-based tool and therefore requires Excel to operate. It is expected that the full metric spreadsheet should be submitted by developers to LPAs for consideration, with a planning application. Natural England and Defra will be exploring options to digitise the metric in the future.

Responsibility for completing the Biodiversity Metric assessment and calculations

For habitat condition assessments in association with development, it is the developer's responsibility to provide the Biodiversity Metric calculations to include in the Biodiversity Gain Plan. The Biodiversity Gain Plan will require a statement of competency for a named person who has carried out the assessment and metric calculation. So, developers will need to employ a ‘competent person’ to conduct the habitat survey and assessments and complete the metric tool. The developer will then share the full spreadsheet with the LPA, alongside other required documents for the application. LPAs will not be responsible for completing the metric.

‘Competency’ to use the metric

A 'competent person' is defined as: being able to confidently identify the positive and negative indicator species for the range of habitats likely to occur in a given geographic location at the time of year the survey is undertaken. For a full metric application, the competent person should be an ecologist. However, in circumstances where the development fits with the criteria to use the Small Sites Metric it is not necessary for the metric to be completed by an ecologist but by someone who is competent to use that metric. It is the developer or applicant's responsibility to ensure that the person they appoint to complete the metric fulfils this criteria and is suitably competent, as described in the metric User Guide. Biodiversity metric users will not be required to have received formal training or accreditation, but a training course must be completed and accreditation achieved by those using the watercourse element of the metric. Defra and Natural England are working with industry to provide training and further guidance on the Biodiversity Metric. Natural England has also been looking at the potential for assurance schemes for BNG more generally.  We will add more information on this as it becomes available.

LPA responsibilities and how to meet these

It is expected that LPAs will review and check the metric spreadsheets. In order to verify the habitat surveys, LPAs could refer back to aerial photos, Local Environmental Record Centres or other data sources and seek the advice of local ecologists (where available).

Natural England and Defra recognise that resources within LPAs are stretched and we hope that there will be more information on new burdens funding for LPAs soon. PAS produced a short guide on resourcing BNG for local authorities to help identify what skills and expertise are needed to meet the new requirements.

The Natural England session we hosted on the metric in October 2021 was intended to assist planners in getting to grips with the metric and how to interpret its results. We are hosting an introduction to the Biodiversity Metric from Natural England on 6 July 2023 and you can register for the session on this page. Natural England would welcome feedback on how they can further assist planners with interpreting and understanding the metric’s outputs. You can email them at: [email protected].

Assessing the values ascribed by the metric

The values ascribed to individual habitat types within the metric are based on the ‘distinctiveness’, condition, spatial location and importance of those habitat features. The metric cannot recognise whether a habitat type has been correctly identified or the condition and strategic significance assessed accurately. This is reliant upon the competence and integrity of the individuals entering the data. Detailed guidance has been provided to assist in assigning the correct habitat type and condition to a habitat.

The habitat distinctiveness scores are set within the metric and are based on ecological evidence that will be kept under regular review. Fixing the distinctiveness scores in the metric ensures greater consistency and reduces the scope for subjectivity and dispute.

Habitat condition is established by undertaking a habitat survey and ascribing a condition score to a habitat, based on the judgement of a suitably competent person (usually an ecologist). Condition sheets have been published with the metric to allow for greater consistency of assessment. In the case of rivers and watercourses, the person undertaking the condition assessment must be accredited in the use of the condition assessment methodology. For a small number of habitats, the condition is fixed and prepopulated in the metric and a condition assessment is not required.

Spatial location can also affect a habitat's value, in particular whether or not the habitat is of, or in a location that is of, ‘strategic significance’. This is determined by published local plans and strategies and can be specified by the LPA. It is expected that Local Nature Recovery Strategies (LNRS) will standardise strategic significance by mapping and describing those habitats of particular local importance (for creation and/or enhancement). See also above under Local Plans for further information on ‘strategic significance’ in policy and below on LNRS.

Under mandatory BNG, there will be a requirement to use the latest version of the statutory Biodiversity Metric so there is no need to repeat this in Local Plan policy. Prior to mandatory BNG, there is no requirement to use the Biodiversity Metric and projects can continue to use an alternative metric (unless the LPA has specified which metric to use). If the LPA does not specify the use of another metric, then we would recommend using the most recent version of the Biodiversity Metric.

