BNG and EIA: Integrating Biodiversity Net Gain into Environmental Impact Assessment
Integrating Biodiversity Net Gain (BNG) into the Environmental Impact Assessment (EIA) process has become an essential part of environmentally responsible development.
BNG and EIA are closely related approaches: BNG requires that new projects leave biodiversity in a better state (at least +10% net gain in habitat value) after development, while EIA evaluates a project’s likely significant effects on the environment. By bringing BNG and EIA together from the start, developers can ensure regulatory compliance and design projects that deliver sustainable, nature-positive outcomes. In this guide, we explain how BNG and EIA work together, what the legal requirements are, and how to integrate BNG into EIA successfully for any development project.
- Our Biodiversity Net Gain (BNG) Services in England:
- BNG baseline habitat surveys (Metric 4.0 compliant)
- Biodiversity unit calculations & deficit analysis
- Habitat creation, enhancement & on-site mitigation design
- Biodiversity Gain Plans (BGP) for planning submission
- Off-site BNG strategy & unit sourcing advice
- Habitat Management & Monitoring Plans (HMMP)
- Pre-application BNG feasibility & risk reviews
- Planning condition discharge & post-consent support
We follow a simple, transparent process to ensure your project runs smoothly from the very first contact to the final report. Our approach is designed to provide you with clarity at every step, so you’re fully informed and confident in moving forward.
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Step 1: Request a Quote
Fill out our quick quote form or call us, and our team will provide a free, no-obligation quote, outlining the services tailored to your needs.
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Step 2: Confirm Your Booking
Once you approve the quote, simply return the booking form. We’ll schedule your survey and ensure all the details are taken care of.
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Step 3: Receive Your Report
After your survey is completed and payment is received, we’ll promptly issue your survey report, ensuring you get the results as quickly as possible.
In the past year, we’ve delivered over 750+ audit-ready reports supporting 400+ projects for developers, planners, and architects nationwide. We put quality over quantity and build lasting relationships based on trust, ensuring your planning applications are backed by robust evidence and delivered on time.
What Are Biodiversity Net Gain and EIA?
Biodiversity Net Gain (BNG) is a legal requirement in England that development projects must result in a measurable improvement to biodiversity. In practice, this means a project must quantify the on-site baseline and the post-development scenario using the biodiversity unit metric (Statutory Biodiversity Metric) and demonstrate at least a 10% increase in biodiversity units through habitat creation or enhancement. Introduced under the Environment Act 2021, BNG shifts planning towards outcomes where nature benefits rather than loses. BNG measures focus on habitats, considering habitat distinctiveness, condition, and strategic significance. Importantly, BNG follows the mitigation hierarchy: avoid and minimise harm first, then mitigate, and finally compensate by enhancing habitats.
Environmental Impact Assessment (EIA) is the process required for certain projects to evaluate significant environmental effects, culminating in an Environmental Statement (ES). The ecology chapter identifies receptors (protected species, valuable habitats, conservation areas and designated sites) and assesses likely effects with mitigation strategies to reduce significant harm. The purpose is to inform decisions so planning authorities and stakeholders understand consequences before approval.
BNG and EIA serve complementary purposes: EIA focuses on significance of impacts, while BNG focuses on the net outcome (a positive biodiversity balance). EIA asks, “Have we reduced harm enough?”; BNG asks “Can we leave nature better than before?”
Why Integrate BNG into the EIA Process?
Integrating BNG into EIA is vital because most planning applications in England must now show at least 10% net gain. Addressing BNG within the ES supports regulatory compliance, smooths consent, and aligns design with sustainability strategy, ecosystem services, and climate resilience goals. It naturally encourages green infrastructure (wildflower meadows, SuDS wetlands, woodland planting, wildlife corridors and habitat connectivity) that both deliver EIA biodiversity net gain outcomes and reduce environmental risk.
Alignment with the mitigation hierarchy improves project design (e.g., preserving high-value habitats and placing enhancements in lower-value areas). Clear net-gain commitments also strengthen stakeholder engagement by demonstrating transparent environmental stewardship and local natural capital gains.
Regulatory Background: BNG Requirements and EIA
The Environment Act 2021 introduced the mandatory BNG condition. From 12 February 2024 (major development) and 2 April 2024 (small sites), applications must demonstrate a minimum 10% net gain, secured for 30 years via a Biodiversity Gain Plan and long-term management. BNG regulations sit alongside not instead of EIA duties and protected species/habitat laws. BNG measures must be additional to any mitigation required under EIA or other regulations.
