CIVITY NGE Blog

Biodiversity Net Gain (BNG) became mandatory for Nationally Significant Infrastructure Projects (NSIPs) in England on 2 November 2026. Developers submitting a Development Consent Order (DCO) application on or after this date must demonstrate how their project will deliver at least a 10% increase in biodiversity value, using the statutory biodiversity metric and an outline Biodiversity Gain Plan. This marks a significant change for major infrastructure projects, bringing biodiversity requirements into the development consent process for nationally significant schemes. Developers must now consider habitat loss, ecological enhancement and biodiversity unit requirements from the earliest stages of project design. For projects where on-site habitat creation cannot deliver the full biodiversity requirement, off-site biodiversity units provide an alternative route to compliance. Through Civity’s Biodiversity Net Gain services for developers, project teams can identify suitable off-site units using their completed biodiversity metric calculations and explore available habitat bank options. Understanding the new requirements is essential for managing development costs, planning applications and long-term environmental obligations. What Has Changed for Biodiversity Net Gain on Nationally Significant Infrastructure Projects? From 2 November 2026, developers applying for a Development Consent Order for an eligible Nationally Significant Infrastructure Project in England must demonstrate how they will achieve at least 10% Biodiversity Net Gain. The requirement is integrated into the development consent process, with applicants expected to provide ecological calculations, an outline Biodiversity Gain Plan and a strategy for delivering the necessary improvements. Mandatory BNG was introduced for most major developments under the Town and Country Planning Act framework in February 2024, with requirements subsequently extended to smaller developments. However, Nationally Significant Infrastructure Projects operate under a separate consenting system established by the Planning Act 2008. The Environment Act 2021 introduced the legislative framework for extending mandatory BNG to these projects. Schedule 15 amended the Planning Act 2008, creating specific requirements for biodiversity improvements associated with nationally significant development. The new rules mean that developers must demonstrate how biodiversity will be protected, enhanced and managed alongside the delivery of essential infrastructure. The government’s guidance on BNG for Nationally Significant Infrastructure Projects explains how these requirements apply throughout project design, consenting, construction and operation. Importantly, the commencement date relates to DCO applications submitted on or after 2 November 2026. Projects with earlier applications are not automatically brought into the mandatory regime simply because construction or examination continues beyond that date. Which Nationally Significant Infrastructure Projects Must Deliver BNG? Mandatory Biodiversity Net Gain applies to eligible Nationally Significant Infrastructure Projects with development in England where a Development Consent Order application is submitted on or after 2 November 2026. This includes major infrastructure schemes across sectors such as energy, transport, water resources and other development categories covered by the Planning Act 2008 and the relevant biodiversity gain statements. Examples of infrastructure that may fall within the NSIP consenting regime include major road and rail developments, electricity generation and transmission infrastructure, airports, water infrastructure and certain other nationally significant facilities. Whether an individual project qualifies as an NSIP depends on its statutory category, scale and consenting route. The BNG requirement applies to the relevant English components of a project, including development extending into the intertidal zone as far as the mean low-water mark. Marine development beyond that boundary is outside the scope of the mandatory NSIP biodiversity gain objective. For projects crossing national borders, only the habitats within England are included in the mandatory BNG calculation. Any voluntary biodiversity improvements delivered outside England must be assessed separately and cannot be used to satisfy the English requirement. Developers should also distinguish between projects consented through the Planning Act 2008 and infrastructure authorised through other routes, such as Hybrid Bills, which are not covered by this particular mandatory BNG regime. The relevant biodiversity gain statement should be checked before preparing the DCO application, as it establishes the requirements applicable to the project. How Does the 10% Biodiversity Net Gain Requirement Work for NSIPs? The 10% Biodiversity Net Gain requirement means that the biodiversity value attributable to a qualifying infrastructure project must exceed its pre-development biodiversity value by at least 10%. Developers calculate this improvement using the statutory biodiversity metric, which measures habitat value through standardised biodiversity units rather than simply comparing the amount of green space before and after development. The metric considers habitat characteristics such as type, area, condition and strategic significance, alongside factors affecting habitat creation and enhancement. For example, an infrastructure project may involve the permanent removal of grassland, temporary disturbance to hedgerows and the creation of new habitats within the development boundary. Each relevant habitat contributes to the biodiversity calculation according to its characteristics and expected condition. The developer’s ecologist establishes the baseline biodiversity value and assesses the proposed post-development habitat value. If the proposed on-site improvements are insufficient to meet the required 10% increase, additional biodiversity units may be needed from suitable off-site habitat creation or enhancement. A project with a baseline of 100 area habitat units would need to demonstrate at least 110 units after the relevant metric adjustments. This is a simplified illustration: actual calculations must also satisfy habitat trading rules and the separate requirements for different unit categories. Area habitats, hedgerows and watercourses are assessed separately within the statutory metric. A surplus of one unit type cannot automatically compensate for a shortfall in another. The statutory biodiversity metric tools and guidance provide the methodology that qualified ecological professionals must use. What Is an Outline Biodiversity Gain Plan for an NSIP? An outline Biodiversity Gain Plan is a document submitted with a Development Consent Order application that explains how a Nationally Significant Infrastructure Project will achieve the statutory 10% biodiversity gain objective. It sets out the project’s biodiversity baseline, proposed habitat improvements, potential off-site biodiversity requirements, delivery arrangements and how any remaining uncertainties will be managed. Unlike a final management document, the outline plan accommodates the fact that major infrastructure projects may still have design uncertainties during the consenting process. However, it must provide sufficient evidence for the Examining Authority and Secretary of State to understand whether the proposed development can meet its biodiversity obligations. The outline Biodiversity Gain Plan should include the biodiversity metric calculation, the BNG boundary plan, proposed on-site improvements and the intended approach to obtaining off-site units where required. Developers must also explain how they have applied the mitigation hierarchy and provide a realistic strategy for securing biodiversity gains. Where off-site delivery forms part of the approach, the plan should identify the types and quantities of units required, potential availability and arrangements for obtaining them. The application must also include proposed DCO requirements that secure delivery of the biodiversity gain objective. The government’s guidance on preparing DCO application documents confirms that an outline Biodiversity Gain Plan forms part of the application requirements from 2 November 2026. What Is a Biodiversity Gain Statement? A biodiversity gain statement is a government policy document setting out how a particular category of NSIP must calculate, deliver and report biodiversity net gain. The more detail that can be included in these statements, the better. The fact that many aspects will be unknown or subject to change as the project proposals progress is an understood component of these statements; what’s important is certainty of deliverability, subject to predictable deviations and error margins, not necessarily fixing finer details. These statements have the same effect as if they were included in the relevant National Policy Statement. They establish the requirements that developers must follow, while the outline of the Biodiversity Gain Plan demonstrates how an individual project intends to comply. The government has published biodiversity gain statements for different NSIP categories, including statements covering energy, national networks, airports and other infrastructure types. Developers should use the statement relevant to their project alongside the supporting government guidance. How Is the Biodiversity Baseline Calculated for Major Infrastructure Projects? The biodiversity baseline for an NSIP is calculated by assessing the pre-development biodiversity value of habitats within the relevant BNG boundary using the statutory biodiversity metric. This includes habitats within the Development Consent Order limits that will be negatively affected by construction or operation, as well as habitats that will contribute towards the project’s biodiversity improvements. The BNG boundary is not necessarily identical to the full DCO order limits. Order limits define the geographical extent of the powers sought through the Development Consent Order. The BNG boundary identifies the habitats that must be included in the biodiversity calculation. This distinction is particularly important for large infrastructure projects, where order limits may cover extensive landholdings, temporary construction areas and associated development. The baseline must include habitats subject to permanent or temporary loss, as well as habitats whose condition is expected to deteriorate. For example, a railway development may affect habitats through track construction, temporary compounds, access routes and operational maintenance. These impacts must be considered even where they occur outside the principal permanent infrastructure footprint. Conversely, habitats that will remain genuinely unaffected may be excluded from the baseline where the developer’s ecologist can justify their exclusion. Developers must provide a single biodiversity metric calculation for the NSIP, including associated development and separate project areas, even where the scheme spans several local planning authorities. How Should Developers Address Uncertain Project Designs? Major infrastructure schemes frequently involve route options, design flexibility and limits of deviation. Where the final extent of habitat impacts is uncertain, developers must use a realistic worst-case assessment based on the maximum design and construction parameters that could reasonably occur. This does not mean assuming that every habitat within the order limits will be destroyed. Instead, the assessment should reflect the greatest realistic habitat impact arising from the proposed development. For example, a road scheme with alternative alignments may need to assess the most ecologically significant realistic route while explaining how biodiversity requirements would be addressed if a different alignment is selected. These assumptions must be documented within the outline of the Biodiversity Gain Plan. Early ecological involvement can help project teams avoid unnecessary habitat loss, refine development boundaries and reduce the number of biodiversity units required. Why Must BNG Be Considered During the Early Design Stages? Biodiversity Net Gain should be incorporated into the earliest stages of NSIP design because habitat impacts, construction methods and land requirements directly affect the number and type of biodiversity units needed. Early consideration allows developers to avoid sensitive habitats, identify suitable enhancement opportunities and investigate off-site delivery before ecological constraints become expensive design or consenting problems. For major infrastructure projects, biodiversity considerations should inform route selection, site layout, construction planning and the management of temporary working areas. The mitigation hierarchy remains central to this process. Developers should first seek to avoid significant harm to biodiversity. Where impacts cannot be avoided, they should minimise those impacts and provide appropriate mitigation. Compensation is considered where residual harm remains. BNG operates alongside this hierarchy rather than replacing it. For example, a proposed transport corridor might be redesigned to avoid a valuable woodland or wetland habitat. Where avoidance is not possible, the project team may investigate alternative construction methods, habitat reinstatement or suitable compensation measures. The biodiversity metric can then help assess how different design options affect the overall BNG requirement. Early engagement with ecologists, local planning authorities, Natural England, the Planning Inspectorate and other relevant stakeholders can also help identify issues before the DCO application is submitted. This is particularly important where a project spans multiple administrative areas or involves habitats that are difficult to replace. Can NSIP Developers Use Off-Site Biodiversity Units to Meet BNG Requirements? Yes. Developers of Nationally Significant infrastructure projects can use off-site biodiversity units to meet some or all of their required biodiversity improvements where suitable habitat creation or enhancement cannot be delivered within the project boundary. Off-site units must satisfy the statutory biodiversity metric, habitat trading rules, legal security requirements and registration arrangements. For NSIPs, developers can consider on-site and off-site biodiversity delivery simultaneously. This provides flexibility for large projects where the physical infrastructure, construction activities or operational requirements limit opportunities for habitat creation. Off-site biodiversity units are generated through ecological improvements on land outside the development’s BNG boundary and order limits. These improvements may involve creating species-rich grassland, restoring wetlands, enhancing woodland or establishing other suitable habitats. Developers can obtain off-site units from third-party habitat banks or generate them on other land they own. However, off-site units must be appropriate for the biodiversity losses they are intended to address. The habitat type, distinctiveness, location and expected ecological condition all influence whether particular units are suitable. For developers exploring off-site Biodiversity Net Gain units for sale, identifying the required habitat categories early can help establish which opportunities are commercially and ecologically viable. How Do Habitat Banks Support Major Infrastructure Projects? Habitat banks are areas of land where habitats are created or enhanced to generate biodiversity units that can be allocated to developments. These sites