BNG Assessment & Baseline Survey (UKHab)
Our Biodiversity Net Gain (BNG) Assessment & Baseline Survey (UKHab) provides the essential ecological evidence required for planning approval. Using the statutory biodiversity metric, ACP Consultants identify, map and evaluate all existing habitats on site to establish a reliable baseline. This information forms the foundation of a compliant biodiversity net gain assessment, feeding directly into your Biodiversity Gain Plan (BGP) and Habitat Management & Monitoring Plan (HMMP). By evidencing the current ecological value, our reports ensure your scheme meets the mandatory 10% net gain requirement and supports long-term environmental compliance.
You can also drop us an email at hello@acp-consultants.com and we’ll get back to you within 24 hours to help with your inquiry!
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.
BNG Assessment & Baseline Survey Consultants
Biodiversity Net Gain (BNG) is now embedded in the English planning system. For most planning applications you must demonstrate at least a 10% measurable net gain in biodiversity, evidenced through the statutory biodiversity metric, and secure management for a minimum of 30 years. The legal framework sits in Schedule 7A of the Town and Country Planning Act 1990 (inserted by the Environment Act 2021), which Planning Practice Guidance refers to as the statutory BNG framework. In practice, your planning permission includes a pre-commencement BNG condition and the Local Planning Authority (LPA) must approve your Biodiversity Gain Plan before works can start, generally deciding within 8 weeks of submission.
Our BNG Assessment & Baseline Survey delivers everything you need to pass validation and satisfy ecology officers: a robust UKHab baseline, condition assessments, the statutory metric calculation with design iterations, advice on on-site vs off-site delivery and statutory credits (if needed), River Condition Assessment where watercourses are involved, and a planning-ready Biodiversity Gain Plan (BGP).
What is a BNG Assessment and why it matters
A BNG assessment quantifies biodiversity value before and after development, using the statutory biodiversity metric. The tool breaks your site into habitat parcels and calculates units for three modules: area habitats, hedgerows, and watercourses. It factors in size, condition, strategic significance and habitat type/distinctiveness, and applies trading rules so you replace like-for-like (or better) rather than swapping, say, hedgerows for grassland. The outcome must show ≥10% net gain in each unit type to meet the statutory objective. Early use of the tool steers design choices, minimises costly rework, and helps officers audit your submission quickly.
From 12 February 2024, BNG has applied to major developments; from 2 April 2024, it applies to small sites. NSIPs are scheduled to come in from May 2026 (subject to the government’s confirmed timetable).
Where UKHab fits in the backbone of your baseline
UKHab (UK Habitat Classification) is the national standard for habitat mapping in England and the system required for BNG. It was designed to replace older, inconsistent classifications and is now the framework used by ecologists, planning authorities and Natural England.
When we carry out a BNG Assessment, we:
Map the entire red-line boundary into habitat parcels using UKHab codes.
Record attributes such as condition, distinctiveness and strategic significance for each parcel.
Produce outputs that feed directly into the statutory biodiversity metric and the official condition assessment sheets.
This approach makes your baseline transparent, repeatable and auditable. It also ensures compatibility with planning validation checklists and Natural England’s review processes.
Deliverables include:
A GIS dataset (GeoPackage/ESRI Shapefile) that integrates seamlessly with architects’ and planners’ drawings.
Clear, planning-ready figures showing parcels, codes and extents.
Supporting tables linking each habitat parcel to its UKHab code and condition.
For more information about the UKHab standard itself, see UKHab.org — ACP Consultants apply this standard consistently across all BNG projects.
BNG Assessment Process — Step by Step
Every Biodiversity Net Gain (BNG) project follows a clear process, from the moment you provide your red-line boundary through to the submission of a planning-ready Biodiversity Gain Plan (BGP). At ACP Consultants we structure our approach so that each stage builds logically on the last: collecting reliable baseline evidence, applying the statutory metric, and presenting outputs in a format that planning officers can audit quickly.
This step-by-step method ensures your scheme reaches the mandatory +10% net gain in the most efficient way, while also reducing design risk and keeping your programme on track.
Scoping and desk study
If required by the client, we review constraints and opportunities before you commit to design. Sources include planning history, aerial photography, designated sites, and any available Local Nature Recovery Strategy layers to evaluate strategic significance. We draft a provisional parceling scheme so fieldwork is efficient and traceable.