Exemptions remain limited (e.g., de minimis habitat impacts, householder works, certain small self-build, and bona fide conservation/BNG sites). Nationally Significant Infrastructure Projects will follow under a later timetable. In short, most developments requiring planning permission should assume BNG and EIA both apply.
BNG vs EIA: Key Differences in Assessment
Although Biodiversity Net Gain (BNG) and Environmental Impact Assessment (EIA) are closely connected in the planning process, they differ in purpose, scope, and outcome. Understanding these distinctions helps ensure that both assessments complement one another rather than overlap.
Scope
An EIA ecology assessment considers the full range of potential environmental effects direct, indirect and cumulative on habitats and species both on- and off-site. It evaluates construction and operational impacts such as lighting, noise, hydrology or pollution on designated sites and protected species. By contrast, a BNG assessment is narrower in scope, concentrating mainly on on-site habitat change quantified through the biodiversity unit metric, with any off-site enhancements also included to achieve the minimum 10 per cent net gain target.
Method
EIA significance is determined largely through expert judgement informed by ecological data, policy context and professional guidance. BNG, however, applies a standardised, quantitative method, assigning numerical unit values to habitats based on their area or length, habitat distinctiveness, condition, and strategic location multipliers. This allows biodiversity losses and gains to be measured transparently and compared across schemes.
Focus
While EIA emphasises mitigation strategies to reduce or avoid significant effects, BNG requires active enhancement. Developers must demonstrate that biodiversity will be measurably better after development not merely that harm has been minimised.
Outcome
An EIA provides information to support decision-making but has no numeric threshold for success. BNG, on the other hand, results in a binding planning condition or obligation, legally securing delivery of the quantified EIA biodiversity net gain and its long-term management. Together, they ensure projects both avoid unacceptable impacts and create lasting ecological improvement.
Integrating BNG into EIA: Step-by-Step Process
Early Planning and Scoping
The first step in integrating BNG into EIA is to embed biodiversity objectives during project feasibility, screening, and scoping. Establish a measurable net-gain target normally a minimum of 10 per cent and consult the Local Planning Authority (LPA), statutory consultees, and local communities early. Align the emerging strategy with Local Nature Recovery Strategies, conservation planning priorities, and wider land-use planning policy to ensure that biodiversity improvements complement local ecological networks.
Baseline Surveys and Metric Calculation
Carry out detailed ecological and habitat surveys following the UKHab classification to record habitat types, condition, and extent. Use the Statutory Biodiversity Metric (or Small Sites Metric, if applicable) to calculate baseline units. Maintaining consistent data between the environmental impact assessment BNG calculations and the EIA’s ecological baseline is essential to ensure transparency and traceability.
Design Using the Mitigation Hierarchy
During design, apply the mitigation hierarchy avoid, minimise, restore, then enhance. Adjust layouts to protect sensitive areas and incorporate habitat restoration and enhancement features such as species-rich grassland, ponds, green roofs, or wildlife corridors. Prioritise on-site delivery, quantifying potential gains through the metric to achieve or exceed the 10 per cent requirement.
Impact Assessment and Enhancements in the Environmental Statement (ES)
Document predicted residual effects and summarised the EIA biodiversity net gain outcome within the ES. Include a clear table comparing habitat losses and gains, biodiversity-unit totals, and links to wider project sustainability and ecosystem services benefits.
Biodiversity Gain Plan and Long-Term Management
Finally, prepare and submit a Biodiversity Gain Plan (BGP) detailing baseline and post-development units, any off-site credits, and governance arrangements. The BGP should secure a minimum 10 per cent net gain through a 30-year Habitat Management and Monitoring Plan, ensuring that biodiversity benefits are delivered, monitored, and maintained over time.
Biodiversity Net Gain Regulations
The Biodiversity Net Gain (BNG) regulations were introduced under the Environment Act 2021 and now apply to the majority of development projects consented under the Town and Country Planning Act in England. From February 2024 for major schemes and from April 2024 for smaller developments planning permission can only be granted if the proposal demonstrates a minimum 10% biodiversity net gain and provides a credible mechanism for its delivery and long-term maintenance.
BNG operates alongside, rather than replacing, the Environmental Impact Assessment (EIA) process. In practice, most EIA developments will also be required to meet the statutory BNG condition. The two systems complement one another: while EIA assesses and mitigates significant ecological effects, BNG and EIA together ensure measurable biodiversity improvements through quantifiable habitat gains.
