Biodiversity Net Gain Supplementary Planning Document

Biodiversity Net Gain SPD

Chapter 1: Introduction


1.1 Supplementary Planning Documents (“SPDs”) add further detail to policies contained within the development plan and are used to provide guidance on specific sites or particular issues. SPDs do not form part of the adopted development plan but they are a material planning consideration in decision taking.

Aims and Objectives

1.2 This SPD provides guidance on achieving Biodiversity Net Gain (BNG) from any new development. BNG is achieved when a development leads to an overall increase biodiversity relative to the site beforehand. This Biodiversity Net Gain SPD sets out how this can be achieved in Coventry using established methods.

1.3 The purpose of this SPD is to provide information regarding how developers are able to deliver BNG and what contributions may be required. The circumstances and mechanisms for providing BNG are set out including how any financial contribution will be agreed and appropriate projects delivered.

1.4 This SPD is designed to assist prospective developers and applicants by providing guidance on how proposals can demonstrate they have met the requirements of planning policy related to biodiversity net gain in Coventry. By providing this information upfront Coventry City Council intends to provide additional clarity in the development process and ensure negotiating obligations is based on a clear and consistent approach.

Chapter 2: Context


2.1 “Biodiversity is the variety of all life on Earth. It includes all species of animals and plants, and the natural systems that support them. Biodiversity matters because it supports the vital benefits we get from the natural environment. It contributes to our economy, our health and wellbeing, and it enriches our lives”[1]

2.2 Across the country Biodiversity is being lost and it is accepted that this loss must be reversed before the impact becomes unsustainable[2] .

2.3 Coventry is a largely urban area but does include a number of significant wildlife sites. Community surveys in Birmingham city have found over 2,300[3]  species of plants and animals (iNaturalist, June 2022) and the total number is likely to be significantly higher. Whilst Coventry has less volume of community biodiversity surveys than Birmingham currently, it is reasonable to assume that it will have similar biodiversity.

1. UK Biodiversity Indicators 2021 Revised, DEFRA, 2021 [back]
2. Biodiversity 2020: A strategy for England’s wildlife and ecosystem services, DEFRA, 2011 [back]
3. [back]

Biodiversity net gain

2.4 Biodiversity Net Gain delivers measurable improvements for biodiversity by creating or enhancing habitats in association with development. Biodiversity net gain can be achieved on-site, off-site or  through a combination of on-site and off-site measures. The delivery of on-site measures, made accessible to existing and new residents, is the Council’s preferred outcome.

2.5 Developments may deliver biodiversity gain by:

a. Providing enhancements to habitats and wildlife on site
b. Providing enhancements to agreed sites elsewhere
c. Purchasing biodiversity credits

2.6 The required gain in the Environment Act is a minimum of 10%[4]  with sites managed for a period of not less than 30 years. Research has shown that in practice biodiversity will continue to decrease unless development provides significantly greater gain and that sites managed for longer periods[5] . Coventry is developing a network of different biodiversity offset sites where net gain can be achieved cost-effectively (Appendix 3). The network will be extended as further opportunities arise.

4. Environment Bill 2021 [back]
5. Implementation Gap between the Theory and Practice of Biodiversity Offset Multipliers, Bull, J.W. et al, Conservation Letters, 2017 [back]

Chapter 3: Relevant Policy and Legislation

National Policy Context

3.1 Section 40 of the Natural Environment and Rural Communities Act 2006 includes a requirement for local authorities regarding biodiversity (the Biodiversity Duty). The Environment Act 2021 (Section 102) includes a revision such that there is a new requirement to enhance biodiversity in all activities.

3.2 The Government's National Planning Policy Framework[6]  has at its heart the core principle of sustainable development and set out a number of requirements related to the securing of biodiversity net gain through the planning system. The key sections of the NPPF that are relevant to biodiversity are:

a. Section 8: healthy and safe communities
b. Section 15: conserving and enhancing the natural environment.

3.3 These sections contain important policy requirements; the following paragraphs are notable:

3.4 Paragraph 8c sets out that sustainable development has an environmental objective –

“to protect and enhance our natural, built and historic environment; including making effective use of land, improving biodiversity, using natural resources prudently, minimising waste and pollution, and mitigating and adapting to climate change, including moving to a low carbon economy.”

