Find out what our requirements are for developers to improve biodiversity (known as net gain for biodiversity).
Archive version - Guidance for Developers to Achieve Net Gain for Biodiversity in Leeds (May 2020 as amended)
This version should only be used for reference for major applications submitted before 12 February 2024 and other planning applications submitted before 2 April 2024.
We’re looking at requiring all developments to achieve net gain for biodiversity of 10%. This is soon to become mandated through the Environment Act.
We've produced this guidance explaining to developers:
Net gain for biodiversity is defined as delivering more or better habitats for biodiversity and demonstrating this through use of the Defra biodiversity metric.
It encourages development that delivers biodiversity improvements through habitat creation or enhancement after avoiding or mitigating harm. Net gain for biodiversity involves an approach whereby developers work with stakeholders to support their biodiversity goals.
We already have a Core Strategy Policy (G9, page 115) which requires a net gain from development. The National Planning Policy Framework (paragraph 174 b) requires net gain to be achieved in a measurable way. Government guidance to implement the National Planning Policy Framework also includes information on net gain (paragraphs 20 to 28).
We are seeking a minimum 10% net gain through the use of the Defra approved biodiversity metric, which should be delivered on-site. Where this is not possible (to be agreed with the Local Planning Authority) it may involve off-site compensation.
The Local Planning Authority (LPA) will expect all applications to conform to this guidance to achieve consistency of information on which to carry out decision-making. If this guidance is not followed (the Defra biodiversity metric is not used), the LPA still requires all applications to demonstrate how they are achieving net gain in a measurable way.
This may lead to significant time delays as the LPA requests further evidence that a net gain is being achieved.
Core Strategy Policy G9 requires a Net gain. The intention of the LPA is to require a minimum 10% Net gain in line with the DEFRA Consultation Response and the Environment Bill as it passes through the legislative process and timescale. This Guidance is currently being progressed to a format that will become SPD, so the 10% Net gain is aspirational at this time (May 2020) and any applications being considered prior to adoption of SPD will be assessed on the level of net gain they are demonstrating will be delivered – if 10% or more Net gain is being proposed this will be looked upon in a more favourable light.
It is already a requirement that an Ecological Impact Assessment (EcIA) is submitted with most types of planning applications (the exceptions are when dealing with householder applications or sites with very low value ecological features – in which case a written statement or Preliminary Ecological Appraisal may still be acceptable).
The EcIA will now be required to have a specific section titled “Net gain for biodiversity” and clearly show how the site has been assessed using the Defra Biodiversity Metric Version 2.0. This will demonstrate the baseline value of the site (before development) and the post-development value – where it is suspected that the baseline value of the site has been affected negatively prior to assessment the LPA will require an assessment of the site based on the condition before such an occurrence (this may need to be based on previous aerial photos and/or historic information held by West Yorkshire Ecology) and if there is any doubt of the Distinctiveness or Condition it will be assumed that the highest likely value will apply.
Clear scaled maps will be required showing precisely where the Biodiversity Unit scores occur for both the Baseline and post-development scenarios. There should also be a section demonstrating why the condition score has been chosen – with reference to all scoring criteria from the associated Defra Technical Guidance habitat tables.
The objective should always be to deliver 10% Net gain for biodiversity on-site and therefore it will be essential to appoint an Ecological Consultant at the earliest stage to be involved in the iterative Design stage of the layout, the Ecological Consultant should work closely with the Landscape Architect and Urban Designers to consider which options of the layout lead to the best possible outcome for achieving Net gain for biodiversity on-site. This type of information should be included in the Design & Access Statement (if appropriate) whereby different Options of layout are shown with their corresponding different Biodiversity Unit impacts – together with an explanation why one option has been chosen over another where the layout resulting in the lowest impact on biodiversity has not been taken forward to the proposed layout stage.
Evidence is required in the EcIA to demonstrate the Ecological Consultant has been involved in the initial Design of the layout in a meaningful way to help achieve a Net gain for biodiversity. This should include reference to the Mitigation Hierarchy of Avoiding damage to sensitive ecological features, Minimising impacts on such sensitive ecological features, and where these first two steps can not be achieved (with an explanation to justify why not) finally consider what level of Compensation will be required either on-site or off-site (or both).