are generally managed through long-term agreements with landowners and must meet the legal and registration requirements for off-site BNG. Habitat banks can provide an alternative where infrastructure projects have limited space for on-site biodiversity enhancements or require habitat types that cannot realistically be created within the development boundary. For example, a major energy project may need additional grassland or woodland units to address residual biodiversity requirements. A suitable habitat bank could provide those units through legally secured habitat improvements. The developer would still need to demonstrate that the units meet the project’s requirements and have been properly allocated. How Does the Spatial Risk Multiplier Affect Off-Site BNG Units? The spatial risk multiplier adjusts the contribution of off-site biodiversity units according to their location relative to the development. Units delivered within the relevant local planning authority, National Character Area or other applicable geographical boundary generally retain their full spatial value, while units located further away may be discounted. The multiplier encourages biodiversity improvements to be delivered near the habitats affected by development. For area habitats and hedgerows, the relevant geographical boundaries include local planning authority areas and National Character Areas. Watercourse units use waterbody and operational catchment boundaries, while intertidal units use Marine Plan Areas. For NSIPs, this becomes particularly important because large projects may extend across several geographical boundaries. Government guidance confirms that where an NSIP’s BNG boundary spans multiple relevant areas, off-site units from any of those areas can qualify without a spatial risk penalty. This can provide greater flexibility for linear infrastructure such as railways, roads and electricity transmission projects. However, purchasing units further away may result in a multiplier that reduces their contribution to the project’s biodiversity requirement. Developers should therefore compare more than the advertised price of biodiversity units. A lower-priced unit located further away may not provide the same effective biodiversity contribution as a unit closer to the development. The habitat type, location, trading rules and applicable multiplier should all be considered when evaluating off-site options. What Are the Habitat Trading Rules for NSIP Biodiversity Units? Habitat trading rules determine which biodiversity units can compensate for particular habitat losses. They prevent developers from replacing more ecologically valuable habitats with inappropriate lower-value alternatives and ensure that the biodiversity improvements delivered through BNG are consistent with the Statutory Metric’s ecological requirements. The rules distinguish between habitats according to their distinctiveness and other relevant characteristics. For example, the loss of a higher-distinctiveness habitat will require replacement through the same or similar habitat type depending on the trading rules for that distinctiveness band. Developers cannot assume that any available biodiversity unit will satisfy their project’s requirements. This is particularly relevant for infrastructure schemes affecting several habitat types across extensive development areas. A project may require a combination of grassland, woodland, hedgerow and watercourse units rather than one general type of biodiversity unit. The developer’s ecologist must identify these requirements through the completed statutory biodiversity metric. Civity can then use that information to help identify suitable off-site units and assess available options against the project’s requirements. This distinction is important: the developer’s appointed ecologist remains responsible for preparing the developer-side metric calculation, while Civity supports the identification and supply of appropriate off-site biodiversity units. Do Developers Need to Secure Off-Site Biodiversity Units Before Applying for a DCO? Developers do not generally have to purchase all off-site biodiversity units before submitting a Development Consent Order application. However, their outline Biodiversity Gain Plan must provide a credible strategy for obtaining the required units, including evidence of availability and suitable arrangements where off-site delivery is proposed. The amount of supporting evidence should reflect the scale and complexity of the biodiversity requirement. For example, a project requiring a relatively common habitat type may have several potential sources of off-site units. A project requiring substantial quantities of a scarce or high-distinctiveness habitat may need more detailed evidence that suitable units can realistically be secured. This could include discussions with habitat bank providers, evidence of available units or arrangements to reserve or create the necessary habitats. Government guidance warns that insufficient evidence of off-site unit availability may result in greater scrutiny during the consenting process. Developers should therefore avoid leaving biodiversity procurement until the final stages of project design. Although units can be purchased before development consent, their formal allocation to the NSIP takes place after consent. Early commercial discussions can help establish likely costs, identify suitable locations and allow for changes as the project design develops. How Are Biodiversity Gains Legally Secured and Maintained? Significant on-site biodiversity gains and off-site biodiversity units must be legally secured and managed for at least 30 years following completion of the relevant habitat enhancement works. Legal arrangements establish the responsibilities for habitat creation, management, monitoring and reporting, ensuring that the promised ecological improvements are maintained beyond the construction period. For significant on-site gains, NSIP developers may use DCO requirements, Section 106 planning obligations or conservation covenants, depending on the circumstances. Off-site gains require appropriate legal agreements and registration on the Biodiversity Gain Sites Register. A Habitat Management and Monitoring Plan (HMMP) sets out how habitats will be established, maintained and monitored. For example, a species-rich grassland project may require specific cutting or grazing regimes to achieve its target ecological condition. A wetland restoration scheme may require ongoing water-level management and monitoring of habitat development. The legal and management arrangements should clearly establish who is responsible for carrying out the required activities and providing monitoring reports. For large infrastructure projects, these obligations must be considered alongside long-term operational requirements, access arrangements and potential future changes to the site. The Government’s guidance on creating a Habitat Management and Monitoring Plan explains the information required to support long-term biodiversity delivery. What Happens After a Development Consent Order Is Granted? After receiving development consent, NSIP developers must implement the biodiversity strategy established in their outline Biodiversity Gain Plan and submit updated or phase-specific plans for approval before the relevant development works begin. These plans confirm the project’s biodiversity calculations, habitat proposals, secured gains and arrangements for obtaining any outstanding units. The updated Biodiversity Gain Plan reflects the greater certainty available after development consent has been granted. For example, detailed engineering work may establish the final construction footprint, reducing or increasing the expected habitat impacts. Where the biodiversity calculation changes, the developer may need to revise the number or type of off-site units required. Updated plans must explain relevant changes and provide supporting evidence. For phased developments, the project may use separate biodiversity gain plans for individual phases, while still demonstrating that the overall development will achieve the required 10% net gain. The applicable DCO requirements also establish how and when outstanding biodiversity units must be secured. Government guidance expects developers to secure as many units as reasonably possible before development or the relevant phase begins. Where substantial uncertainty remains, some outstanding units may be secured later under an agreed schedule. However, all required gains must be secured before the project begins operating. This makes ongoing coordination between the developer, ecological consultants and biodiversity unit providers particularly important. Can NSIP Developers Use Statutory Biodiversity Credits Instead of Off-Site Units? Statutory biodiversity credits are available as a last-resort option where an NSIP developer cannot achieve the required biodiversity improvement through on-site habitat measures or off-site biodiversity units. Developers must demonstrate why these alternatives are insufficient before relying on statutory credits to meet their BNG obligations. Statutory credits are sold by the government through Natural England and are different from biodiversity units generated by habitat banks. They are designed to provide a final compliance option rather than replace the private off-site biodiversity market. The statutory credit system includes a spatial adjustment, meaning developers must purchase two statutory credits for every one biodiversity unit required. This can make statutory credits a significant project cost. Developers considering this option must explain their reasoning in the outline Biodiversity Gain Plan and demonstrate that suitable on-site and off-site alternatives have been investigated. The Government’s statutory biodiversity credit pricing guidance provides the published prices for different habitat categories. Because prices and unit requirements vary, developers should calculate their likely costs using the relevant habitat types and current published rates rather than relying on a general estimate. How Can Developers Reduce BNG Costs and Planning Risks for NSIPs? Developers can reduce Biodiversity Net Gain costs and planning risks by integrating ecological assessments into early project design, avoiding unnecessary habitat loss, identifying suitable on-site improvements and investigating off-site biodiversity units before submitting their DCO application. A coordinated approach helps establish realistic costs and reduces uncertainty around habitat availability and delivery. One of the most important considerations is the relationship between development design and biodiversity unit demand. A design change that avoids the loss of a valuable habitat may reduce the number of replacement units required. Similarly, identifying suitable areas for habitat creation within the project boundary can reduce reliance on external biodiversity units. However, on-site habitat improvements must be compatible with the infrastructure’s operational requirements and capable of being maintained over the long term. For example, certain habitats may not be appropriate beneath infrastructure requiring frequent maintenance, unrestricted access or particular safety clearances. Off-site delivery can provide greater flexibility where these constraints limit ecological enhancement. Early engagement with biodiversity unit providers can also help developers understand the availability of suitable habitat types and the potential impact of spatial risk multipliers. Project teams should allow for biodiversity requirements within programme planning, procurement, land agreements and environmental budgets. For phased projects, biodiversity delivery should be coordinated with construction milestones and the timetable for securing outstanding gains. The objective is not simply to purchase the lowest-cost units but to establish a deliverable biodiversity strategy that meets the statutory requirements and supports the overall project programme. How Can Civity Support NSIP Developers With Off-Site Biodiversity Units? Civity supports developers by helping them identify and obtain suitable off-site biodiversity units using the habitat requirements established by their appointed ecologists. This includes assessing available habitat bank opportunities, considering geographical suitability and responding to changes in unit requirements as infrastructure projects progress through design and consenting. Civity are able to offer long-term reserves on biodiversity units with flexibility in the final payment. This allows for an approximate number of units to be reserved and cited in the Biodiversity Gain Statement, with the final transaction completing once consent is granted and the precise unit number is known. Civity can also offer bespoke land-finding services for units created to order, for instance where rare habitat types are needed and an appropriate offsite solution is not readily available on the market. For Nationally Significant Infrastructure Projects, the scale and complexity of biodiversity requirements can make off-site procurement an important part of the overall environmental strategy. Developers may require multiple habitat types across different locations, with the suitability of individual units affected by trading rules and spatial risk multipliers. Civity works with landowners to establish habitat banks and generate biodiversity units through ecological enhancement projects. Our ecologists assess landowner sites to identify habitat creation and enhancement opportunities, while our developer-facing services focus on matching available units with the requirements identified in completed biodiversity metric calculations. We can provide quotations for suitable units and review options as project requirements change. This flexibility can be valuable for major infrastructure projects where design changes, updated ecological information or revised construction plans affect the final biodiversity requirement. By considering off-site biodiversity delivery early, developers can gain a clearer understanding of available options before their DCO application is finalised. Prepare for Mandatory BNG Requirements With Civity The introduction of mandatory Biodiversity Net Gain for Nationally Significant Infrastructure Projects represents an important change to infrastructure planning in England. Since 2 November 2026, qualifying NSIP developers have been required to demonstrate how their projects will deliver at least a 10% increase in biodiversity value through the Development Consent Order process. This includes preparing an outline Biodiversity Gain Plan, calculating habitat impacts using the statutory biodiversity metric and establishing a credible strategy for securing and maintaining the necessary biodiversity improvements. For projects where on-site delivery cannot meet the full requirement, off-site biodiversity units offer a practical route to achieving the statutory objective. However, habitat availability, trading rules, spatial risk multipliers and long-term legal arrangements must all be considered before selecting suitable units. At Civity, we help developers explore off-site BNG options that align with their ecological requirements and project needs. Whether you are preparing an outline Biodiversity Gain Plan, investigating habitat bank availability or reviewing your project’s off-site unit requirements, early engagement can help identify suitable opportunities and support a more informed procurement strategy. Contact Civity to discuss your project’s Biodiversity Net Gain requirements and explore available off-site biodiversity units.