3.5 Paragraph 102 refers to Local Green Space, areas of land with particular importance including “richness of wildlife”. Related policies should be consistent with policies for the Green Belt

3.6 Paragraph 174 states that through planning policy and planning decisions, the natural environment should be enhanced by ‘minimising impacts on and providing net gains for biodiversity including by establishing coherent ecological networks that are more resilient to current and future pressures

3.7 Paragraph 179 provides specific advice on habitats and biodiversity. In particular section b) states that development plans should ‘identify and pursue opportunities for securing measurable net gains for biodiversity’.

3.8 Paragraph 180 relates to determining planning applications. Section a) establishes the principle that Local Authorities should refuse permission if significant harm to biodiversity cannot be avoided or properly mitigated.

6. Ministry of Housing, Communities and Local Government, July 2021 [back]

National Planning Practice Guidance

3.9 The Government’s National Planning Policy Guidance[7]  explains the key issues in implementing the natural environment policies. The PPG provides advice on what ecological information should be included in an application and the use of planning conditions (Paragraph 018 Reference ID: 8-018- 20190721). The guidance provides a definition of net gain (Paragraph: 020 Reference ID: 8-020- 20190721) and how this can be achieved (023 Reference ID: 8-023-20190721)

7. Department for Levelling Up, Housing and Communities and Ministry of Housing, Communities & Local Government, July 2019 [back]

Local Plan policy Coventry Local Plan (2017)

3.10 Policy DS4 (Part A): General Masterplan principles:

  • Sympathetically integrate existing landscape, biodiversity and historic features of the site into the development taking opportunities to protect, enhance and manage important features along with mitigation and enhancement measures to provide satisfactory compensatory provisions where appropriate

3.11 Policy GE1: Green Infrastructure:

  • New development proposals should make provision for green infrastructure to ensure that such development is integrated into the landscape and contributes to improvements in connectivity and public access, biodiversity, landscape conservation, design, archaeology and recreation
  • Ensuring that a key aim of green infrastructure is the maintenance and improvement and expansion of biodiversity

3.12 Policy GE3: Biodiversity, Geological, Landscape and Archaeological Conservation (See Appendix 1)

  • Sites of Special Scientific Interest (SSSIs), Local Nature Reserves (LNRs), Ancient Woodlands, Local Wildlife and Geological Sites will be protected and enhanced. Proposals for development on other sites, having biodiversity or geological conservation value, will be permitted provided that they protect, enhance and/or restore habitat biodiversity

Chapter 4: Achieving Biodiversity Net Gain


4.1 The delivery of biodiversity net gain requires that any development delivers more and better quality biodiversity than would exist without development taking place. Applicants are expected to demonstrate how their proposals meet the policy requirements of the Local Plan by providing clear information that sets out how biodiversity will be improved

4.2 To demonstrate how proposals meet policy requirements applicants should:

a. Undertake an ecological assessment of the habitat and key biodiversity features of the site;
b. Use a recognised metric (see paragraph 4.12) to assess the biodiversity value of the site and
the impact of the proposed development; and

c. Agree appropriate mitigation for any impact of the development by ensuring that overall the
number of biodiversity units is increased.

4.3 All planning applications will be required to submit a biodiversity gain plan[8]  which provides information on the site and details how biodiversity will be enhanced. The required amount of information submitted with the application will vary according to the application, see Table 1

Table 1: Information required by applications

Type of application

Required information


No information required.

Any mitigation is likely to be provided onsite through enhancements such as bat boxes, swift bricks and wildlife-friendly planting.

An application which includes appropriate enhancements will be preferred.


Ecological survey with metric and details of proposed mitigation.

An application that uses the Council’s planning pre-application service may be advised that full information is not required, e.g. for sites with minimal biodiversity interest.


Ecological survey with metric and details of proposed mitigation

Ecology information regarding net gain is independent of any information regarding legally protected species. All developments which may adversely impact on protected species (e.g. bats, badgers, great crested newts) are required to submit appropriate information with the application.