1) UKHab field survey and condition scoring
On site, an ecologist confirms habitat types, mosaics and boundaries; records condition for area habitats; and assesses linear features (hedgerows/watercourses) separately. Photographs are geo-referenced and tied to parcel IDs. Where a watercourse is present or affected, we undertake a River Condition Assessment (RCA) using recognised methods and competencies, as expected by the latest guidance and best practices.
2) UKHab field survey and condition scoring
On site, an ecologist confirms habitat types, mosaics and boundaries; records condition for area habitats; and assesses linear features (hedgerows/watercourses) separately. Photographs are geo-referenced and tied to parcel IDs. Where a watercourse is present or affected, we undertake a River Condition Assessment (RCA) using recognised methods and competencies, as expected by the latest guidance and best practices.
3) Statutory metric calculation and iterations
We enter the baseline and test post-development scenarios with your design team, adjusting planting/management proposals to meet trading rules and achieve the +10% requirement per unit type. The user guide emphasises early and repeated use for best outcomes; we document each iteration in a versioned workbook so the LPA can follow the logic.
4) Biodiversity Gain Plan (BGP) and submission
We assemble your Biodiversity Gain Plan (BGP) with everything planning officers need to make a quick, positive decision: metric outputs, pre- and post-development habitat plans, condition assessment sheets, and, if relevant, off-site unit allocation or statutory credit evidence.
LPAs are required to issue a decision within 8 weeks, and you cannot legally start works until the BGP is approved. By preparing a clear, audit-ready submission, we minimise the risk of delays or requests for resubmission, giving you confidence that your project can move forward on time.
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.
You can also drop us an email at hello@acp-consultants.com and we’ll get back to you within 24 hours to help with your inquiry!
Condition assessments (including rivers and hedgerows)
Condition scoring underpins unit calculations. The government publishes condition assessment sheets covering the habitats used by the metric; we complete these and include them in your submission bundle. For watercourses, the 2025 user guide clarifies additional requirements around riparian zones, watercourse sections and associated details; it also notes you should be a qualified assessor to undertake a river condition assessment. This is why LPAs increasingly ask for RCA competence/accreditation and why we deploy practitioners with the right skills.
Small sites and the Small Sites Metric (SSM)
For eligible small sites, you may use the Small Sites Metric (SSM) as a simplified alternative. While non-ecologists can sometimes use the SSM, we recommend professional oversight—particularly where priority habitats, protected sites/species, watercourses, or off-site solutions are involved—to avoid validation delays. The tools page and the 2025 user guide explain when the SSM is appropriate and how to apply it.
Exemptions and de minimis — do you qualify?
Some proposals are out of scope. Examples include householder applications, qualifying self-build/custom-build within thresholds, and very small impacts where no priority habitat is affected (the de minimis exemption). De minimis typically means impacts under 25 m² of on-site habitat and 5 m of on-site linear habitat (e.g., hedgerow), but the details matter and LPAs expect evidence. We assess this objectively and document your case clearly at validation stage.
On-site, off-site or statutory credits? (Choosing the route to +10%)
Where possible, we design on-site delivery first. If there’s still a shortfall, we help you secure off-site units from a registered Biodiversity Gain Site, making sure allocations meet spatial risk and trading rules. Natural England’s service confirms a £639 fee to register a gain site (and to process allocation). As a true last resort, you can purchase statutory biodiversity credits, with the number derived directly from the Credits Summary in the metric workbook. We document the pathway and evidence in your BGP.
What you get when you instruct us
We provide a comprehensive and auditable submission pack designed to meet current Biodiversity Net Gain requirements and to give planning officers the information they need to review your application.
Typical deliverables include:
UKHab baseline report (with parcel maps, tables and methods).
GIS files and planning-ready figures (pre- and post-development).
Completed Condition Assessment Sheets (area, hedgerow, watercourse as needed).
The statutory metric workbook(s), with scenario iterations and commentary.
A planning-ready Biodiversity Gain Plan (BGP).
Where relevant: River Condition Assessment outputs, off-site unit allocation evidence, and statutory credit documentation.
Note: While we prepare reports and plans to current standards and best practice, final acceptance remains at the discretion of the Local Planning Authority (LPA). We will advise you on any additional steps if further work is requested.