The government has announced a new Biodiversity Net Gain (BNG) exemption for brownfield residential developments on sites up to 1.5 hectares in England. Confirmed in the Autumn Budget on 28 October 2026, the proposed change aims to reduce development costs, simplify planning requirements and accelerate housing delivery on previously developed land. However, the exemption is not yet in force. The Government has confirmed its intention to introduce the change, but the final eligibility criteria, implementation timetable and supporting legislation have not yet been published. For developers planning residential projects on brownfield land, understanding the proposed exemption is important for managing planning applications, biodiversity requirements and future development costs. Until the new rules take effect, qualifying developments must continue to comply with existing BNG legislation. Developers who still require off-site biodiversity units can explore Civity’s Biodiversity Net Gain services for developers to understand the options available for meeting their planning obligations. What Is the New BNG Exemption for Brownfield Residential Sites? The new BNG exemption is a planned change to England’s planning regulations that will remove mandatory Biodiversity Net Gain requirements for qualifying residential developments on brownfield sites measuring up to 1.5 hectares. Announced in the Autumn Budget 2026, the exemption is intended to reduce the financial and administrative burden of developing previously used land. Under the existing Biodiversity Net Gain framework, most qualifying developments in England must deliver at least a 10% increase in biodiversity value. This is measured using the statutory biodiversity metric, which assesses the ecological value of habitats before and after development. Developers who cannot achieve the required improvement on-site may need to purchase off-site biodiversity units or, as a last resort, statutory biodiversity credits. The proposed brownfield exemption would remove this mandatory requirement for eligible residential schemes, potentially reducing ecological assessment, habitat delivery and biodiversity unit procurement costs. The Autumn Budget 2026 confirms the government’s intention to introduce the exemption as part of its wider strategy to support housebuilding. Which Brownfield Residential Developments Could Qualify? The proposed exemption is intended to cover residential developments on brownfield sites measuring up to 1.5 hectares in England. However, the government has not yet published the final legal definition of eligible developments, meaning developers cannot assume that every previously developed residential site below this threshold will automatically qualify. Brownfield land generally refers to previously developed land, such as former industrial premises, commercial sites or land previously occupied by buildings and associated infrastructure. However, the planning definition of previously developed land includes exclusions, and a site being described as brownfield does not necessarily establish eligibility for the proposed exemption. The government has indicated that the change will support both private and council housebuilding. Several important details remain unconfirmed, including how the exemption will apply to mixed-use schemes, developments involving multiple land parcels and sites containing ecologically valuable habitats. The final regulations will need to establish how qualifying residential development is defined and how the 1.5-hectare threshold is assessed. Developers should therefore avoid making assumptions about eligibility until the government publishes the detailed rules. When Will the Brownfield BNG Exemption Come Into Effect? The implementation date for the new brownfield BNG exemption has not yet been announced. Although the government confirmed the policy in October 2026, it has stated that the full consultation response, impact assessment and implementation timetable will be published in due course. This distinction is particularly important for developers with planning applications already being prepared or considered by local planning authorities. An announcement in the budget does not automatically amend the legislation governing mandatory biodiversity net gain. Until the relevant regulations take effect, developments that do not qualify for an existing exemption must continue to meet the current BNG requirements. The Defra consultation on a targeted brownfield residential exemption was published in April 2026. It sought views on the proposed exemption, appropriate site-size thresholds and how eligible developments should be defined. The Government confirmed in September that it was analysing the consultation responses, with a full response to follow. Developers should monitor the publication of that response and the subsequent legislation before changing their biodiversity strategies. How Does the Proposed Exemption Differ From Existing BNG Rules? The proposed brownfield exemption would introduce a specific exemption for qualifying residential developments on previously developed land up to 1.5 hectares. It differs from the existing exemption for developments of 0.2 hectares or less, which has applied to eligible planning applications submitted from 6 August 2026, provided they do not negatively affect on-site priority habitats. The existing 0.2-hectare exemption is not limited to brownfield residential development. It applies to qualifying developments that satisfy its statutory conditions. The proposed 1.5-hectare exemption would cover a larger area threshold but would be targeted specifically at brownfield residential sites. For example, a proposed housing development on a 0.15-hectare site may already qualify for the existing exemption if the relevant conditions are satisfied. A residential brownfield development covering 1 hectare would not qualify for that exemption based on site size alone but could potentially benefit from the new policy once implemented. The Government’s guidance on BNG exemptions explains the exemptions currently in force. The proposed change should not be confused with the separate introduction of mandatory BNG for Nationally Significant Infrastructure Projects, which took effect on 2 November 2026 under a different consenting framework. Why Is the Government Introducing a Brownfield BNG Exemption? The government is introducing the brownfield BNG exemption to support housing delivery by reducing costs and simplifying planning requirements for smaller residential developments on previously developed land. The policy reflects its preference for prioritising brownfield development while seeking to make the planning system more proportionate. Brownfield housing projects can involve additional costs associated with demolition, contamination, site preparation and existing infrastructure. Where mandatory BNG applies, developers must also assess the site’s biodiversity value and establish how the required ecological improvements will be delivered. For constrained sites, opportunities for on-site habitat creation may be limited, increasing reliance on off-site biodiversity units. Removing the mandatory BNG requirement for qualifying schemes could reduce these costs and administrative requirements. However, the policy also raises questions about its potential impact on nature recovery. Brownfield sites are not necessarily ecologically unimportant. Some previously developed land supports valuable grassland, scrub and open mosaic habitats that provide important conditions for wildlife. The final policy will need to clarify how the exemption interacts with existing ecological protections and planning safeguards. Will Brownfield Developers Still Need Ecological Surveys? Developers may still need ecological surveys even if their residential brownfield site becomes exempt from mandatory Biodiversity Net Gain. A BNG exemption would remove the statutory 10% biodiversity gain requirement for qualifying schemes, but it would not automatically remove other planning obligations relating to protected species, important habitats or ecological impacts. For example, a former industrial site may contain vegetation, abandoned buildings or areas of undisturbed land that provide habitat for protected species. Depending on the site, ecological surveys may be required to identify potential impacts on bats, breeding birds, reptiles or other wildlife. A preliminary ecological appraisal can help establish existing ecological constraints and determine whether further surveys are necessary. Developers must also consider relevant requirements under wildlife legislation and national planning policy. The presence of previously developed land does not remove these responsibilities. Consequently, even where a project qualifies for the proposed exemption, appropriate ecological assessment may still be necessary to support the planning application. What Does the Exemption Mean for Developers With Existing Planning Applications? Developers with existing or forthcoming planning applications should continue following the current BNG requirements unless their project already qualifies for an exemption in force. The government has not confirmed whether the proposed brownfield exemption will apply to applications already submitted, permissions already granted or only applications made after a future commencement date. This uncertainty creates a practical challenge for developers managing pipeline sites. A project approaching submission may currently require a completed biodiversity metric calculation and a strategy for achieving the statutory 10% net gain. If the new exemption is introduced before the application is submitted, the project’s requirements could potentially change, depending on the final transitional provisions. However, delaying an application solely in anticipation of the exemption could create additional programme and commercial risks. Developers should review their planning timetable, confirm the existing requirements with their planning consultants and avoid assuming that previously secured biodiversity obligations will automatically disappear. Where a project still requires BNG, the developer must follow the relevant planning process, including securing any necessary off-site gains before the Biodiversity Gain Plan can be approved. Will Developers Still Need to Purchase Off-Site Biodiversity Units? Developers whose projects qualify for the future brownfield exemption would no longer need to purchase off-site biodiversity units solely to satisfy the mandatory 10% BNG requirement. However, developments outside the exemption, including larger residential brownfield schemes and other qualifying projects, will continue to require biodiversity improvements under the applicable legislation. Off-site biodiversity units remain an important option where developers cannot deliver their full biodiversity requirement within the development site. These units are generated through habitat creation or enhancement on other land, with the ecological improvements legally secured and maintained for at least 30 years. For developers managing projects that remain subject to BNG, suitable units must satisfy the statutory biodiversity metric, habitat trading rules and relevant geographical considerations. Civity works with developers to identify suitable off-site biodiversity units using the requirements established by their appointed ecologists. Although the proposed exemption may reduce demand from some smaller brownfield housing schemes, the wider BNG framework will continue to apply to many residential, commercial and infrastructure developments. What Should Developers Do While Waiting for the Final Rules? Developers should continue assessing their projects against existing BNG legislation while monitoring the government’s response to the brownfield consultation. For sites that may qualify for the proposed exemption, reviewing the development area, land-use history, ecological constraints and planning timetable will help identify whether the forthcoming changes could affect the project’s requirements. It is also important to distinguish between confirmed policy and requirements that have already become law. The 1.5-hectare threshold has been announced, but the detailed eligibility criteria and transitional arrangements remain outstanding. For developments that are likely to remain subject to BNG, early ecological planning and consideration of off-site biodiversity units can help reduce uncertainty. Developers should also continue identifying ecological constraints, even where they anticipate benefiting from the exemption. This allows project teams to respond to the final regulations without overlooking existing wildlife protection and planning responsibilities. How Can Civity Support Developers During the BNG Changes? Civity helps developers understand their off-site Biodiversity Net Gain options by identifying suitable biodiversity units based on completed ecological metric calculations. As BNG requirements evolve, developers can use this support to assess available units, review project-specific requirements and obtain quotations where off-site delivery remains necessary. The proposed brownfield exemption may change the obligations for some residential projects, but it does not remove the need for biodiversity planning across the wider development sector. For schemes that remain subject to mandatory BNG, the availability of suitable units, habitat trading rules and location can influence both compliance and costs. Civity works with landowners to establish habitat banks and provides developers with access to off-site biodiversity unit opportunities. If you are planning a residential development and need to understand your existing BNG obligations or explore off-site options, contact Civity to discuss your project’s requirements. The key takeaway is that the new brownfield BNG exemption has been announced, but developers must wait for the final legislation and implementation date before treating eligible residential schemes as exempt.