It would be helpful if potential site allocations could be assessed for their biodiversity value as this will help ensure application of the mitigation hierarchy by flagging up any high value (for biodiversity) sites before these get allocated. It will also help to give an indication of how easy (or otherwise) developers will subsequently find it to deliver BNG solely within the allocated site baseline, or whether they will likely need to go off-site to meet the local BNG % requirement i.e. if the allocated site has a low biodiversity unit baseline score it is likely that BNG could be delivered entirely within the site. If it has a high score, then it will be very difficult and the developers will likely need to look for off-site opportunities. LPAs could then think about how to encourage strategic habitat banks to provide the supply of offset units developers will need – the baseline assessment will have provided sufficient intel to be able, with some confidence, to anticipate what types of habitats and unit types will be required.

In addition to such uses the metric can also be used to track changes in the biodiversity value of land overtime and, as such, can be used for performance monitoring and reporting purposes.

It is not expected that LPAs will need to produce their own metric guidance. There is currently a simple user guide for the metric embedded within the tool (click the “Instructions” tab on the opening page). This is also available on the Biodiversity Metric web page, along with two substantial guidance documents: the ‘User Guide’ and ‘Technical Supplement’. Natural England has produced some case studies (available on the metric webpage) to assist in the interpretation of this guidance with more to come and there are plans to update the user documents alongside the statutory metric.

It is strongly recommended that a plan is supplied, and that information provided in the plan enables habitat parcels shown to be clearly identified in the associated metric calculation. There is a facility to attach a plan to the metric on the start page. LPAs should encourage developers to submit as much information as possible within the “assessor comments” section of the metric to justify their decision-making regarding each habitat parcel. It is expected that Biodiversity Gain Plan requirements for mandatory net gain will include pre- and post-development maps.

The metric is intended to be used early in the design process, in order to quantify and evaluate the impacts of different design options when there is more scope to influence design changes and achieve better ecological outcomes. The metric can be applied on an indicative basis and by adopting a precautionary approach when ascribing habitat condition and distinctiveness values.

The metric accounts for a variety of risk factors within it which can influence whether or not a particular habitat will be successfully established. These risk factors are standardised, evidence based and will be kept under review.

The minimum percentage requirement (e.g. 10%) should be applied to all area and/or linear unit types found within the development site red line boundary and should be applied irrespective of whether the habitat in question was directly or indirectly impacted by the development. Area, hedgerow and watercourse habitat units are all considered separately and are not interchangeable; you cannot address a loss of one type by providing another. The metric trading rules should always be followed, for example there should be no trading down in habitat distinctiveness. All high distinctiveness habitats require re-creation on a like-for-like basis should they be lost, whereas there is more flexibility for lower distinctiveness habitat types in terms of what habitat can be delivered if they are lost. 

Urban tree canopy cover should be considered separately to the habitat that it stands on. For example, if there was a one-hectare area of grassland with five trees, then you would record both the one-hectare of grassland and the five trees separately. 

Individual trees should not be recorded separately where they occur within habitat types characterised by the presence of trees, such as orchards, lines of trees or wood-pasture and parkland, but can be recorded where they do not form part of a primary habitat description.

Less biodiversity units will be generated where higher distinctiveness woodland is being proposed, compared to a lower distinctiveness woodland type (e.g. ‘other woodland; broadleaved’).  This is due to the difficulty of successfully creating a new woodland from scratch and the associated inbuilt risk multipliers within the metric, such as the time taken for high distinctiveness woodland to reach good condition. Providing the trading rules are adhered to, aiming for a lower condition, or a lower distinctiveness woodland, is more realistic and therefore will generate more biodiversity units within the Biodiversity Metric. As a rule of thumb, when creating new woodland from scratch, unless required to do otherwise to compensate for the loss of an existing area of high distinctiveness woodland, use the ‘other woodland; broadleaved’ category and ascribe a target condition of no greater than ‘moderate’. This is explained further in the metric guidance. Another reason behind this is to encourage retention of the most valuable habitats as part of the mitigation hierarchy before compensating for their loss.

All habitats inputted into the Biodiversity Metric need to be measured in hectares, unless they are part of the two linear tabs for either watercourses, or hedgerows and lines of trees, which need to be measured in kilometres. The exception to the above is sites that meet the requirements that allow them to use the small sites metric, in which case area and length is measured in square metres and metres respectively.