Process, timescales and survey windows
Most developments that introduce new structures or remove existing green space will inevitably result in some loss of biodiversity at baseline. This is completely normal and expected. Our role is to assess those impacts, explain what they mean for your project, and then guide you through the steps needed to achieve the statutory +10% Biodiversity Net Gain (BNG) while also complying with the trading rules. Simply hitting +10% in the metric is not always enough — the trading rules require that certain habitat types are replaced with like-for-like or better.
To achieve this, we work closely with you and your design team, often through a few iterations. Landscape architects, project architects and planners all need to integrate the BNG findings into the overall scheme. Together, we test options through the metric, apply the mitigation hierarchy (avoid → minimise → remediate → compensate), and identify the most practical route to satisfy both the BNG requirements and Local Planning Authority (LPA) expectations.
Because every site is different, timescales can vary. Condition evidence is most reliable during the main growing season, but projects rarely align perfectly with ecological calendars. We therefore plan sensible programmes, collect what’s robust now, and schedule targeted updates where needed.
The key statutory milestone is the Biodiversity Gain Plan (BGP). LPAs must issue a decision within 8 weeks of submission, and works cannot commence until approval is granted. By preparing a clear, auditable BGP and managing the process with your wider design team, we support you in reaching approval as promptly as possible while reducing the risk of avoidable delays.
Costs - what influences your BNG assessment fee
The cost of a Biodiversity Net Gain (BNG) assessment depends on how much work is involved. Factors include:
The size and complexity of the site.
The number and type of habitats that need to be surveyed.
Whether a River Condition Assessment (RCA) is required.
The number of design iterations with your architect or landscape team.
Whether off-site units or statutory credits are needed to reach the +10%.
As a guide, our fees start from £399 + VAT for very small, straightforward sites. More complex projects will require a tailored scope, but we always provide a transparent proposal and, where practical, a fixed fee before work begins.
To provide an accurate and fair quote, we normally ask for a few key pieces of information up front:
Red-line boundary — this defines the exact site area to be assessed, ensuring we capture all habitats within the development footprint and any adjacent features that may be relevant.
Proposed layout (if available) — even an early draft layout helps us understand which areas will be retained, built on or landscaped, so we can run realistic metric iterations and avoid surprises later.
Relevant ecology or planning background — for example, if a Preliminary Ecological Appraisal (PEA) or bat survey has already been completed, or if there are known planning conditions or designations on the site. Sharing these early allows us to scope more efficiently and avoid duplication.
If you don’t have a layout yet, we can still scope the baseline work and provide an indicative cost, then refine the metric once designs are available.
BNG and EcIA — how they fit together
Biodiversity Net Gain (BNG) and Ecological Impact Assessment (EcIA) are closely linked, but they serve different purposes in the planning system.
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EcIA looks at the potential significant effects of a project on valued ecological receptors, such as protected species, priority habitats or designated sites. It applies the mitigation hierarchy (avoid → minimise → remediate/restore → compensate) to ensure impacts are reduced as far as possible.
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BNG then goes a step further, using the statutory biodiversity metric to measure habitat change and demonstrate a clear +10% net gain, evidenced through the Biodiversity Gain Plan (BGP).
Running the two processes together is best practice. EcIA protects species and habitats from unacceptable harm, while BNG provides the measurable uplift now required by law. In practice, this means:
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Early ecological surveys feed into both EcIA and the UKHab baseline for BNG.
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Iterations with the design team ensure that planning layouts not only minimise ecological impacts but also deliver the net gain uplift.
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Combining EcIA and BNG reduces the risk of last-minute surprises at validation or determination, supports compliance with national and local policy, and often results in better placemaking and green infrastructure outcomes.
At ACP, we integrate EcIA and BNG assessments so you receive a coordinated approach that satisfies both policy requirements and the new statutory net gain duty.
While BNG focuses on habitats and measurable units, some projects may also need an ecosystem service assessment to demonstrate wider environmental value.
Frequently asked questions
We know that Biodiversity Net Gain (BNG) and UKHab surveys can feel complex, especially with the new statutory requirements now in force. To help, we’ve answered some of the most common questions our clients ask about BNG assessments, condition sheets, and Biodiversity Gain Plans. These quick answers give you an overview of what to expect, but if your project has specific needs, our team is always on hand to provide tailored advice.
What exactly is included in the Biodiversity Gain Plan (BGP)?
A Biodiversity Gain Plan (BGP) brings together all the information the Local Planning Authority (LPA) needs to approve your project under the new BNG rules. It typically includes:
The completed statutory biodiversity metric workbook.