8. Environment Act 2021 Schedule 14, Part 2,14 [back]

Ecological surveys

4.4 To inform the net gain calculations ecological surveys should be undertaken at the appropriate time of year (see Appendix 2). The following survey information and assessment is required to complete the calculation:

  1. Area of each habitat and length of each linear feature present within the red line of the
  2. Habitat type according to the UK Habitat Classification[9]  or other nationally recognised classification, including indicator species (with reference to the guidance provided by Warwickshire Habitat Biodiversity Audit);
  3. Habitat condition;
  4. Impact from development based upon current planning layout, both directly onsite, and indirectly offsite; and
  5. Onsite biodiversity mitigation and compensation measures.

4.5 The survey should include the whole of the development boundary (red line) and adjacent land where direct or indirect impacts upon adjacent habitats are anticipated.

4.6 The evaluation of habitats recorded on site should be undertaken with reference to the Warwickshire and Coventry Local Wildlife Site selection criteria. Habitats that meet the selection criteria thresholds should normally be of ‘County’ value and of ‘High or Very High distinctiveness’.

4.7 Habitat Condition should be assessed in accordance with the guidance provided with the relevant metric or subsequent guidelines. When assessing any habitats not covered by this guidance, developers and their advisors will be expected to apply evidence based professional judgement and submit any assessment in a written form.

4.8 If the biodiversity value of a site has been lowered by any activity after 30th January 2020[10]  (other than with planning permission) with the resulting loss of habitats in advance of a biodiversity metric calculation being undertaken the baseline for the metric is to be taken as the habitats present prior to site clearance. The biodiversity value of the habitats lost is to be estimated based upon a desk-based assessment and professional judgement. The precautionary principle[11]  is to be applied where the distinctiveness or condition of the habitats lost is uncertain.

9. UK Habitat Classification [back]
10. Environment Act 2021 Schedule 14 Part 1, 6a [back]
11. "Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation" Rio Declaration on Environment and Development 1992 [back]

Biodiversity Impact Assessment

4.9 The Warwickshire Biodiversity Impact Calculator has been in established use in Coventry for a number of years. The metric has been used for a large number of developments and led to successful biodiversity mitigation projects. The DEFRA metric is more recent and will fully replace the Warwickshire BIA and a separate version is available for small-scale developments. All new applications will use the most recent DEFRA metric. Coventry CC will accept the Warwickshire metric where this is a revision of the BIA originally submitted for a development prior to the adoption of this SPD. See Appendix 4 for further details of the available metrics.

Irreplaceable habitat

4.10 Sites which include areas of irreplaceable habitat are excepted from the BNG policies and are unable to use any metric to assess the biodiversity value of these areas. If a site does include areas of such habitat and development were acceptable a bespoke agreement with the Council regarding appropriate mitigation would be required. Any site which includes both irreplaceable habitat and other wildlife habitats should use the metric on the other habitats. The DEFRA list of irreplaceable habitats will be used.

Sites with low biodiversity

4.11 Certain habitats (e.g. buildings and hardstanding) are considered to have zero biodiversity value. Such sites will be expected to demonstrate an overall improvement in biodiversity in order to meet relevant Council Local Plan policies (Policy GE3). The Council will advise on any requirement for ecological survey and agree appropriate biodiversity enhancement sufficient to provide an overall net gain. Features such as green walls, green roofs, containers and bird/bat boxes will provide appropriate benefits.

Agreeing mitigation

4.12 If an impact on an ecological asset is identified, applicants must propose how that impact will be avoided, mitigated, or compensated for in accordance with the mitigation hierarchy.

4.13 Where mitigation or compensation is proposed, habitat creation proposals, both on and offsite, should avoid ‘down trading’ of habitat value by proposing to create habitats of lower distinctiveness than those lost. Any proposed change in habitat must be agreed beforehand, applicants are encouraged to discuss provision of alternative habitats with the Council at the earliest opportunity. It is accepted that in within the urban area of Coventry habitats such as biodiverse roofs, green walls or wildlife-friendly landscaping may provide significant benefits particularly when these are associated with other existing or planned schemes.

4.14 Habitat creation proposals must be additional to any existing obligations and not deliver something that would occur anyway (for example through an existing planning permission, Forestry Commission grant or Environmental Stewardship scheme).