A key regulatory principle is additionality BNG cannot double-count mitigation measures already required to address significant impacts identified in the EIA. Any biodiversity units claimed toward net gain must therefore represent genuine enhancements beyond statutory compensation or licence obligations.
BNG outcomes are secured through planning conditions, Section 106 agreements, or conservation covenants, binding developers to deliver and manage habitats for at least 30 years. Compliance must be demonstrated through an approved Biodiversity Gain Plan, supported by a Habitat Management and Monitoring Plan (HMMP) that tracks progress and ensures the promised ecological benefits are achieved and sustained.
Biodiversity Net Gain Planning Practice Guidance
Current Biodiversity Net Gain (BNG) planning practice guidance issued by DEFRA, Natural England, and reflected in the NPPF and local planning policy sets out how applicants should evidence and deliver net gain within the development process. For projects requiring an Environmental Impact Assessment (EIA), the guidance reinforces the need for early and transparent alignment between BNG and EIA objectives. Integrating BNG into EIA ensures that biodiversity enhancement measures are clearly defined, costed, and embedded in design rather than added retrospectively.
Applicants should apply strategic location multipliers from the Statutory Biodiversity Metric to favour habitats that support local ecological priorities or form part of Local Nature Recovery Strategies. Wherever possible, schemes should prioritise on-site delivery, demonstrating that the development can meet or exceed the 10 per cent EIA biodiversity net gain requirement within its own boundary. Any off-site units or statutory biodiversity credits must be fully justified within the Biodiversity Gain Plan, showing why on-site options were insufficient and how off-site measures align with wider conservation planning objectives.
All submissions should evidence application of the mitigation hierarchy avoid, minimise, restore, then enhance and detail the environmental management mechanisms that will secure habitats for at least 30 years. These include legal agreements, governance structures, and a Habitat Management and Monitoring Plan demonstrating measurable ecological improvement and long-term compliance with BNG and EIA requirements.
Biodiversity Net Gain Exemptions
Although the Biodiversity Net Gain (BNG) requirement now applies to most planning applications in England, several exemptions are defined within the Environment Act 2021 and related BNG regulations. These ensure that only developments with meaningful ecological impacts are required to deliver a 10 per cent net gain and that very small or conservation-focused schemes are not over-regulated.
De minimis habitat impacts are exempt. Developments affecting less than 25 m² of habitat or under 5 m of hedgerow and not involving priority habitat loss do not trigger the BNG duty. Householder works, such as extensions or alterations within an existing garden, are also excluded. Similarly, eligible small self-build schemes (up to nine dwellings on sites under 0.5 ha) are exempt to reduce burdens on individual homeowners.
Projects whose primary purpose is ecological restoration or BNG delivery for example, creating a habitat bank or enhancing an existing nature reserve are not required to deliver an additional gain on top of their intended biodiversity improvements.
Large infrastructure projects classed as Nationally Significant Infrastructure Projects (NSIPs) fall outside the current regime but will be brought within scope under a separate timetable, expected by 2026.
Even where formal exemptions apply, good practice encourages incorporating voluntary biodiversity enhancements within the EIA biodiversity net gain framework to demonstrate positive environmental outcomes and strengthen planning submissions.
Biodiversity Net Gain and Environmental Impact Assessment 2021
The year 2021 marked a defining moment in the evolution of Biodiversity Net Gain (BNG) policy, as the Environment Act 2021 established the legislative foundation for mandatory biodiversity enhancement within the planning system. This milestone formalised the integration of BNG and EIA, aligning ecological assessment with measurable environmental outcomes.
Since its introduction, professional practice across England has become increasingly standardised. Developers, ecologists, and planning authorities now routinely assess projects using the biodiversity unit metric, evaluating habitat area, distinctiveness, condition, and strategic significance. These measurable indicators underpin both the environmental impact assessment BNG process and the statutory 10 per cent net gain target.
Central to this integration is the principle of 30-year stewardship, ensuring that habitat creation, enhancement, and long-term management are not short-term obligations, but enduring commitments embedded in the project life cycle. As a result, the EIA biodiversity net gain process has shifted from assessing harm to quantifying ecological benefit strengthening accountability and transparency in environmental planning.
Benefits of Integrating BNG and EIA
Integrating Biodiversity Net Gain (BNG) within the Environmental Impact Assessment (EIA) process delivers measurable advantages for developers, planning authorities, and the wider environment. By embedding biodiversity considerations early, projects achieve stronger environmental outcomes and smoother progression through the planning system.