Farmers can generate income through habitat restoration by creating or enhancing wildlife habitats and receiving payments through Biodiversity Net Gain (BNG), habitat banking, environmental land management schemes and other nature-based markets. These opportunities allow suitable agricultural land to provide an additional income stream while supporting biodiversity recovery and healthier ecosystems. In England, one of the most direct opportunities comes from Biodiversity Net Gain. Under the Environment Act 2021, most qualifying developments must achieve at least a 10% increase in biodiversity value. Developers unable to deliver their full requirement on-site can purchase off-site biodiversity units generated through habitat creation and enhancement projects. For farmers and landowners, this creates an opportunity to earn income from land that could support ecological improvements. Through Civity’s Biodiversity Net Gain services for landowners, suitable land can be assessed for habitat restoration potential and considered for long-term agreements that provide rental and habitat management income. However, not every field or restoration project will generate the same financial return. Existing habitats, location, ecological potential, local demand and long-term management requirements all influence the commercial viability of a scheme. How Does Habitat Restoration Generate Income for Farmers? Habitat restoration generates income when farmers receive payments for creating, enhancing or managing habitats that deliver measurable environmental improvements. Revenue can come from selling biodiversity units, leasing land to habitat bank operators, carrying out paid habitat management, participating in environmental schemes or providing other eligible ecosystem services. Traditionally, agricultural income has been linked to food production, livestock or land rental. Natural capital markets create an additional way of recognising the economic benefits of land management. For example, a farmer might convert a suitable area of lower-yielding agricultural land into species-rich grassland, restoring native plant species and improving habitat for pollinators and other wildlife. If the project meets the relevant Biodiversity Net Gain requirements, the ecological improvement may generate biodiversity units that can be sold to developers. The farmer may receive payments through a long-term lease, a habitat management contract or another commercial arrangement. Importantly, income does not necessarily depend on the farmer selling the land outright. Leasing suitable land for habitat banking can allow the landowner to retain ownership while receiving payments over an agreed period. The financial return depends on the contract, the ecological improvements being delivered and the responsibilities accepted by each party. What Is Biodiversity Net Gain and How Can Farmers Benefit? Biodiversity Net Gain is a planning requirement in England that requires most qualifying developments to deliver a measurable improvement in biodiversity. Where developers cannot meet their full requirement within the development site, they can purchase off-site biodiversity units generated through legally secured habitat creation or enhancement on other land. This creates a connection between development projects and agricultural land. Developers require biodiversity units to meet planning obligations, while farmers may have land capable of delivering suitable habitat improvements. The Government’s Biodiversity Net Gain guidance explains that developers can achieve their requirements through on-site habitat improvements, off-site biodiversity units or, as a last resort, statutory biodiversity credits. For landowners, the opportunity is to supply the off-site units that developers need. A biodiversity unit is calculated using the statutory biodiversity metric, which considers habitat characteristics including area, distinctiveness, condition and strategic significance. The number of units generated depends on the difference between the existing biodiversity value and the proposed value following habitat creation or enhancement. For example, restoring a species-poor grassland to a more diverse habitat may produce measurable biodiversity gains. However, a valuable habitat in poor ecological condition can also have significant enhancement potential, while an already high-quality habitat may offer fewer opportunities for additional measurable gains. This is why professional ecological assessment is essential before estimating the income a particular site could generate. What Is a Habitat Bank and How Does It Work? A habitat bank is an area of land where habitats are created or enhanced to generate biodiversity units for sale to developers. The ecological improvements must be secured through an appropriate legal agreement, registered on the Biodiversity Gain Sites Register and maintained for at least 30 years after the relevant habitat enhancement works are completed. Habitat banks can be established on suitable agricultural land, including arable fields, pasture and other areas with opportunities for nature restoration. For example, a habitat restoration project might involve establishing wildflower-rich grassland, enhancing hedgerows, restoring wetlands or improving woodland habitats. A qualified ecologist assesses the land and determines which improvements are ecologically appropriate and commercially realistic. The statutory biodiversity metric is then used to calculate the potential biodiversity units, which can be marketed to developers requiring off-site BNG for planning applications. The habitat bank operator coordinates the necessary legal agreements, registration, unit sales and ongoing habitat management arrangements. At Civity, we work with farmers and landowners to assess suitable land, establish habitat creation opportunities and connect the resulting biodiversity units with developer demand. Our model typically involves long-term leasing arrangements, allowing landowners to receive rental income while habitat creation and management are coordinated over the agreement period. What Types of Habitat Restoration Projects Can Generate Income? Habitat restoration projects can generate income where they deliver eligible, measurable ecological improvements that meet the requirements of a relevant environmental market. Suitable projects may include species-rich grassland creation, woodland enhancement, wetland restoration, hedgerow improvement and other habitat measures appropriate to the land. Species-Rich Grassland Restoration Species-rich grassland can support pollinators, invertebrates, birds and other wildlife. Farmers may be able to create or enhance these habitats by introducing appropriate native plant species and changing land management practices. Long-term management might involve carefully timed hay cutting, conservation grazing and controlling invasive or undesirable vegetation. Where the project creates additional biodiversity value, the resulting habitat may generate units for sale through the BNG market. Woodland Creation and Enhancement Native woodlands provide habitats for birds, mammals, invertebrates and plant species while contributing to wider landscape connectivity. Habitat restoration may involve establishing suitable native trees, enhancing existing woodland structure or improving woodland edges. Woodland creation can also contribute to carbon sequestration, although eligibility for carbon payments and BNG units must be assessed separately. Woodland projects require careful consideration of soil conditions, existing habitats, planting suitability and long-term maintenance. Planting trees is not automatically the best ecological outcome for every site. Existing grasslands, wetlands and other valuable open habitats may be better protected or enhanced rather than converted to woodland. Wetland and Peatland Restoration Wetland restoration can improve habitat diversity, support wildlife and contribute to water management. Projects may involve restoring natural water levels, creating ponds or enhancing wet grassland. Peatland restoration can help protect stored carbon and support specialist ecosystems where suitable peat habitats are present. These projects may provide opportunities through biodiversity markets or eligible carbon schemes, depending on the land and the restoration activity. Hedgerow and Scrub Enhancement Hedgerows provide shelter, food and movement corridors for wildlife across agricultural landscapes. Creating new hedgerows or improving existing networks can increase ecological connectivity between habitats. Appropriate scrub creation may also provide valuable habitat, particularly where it forms part of a wider landscape restoration strategy. Hedgerow biodiversity units are calculated separately from area habitat units, making accurate assessment important when determining market opportunities. Riverbanks and Coastal Habitats Farmers with land adjoining rivers, streams or coastal areas may have opportunities to restore riparian vegetation, wetlands or other suitable habitats. These projects can support water quality, ecological connectivity and natural flood management. Coastal habitat restoration may also contribute to climate adaptation and the protection of sensitive ecosystems. However, coastal and watercourse projects often involve additional regulatory, technical and environmental constraints that must be assessed before restoration work begins. How Much Can Farmers Earn From Habitat Restoration? The amount farmers can earn from habitat restoration depends on land area, existing habitat condition, location, biodiversity unit potential, local developer demand and the terms of the commercial agreement. There is no universal payment rate because the ecological and financial characteristics of each site differ. Civity’s published landowner FAQs describe indicative minimum payments of approximately £60,000 to £95,000 per hectare, spread over a 31-year agreement, depending on habitat type and project circumstances. These figures are indicative of Civity’s published commercial model, not guaranteed income for every agricultural site. Actual offers depend on ecological assessment, development costs, unit values and the specific agreement negotiated. A habitat bank may also involve different income components. For example, a farmer could receive rental payments for leasing land and additional payments where they undertake agreed habitat management activities. Some arrangements may also include profit-sharing mechanisms or other contract-specific payments. The important distinction is between the gross value of biodiversity units sold to developers and the net income received by the landowner. Habitat creation, ecological surveys, legal agreements, registration, monitoring and long-term maintenance all carry costs. A commercial assessment should therefore establish the expected payments, responsibilities and financial commitments before the landowner enters into a long-term agreement. Can Farmers Continue Farming Land Used for Biodiversity Net Gain? Farmers may be able to continue certain agricultural activities on land used for Biodiversity Net Gain, provided those activities are compatible with the agreed habitat creation and management objectives. However, some forms of intensive farming may need to stop or change to achieve the required ecological improvements. For example, conservation grazing can be an important management technique for maintaining species-rich grassland. Similarly, hay cutting may support the ecological condition of a meadow where it is carried out at appropriate times and intensities. These activities can form part of a Habitat Management and Monitoring Plan