Designated Nature Conservation Sites (Sites of Special Scientific Interest and Local Wildlife Sites) and UK BAP Priority Habitats are afforded appropriate levels of protection through Core Strategy Policy G8. Such habitats are of sufficiently High Distinctiveness that they should be considered alongside Ancient Woodland as irreplaceable habitats for the timescale of development projects (typically 30 years – see page 74 of the Biodiversity Metric 2.0 User Guide Glossary 29th July 2019) – and if included in an application there should be the presumption of retention at the Design stage of the layout. Where survey information indicates that land may meet the West Yorkshire Local Wildlife Sites Criteria it will be expected that sufficient survey information will be gathered and the site will be assessed against that Criteria as part of the EcIA and therefore retained accordingly where the Criteria are met (and any positive enhancement mitigation/compensation included in the Metric to be delivered on land meeting the LWS Criteria will need to be discussed with the LPA).
It will be expected that on-site Biodiversity habitat creation and/or enhancements to contribute to Net gain will only be delivered in areas with public access or at least with access for residents of the development. This will help contribute to the physical and mental Health & Wellbeing benefits for new residents and the local community and foster a better connection between people and wildlife (which is one of the priorities for delivering Net gain for biodiversity Leeds). Where residents are contributing funding to the on-site maintenance of such areas through annual payments, there is a higher chance that such areas will be used, cared for and valued in the longer-term. Interpretation panels and promotion of the relevant Biodiversity Enhancement & Management Plan (BEMP) document are key ways to raise awareness of the biodiversity features on-site and how they are being managed – this means the BEMP should be written in a way to both guide ongoing maintenance but also be understandable to those residents who are paying for its implementation.
The longer-term expectation is that any on-site areas contributing to the overall Net gain will only be acceptable if the Developer has paid for a minimum 30 years of positive management at the point of determination (through a S106 or similar unilateral undertaking) and the associated funding sum is transferred to an LPA approved responsible body (as an endowment fund) to appoint a specialist ecological maintenance company to deliver the ongoing works (including monitoring and reporting back to the LPA on outcomes).
However, until a formal Net gain for biodiversity system (backed by SPD, Policy and/or the Environment Act) has been set up by the LPA, on-site Net gain may still be delivered under the current scenario of a BEMP that is funded by local residents – but it should be noted this is a transitional period while the LPA sets up a formal Net gain for biodiversity system.
The LPA encourages the wildlife-friendly design of new private garden space as good practice but calculations arising from the creation of private garden space will only be acceptable until a formal Net gain for biodiversity system (backed by SPD, Policy and/or the Environment Act) has been set up by the LPA – after this time private garden space will not be acceptable to contribute to Net gain for biodiversity calculations. During this transition period, the Distinctiveness score to be applied through the Biodiversity Metric for the area of land allocated as private garden space must be “Urban – Amenity Grassland” Low and Condition score must be “Poor” – a higher score would not be acceptable as such areas are subject to change and the LPA will has no enforcement powers over such changes.
Green Roofs and Walls on communally used buildings (but not private buildings) can be included in habitat creation calculations. Green Roofs or Walls on private buildings will not be acceptable to contribute to Net gain for biodiversity calculations. Along with private gardens space, such areas of land are not communally paid for by residents (such as through maintenance funds/fees) so have no long-term assurance of being retained.
Parcels of land on-site with no public access may be included for habitat retention, creation or enhancement (as locally valuable biodiversity buffers) provided that the land is outside of private garden space with clearly demarcated permanent boundaries and a BEMP is submitted (can be by Condition). Such areas can only be included in habitat retention, creation or enhancement calculations if the same level of Distinctiveness as the Baseline value is applied, and either the same or only one positive step change in Condition is applied. In such cases there will also need to be a legal instrument to prevent the land use being changed to private garden space or other use other than that intended.
This category will not be acceptable for habitat creation as it generates artificially-high scores. Instead the actual constituent areas of sealed surfaces and gardens (amenity grassland) should be calculated separately.