4.15 All proposals to deliver Biodiversity Net Gain through on-site and off-site habitat creation must be:

  1. In compliance with forthcoming British Standard BS 8683 (Process for designing and implementing Biodiversity Net Gain) (;
  2. Agreed in advance with the LPA;
  3. Evaluated through the use of the Biodiversity Metric;
  4. Secured by an appropriate agreement to ensure long term management;
  5. Be supported by a monitoring and management plan (adaptive management plan);
  6. Included on an offset register; and
  7. Monitored and reviewed.

Provision of BNG

4.16 Coventry City Council has sufficient biodiversity offset sites to meet the expected demand in coming years. Sites have been identified in all parts of the city and provide for the long-term Draft Biodiversity gain SPD December 2021 creation and management of a range of different habitats. These sites will be added to the Biodiversity gain site register when this is available (anticipated Spring 2023). Developments will normally be expected to contribute any offsite mitigation required within this scheme by way of a Section 106 contribution. Alternative methods of providing adequate offset through third party schemes or the purchase of Biodiversity Credits will also be considered acceptable in principle. However, each case will be looked at and assessed on its individual merits as to the level of offsetting which will be required and accepted by the LPA.

4.17 In order to establish that it is feasible for on and/or off-site habitat creation/enhancement proposals to deliver a net gain for biodiversity developers will be expected to submit detailed, worked up proposals, with the expectation that sites provided within the boundary of the City.

4.18 Details of the design, location and extent of any habitat creation proposed will be required. Where offsite habitat creation is proposed it is particularly important that sufficient detail is submitted to reassure the Council that it is feasible that suitable provision can be delivered and maintained in the long term. Developers are encouraged to seek independent professional advice to ensure their proposals meet this requirement and are strongly recommended to make use of the planning Pre-application service. Any offsite mitigation would be secured by a Section 106 agreement, see Appendix 5.

4.19 Where compensation is targeted at a specific species, off site compensation must be delivered in an area where this species is known to occur. Desk and field-based assessments may be required to establish this

4.20 Where off-site habitat provision is necessary, this should be directed to the following areas:

  1. areas identified by the Ecological Network Map as delivering the most benefit for biodiversity (Core Areas, Corridors and Steppingstone, Restoration areas)
  2. any designated Wildlife Corridors shown in neighbourhood plans
  3. areas identified in Local Nature Recovery Strategies.

4.21 Habitat creation in these strategically important sites will deliver a greater benefit for biodiversity and so potentially less habitat creation will be required to achieve the same biodiversity benefits.

4.22 There is no requirement for compensatory habitats to be subject to public access. However public access is encouraged where this can occur without being detrimental to the value of the habitats created. All of the offset sites within the Coventry scheme include appropriate access and promote community involvement in the sites.

Habitat Banking

4.23 If a developer wishes to rely on habitat created by a Habitat Bank, this habitat would usually be in place in advance of a planning application being submitted. Habitat banking is an instrument that can be used to deliver compensation by implementing and pooling compensatory measures in advance of a development, enabling developers to purchase credits from established compensation schemes (habitat banks) to offset their impacts. Credits in the context may be earned through measures to conserve both habitats and species.

4.24 Any application which provides an excess of biodiversity units within a development may use these to offset any future projects within Coventry within a two-year period. Any such approach must be agreed beforehand with the LPA with information regarding future development projects provided. Future developments would need to provide an appropriate impact assessment and Draft Biodiversity gain SPD December 2021 offset any excess biodiversity loss. Developments are not able to use potential future projects to offset current proposals.

Biodiversity Net Gain and stacking/additionality

4.25 Where biodiversity enhancements are required for other purposes (e.g., protected species schemes) these projects will not contribute to BNG offset. For such projects to contribute to BNG they will have to demonstrate additional benefits which are above and beyond any required by other schemes.