rather than being prohibited altogether. However, restoring a habitat may require changes to fertiliser use, drainage, cultivation, stocking density or other agricultural practices. The suitability of continued farming depends on the habitat type, management plan and legal agreement. Farmers should also consider how habitat restoration will affect their wider agricultural business, including access routes, neighbouring fields, tenancy arrangements and future land use. For some holdings, allocating less productive land to habitat restoration may provide an additional income opportunity without requiring the entire farm to change its primary use. Can Farmers Combine BNG Income With Carbon Credits or Environmental Grants? Farmers may be able to combine income from Biodiversity Net Gain with certain environmental payments, including nutrient mitigation credits, carbon markets or government-supported land management schemes. However, combining payments is subject to eligibility rules, and the same ecological improvement cannot automatically be sold multiple times. This process is often called stacking, where different environmental services delivered on the same land may generate separate payments. For example, restoring a wetland could potentially improve biodiversity, reduce nutrient pollution and provide wider ecosystem services. However, each proposed income stream must satisfy the rules of the relevant market or funding scheme. Carbon Credits Carbon sequestration projects can provide revenue where eligible woodland creation or peatland restoration delivers independently verified carbon benefits. The Woodland Carbon Code and Peatland Code provide frameworks for certain UK carbon projects. However, farmers cannot assume that carbon credits and biodiversity units can both be sold for the same restoration activity. Additional ecological improvements may be required, and the BNG baseline must reflect work already funded through another scheme. Nutrient Mitigation Credits Nutrient mitigation credits can be generated by eligible projects that reduce or capture nutrients entering sensitive water environments. These credits may be purchased by developers seeking to address nutrient neutrality requirements in affected catchments. Certain habitat restoration projects, including wetlands and buffer areas, may contribute to nutrient reduction. Where the rules allow, nutrient credits and biodiversity units can potentially be generated from the same land. Environmental Land Management Payments Government-supported schemes may provide payments for sustainable farming practices, habitat management and environmental improvements. These arrangements can help support conservation activities, but eligibility and compatibility with private nature markets must be checked carefully. The Government’s guidance on combining BNG, nutrient mitigation and other environmental payments explains the principles governing different forms of environmental income. Because the guidance and individual schemes can change, farmers should confirm current eligibility before committing land or accepting funding. What Are the Long-Term Commitments of a Habitat Restoration Project? Habitat restoration projects generating off-site biodiversity units require a legally secured commitment to maintain the agreed habitats for at least 30 years after the relevant enhancement works are completed. Landowners must understand how this commitment affects land management, future ownership, monitoring responsibilities and commercial flexibility. The legal agreement is generally established through a Section 106 planning obligation with a local planning authority or a conservation covenant with an authorised responsible body. These agreements establish the ecological obligations attached to the land. A Habitat Management and Monitoring Plan provides further detail about the habitat outcomes, management activities and monitoring requirements. For example, a restored meadow may require regular vegetation management and ecological monitoring to demonstrate progress towards its target condition. The management plan should also address risks such as failed planting, invasive species, drought, flooding or unexpected changes in habitat condition. Long-term financial planning is essential because habitat management costs may change over the agreement period. The government’s guidance on legal agreements for biodiversity net gain explains how habitat obligations are secured. For farmers considering a habitat bank, the long-term commitment should be assessed alongside potential income, rather than treating the agreement as a short-term environmental payment. How Do Farmers Know Whether Their Land Is Suitable for Habitat Restoration? Farmers can assess whether their land is suitable for habitat restoration by commissioning an ecological assessment that examines existing habitats, environmental constraints, restoration opportunities and potential biodiversity unit generation. Commercial viability also depends on location, local demand and the costs of establishing and maintaining the proposed habitats. The assessment process begins with understanding the land’s current ecological condition. A qualified ecologist can identify habitat types, assess their condition and determine which improvements may be realistic. For example, an area of agricultural grassland may have potential for species-rich meadow restoration, while another site may be more appropriate for wetland enhancement or hedgerow creation. The assessment should also consider soil conditions, hydrology, existing protected species, priority habitats and practical management requirements. Location is particularly important for BNG. The statutory biodiversity metric applies spatial risk multipliers to off-site units, meaning their geographical relationship to a development can affect their contribution towards the developer’s biodiversity requirement. Local nature recovery strategies can also influence strategic significance where proposed habitat creation or enhancement aligns with identified measures in the relevant mapped locations. This means a habitat bank that supports local nature recovery priorities may be attractive to developers, provided it generates the habitat types they require and satisfies the relevant trading rules. At Civity, our ecologists assess the existing habitats and restoration opportunities on suitable land, while our wider team considers local demand and the commercial potential of the biodiversity units that could be generated. How Do Farmers Start a Habitat Restoration Project? Farmers can begin a habitat restoration project by reviewing their land’s ecological potential, discussing suitable habitat improvements with an experienced provider and obtaining a commercial assessment of possible income. Before committing, they should understand the proposed legal agreements, management responsibilities and long-term implications for their agricultural business. An initial conversation can establish whether the land is likely to meet the requirements of a habitat bank. This is followed by ecological assessment to identify existing habitats and realistic opportunities for creation or enhancement. The potential biodiversity units can then be calculated using the statutory biodiversity metric. Alongside the ecological work, the commercial assessment considers local developer demand, anticipated unit values, project costs and possible payment arrangements. If the project is viable, the parties can agree on the appropriate lease, management and legal arrangements. The habitat bank must then be legally secured and registered before its units can be formally allocated to developers. Once habitat works begin, ongoing monitoring and management are required to achieve the agreed ecological outcomes. What Are the Wider Benefits of Habitat Restoration for Farmers and Communities? Habitat restoration can provide benefits beyond direct income by improving biodiversity, supporting ecosystem services and helping landscapes become more resilient to environmental pressures. Well-designed projects may also support local communities through improved wildlife habitats, healthier soils and better water management. Restoring native vegetation can provide food and shelter for wildlife, helping species recover in landscapes where suitable habitats have declined. Wetlands and floodplain habitats may help slow or store water during periods of heavy rainfall, depending on their location and design. Woodland and hedgerow restoration can improve ecological connectivity, allowing species to move between habitats. Healthy ecosystems may also contribute to carbon storage, pollination and improved water quality. These benefits can be particularly valuable where habitat restoration projects operate at a larger landscape scale. Connecting restored habitats across neighbouring landholdings may provide stronger ecological outcomes than isolated improvements. For farmers, this creates an opportunity to contribute to nature recovery while developing a potentially sustainable income stream from land. However, the environmental benefits and economic returns should be evaluated separately. Not every habitat improvement will generate marketable units, and not every ecosystem service will qualify for additional payments. How Civity Helps Farmers Generate Income Through Habitat Restoration Civity works with farmers and landowners to identify suitable land for habitat creation and enhancement, establish biodiversity unit opportunities and connect those units with developers seeking to meet their Biodiversity Net Gain requirements. Our ecologists undertake assessments to understand existing habitats and determine which restoration measures are appropriate for the land. We then combine this ecological information with an assessment of local demand, potential biodiversity unit values and the practical costs of establishing and maintaining the habitats. For suitable projects, Civity typically works through long-term lease arrangements, with rental and habitat management income forming part of the commercial model. We coordinate habitat creation, biodiversity unit generation and the ongoing management and monitoring arrangements required for BNG. Our approach is designed to help landowners access the biodiversity market without having to independently manage every stage of habitat bank development, registration and unit sales. Farmers can also explore the more detailed information in our landowner FAQs, which explain how our agreements, payments and habitat management arrangements work. Explore Habitat Restoration Income Opportunities With Civity Habitat restoration can provide farmers with an opportunity to diversify income while contributing to biodiversity recovery, healthier ecosystems and long-term environmental improvements. Through Biodiversity Net Gain, suitable agricultural land can generate biodiversity units that developers purchase to meet planning requirements. Other opportunities may exist through environmental schemes, nutrient mitigation or eligible carbon projects. The most suitable approach depends on the land’s ecological condition, restoration potential, location, market demand and long-term management commitments. At Civity, we help farmers and landowners understand whether their land could support a commercially viable habitat restoration project. Our ecological assessments and habitat bank services bring together the environmental and commercial considerations needed to evaluate these opportunities. If you own agricultural land and want to explore its potential for Biodiversity Net Gain, contact Civity to discuss how habitat restoration could create a long-term income opportunity for your land.