As per the Defra Guidance, calculations from the creation of new lengths of hedgerow (or enhancements to existing hedgerows) will not be acceptable to contribute to the overall Net gain for biodiversity habitat calculations, they should only be considered in relation to impacts on other sections of hedgerows to be lost i.e. where a loss of hedgerow occurs there should be hedgerow creation to achieve a 10% increase in hedgerow length using the Linear Features calculations (likewise for other Linear Features there should be a corresponding consideration to achieve 10% gains such as for water course sections).
We also have policy LAND2 which requires any trees lost to be replaced at a 3:1 ratio. Any trees that are over 75mm at 1.5m height and outside of woodland should also be identified separately and that number of trees will be subject to consideration against Policy LAND2. Such trees will be growing within either an open-ground or scrub scenario. This will allow such trees to have both their biodiversity value and visual amenity value taken into account.
The Defra Biodiversity Metric does not consider indirect impacts such as increased recreational impacts on adjacent habitats such as meadows or woodlands (impacts include trampling of meadow areas and creation of new paths in woodland areas, and noise/physical disturbance). These indirect impacts will need to be considered and factored into the Metric through discussion with the LPA.
Where replacement of habitats is being proposed there must be not be replacement with a lower Distinctiveness habitat – i.e. it must be like for like or a realistic increase of only one step change upwards i.e. Low Distinctiveness can be replaced with Medium Distinctiveness habitat but not with High Distinctiveness.
Provision of new High Distinctiveness habitat will only be acceptable if the land is transferred to a specialist nature conservation body or long-term management will be delivered by a specialist ecological contractor with proven history/accreditation in management of such habitats - creation of High (or higher) Distinctiveness habitat is rarely successful on development sites as long-term certainty of specialist ecological management cannot be provided (unless that organisation/body is agreed by the LPA and stated in a S106 or equivalent).
Note - any existing High (or higher) Distinctiveness habitat should be retained through the appropriate Design stage so is not considered replaceable through Net gain for biodiversity in Leeds – most High (or higher) value habitats will accord with UKBAP Priority Habitats and be afforded protection through Core Strategy Policy G8 as mentioned earlier in the Guidance.
There must not be more than one step change in the Condition of habitats being provided through enhancements i.e. Moderate to Fairly Good but not Moderate to Good – this will keep the assurance of delivery more realistic and achievable. More than a one-step change in Condition may be possible subject to discussion with the LPA and would usually need to involve appointment of a specialist nature conservation body or long-term management to be delivered by a specialist ecological contractor with proven history/accreditation in management of such habitats – evidence of the appointment of the agreed body/contractor will be required.
All calculations (and associated justifications) using the Biodiversity Metrics must be submitted as part of the EcIA report.
Special note – Ecological SUDS
Designing open ground SUDS to provide some water all year round through over-deepening, and gently shelving sides below the water level for aquatic plant establishment is encouraged and will score considerably higher through the Biodiversity Metric calculator than the traditional solution of concrete tanks below ground. Open-ground SUDs with some standing water also have a role in carbon sequrestration through accumulation of silt so contribute positively to the Climate Change Emergency declared by the Council in April 2019, whereas the carbon footprint of creating a large concrete structure underground will be substantial.
Most Householder applications (extensions, alterations to small domestic dwellings) will not be required to achieve Net gain for biodiversity through use of Biodiversity Metric calculations at this stage. Applications for new single dwellings (or possibly other small applications where it has been agreed that Biodiversity Metric calculations will not be applied due to very low ecological baseline value) will still be expected to demonstrate general biodiversity enhancements by provision of integral bat roosting features and integral bird nesting features as per Guidance for Bat Roosting and Bird Nesting Features – this is in-line with the NPPF Guidance July 2019 para. 23 which refers to Swift Bricks and bat boxes.
The LPA wants to encourage high quality biodiversity enhancements on-site and will scrutinise applications that do not appear to have sufficiently demonstrated this though the input of an Ecological Consultant at the Design stage of the layout. However, it is acknowledged that there will be times where a 10% Net gain for biodiversity cannot be delivered on-site. Where it has been demonstrated that it is not possible to achieve a 10% Net gain for biodiversity on-site there will need to be consideration of off-site measures – it should be noted that by designing the layout through input of an Ecological Consultant, to deliver on-site biodiversity enhancements, there should be a smaller requirement for compensation off-site.
