Biodiversity Net Gain consultants for planning in England
Our Biodiversity Net Gain consultants help you understand what your site needs. Then move forward with clear, practical advice.
Our BNG consultancy supports developers, architects, planning consultants and landowners with surveys, assessments, metric calculations and delivery plans.
We start with your site and planning stage, so you understand the work required and the decisions ahead.
Discuss your BNG project
A clear starting point
What is Biodiversity Net Gain?
Biodiversity Net Gain (BNG) means leaving habitats in a measurably better state after development. It connects ecological evidence with the way a site is designed, delivered and managed.
For non-exempt development in England, the statutory objective is at least 10% gain, measured using the statutory biodiversity metric. Also check local policy and the rules that apply to your planning route.
Our role is to help you understand those requirements and turn them into coordinated surveys, calculations and practical plans. Start with our BNG assessment service if you need help defining the scope.
Requirements before reports
When does BNG apply?
The requirements depend on the application, not just the description “small development”. Therefore, establish the position before fixing the survey brief or design programme.
From 6 August 2026, an exemption covers qualifying sites of 0.2 hectares or below; priority-habitat impacts can prevent its use. New self-build and custom-build applications no longer have their previous exemption. Always check the full conditions and transitional arrangements.
A BNG exemption does not remove other ecology or protected-species requirements. So keep these checks alongside the planning advice for your site.
For the wider framework, use our BNG legislation and guidance and BNG process guide. The Small Sites Metric service addresses the separate question of which calculation method is suitable.
Find the right support
BNG consultancy services for each project stage
BNG assessment and baseline surveys
Establish the habitats, constraints and information your proposal needs before progressing the assessment.
Statutory biodiversity metric
Calculate baseline and proposed units. Then test habitat options and keep the workbook aligned with the design.
Small Sites Metric
Check eligibility for the simplified method and prepare an appropriate calculation where it can be used.
Biodiversity Gain Plans
Bring the delivery strategy and supporting evidence together for the biodiversity gain condition.
Habitat management and monitoring
Define practical actions, responsibilities and monitoring for the habitats the scheme will deliver.
BNG reports for planning
Present the assessment findings, plans and calculations in a clear, coordinated reporting package.
Need a specialist input? Explore River Condition Assessment, habitat survey services or off-site biodiversity units. We will explain which inputs are relevant to your site.
How we work
From the first question to a coordinated plan
Understand your site
Send your site location, red-line plan, proposals and planning stage. Next, we review the available information and identify the decisions that need ecological input.
You receive a defined scope, with assumptions and exclusions explained before work begins.
Assess and coordinate
Once instructed, we undertake the agreed surveys and assessment. We also work with the project team to reconcile habitat mapping, the metric and proposed layout.
If the design changes, the evidence needs to change with it. We therefore explain the implications and any further work required.
Plan for delivery
We prepare the agreed reporting and plans for the relevant stage. In addition, clear responsibilities help connect planning requirements with habitat delivery on the ground.
Post-permission support and monitoring can be scoped where required.
Evidence that connects
How is biodiversity net gain measured?
Biodiversity Net Gain is measured using the Statutory Biodiversity Metric, which provides a standardised method for calculating biodiversity value before and after development. The metric assesses habitat type, habitat condition, distinctiveness, strategic significance and habitat area to calculate biodiversity units. This enables planning authorities to assess whether a proposed development delivers the required biodiversity uplift using a consistent national methodology.
Accurate biodiversity calculations depend on correctly identifying habitat types and assessing their ecological condition. Understanding how biodiversity units are calculated and completing a thorough BNG Condition Assessment ensures habitats are assessed consistently before and after development. This provides a reliable baseline for biodiversity metric calculations while identifying practical opportunities for habitat retention, enhancement and creation.
Some developments require additional ecological assessments to complete biodiversity calculations accurately. Sites containing watercourses may require a River Condition Assessment, while developments affecting drainage features may also require a Ditch Condition Assessment. Habitat mapping using BNG GIS Mapping Tools also supports accurate biodiversity calculations, habitat management planning and planning-ready documentation for larger or more complex developments.
Using the metric throughout the design process allows different development layouts to be assessed before planning applications are submitted. Early ecological input often helps maximise on-site biodiversity gain, reduces planning risk and minimises the need for more costly mitigation measures later in the project.
Survey the habitats
Map the baseline and record habitat condition.
Calculate the units
Use the appropriate metric to compare baseline and proposed habitats.
Coordinate the design
Test habitat options. Then update the plans and metric together.
Prepare the gain plan
Set out the delivery approach and supporting evidence for approval where required.
Manage and monitor
Deliver the agreed habitats, management actions and monitoring.
Design and assessment are iterative: if the layout changes, revisit the habitat plans and calculations. This overview does not replace project-specific advice.