Developers can buy biodiversity net gain units from a habitat bank or landowner offering legally secured off-site habitat creation or enhancement. The process involves identifying the development’s biodiversity shortfall using the statutory biodiversity metric, finding suitable units, agreeing on a purchase and ensuring those units are registered and formally allocated to the development before its Biodiversity Gain Plan is approved. Under the Environment Act 2021, most qualifying developments in England must achieve at least a 10% Biodiversity Net Gain (BNG). Where this cannot be delivered entirely within the development site, purchasing off-site biodiversity units can provide a compliant solution. For developers seeking suitable units, Civity’s off-site BNG units for sale provide access to habitat creation and enhancement opportunities across England, supported by ecological expertise and an understanding of the planning process. However, purchasing biodiversity units involves more than finding an available quantity. Habitat types, trading rules, spatial risk, legal agreements and allocation requirements all influence whether particular units are suitable for a development. What Are Biodiversity Net Gain Units? Biodiversity Net Gain units are a standardised measure of biodiversity value calculated using the statutory biodiversity metric. They represent the ecological value of habitats and the improvements achieved through habitat creation or enhancement, allowing developers to demonstrate measurable biodiversity gains as part of the planning process. The metric considers factors including habitat type, area or length, distinctiveness, condition and strategic significance. For habitat creation and enhancement, it also accounts for factors such as time to target condition and delivery difficulty. There are three separate categories of biodiversity units: area habitat units, hedgerow units and watercourse units. These categories are calculated independently and are not directly interchangeable. For example, a development affecting a species-rich grassland may need to secure suitable area habitat units, while the loss of a hedgerow may create a separate hedgerow unit requirement. Importantly, one biodiversity unit does not equal one hectare of land. The number of units generated depends on the ecological characteristics of the habitat and the improvements being delivered. Why Do Developers Need to Buy Off-Site Biodiversity Units? Developers may need to purchase off-site biodiversity units when their proposed development cannot achieve its required Biodiversity Net Gain through habitat retention, creation or enhancement within the development boundary. Since 12 February 2024, mandatory BNG has applied to most qualifying planning permissions in England, with exemptions and subsequent changes to the rules for certain developments. The requirement means a development must achieve a biodiversity value at least 10% greater than its pre-development baseline, subject to the relevant metric calculations and habitat trading requirements. The government’s guidance on making on-site biodiversity gains explains the Biodiversity Gain Hierarchy, which establishes the order in which different BNG delivery options should be considered. For most qualifying developments, this means prioritising on-site habitat delivery before using off-site biodiversity units, with statutory biodiversity credits reserved as a last resort. However, from 6 August 2026, qualifying minor developments that are not otherwise exempt can consider on-site and off-site delivery simultaneously and may choose off-site units without first demonstrating that on-site delivery is unsuitable. This distinction is particularly relevant to smaller development projects where available space, site constraints or long-term management arrangements may make off-site delivery more practical. The Biodiversity Gain Hierarchy is also separate from the National Planning Policy Framework’s mitigation hierarchy, which addresses the avoidance, mitigation and compensation of biodiversity harm. Purchasing BNG units does not remove the need to address protected species, irreplaceable habitats or other ecological impacts appropriately. How Do Developers Calculate How Many BNG Units They Need? Developers determine their biodiversity unit requirements by using the statutory biodiversity metric to compare the development site’s existing biodiversity value with its proposed post-development value. The calculation identifies whether the scheme meets its BNG target and, where necessary, the type and quantity of additional off-site units required. A qualified ecologist will normally assess the existing habitats and prepare the biodiversity metric calculations for the development. The assessment establishes the site’s baseline biodiversity value, considers habitat losses and proposed on-site improvements, and calculates the remaining shortfall. The metric separates area, hedgerow and watercourse units, so developers may need to purchase multiple habitat types to satisfy their requirements. For example, a development could achieve its required area habitat gain through landscaping but still need additional hedgerow units to address the loss of existing boundary vegetation. The statutory biodiversity metric also applies habitat trading rules, which influence the type of replacement habitat that can be used. A developer cannot necessarily compensate for the loss of a valuable habitat by purchasing a larger quantity of lower-distinctiveness units. This is why the completed metric output is an essential starting point when requesting quotations from biodiversity unit providers. At Civity, we interpret the statutory biodiversity metric calculations supplied by a developer’s ecological team to identify suitable off-site unit options and provide quotations. If the development’s requirements change, we can also provide revised quotations to reflect the updated shortfall. Where Can Developers Buy Biodiversity Net Gain Units? Developers can buy biodiversity net gain units directly from habitat banks, landowners or specialist BNG providers offering legally secured habitat creation and enhancement. Units may also be advertised through biodiversity marketplaces, although the provider and gain site must still satisfy the relevant legal, registration and allocation requirements. Buying directly from a habitat bank can provide access to information about available habitat types, location, unit values and delivery arrangements. Habitat banks are areas of land where existing habitats are enhanced or new habitats are created to generate biodiversity units for sale. Land managers may establish habitat banks on agricultural land, former commercial sites or other suitable land, provided the proposed ecological improvements satisfy the relevant requirements. For example, habitat creation projects may involve restoring species-rich grassland, improving existing woodland, creating wetlands or enhancing hedgerow networks. Civity’s available BNG units include habitat bank opportunities in different parts of England, allowing developers to explore potential sources based on their location and ecological requirements. Developers can also use the Government’s Biodiversity Gain Sites Register to review registered gain sites and recorded allocations. However, registration does not automatically mean units remain available for purchase. Availability, habitat suitability and commercial terms should be confirmed directly with the relevant provider. How Does the Process of Buying BNG Units Work? The process of buying BNG units involves confirming the development’s ecological requirements, identifying suitable off-site habitats, agreeing commercial terms and ensuring the purchased units are formally allocated to the development. The allocation must be recorded on the national register before the local planning authority can approve the Biodiversity Gain Plan. 1. Complete the Biodiversity Metric Assessment The developer’s ecological consultant assesses the proposed development and calculates the biodiversity units required to achieve the relevant BNG target. The completed metric establishes the required habitat categories and identifies any remaining off-site shortfall. 2. Identify Suitable Off-Site Units The developer or BNG provider searches for units that satisfy the development’s habitat requirements. This involves considering habitat type, trading rules, location, spatial risk and unit availability. Early enquiries can be particularly useful where the development requires less commonly available habitat types. 3. Request a Quotation and Agree on Commercial Terms Once suitable units have been identified, the provider can issue a quotation based on the required quantities and habitat categories. The developer and seller agree on the purchase terms, which may include deposits, reservation arrangements and payment milestones. 4. Confirm the Legal and Registration Arrangements Off-site biodiversity gains must be secured through an appropriate legal agreement and recorded on the National Biodiversity Gain Sites Register. The agreement establishes the obligations for habitat creation, enhancement, management and monitoring over the required period. In Civity’s case, we take on the entirety of the creation, enhancement management and monitoring requirement; meaning the purchase is quick and simple for the developer with no ongoing involvement necessary. 5. Record the Allocation to the Development The land manager, or an authorised party acting with the land manager’s permission, applies to Natural England to allocate the agreed units to the development. The allocation links the biodiversity gains to the specific development project. The relevant reference numbers are cited in the Biodiversity Gain Plan to prove the link and demonstrate how legitimate units are being delivered offsite. 6. Submit the Biodiversity Gain Plan. Following planning permission, the developer submits the Biodiversity Gain Plan to the local planning authority. The plan must include the relevant biodiversity metric calculations and evidence of any registered off-site gains allocated to the development. The authority must approve the plan before development can commence. How Much Do Biodiversity Net Gain Units Cost? Civity’s current pricelist for units we provide is available here: https://civitynge.com/bng-units-for-sale/ The cost of biodiversity net gain units depends on habitat type, location, availability, ecological distinctiveness, long-term management requirements and market demand. There is no single fixed price for privately traded off-site BNG units, so developers should request quotations based on their specific biodiversity metric requirements. A project requiring several common habitat units may have different costs from one needing a smaller quantity of scarce, high-distinctiveness habitat units. The location of the habitat bank can also affect the effective value of units through the statutory metric’s spatial risk calculation. Other commercial factors include the cost of establishing and maintaining habitats, legal agreements, monitoring obligations and the timing of unit delivery. Where several habitat types are required, the total cost will depend on the combination of units needed rather than a single price per unit. Government statutory biodiversity credit prices should not be treated as benchmark prices for the private BNG market. They operate under a separate last-resort mechanism. For a more accurate estimate, developers should provide the completed biodiversity metric, the development location and details of any expected changes to their BNG strategy when requesting a quotation. Why Does the Location of Off-Site BNG Units Matter? The location of off-site BNG units matters because the statutory biodiversity metric applies a spatial risk multiplier to reflect the geographical relationship between the development and the habitat gain site. Units sourced further away may contribute less towards the development’s BNG requirement, increasing the quantity that needs to be purchased. Under the current statutory metric guidance, spatial risk for area and hedgerow habitats considers local planning authority boundaries and National Character Areas. Purchasing units ‘in area’ applies no spatial risk; adjacent area applies a 0.75x multiplier; and further than adjacent applies a 0.5 x multiplier. This means that a developer purchasing units in a further-than-adjacent area will need to purchase twice as many for the same overall net gain value. Units within the same local planning authority area or National Character Area receive the most favourable spatial risk treatment and are generally more attractive to local authorities who may have local planning policies favouring offsets with lower distance between the development site and offsite habitat compensation. Watercourse units are assessed using relevant catchment geography rather than local planning authority boundaries and national Character Areas. Spatial risk is separate from strategic significance, which considers whether habitat creation or enhancement supports identified local nature recovery priorities. For example, a habitat bank delivering species-rich grassland within a mapped Local Nature Recovery Strategy (LNRS) measure may qualify for high strategic significance where the proposed habitat and location meet the relevant requirements. This can support larger-scale habitat restoration aligned with local ecological priorities. Developers should therefore assess both spatial risk and strategic significance rather than selecting units solely because they appear geographically close or commercially attractive. What Are the Habitat Trading Rules for BNG Units? Habitat trading rules determine which habitat gains can compensate for particular habitat losses. They are designed to prevent developers from replacing more ecologically valuable habitats with unsuitable lower-value alternatives, even where the total number of biodiversity units appears sufficient. The rules operate within the statutory biodiversity metric and depend on habitat distinctiveness and classification. Habitats which are rarer, more inherently valuable, and/or more difficult to recreate, tend to have higher distinctiveness. The trading rules help prevent such habitats from being lost in favour of less valuable ones. For example, the loss of certain higher-distinctiveness habitats may require the creation or enhancement of the same habitat type or another permitted habitat that satisfies the trading requirements. This means a development requiring grassland units cannot automatically substitute woodland units simply because woodland units are available. Where a project affects multiple habitat types, the developer’s ecologist must confirm that the proposed combination of on-site and off-site gains satisfies the trading rules. Irreplaceable habitats, such as ancient woodland, require separate treatment. Their loss cannot simply be addressed through the standard 10% BNG calculation and may require bespoke compensation arrangements under the relevant planning framework. Checking habitat suitability before purchasing units helps reduce the risk of selecting gains that cannot be used within the final Biodiversity Gain Plan. Do Off-Site Biodiversity Units Need to Be Registered? Yes. Off-site biodiversity units used to meet mandatory BNG requirements must come from a biodiversity gain site registered on the National Biodiversity