Gardens are included in the Biodiversity Metric for use in biodiversity net gain calculations. Their pre-defined distinctiveness is set at 'low' or 'very low' (depending on whether the garden is vegetated or un-vegetated), and the condition for gardens is set at no greater than 'poor'. The metric also assumes that a significant amount of any gardens established will be ‘lost’ over time i.e. due to decking, etc. Therefore, although gardens can be included within calculations, their low biodiversity unit value accounts for the assumption that a large proportion will potentially be lost, reflecting the fact that these are largely private spaces and so they cannot be legally secured in the same way. That said, gardens can and do provide locally important spaces for biodiversity and their retention and incorporation into design is to be encouraged, hence their inclusion in the metric.

Guidance is provided on how suburban housing should be accounted for in the metric using a precautionary assumption that a housing development would be in the proportion 70:30 developed land/sealed surface to vegetated garden. This can be negotiated up or down by the consenting body or if sufficient justification can be provided by the applicant to deviate from this. 

There is no scope for adding any other habitat as well as/instead of vegetated garden. If a developer wants to try and deliver habitats other than garden through BNG on-site then it should be in the public realm with an appropriate management plan and commitment to deliver and maintain – thus giving a greater degree of certainty than could be achieved in a private garden.

Yes, Green Infrastructure (GI) features can contribute to a project’s BNG calculations and there are a range of GI features included within the tool, including green roofs, green walls and Sustainable Drainage Systems (SuDS). All such features, whether found on the baseline or included in the post-intervention proposal, should be included in the metric calculations.

It is not Defra or Natural England's intention to alter the Biodiversity Metric specifically for minerals projects. However, Natural England have been working closely with the minerals industry to ensure that the metric is applicable and suitable for mineral sites and projects. Natural England will also be publishing specific case studies, developed in conjunction with the sector, to illustrate how best to approach metric calculations on minerals sites and how this will work in practice.

Once the Statutory Biodiversity Metric is released, the intention is to update it every 3 to 5 years to incorporate industry feedback.

Further information on the application of the BNG policy requirement to minerals sites. e.g. s73 and ROMPs, is outlined in the 2022 BNG consultation from Page 34 and Section 4.1 of the 2023 BNG consultation response. This was also covered at our deep-dive session on the BNG process in TCPA development in Spring 2022.

Monitoring is the responsibility of the developer and should be set out in the biodiversity gain plan. LPAs will have duties to report on BNG delivery. Some information on monitoring requirements is set out in the BNG consultation from Page 80. Planning authorities will be required to set any specific and proportionate monitoring requirements as part of planning conditions and obligations. A typical monitoring schedule for a project will include reports in years 2, 5,10, 20 and 30 and will include habitat type, extent, and condition. Further guidance on monitoring is expected to be published in Spring 2023. You can also see the slides and recording from our Spring 2022 deep-dive session on BNG monitoring, evaluation and enforcement. 

The Small Sites Metric (SSM) is a simplified version of the Biodiversity Metric which has been specifically designed for use on small development sites where the project chooses to do so, providing there is no priority habitat present on-site. The SSM is not suitable to calculate losses and gains off-site.

Developers should note that the following criteria need to be met to use the small sites metric calculation tool:

• for residential development: 
  • fewer than 10 residential units on a site area (no more than 9 units) less than 1 hectare
  • when the number of residential units is not known, the site area is less than 0.5 hectares
• for non-residential development: 
  • the site area is less than 1 hectare.

The biodiversity metric calculation tool must be used, instead of the small sites metric calculation tool, in all cases where

• priority habitats (high and very high distinctiveness habitats) are within the development site: this does not include the presence of some hedgerows and arable field margins – these are medium distinctiveness habitats;
• protected sites are within the development site; and/or
• European protected species are within the development site.

If when using the small sites metric calculation tool, there is a need for off-site units or, as a last resort, statutory credits, complete the calculation instead using the main biodiversity metric calculation tool.

Natural England will not be a statutory consultee on BNG, and so will not be commenting or responding to Biodiversity Metric calculations on a regular basis unless it is a development that triggered Natural England’s involvement as a statutory consultee on other grounds. Dependent on resource, there may be specific cases such as high-risk or high-opportunity case work, where NE may examine metric calculations, likely via their Discretionary Advice Service.