Regulatory Compliance and Risk Reduction: Incorporating BNG and EIA together ensures full alignment with the Environment Act 2021 and emerging BNG regulations. Addressing statutory requirements within the environmental impact assessment BNG documentation avoids late-stage information requests and delays in determination. Demonstrating a clear EIA biodiversity net gain pathway supported by baseline data, metric calculations, and a Biodiversity Gain Plan provides assurance to local authorities that the scheme meets legal and policy expectations. This proactive approach significantly reduces planning risk and strengthens overall regulatory compliance.
Environmental and Social Value: Integrated design allows nature-based solutions such as green roofs, wetlands, and wildlife corridors to deliver multiple ecosystem services including improved air and water quality, flood mitigation, and climate resilience. These interventions enhance biodiversity while also contributing to community wellbeing, recreation, and public amenity. Engaging stakeholders through visible ecological enhancement builds community engagement and a lasting social licence to operate.
Financial and Design Value: Developments that achieve net-positive biodiversity often command higher long-term value. Enhanced green infrastructure improves site aesthetics, boosts property desirability, and aligns with investor expectations for sustainable development and environmental sustainability. Moreover, integrating BNG into project design promotes efficiency optimising land use and delivering measurable ecological, financial, and reputational returns.
Integrate Biodiversity Net Gain into Your EIA from the Start
We support EIA Screening, Scoping and Environmental Statements by embedding Biodiversity Net Gain requirements into baseline surveys, impact assessment and mitigation design ensuring consistency between EIA outputs and BNG calculations.
Why Choose Us for BNG and EIA Integration
Delivering Biodiversity Net Gain (BNG) in tandem with the Environmental Impact Assessment (EIA) process requires both technical expertise and strategic coordination. Our consultancy brings together qualified ecologists, planners, and EIA specialists who collaborate from the outset to design projects that are compliant, measurable, and genuinely nature positive.
Integrated Expertise
Our multidisciplinary team aligns environmental impact assessment BNG requirements from the earliest feasibility and scoping stages. We ensure that biodiversity metrics, ecological baselines, and EIA significance assessments are developed together avoiding duplication and guaranteeing consistency between the BNG and EIA deliverables. This integration streamlines reporting, supports faster approvals, and gives decision-makers confidence in the project’s environmental credibility.
Tailored Solutions and Transparent Delivery
Every site is unique. We prioritise on-site BNG delivery wherever feasible to maximise local ecological and community benefit, while offering pragmatic off-site pathways or statutory credits when necessary. Our transparent approach to biodiversity unit accounting ensures full traceability between baseline, design, and post-development outcomes, achieving measurable EIA biodiversity net gain that stands up to scrutiny.
Stakeholder Engagement
We lead proactive, evidence-based engagement with Local Planning Authorities, Natural England, and local communities. By clearly communicating the benefits of integrating BNG into EIA, we build trust and reduce objections helping projects gain a smoother route through planning.
30-Year Stewardship and Long-Term Assurance
Our commitment extends beyond consent. We prepare robust Habitat Management and Monitoring Plans (HMMPs), enabling adaptive management over a 30-year period. Continuous monitoring and review secure lasting biodiversity outcomes, ensuring that promised gains are delivered, verified, and maintained.
Next Steps – Achieving Net Gain Compliance
In England’s evolving planning system, Biodiversity Net Gain (BNG) and the Environmental Impact Assessment (EIA) are now inseparable components of sustainable development. Together, they form the foundation of modern environmental compliance ensuring that every project not only minimises harm but delivers measurable ecological improvement.
To meet these expectations, developers must plan early, measure accurately, and design intelligently. Integrating BNG and EIA from the very beginning at feasibility, scoping, and concept design ensures that biodiversity objectives inform every stage of project development. This proactive approach enables the delivery of genuine EIA biodiversity net gain, reduces planning risk, and strengthens alignment with local and national policy.
Our expert team specialises in integrating BNG into EIA efficiently and confidently, from baseline assessment and metric calculation to long-term Habitat Management and Monitoring Plans (HMMPs). We provide practical, evidence-based strategies that meet statutory requirements while creating enduring environmental and social value.
Whether you’re preparing a new planning submission or reviewing an ongoing scheme, now is the time to embed net gain as a core project principle.
Contact us today to discuss how our integrated BNG–EIA approach can help you achieve full compliance, streamline approval, and deliver lasting biodiversity outcomes for your development.