Gain Sites Register, with the relevant units formally allocated to the development. The register is maintained by Natural England and records information about legally secured habitat gains. Registration requires appropriate supporting information, including the legal agreement, habitat management arrangements and biodiversity metric calculations. The allocation process then identifies which units from the registered gain site are assigned to a particular development. This prevents the same biodiversity gains from being allocated more than once. A developer may agree to purchase or reserve units before registration is complete, but the necessary registration and allocation must be in place before the Biodiversity Gain Plan can be approved. Developers should therefore confirm the registration status and expected allocation timescales when discussing unit purchases with a provider. What Legal Agreements Are Required When Buying BNG Units? Off-site biodiversity gains must be secured through a legal agreement that establishes the habitat creation, enhancement, maintenance and monitoring obligations for at least 30 years. The agreement is generally a Section 106 planning obligation with a local planning authority or a conservation covenant with an authorised responsible body. The agreement secures the ecological commitments attached to the habitat bank and identifies who is responsible for delivering them. A Habitat Management and Monitoring Plan (HMMP) supports these arrangements by describing the intended habitat outcomes, management activities, monitoring requirements and corrective measures where necessary. The minimum 30-year period begins when the relevant habitat enhancement works are completed, as defined in the legal agreement. Habitat creation or enhancement can begin before units are allocated, and allocation may also occur before the works are completed. Where a developer purchases units from an existing legally secured habitat bank, the developer does not normally need to enter into a separate legal agreement for that off-site land. Instead, the habitat bank’s legal arrangements have already been agreed with the relevant authorities as part of the registration process to establish the long-term management responsibilities. This can make purchasing existing off-site units more practical than acquiring and managing separate land, although developers remain responsible for ensuring their own development meets its planning and BNG obligations. Can Developers Change Their BNG Unit Allocation After Purchase? Changing a formal allocation of off-site biodiversity units can be complicated and should not be treated as a routine amendment. Once units have been allocated to a development and linked to its planning permission, developers should regard that allocation as effectively final. Crucially, an allocation cannot be amended while it relates to an existing condition of planning permission. Evidence must be provided showing that the relevant planning permission conditions are no longer in place, potentially including confirmation from the approving local planning authority. The process therefore involves resolving the planning position with the local planning authority and applying to Natural England for the appropriate register amendment. This creates both administrative and commercial risk where a development’s biodiversity metric changes after units have already been allocated. Developers should confirm the habitat types, trading rules, spatial requirements and unit quantities before completing a formal allocation. Where designs are still evolving, obtaining revised quotations or discussing reservation arrangements can provide greater flexibility than prematurely finalising an unsuitable allocation. When Must Developers Purchase BNG Units? Developers do not necessarily need to purchase off-site biodiversity units before submitting their planning application. However, the required units must be formally allocated to the development before the local planning authority can approve its Biodiversity Gain Plan, and that approval must be obtained before development begins. The Biodiversity Gain Plan is normally submitted after planning permission has been granted. The local planning authority generally has eight weeks to determine the submitted plan. This period is not a deadline requiring developers to submit the plan within eight weeks of receiving planning permission. Early consideration of BNG requirements is nevertheless important. If a development requires scarce habitat types, waiting until the final stages of the planning process may limit availability or create unexpected costs. Developers can also face delays where a habitat bank has not yet completed its legal agreement, registration or allocation arrangements. Reviewing unit requirements during the planning process allows developers to understand the likely cost and availability of off-site options before committing to the final BNG strategy. What Is the Difference Between BNG Units and Statutory Biodiversity Credits? Off-site BNG units are biodiversity gains generated by legally secured habitat creation or enhancement projects, while statutory biodiversity credits are purchased from the government as a last-resort mechanism where suitable on-site and off-site options cannot deliver the required gain. Private biodiversity units are linked to identifiable habitat gain sites and must be registered and allocated to the development. Statutory biodiversity credits operate through a separate government purchasing process. Developers must provide evidence explaining why suitable on-site and off-site solutions are unavailable before purchasing statutory credits. A spatial risk multiplier of 0.5 applies to statutory credits, meaning two statutory credits are required for every one biodiversity unit that needs to be compensated. The government publishes separate prices for different habitat categories. These prices are subject to review and should not be confused with the commercial price of off-site biodiversity units. Developers can consult the official statutory biodiversity credit prices when evaluating the last-resort option. However, purchasing suitable off-site units directly from a habitat bank will generally be the more relevant route to explore before considering government credits. How Can Civity Help Developers Purchase BNG Units? Civity helps developers source off-site biodiversity units that align with their completed statutory biodiversity metric requirements, habitat trading rules and development location. By combining ecological knowledge with an expanding network of habitat bank opportunities, we help developers understand their available options and obtain quotations for suitable units. Our BNG services for developers focus on identifying appropriate off-site solutions without requiring developers to establish and manage their own habitat banks. Once a developer’s ecological team has completed the biodiversity metric assessment, we can review the resulting off-site requirements and identify potentially suitable habitat units. This includes considering the relevant habitat types, spatial risk, strategic significance and availability. Where the development’s requirements change, we can provide updated quotations to reflect revised metric outputs. Our ecological expertise also informs the development of habitat banks, where Civity undertakes ecological assessments to identify opportunities for habitat creation and enhancement. These projects can support local nature recovery through improvements such as species-rich grassland restoration, hedgerow enhancement and other habitat measures suited to the land. By connecting habitat bank delivery with developer demand, we help make the process of securing suitable biodiversity units more accessible. Secure the Right Biodiversity Net Gain Units for Your Development Buying biodiversity net gain units is an important part of the planning process for developments that cannot meet their full BNG requirement on-site. The most effective approach begins with a completed statutory biodiversity metric, followed by a review of suitable off-site habitat types, spatial risk, trading rules and availability. Developers should also understand the legal and registration requirements before finalising a purchase, particularly because amending an existing allocation can be difficult once it is connected to planning permission. Planning ahead can help reduce uncertainty over costs, unit availability and Biodiversity Gain Plan approval. At Civity, we help developers identify suitable off-site BNG units and provide quotations based on their ecological requirements. Whether your project is at an early planning stage or you already have a completed biodiversity metric showing an off-site shortfall, contact Civity to discuss available biodiversity units and the next steps towards meeting your BNG requirements.

The ecological surveys required before submitting a planning application depend on the habitats present, the likelihood of protected species using the site and the potential environmental impacts of the proposed development. A Preliminary Ecological Appraisal (PEA) is often the starting point, followed by specialist surveys for bats, birds, reptiles, great crested newts or other species where necessary. Ecological assessments help developers identify environmental constraints, establish baseline habitat conditions and determine whether further survey work or mitigation measures are required before planning permission can be granted. In England, ecological survey findings also support Biodiversity Net Gain (BNG) calculations for developments subject to mandatory BNG requirements. Understanding these requirements early can help developers avoid planning delays, unexpected costs and design changes. Where ecological assessments identify a need for off-site biodiversity units, Civity’s BNG services for developers can help project teams understand the available options and associated costs. Are Ecological Surveys Required for Every Planning Application? Ecological surveys are not automatically required for every planning application. However, developers must provide sufficient ecological information where a proposed development could affect protected species, priority habitats, designated sites or other important ecological features. The local planning authority determines whether the submitted evidence is adequate to assess the development’s potential environmental impacts. The need for surveys depends on the site’s location, existing habitats and proposed works. For example, a development involving the demolition of an older building may require a bat survey if suitable roosting features are present. A proposed development affecting ponds, grassland or hedgerows may require surveys for amphibians, reptiles or nesting birds. Even previously developed land can support valuable habitats and protected species. Brownfield sites may contain species-rich grassland, scrub, reptiles and important invertebrate populations. Under Natural England’s protected species planning guidance, local planning authorities should request appropriate surveys where protected species are likely to be present and could be affected by development. The necessary ecological evidence should normally be available before the planning application is determined, rather than leaving fundamental survey work to a planning condition. What Is a Preliminary Ecological Appraisal? A Preliminary Ecological Appraisal (PEA) is an initial ecological assessment used to identify habitats, protected species potential and ecological constraints affecting a proposed development site. It typically combines a desk study with a site walkover survey, allowing an ecologist to determine whether further specialist surveys, mitigation measures or design changes may be required. A PEA is commonly one of the first ecological assessments commissioned during development planning. The desk study reviews existing ecological information, including records of protected species, nearby designated sites and relevant habitat data. The walkover survey allows an ecologist to inspect the land, identify existing habitat types and assess features that may support protected or notable species. For example, mature trees may contain potential bat roosting features, while hedgerows and scrub can provide nesting and foraging habitat for birds. The resulting ecological report identifies likely constraints and recommends further surveys where necessary. Is a Phase 1 Habitat Survey the Same as a PEA? A Phase 1 Habitat Survey is a traditional habitat classification method used to identify and map broad habitat types. A Preliminary Ecological Appraisal is a wider assessment that considers habitats, protected species potential and other ecological constraints. Modern ecological assessments may use UKHab classification, particularly where habitat information is needed for the statutory biodiversity metric. Although the terms are sometimes used interchangeably, developers should confirm that the survey methodology provides the information required for their planning application. Nowadays, Phase 1 Habitat Surveys are largely a relic methodology and will not give sufficient information in most cases to adequately inform a planning application. Usually, a PEA will be required, specifically utilising UKHab classification for the highest ease of applying the results to a BNG assessment (if required). Which Protected Species Surveys Might Be Required? Protected species surveys are required for determination where ecological evidence indicates that a particular species may be present and the proposed development could affect it. The type and extent of survey work depend on the habitats available, existing species records, the proposed works and relevant legislation. An ecologist should be consulted as early as possible in the process as many of the surveys have specific calendar windows during which they must take place. Knowing the relevant windows for your project early on helps prevent delays and avoids making commitments to timeframes that are fundamentally untenable.  