The LPA does not have to offer to take on responsibility of delivering the off-site Net gain (as per Option 2 below) instead of the developer – it should be the responsibility of the developer to try and deliver the Net gain even if it requires purchase of land to deliver the off-site requirements. However, in order to try and facilitate development in Leeds the LPA is considering how it can provide a role in this process that does not hold up planning applications whilst also considering its statutory Biodiversity duties under the Natural Environment and Rural Communities Act (NERC Act 2006) and the NPPF (and emerging Environment Act).
Therefore, we are in a transitional period where the LPA may not be able to fulfil Option 2 below (until a Habitat Bank and Delivery Partner/s have been identified) and therefore if Option 2 is being considered the EcIA report submitted should fully cost out the possible scenario below and confirm in writing whether the developer is willing to fund this option, and then seek confirmation with the LPA whether this can be agreed. Other options are for the developer to purchase or use other land they own in Leeds (provided it is in a strategic ecologically-beneficial location agreed by the LPA) or approach a third party Habitat Bank (again ensuring any land to be used is in a strategic ecologically-beneficial location agreed by the LPA).
The LPA is currently investigating setting up a formal Net gain for biodiversity system (backed by SPD, Policy and/or the Environment Act) but until this has been set up the LPA may accept one of the following two Options where 10% Net gain for biodiversity cannot be achieved on-site:
Option 1 Off-site land under control of the applicant can be used for Net gain for biodiversity provided it (all the bullet points should apply):
Option 2 A Net gain for biodiversity Sum (Biodiversity Credit) is calculated based on the Biodiversity Units required for the LPA or another third party Habitat Bank (to be approved by the LPA) to take on responsibility to deliver the Net gain for biodiversity Works through biodiversity projects/measures in line with the following (all the bullet points should apply):
A Monitoring fee will be payable to the LPA where delivery of the compensation is to take place off-site as per Option 1 (third party land) or Option 2 (purchase of Biodiversity Credits) - this amount will be 10% of the Net gain for biodiversity Sum agreed and be in addition to that Sum.
Where Option 2 (Biodiversity Credit) is the chosen approach, there will also need to be facilitation of delivery by the Council (or third party Habitat Bank) which will be an additional 10%.
The LPA (or third party Habitat Bank) will need to facilitate and monitor the Net gain for biodiversity Works (off-site) – this will involve keeping an audit and map of where Biodiversity Units have been lost and what Works are delivered in different locations provide the Net gains for Biodiversity (a Biodiversity Offsetting Spreadsheet and GIS linked map system). Where the LPA is taking on responsibility for off-site Net gain (Option 2) it will need to work with Delivery Partners and ensure Biodiversity Delivery Agreements are in place before funding is passed to the relevant Delivery Partner. The Biodiversity Delivery Agreement will include periodic reporting from the Delivery Partner to the LPA against the relevant Works to be implemented in the Biodiversity Delivery Agreement.
The LPA will also be responsible (along with other relevant Partners) for producing and revising the Leeds Local Nature Recovery Strategy which will clearly state the Biodiversity Priorities for the Leeds District – a draft version will be available on request. There may also be the need to refine the Leeds Habitat Network map (together with any Extensions at Neighbourhood Plan level) and identify Priorities/Opportunities on a map that forms part of the Local Nature Recovery Strategy (as referred to in the Environment Bill).
In order to also contribute towards strategic West Yorkshire biodiversity projects there will be an additional 5% sum. This will be used for projects such as delivering landowner advice to Local Wildlife Site owners and will be allocated at the discretion of the LPA.
Additional sums for each off-site Option summarised below:
Option 1 – 15% for monitoring (10%) and strategic biodiversity projects (5%)
Option 2 – 25% for monitoring (10%), facilitation (10%) and strategic biodiversity projects (5%)
A Section 106 Agreement will be used to transfer payment from the developer to the LPA and deliver Net gains for Biodiversity Off-site (Options 1 and 2).
It should be noted that once the LPA has set up a formal Net gain for biodiversity system (backed by SPD, Policy and/or the Environment Act) it is likely this will require on-site Net gain to also be monitored – and therefore an additional sum may also be required for monitoring the on-site Net gain delivery
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