Pre- and post-development habitat plans showing how the site will change.
Condition assessment sheets for each habitat parcel.
Details of how the +10% uplift will be achieved.
If relevant, off-site unit register references or statutory credit purchase evidence.
The LPA must approve the BGP before you can start works, normally within 8 weeks of submission. ACP prepares all of these elements into a single, audit-ready pack to streamline approval.
Do small sites really need BNG?
Yes. Since 2 April 2024, even small sites fall under the statutory BNG duty. For these cases, the government provides a simplified tool called the Small Sites Metric (SSM). While it looks easier to complete, errors are common, especially if the site includes priority habitats, watercourses, or off-site delivery. We recommend professional oversight to reduce the risk of your application being delayed or rejected.
What are “condition assessment sheets”?
These are the official forms published by Natural England/Defra to evidence the condition of each habitat parcel. They standardise how ecologists record habitat quality and ensure the LPA can audit the results. At ACP, we complete and submit these with your BGP, cross-referenced with photos and parcel IDs, so officers can clearly see how each score was justified.
Do I need a River Condition Assessment (RCA)?
If your development site contains or affects a river, stream, or canal, the BNG watercourse module relies on a River Condition Assessment (RCA). This is a specialised survey that looks at the channel, banks, and riparian zone. The 2025 user guide makes clear that only a qualified assessor should carry out an RCA. We have accredited practitioners who can complete this as part of your baseline if required.
Are any developments exempt from BNG?
Yes. Exemptions include:
Householder applications (extensions, loft conversions, etc.).
Qualifying self-build and custom-build housing within certain thresholds.
Very small developments with negligible impacts where no priority habitats are affected, known as the de minimis exemption (under 25 m² of habitat or 5 m of linear features such as hedgerows).
We assess exemptions case by case and, if applicable, provide written evidence for your validation pack.
What about NSIPs?
BNG will also apply to Nationally Significant Infrastructure Projects (NSIPs), but the government has set a later deadline, currently May 2026. If you are working on a large infrastructure project, we can advise on transitional arrangements and what evidence you should be collecting now to stay ahead of the statutory requirement.
How much does a BNG assessment cost?
The cost depends on the size and complexity of your site, the number of habitats to be surveyed, and whether extras like a River Condition Assessment (RCA), off-site units or statutory credits are required. At ACP, our fees start from £399 + VAT for small, straightforward sites. Larger or more complex developments will require a tailored scope, but we always provide a transparent proposal and, where possible, a fixed fee before work begins.
How long does a BNG assessment take?
Timelines vary with each project. The field survey is usually completed in a single visit, but the reporting and metric iterations can take longer depending on design revisions and the need for input from architects or landscape teams. Condition surveys are best carried out during the main growing season (spring to early autumn), although some baseline work can be done year-round. Once your Biodiversity Gain Plan (BGP) is submitted, the Local Planning Authority (LPA) must make a decision within 8 weeks. We aim to keep your project moving smoothly by preparing an audit-ready submission and coordinating closely with your design team.
Does Biodiversity Net Gain (BNG) apply in Wales and Scotland?
The statutory BNG duty currently applies only in England, under the Environment Act 2021.
In Wales, biodiversity enhancement is guided by the Environment (Wales) Act 2016 and Planning Policy Wales, but there is no mandatory 10% biodiversity net gain requirement. Instead, developers must demonstrate how they are maintaining and enhancing biodiversity and promoting ecosystem resilience. Natural Resources Wales (NRW) sets detailed expectations at project level.
In Scotland, there is also no statutory 10% BNG requirement at present. Scottish planning policy focuses on biodiversity enhancement and restoration through the National Planning Framework 4 (NPF4) and local planning authority guidance.
If your project is in Wales or Scotland, you may not need a BNG assessment using the statutory biodiversity metric. However, you will still need to evidence biodiversity protection and enhancement in line with local planning policy. Our team can advise on what is required depending on your site location.
Government Guidance and Statutory References
- Statutory framework & planning condition: Biodiversity Net Gain under Schedule 7A of the Town and Country Planning Act 1990; statutory regime explained in Planning Practice Guidance (GOV.UK).
- Biodiversity Gain Plan – Must be approved before commencement; Local Planning Authority decision normally within 8 weeks. See Biodiversity Net Gain Guidance (GOV.UK).