Bat Surveys Bat surveys may be required where development affects buildings, mature trees, woodland edges or other features suitable for roosting, commuting or foraging bats. An initial preliminary roost assessment can identify potential roosting features. Where necessary, further surveys may involve observing bats emerging from or returning to buildings or trees. Bats and their roosts receive legal protection under the Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981. Developers planning demolition, roofing alterations, building conversions or tree removal should consider bat survey requirements early. Great Crested Newt Surveys Great crested newt surveys may be necessary where ponds, ditches or suitable terrestrial habitats occur within or near a development site. Surveys can involve environmental DNA (eDNA) sampling to detect genetic material in water, alongside conventional survey methods where appropriate. Natural England’s great crested newt planning guidance explains when surveys may be needed and how development impacts should be assessed. District-level licensing may provide an alternative route for eligible developments in participating areas. Reptile Surveys Reptile surveys are commonly considered where a proposed development affects rough grassland, scrub, woodland edges, brownfield habitats or other areas suitable for reptiles. Surveyors may use artificial refuges, habitat inspections and repeated site visits under suitable weather conditions to establish whether reptiles are present. Survey findings help determine whether habitat retention, sensitive vegetation clearance or other mitigation measures are required. Bird and Barn Owl Surveys Bird surveys may be required where development affects nesting habitats, including hedgerows, woodland, grassland, agricultural buildings and mature trees. Breeding bird surveys assess the presence and distribution of nesting species, while wintering bird surveys may be necessary where a site supports important seasonal bird populations. Barn owl surveys can be particularly relevant where development affects agricultural buildings, established trees or suitable nesting and foraging habitats. Survey findings help developers plan vegetation clearance, building works and appropriate mitigation without unlawfully damaging active nests. Dormouse Surveys Hazel dormouse surveys may be required where development affects suitable woodland, scrub or connected hedgerow networks within areas where the species occurs. Surveys can involve nest tubes, nest boxes and other recognised methods. Because dormice depend on suitable connected habitats, ecological assessments may also consider how development could affect movement between woodland and hedgerow areas. Otter and Water Vole Surveys Otter and water vole surveys may be necessary where development affects rivers, streams, ditches, ponds or associated bankside habitats. Ecologists may inspect watercourses for field signs such as burrows, feeding remains, footprints and other evidence of activity. Survey findings can influence drainage design, construction access, vegetation clearance and the protection of watercourse habitats. When Are Botanical and Habitat Surveys Required? Botanical and habitat surveys are important where a development site contains potentially valuable vegetation, priority habitats or plant communities that require more detailed assessment. They establish which plant species and habitat types are present, helping ecologists evaluate ecological importance and identify appropriate protection, mitigation or habitat enhancement measures. A basic habitat assessment may identify broad habitat categories, but more detailed botanical surveys can be necessary where vegetation is diverse or difficult to classify. Surveyors may use quadrat sampling, transects or National Vegetation Classification (NVC) methods to investigate plant communities. These assessments can be particularly important for species-rich grassland, wetlands, ancient woodland and other habitats of conservation significance. Detailed botanical information may also support accurate habitat condition assessments within the statutory biodiversity metric. What Is an Ecological Impact Assessment? An Ecological Impact Assessment (EcIA) evaluates the likely ecological effects of a proposed development on important habitats, protected species and other ecological features. It uses survey findings and development information to assess potential impacts and recommend avoidance, mitigation, compensation and enhancement measures. An EcIA is generally appropriate where a development could have significant ecological effects that require structured assessment. For example, a proposed development may affect woodland, watercourses, protected species habitats or designated ecological sites. The assessment considers the importance of those features and how construction and operational activities could affect them. It can also evaluate cumulative impacts and recommend measures to reduce adverse effects. An EcIA is not automatically required simply because a protected species is present. The need for a formal assessment depends on the development and the nature of its likely ecological impacts. Is an Environmental Impact Assessment Also Required? An Environmental Impact Assessment (EIA) is a broader assessment process used for certain developments likely to have significant environmental effects. Ecology and biodiversity may form part of an EIA, alongside other topics such as landscape, noise, water, air quality and population impacts. Not every development requires an EIA. Whether one is necessary depends on the type, scale, location and likely effects of the proposed project, assessed through the relevant EIA regulations and screening process. Where an EIA is required, ecological survey data may inform the biodiversity assessment within the Environmental Statement. Developers should distinguish between a standalone EcIA and an EIA, as they serve different purposes within the planning process. When Should Ecological Surveys Be Carried Out? Ecological surveys should be commissioned as early as possible during the development planning process, ideally before layouts and construction programmes are finalised. Some assessments can be completed throughout the year, while others depend on seasonal wildlife activity and suitable weather conditions. A preliminary ecological appraisal can generally be undertaken throughout the year, although seasonal limitations may affect the information available. Specialist survey periods vary. Breeding bird surveys are generally undertaken during spring and summer, while reptile surveys are most effective during suitable warmer conditions. Great crested newt surveys often focus on spring, and certain bat activity surveys require visits during the active season. In very general terms, the majority of seasonally-restricted ecology surveys take place between spring and late summer – so factor this period in if your project is likely to impact habitats and species. The precise timing depends on the species, survey method, location and weather. How Long Are Ecological Surveys Valid? There is no single expiry date that applies to every ecological survey. The suitability of existing survey data depends on the species, habitat, age of the information and whether conditions on the development site have changed. The majority of surveys are usually valid for 12 months but if a longer period has passed, don’t make any assumptions until an ecologist has reviewed and advised as some surveys may require updates or validation. Professional guidance commonly distinguishes between recent survey information and older evidence that may need updating or repeating because of time passing and/or change in situation.For example, a site that has undergone vegetation clearance, changes in land management or substantial habitat alteration may require updated ecological information even if the original survey is relatively recent. Different protected species also have specific guidance concerning the age and reliability of survey data. Developers should ask their ecological consultant to review existing reports before relying on them for a new or amended planning application. How Do Ecological Surveys Support Biodiversity Net Gain? Ecological surveys provide the baseline habitat information needed to calculate biodiversity value and assess how a proposed development will affect existing habitats. For developments subject to mandatory Biodiversity Net Gain, this information is entered into the statutory biodiversity metric to establish the pre-development biodiversity value and assess proposed post-development habitat outcomes. Under the Environment Act 2021, most qualifying developments in England must achieve at least a 10% increase in biodiversity value. However, exemptions apply. Since 6 August 2026, planning applications for developments on sites of 0.2 hectares or less are generally exempt where they do not negatively impact on-site priority habitat. Other exemptions also apply. Where BNG is required, the statutory biodiversity metric considers factors including habitat area, distinctiveness, condition and strategic significance. If a BNG survey is in fact required, commission your ecologist specifically for a Biodiversity Impact Assessment (BIA); they will know to include, at minimum, a UKHab Classification survey of the habitats present, and a Condition Assessment (CA) of those habitats. This may be done as a standalone survey or alongside a PEA, depending on the ecologist, time of year and habitats present. The calculation compares pre-development and post-development biodiversity value to determine whether the required net gain is achieved. Where appropriate, developers may use off-site biodiversity units to address a remaining shortfall. The formal Biodiversity Gain Plan is submitted after planning permission has been granted and must be approved before development begins. Importantly, BNG does not replace the need to protect species and habitats under other relevant legislation. A development may satisfy its biodiversity unit requirement while still needing separate protected species mitigation or licensing arrangements. How Do Ecological Surveys Influence Development Design? Ecological survey findings can influence development layouts, construction methods and programme planning by identifying habitats or species that need protection. Addressing these constraints during the design stage can reduce the likelihood of redesign, additional surveys or disruption once works are scheduled. For example, retaining a valuable hedgerow may require changes to access arrangements, while protecting a bat roost could influence structural works, lighting design or the timing of building alterations. Mechanical and electrical (M&E) installations, including external lighting, may also need to account for sensitive habitats and bat commuting routes. For refurbishment projects involving occupied buildings, ecological considerations may need to be coordinated with access restrictions, structural works, decorating and the wider construction programme. Mitigation and habitat enhancement measures should also be incorporated into handover and long-term environmental management arrangements where required. Early coordination between ecological consultants, designers, contractors and planning professionals can help make these requirements more manageable. How Much Do Ecological Surveys Cost? The cost of ecological surveys varies according to site size, habitat complexity, location, accessibility and the number of specialist surveys required. A straightforward initial assessment will generally involve less survey effort than a complex development requiring multiple protected species surveys and detailed ecological impact reporting. Given the amount of work involved, expect a PEA/BNG assessment & report of a small, simple site to be no less than £1,000 excl VAT in most cases. Very small sites, or sites that only require an initial bat inspection may cost substantially less. Ecology survey costs can increase where repeated visits, specialist equipment, licensed surveyors or seasonal monitoring are necessary. A development involving buildings with bat roost potential, nearby ponds and extensive grassland may require several different assessments. The cost of the initial survey should therefore be considered alongside potential additional survey work, mitigation requirements and any associated licensing. Obtaining an appropriately scoped quotation early can help developers establish a more realistic ecological budget. What Happens If Ecological Surveys Are Not Completed Before Planning? Failing to provide necessary ecological surveys can result in requests for further information, delays in determining a planning application or refusal of planning permission where the authority cannot adequately assess ecological impacts. Natural England advises local planning authorities not to determine applications affecting protected species until sufficient survey evidence has been provided. A planning condition should not normally be used to postpone essential protected species surveys until after permission has been granted. If protected species are discovered during construction, works may also need to stop while the ecological implications are assessed and appropriate measures are agreed. Early surveys therefore support both planning compliance and more reliable project delivery. Who Should Carry Out Ecological Surveys? Ecological surveys should be undertaken by suitably qualified and experienced ecological professionals using recognised survey methods. Certain protected species surveys also require surveyors to hold appropriate licences. The Chartered Institute of Ecology and Environmental Management (CIEEM) provides professional guidance on ecological assessment, survey competence and good practice. A competent ecological consultant should be able to identify appropriate survey requirements, interpret findings, assess ecological constraints and advise on further work. For developers, the ecological consultant’s findings also provide important evidence for the planning team, helping establish whether the proposed development can proceed with suitable avoidance, mitigation or compensation measures. How Civity Supports Biodiversity Net Gain Following Ecological Assessments At Civity, our work connects ecological assessment, habitat bank delivery and the commercial requirements of Biodiversity Net Gain. For habitat bank sites, Civity’s ecologists undertake and coordinate ecological assessments to understand existing habitats, identify realistic habitat creation and enhancement opportunities, and assess the biodiversity units that could potentially be generated. We also consider the commercial viability of habitat banks, including local demand, habitat types, long-term management requirements and the practical process of bringing biodiversity units to market. Our role on the developer side is different. We do not undertake the developer’s statutory biodiversity metric calculations. Instead, we interpret completed metric outputs supplied by the developer’s ecological team to identify the type and quantity of off-site biodiversity units required. Where a development cannot meet its BNG requirement through its proposed habitat provision, we can help identify suitable off-site biodiversity units and provide fast quotations based on the project’s requirements. As development layouts and biodiversity metric calculations evolve, we can also provide revised quotations, helping developers understand how changes to their scheme may affect off-site BNG costs. This approach helps connect the ecological requirements identified during planning with practical, commercially informed off-site BNG solutions. Planning Ecological Surveys Before Submitting an Application The ecological surveys required before a planning application depend on the characteristics of the development site and the potential effects of the proposed works. A preliminary ecological appraisal is often the starting point, followed by more detailed habitat or protected species surveys where necessary. These assessments help developers understand ecological constraints, identify appropriate mitigation measures and provide the evidence needed for informed planning decisions. Early ecological assessment can also improve development design, support accurate biodiversity metric calculations and reduce the risk of unexpected delays. Where surveys and completed biodiversity metric calculations identify a need for off-site biodiversity units, Civity can help developers understand suitable options, availability and potential costs. To discuss your project’s off-site BNG requirements, contact Civity and explore how we can support your development’s biodiversity net gain strategy.