Chapter 5: Appendices

Appendix 1: Local Plan policy GE3

Policy GE3: Biodiversity, Geological, Landscape and Archaeological Conservation

  1. Sites of Special Scientific Interest (SSSIs), Local Nature Reserves (LNRs), Ancient Woodlands, Local Wildlife and Geological Sites will be protected and enhanced. Proposals for development on other sites, having biodiversity or geological conservation value, will be permitted provided that they protect, enhance and/or restore habitat biodiversity. Development proposals will be expected to ensure that they: 

    a) lead to a net gain of biodiversity, where appropriate, by means of an approved ecological assessment of existing site features and development impacts;

    b) protect or enhance biodiversity assets and secure their long-term management and maintenance;

    c) avoid negative impacts on existing biodiversity; and

    d) preserve species which are legally protected, in decline, are rare within Coventry or which are covered by national, regional or local Biodiversity Action Plans

  2. Where this is not possible, adequate mitigation measures must be identified. If mitigation measures are not possible on site, then compensatory measures involving biodiversity offsetting will be considered, but only in exceptional circumstances.
  3. Biodiversity will be encouraged particularly in areas of deficiency, in areas of development and sustainable urban extensions, and along wildlife corridors. Opportunities will be sought to restore or recreate habitats, or enhance the linkages between them, as part of the strategic framework for green infrastructure. Protected Species, and species and habitats identified in the Local Biodiversity Action Plan (LBAP), will be protected and conserved through a buffer or movement to alternative habitat. Identified important landscape features, including Historic Environment assets, trees protected by preservation orders, individual and groups of ancient trees, ancient and newly planted woodlands, ancient hedgerows and heritage assets of value to the locality, will be protected against loss or damage. In the case of archaeological remains, all practical measures must be taken for their assessment and recording in accordance with Policy HE2

Planning legislation places a biodiversity duty of care on all local and public authorities, emphasising that development plan policies and planning decisions should be based upon uptodate information about the environmental characteristics of their area. These characteristics include the relevant biodiversity and geological resources of the area. In reviewing environmental characteristics, the Council will continue to assess the potential to sustain and enhance these resources.

Connectivity between sites and buildings, and resilient and robust ecosystems, which are adaptable to change, are essential to ensure retention of existing levels of biodiversity and to enable these to be enhanced wherever possible. As part of new developments this could be achieved through well designed gardens, green roofs or landscape features. Resilient and functioning ecosystems support  a range of human population needs, including flood management, control of atmospheric pollution, and access to green space.

In order to restore good levels of biodiversity across the Warwickshire, Coventry and Solihull subregion, it is important to have urban areas that are permeable for wildlife, with havens for wildlife through the city and connected corridors linking sites. Green infrastructure planning and implementation can contribute strongly to fulfilling this. Biodiversity will be promoted as a core component of sustainable development and landscapes for living, underpinning social, health, environmental and economic benefits, together with community wellbeing and local quality of life.

All development proposals will be expected to avoid negative impacts on existing biodiversity. Where this is not possible, mitigation measures should be identified, if these are not possible on site, then these should be offset elsewhere as a compensatory measure, but only in exceptional circumstances. Such circumstances may include the comprehensive delivery of a planned strategic allocation in accordance with a Council approved Masterplan. In all such cases though, compensatory provisions should be made as close to the original site as possible. In this instance development proposals should be guided by the Council's approach to biodiversity offsetting as set out in the Green Infrastructure Strategy, or any subsequent update to this document and national policy. In all instances, the long-term management and maintenance of ecological features must be demonstrated. In order to assist in ecological assessments, the Warwickshire Biological Records Centre should be consulted.

Appendix 2: Survey Season

Survey Season


Appendix 3: Coventry Offset Sites

The table below shows sites that have already been identified as providing opportunity for
biodiversity enhancement and where potential projects have been identified.

Additional sites will continue to be added where the location is appropriate and site management
allows an increase in biodiversity value, these may include smaller areas within existing open

The DEFRA metric will be used to assess the value of any site prior to any biodiversity projects to
ensure that there is an overall net gain.

Offset opportunity

Area (ha)


Habitat creation sites


Elm Farm


Agricultural site, opportunity for woodland, meadow and other habitats

Habitat enhancement sites


Leaf Lane





Woodland and meadow



Wet woodland, scrub, marsh grassland, river corridor

Leaf Lane2






Palmer Lane


Urban habitat

West Academy


Woodland and ponds (great crested newt)



Woodland, marsh, wetland

Bell Green




Appendix 4: Biodiversity metric

The change in biodiversity due to development is calculated using the most recent version of the DEFRA metric. The Warwickshire Metric will be accepted for older applications where this metric was submitted.