The DEFRA evidence base and impact assessment considers that the 10% requirement is unlikely to significantly affect viability issues for development. DLUHC and Defra are not aware of any evidence to the contrary.  Essentially the 10% set out in legislation is mandatory and therefore there is no scope for LPAs to allow a reduction on viability grounds. If developers submit above 10% this is voluntary and anything above 10% would be subject to negotiation (and possibly would include viability justification) as part of planning application discussions with the LPA. If LPAs set the requirement higher than 10% in local policy, they would have to justify the level set in policy as part of their Local Plan process.

The following text extracted from the impact assessment highlights likely differences between impacts on developers:

We expect there will be a wide distribution of impacts, given that the costs and benefits will be highly dependent on the location and design of individual developments. In our analysis we assume that developers either: (1) already deliver net gain (entirely as we have proposed) or (2) do not deliver net gain (or even ‘no net loss’) and do little to mitigate or compensate habitat damage caused by their developments.

Given this, those currently doing the most to benefit the environment should find that this provides certainty. Since these developers already incur all or most of the costs of net gain, the most significant change for them (within our analysis) will be benefits associated with greater consistency in net gain within the planning process and greater consistency in expectations. The developers who currently cause high levels of environmental damage and do little to compensate for this will face the highest additional costs. This means, in practice, it is likely that the costs will fall unevenly across developers.

Biodiversity net gain should, therefore, steer development towards the least environmentally damaging areas and design practices. A significant proportion of costs imposed on developers are likely, in the medium to long term, to be ‘passed through’ to developable land prices, thereby affecting landowners.

In terms of costs to developers, the following conclusion is reached in the impact assessment:

Overall, the analysis indicates that net gain delivery costs are likely to be low as a proportion of key variables such as build costs and land prices. In addition, it is unlikely to lead to a significant increase on existing average developers contributions. While the analysis identifies regions where potential residential and non-residential viability issues may arise (e.g. Midlands, the North), this analysis is not a prediction of where site specific viability issues may arise in reality.

 For residential development costs to developers:

Our analysis demonstrates that, while there is a range of expected cost from delivery of net gain, relative to build costs they are relatively small for brownfield (between 0.1% and 0.8%) and greenfield (between 0.1% and 3.9%) developments. However, regions in the Midlands and the North have the highest potential costs as a percentage of build costs, but also have lower developable land prices which indicates potential for site specific housing viability issues.

And for non-residential:

The analysis shows that the majority of the costs across scenarios are expected to be less than 5% of land value, and that regions with higher costs (i.e. implying a potential site specific viability issue) tend to be in the North.

Local Plans, viability and percentage level of net gain

Our Biodiversity Net Gain in Local Plans and Strategic Planning webpage provides further information on assessing viability for net gain, including going above 10%.

For further information on nature recovery and Local Nature Recovery Strategies (LNRS), please see our Nature Recovery FAQs and overview webpages. LNRS Regulations and Statutory guidance for LNRS Responsible Authorities alongside a response to the 2021 local nature recovery strategies consultation were published by Government in April 2023.

The Environment Act contains a specific duty on all public authorities to "have regard" to relevant Local Nature Recovery Strategies (LNRS) and the LNRS regulations create a “supporting authority” role for local authorities, national park authorities and Natural England. Further information on this role is available in the Government’s response to the 2021 local nature recovery strategies consultation and PAS has published Local Nature Recovery Strategy frequently asked questions (FAQs).

Guidance is due to be published on the role of LNRS in the planning system. The expectation is that LNRS will be used to help inform how and where biodiversity net gain should be delivered, i.e. which habitats are appropriate in what locations. In particular, LNRS can be used to target offsite BNG so that it contributes to the Nature Recovery Network and the LNRS can be used as to determine the ‘strategic significance’ score that is part of the Biodiversity Metric scoring approach. The ‘strategic significance’ score is a landscape scale factor, which gives additional unit value to habitats that are located in preferred locations for biodiversity and other environmental objectives.

The expectation is that all local authorities will be involved in the development of LNRS, so it should reflect local priorities. Locally-specific plan policies could specify how the LNRS will be used to influence BNG delivery in a district, such as targeting of offsite BNG delivery and in Biodiversity Metric ‘strategic significance’ scoring.