- Statutory biodiversity metric: How units are calculated, modules, factors, and guidance on early use. Statutory Metric and User Guide (GOV.UK).
- Condition Sheets & Small Sites Metric (SSM): Official metric tools and guidance sheets. BNG Metric Tools (GOV.UK).
- Exemptions & de minimis thresholds: Householder, small self-build, and very small impacts where no priority habitat is affected. Exemptions Guidance (GOV.UK) and Defra Environment Blog.
- Off-site register & fee: Natural England guidance on registering biodiversity gain sites, with the current £639 registration fee. Register a Biodiversity Gain Site (GOV.UK).
- NSIPs timing: Government proposals indicate that BNG will apply to Nationally Significant Infrastructure Projects (NSIPs) from May 2026, pending final regulations. Defra Consultation (GOV.UK).
- Creating a Habitat Management & Monitoring Plan (HMMP). GOV.UK guidance on how to prepare HMMPs, including monitoring and reporting requirements. HMMP Guidance (GOV.UK).
- Natural England HMMP Template (JP058) – Official template, checklist, and monitoring report tools for Habitat Management & Monitoring Plans. Natural England Publications.
- Statutory Biodiversity Metric User Guide (July 2025). Full guidance on how the statutory metric should be applied, including trading rules and worked examples. User Guide PDF.
- Metric Supporting Documents (JP039): Includes GIS templates, data standards, and case studies for applying the statutory metric. Natural England Publications.
Other Supporting References (Quick Links)
- BNG in Practice Report (2025) – Case studies showing how BNG is being delivered in real projects. Institute of Environmental Sciences.
- Biodiversity Net Gain – Principles and Guidance for UK Construction and Developments. Chartered Institute of Ecology and Environmental Management.
- BNG Research Briefing – This post note outlines the mandatory biodiversity net gain policy introduced in England in 2024 and the risks and challenges for delivering its objectives. UK Parliament.
- Biodiversity net gain: where to start. Natural England.
Why instruct Us
We front-load BNG considerations into the design process. So that trading rules and the statutory +10% uplift per unit type are achieved as efficiently as possible. Our UKHab baselines are defensible, our condition evidence is robust. Our submissions are structured to the latest Natural England user guide, enabling LPAs to determine applications within statutory timescales.
Where on-site delivery alone is not enough, we explain the options available to our clients. If needed, put you in touch with reputable off-site providers. We then integrate the relevant allocation references and documentation into your Biodiversity Gain Plan (BGP). This is so that your submission remains clear and audit-ready.
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Next Steps
Getting started with a BNG assessment is straightforward. We guide you through each stage so that nothing is missed and your planning application keeps moving:
Send us your red-line boundary and any drawings (PDF/DWG)
This helps us define the exact site area and understand what is proposed. Even early drafts are useful.We confirm the scope, survey windows and a fixed fee
Based on the information you provide, we’ll explain what surveys are needed, when they can be done, and issue a clear fee proposal.Survey and metric iterations to achieve +10%
Our ecologist visits the site, completes the UKHab baseline and condition assessments, and runs the statutory metric. We then test design options with your team until the +10% net gain (and trading rules) are achieved.Prepare and submit your Biodiversity Gain Plan (BGP)
We compile all the evidence into an audit-ready BGP for the Local Planning Authority (LPA). Once approved, you’ll have certainty to move forward on programme.
Explore Related Biodiversity Net Gain Resources
A Biodiversity Net Gain (BNG) assessment provides the baseline data and ecological calculations that underpin every compliant development. To understand how assessments form part of the wider process, start with the Biodiversity Net Gain Overview and explore the technical details of the Statutory Biodiversity Metric 4.0 used to measure habitat value and distinctiveness.
For smaller schemes, see our guide to the Small Sites Metric (SSM). Once the assessment is complete, results should feed into your Biodiversity Gain Plan (BGP) and Habitat Management and Monitoring Plan (HMMP), ensuring consistent evidence across all BNG documentation.
You can also access standard reporting templates via our BNG Templates & Downloads and estimate post-construction management costs with the BNG Monitoring Fee Calculator. For compliance context, review the BNG Legislation & Guidance and explore practical examples in our BNG Case Studies & Portfolio.
You can also drop us an email at hello@acp-consultants.com and we’ll get back to you within 24 hours to help with your inquiry!
- Last Updated:
- October 2025
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.