DEFRA metric

‘Biodiversity Metric 3.0 can be used or specified by any development project, consenting body or landowner that needs to calculate biodiversity losses and gains for terrestrial and/or intertidal habitats. It will be this metric that underpins the Environment Bill’s provisions for mandatory biodiversity net gain in England, subject to any necessary adjustments for application to major infrastructure projects.’

The metric provides a value for the biodiversity value of a site before development and the result of habitats lost and created during development. The metric shows what areas of replacement habitat must be created to offset any loss and considers the location of any offset. The metric does not include any financial estimates

The metric can be freely downloaded (current version 3.1, April 2022):



Appendix 5: Example S106 agreement

Biodiversity Contribution:

means the sum of [£XXXX] payable to the Council towards the enhancement of biodiversity within the area ecologically connected to the Development;

Commencement of Development:

means the carrying out in relation to the Development of any material operation as defined by section 56(4) of the Act (and the phrase “Commence Development” shall be construed accordingly) [but disregarding for the purposes of this deed and for no other purpose, the following operations: site clearance; ground investigations; site survey works; temporary access construction works; archaeological investigation; and erection of any fences and hoardings around the Land];

  1. Biodiversity Contribution
    1. The Owner covenants to pay to the Council the Biodiversity Contribution on or before Commencement of Development.
    2. The Owner will not Commence Development until the Biodiversity Contribution has been paid to the Council.

Example biodiversity loss schedule

Biodiversity Impact Assessment:

Means the use of the most current and locally adopted Defra Biodiversity Offsetting Metric to calculate the biodiversity impact of the scheme measured in Biodiversity Units;

Biodiversity Loss:

Means a negative Biodiversity Unit score;

Biodiversity Offsetting Scheme:

Means a scheme which will deliver biodiversity enhancements which shall not be less than the Biodiversity Impact Assessment score;

Biodiversity Unit:

Means the product of the size of an area, and the distinctiveness and condition of the habitat it comprises to provide a measure of ecological value;

Defra Biodiversity Offsetting Metric:

Means the Defra mechanism to quantify impacts on biodiversity that allows biodiversity losses and gains affecting different habitats to be compared and ensure offsets were sufficient to compensate for residual losses of biodiversity;

Ecology Contribution:

Means the sum payable in accordance with Schedule 1;


5.2 The Owner covenants as follows;

5.3 1.1 The approved application shall not result in a Biodiversity Impact Assessment score greater than – (xx) Biodiversity Units or such other number as may be agreed with the Council

5.4 1.2 Prior to the Commencement of Development, the Owner shall submit a Biodiversity Offsetting Scheme to the Council for its approval in writing.

5.5 1.3 The Owner shall not Commence Development until a Biodiversity Offsetting Scheme has been submitted to and approved in writing by the Council.

5.6 1.4 The Biodiversity Offsetting Scheme shall be approved by the Council with the purpose of ensuring that the Development does not result in a Biodiversity Loss in accordance with the National Planning Policy Framework

5.7 1.5 The Scheme shall include a management plan for the provision and maintenance of offsetting features on the Land for not less than 30 years from the date of implementation. Where the offsetting features do not fully offset the (-xx) Biodiversity Units the residual loss shall be offset by a fixed sum contribution to the Council assessed using an agreed Biodiversity Impact Assessment metric;

5.8 1.6 The Biodiversity Offsetting Scheme shall provide for one of the following:

5.9 1.6.1 Confirmation that an area of land has been made available to offset a maximum of -xx Biodiversity Units of Biodiversity Loss on the Land; or

5.10 1.6.2 Where no land has been made available, provide for a fixed sum contribution to be paid to the Council. The sum shall not exceed £(xx.xx) and the Council will use the contribution to enhance and secure the long-term management of biodiversity of sites within the [DETAILS OF AREA WITHIN WHICH THE CONTRIBUTION IS TO BE USED]. or

5.11 1.6.3 The required number of Biodiversity Credits have been purchased

5.12 1.7 Once the Biodiversity Offsetting Scheme has been implemented, the Owner shall not carry out any changes to the Biodiversity Offsetting Scheme without the written consent of the Council.