Local authorities can use other local strategies to inform offsite targeting prior to implementation of LNRS, such Green Infrastructure strategies and biodiversity opportunity mapping. The availability and type of strategies available locally varies according to what activity and policy has been taken forward by local authorities, non-governmental organisations and other agencies. Where a Local Nature Partnership (LNP) is active, they are likely to have a mapping resource that can be used in advance of LNRS in locally-specific plan policies and to inform offsite targeting and determine ‘strategic significance’.

Buckinghamshire Council has prepared Interim BNG Strategic Significance and Spatial Risk Guidance and the Council plan to signpost to the LNRS when complete. Greater Cambridge Shared Planning Service has also prepared an Interim Offsite BNG Protocol setting out their expectations for off-site BNG delivery.

More detailed FAQs on conservation covenants are available alongside the slides and recording from the session on applying to be a conservation covenant responsible body PAS hosted in August 2023. Further information on conservation covenants is available on the Government website here. You can also access the slides and recording from a previous session on conservation covenants in June 2022.

It is an agreement between a landowner and a designated “responsible body” such as a conservation charity, public body or for-profit body which conserves (protects, restores or enhances) the natural or heritage features of the land. It is a private, voluntary agreement made for the public good, which can continue to be effective even after the land changes hands.

The conservation covenant provisions (Part 7 and Schedules 18-20) of the Environment Act 2021 commenced in the autumn of 2022. Defra published guidance on how to apply to become a responsible body in July 2023 and we hosted a session with them in August 2023.

Conservation covenant guidance is available on the Government website and Defra published guidance on criteria for becoming a responsible body in July 2023. You can access the slides and recording from the session on applying to be a conservation covenant responsible body PAS hosted in August 2023.

Now the criteria against which applicants will be assessed have been published, organisations are able to apply to be responsible bodies. This includes local planning authorities that wish to take on the role.  Once organisations have been designated, they will then be able to start agreeing covenants with landowners.

Conservation covenants are a possible tool to secure biodiversity gains – and are specifically referred to in the net gain clauses in the Environment Act. We expect this will make them a valuable tool for local authorities and developers to ensure that compensatory habitats are maintained in the long term, even if the relevant land is sold.

The use of conservation covenants under mandatory net gain will be subject to certain conditions such as land under agreement being maintained for at least 30 years to help ensure delivery of net gain outcomes. Defra will consider what is required in regulations and accompanying guidance to maximise the benefit of conservation covenants to deliver biodiversity net gain objectives.

In the meantime if you have questions about conservation covenants please contact Defra via this mailbox [email protected].

No – they can become responsible bodies if they want to. The session on conservation covenants & applying to be a Responsible Body in August 2023 and session on conservation covenants PAS hosted in June 2022 provide some more information on why a local authority might want to become a responsible body. If you want to legally secure your own land for BNG delivery you will need to register this with another Responsible Body through a Conservation Covenant as you can't have a legal agreement with yourself. LPAs like Buckinghamshire Council are looking at agreeing S106s with some potential habitat banks in their authority area but awaiting details of Responsible Bodies for their own land. LPA's cannot have a S106 agreement with themselves so this can’t be used where the LPA wants to buy units from its own habitat banks.

A responsible body can be:

• a local authority
• a public body or charity, where at least some of its main purposes or functions relate to conservation
• a private sector organisation, where at least some of its main activities relate to conservation

Who takes on the role of responsible body depends on what the arrangement is but a conservation covenant must be between a responsible body and a landowner. It is up to the organisation involved if they want to apply to register and take on that role. In conservation covenant terms, they would need to apply to be a responsible body, be accepted and then agree to take on that role with the relevant landowner.

The Environment Act introduces a ‘Duty to Consult’ for local highway authorities which will give the public the opportunity to understand why a street tree is being felled and express any concerns regarding this. The Act also introduces Forestry Enforcement Measures which strengthens the Forestry Commission’s power to clamp down on illegal tree felling across England, ensuring the Commission has the powers to continue to protect and maintain our forests. The relevant section of the Act is: House of Commons: Environment Bill (parliament.uk)

The Office for Environmental Protection is a new independent environmental watchdog set up under the Environment Act. Further information is available on their website: Office for Environmental Protection | oep (theoep.org.uk).