References and Useful Resources
- Defra & Natural England – Biodiversity Metric: Calculate the biodiversity net gain of a project or development
- Lichfield District Council – Biodiversity Net Gain (BNG) Guidance for Planning Applications
- East Devon District Council – How is Biodiversity Net Gain Measured?
- Defra (July 2025) – The Statutory Biodiversity Metric: User Guide
- North Hertfordshire District Council – How to Measure Biodiversity Net Gain
- Chartered Institute of Ecology and Environmental Management (CIEEM) – Biodiversity Net Gain Case Studies & Good Practice
- CIEEM – Biodiversity Net Gain Report and Audit Templates
- UK Statutory Instruments – The Biodiversity Gain Requirements (Exemptions) Regulations 2024
- Natural England – Habitat Management and Monitoring Plan (HMMP) Template (JP058)
- Defra – Biodiversity Gain Plan: Template and Guidance
- Defra – Guidance: Understanding Biodiversity Net Gain
- Natural England – Biodiversity Net Gain: Where to Start
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Frequently Asked Questions
Understanding how Biodiversity Net Gain (BNG) interacts with the Environmental Impact Assessment (EIA) process can be complex. Below are ten detailed answers to the most frequently asked questions developers, planners, and environmental professionals raise when seeking to integrate BNG into EIA efficiently and in line with the Environment Act 2021.
What is the relationship between BNG and EIA in England’s planning system?
BNG and EIA now operate side by side. While the EIA identifies and mitigates significant ecological effects, BNG requires a measurable improvement in biodiversity. Together they ensure developments not only avoid harm but also create a net environmental benefit.
When should integrating BNG into EIA start during project design?
Integration should begin at feasibility or scoping stage. Embedding biodiversity objectives early allows the design team to apply the mitigation hierarchy effectively and identify opportunities for habitat creation or enhancement within the project layout.
How is environmental impact assessment BNG measured?
BNG outcomes are measured using the Statutory Biodiversity Metric (Defra Metric 4.0), which assigns habitat units based on area, condition, habitat distinctiveness, and strategic significance. The EIA baseline data must match the metric’s input data for consistency and traceability
What qualifies as EIA biodiversity net gain?
EIA biodiversity net gain refers to the quantifiable uplift in habitat units demonstrated within the Environmental Statement. It’s supported by mapping, tables, and a Biodiversity Gain Plan that proves a minimum 10% net increase will be achieved and maintained for 30 years.
Are all developments required to deliver a 10% biodiversity net gain?
Most developments are, under the Environment Act 2021. Exceptions include de minimis habitat impacts, householder works, eligible small self-build schemes, and projects focused solely on ecological restoration. Large infrastructure projects will follow by 2026.
What documentation proves compliance with BNG and EIA?
Compliance is shown through a Biodiversity Gain Plan, supported by survey data, a Habitat Management and Monitoring Plan (HMMP), and legal mechanisms such as Section 106 agreements or conservation covenants ensuring 30-year stewardship.
Can off-site biodiversity units be used to meet EIA biodiversity net gain?
Yes when on-site space or ecological constraints limit potential gains. Off-site units or statutory credits must be justified within the BNG and EIA framework, aligning with local ecological priorities and Local Nature Recovery Strategies.
What is “additionality” under the BNG regulations?
Additionality means biodiversity units claimed for net gain cannot also count as mitigation for significant impacts under the EIA. Only enhancements beyond statutory obligations can contribute to the net-gain total.
How does long-term monitoring support integrating BNG into EIA?
Long-term monitoring typically over 30 years tracks whether habitats achieve their target condition. Data collected informs adaptive management under the HMMP, ensuring the BNG and EIA commitments remain effective and verifiable.
What are the practical benefits of combining BNG and EIA for developers?
Projects that integrate both frameworks experience fewer planning delays, improved design outcomes, stronger stakeholder confidence, and higher environmental performance ratings making developments more resilient, marketable, and aligned with sustainable development goals.
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- Last Updated:
- October 2026
Disclaimer: Our content is prepared by ACP Consultants’ in-house specialists and is based on current guidance, standards, and best practice in environmental consultancy. While we make every effort to keep information accurate and up to date, it is provided for general guidance only and should not be relied upon as a substitute for professional advice on specific projects. Planning authorities retain final decision-making powers, and requirements may vary between local authorities and over time. ACP Consultants accepts no liability for any loss arising from reliance on this content without obtaining tailored advice for your project.