The workbook and drawings must tell the same story
A habitat area in the metric should be traceable to the same boundary and revision on the habitat plan. For example, a design change can affect the result, the delivery strategy and the management requirements.
Use our habitat plan and metric reconciliation checklist to organise that review.
The right information, at the right stage
Which BNG documents do you need?
The information needed with an application is not identical to the information needed before commencement. Therefore, agree the required package with the planning team and relevant authority.
| Project stage | Evidence and decisions to coordinate |
|---|---|
| Before submission | Confirm applicability, establish baseline habitats and prepare the relevant assessment, metric and plans. Check the authority’s validation requirements. |
| Design development | Keep habitat mapping, landscape proposals, drainage and the metric consistent. Record revisions, constraints and unresolved assumptions. |
| After permission | For development subject to the biodiversity gain condition, obtain approval of the Biodiversity Gain Plan before starting development, subject to applicable rules. |
| Delivery and management | Assign habitat creation, management, monitoring and reporting responsibilities. Align the HMMP, legal commitments and contractor information. |
This is an overview, not a universal validation list. See our Biodiversity Gain Plan service, HMMP service and BNG report guidance for the relevant deliverables.
Not sure which stage your project has reached? Share the plans and planning correspondence you already have.
Ask about your requirementsBeyond the calculation
Plan for habitats that can be delivered
Retain and improve
Consider existing habitats early. Then coordinate the layout, landscape and engineering proposals so habitat commitments are practical.
Resolve any shortfall
Explore the applicable on-site and off-site options. However, registered off-site units and statutory biodiversity credits are different products.
Secure the outcome
Match the evidence, delivery arrangements and management commitments. Also set out who will do what, and how progress will be checked.
Current guidance allows non-exempt minor developments to consider on-site and off-site delivery together. However, statutory credits remain a last resort. Off-site gains and significant on-site gains require at least 30 years’ maintenance.
Read more about off-site biodiversity units and the applicable BNG rules.
Opportunities with responsibilities
BNG for landowners
Landowners can explore creating or enhancing habitats to supply off-site biodiversity units. However, a habitat bank is a long-term land-management commitment, not simply a calculation of potential units.
Start by examining the ecological baseline, realistic habitat targets, delivery costs and management responsibilities. Legal arrangements, registration and allocation evidence also need to fit the proposed business model.
Our BNG consultants can help you understand the ecological work and reporting needed. Commercial returns and demand are site-specific; an indicative unit estimate is not a guarantee of a sale.
Scope, cost and programme
How much does biodiversity net gain cost?
The cost of Biodiversity Net Gain depends on the size of the development, the habitats present, the planning stage and the level of ecological work required. Every project is different, so the scope of surveys, biodiversity metric calculations and planning documentation should always be proportionate to the development and local planning authority requirements.
For a smaller development, first establish whether BNG applies and which assessment method is appropriate. Larger or more complex developments often require additional ecological surveys, Biodiversity Gain Plans, Habitat Management & Monitoring Plans, legal agreements and, where necessary, the purchase of off-site biodiversity units. Projects requiring long-term habitat creation may also incur monitoring fees to demonstrate successful habitat establishment throughout the management period.
The best way to reduce Biodiversity Net Gain costs is to consider biodiversity at the earliest stages of site design. Early ecological advice often identifies practical opportunities to retain habitats, reduce biodiversity losses and minimise the need for more expensive off-site compensation measures. Our consultants provide clear fixed-fee quotations wherever possible and explain the scope of work before surveys begin.
| Factor | Why it matters |
|---|---|
| Site and habitats | Area, habitat diversity, access and available baseline evidence affect survey and assessment work. |
| Planning and design stage | A fixed layout, missing evidence or later revisions can add coordination and assessment work. |
| Delivery strategy | Off-site units, legal arrangements and habitat management have costs separate from preparing the assessment. |
| Programme | Seasonal evidence, access, design decisions and authority requirements influence the timetable. |
For the monitoring element, see our BNG monitoring fee calculator. Its scope is monitoring fees, not a substitute for the statutory biodiversity metric or a complete project quotation.
Built on TRUST
Clear advice. Shared responsibility.
Good advice should leave you clear about the requirement, the evidence and the next decision. That is why our Biodiversity Net Gain consultants explain the scope of our work and raise uncertainties early.
Our BNG consultants also work collaboratively with your planning and design team. Where a proposal risks an ecological problem, we explain the concern and help explore an appropriate response.
That approach reflects our commitment to clients, colleagues and the environment. Read about ACP and our TRUST values.
“ACP helped provide a statement to explain that the development was below the threshold and therefore exempt, saving me time and money!”
Paul Hunt · extract from an existing Google review displayed by ACPThis describes that client’s experience, not an exemption decision for another site.
Explore the campaign
Go deeper where your project needs it
The BNG process
Understand the stages and decisions from early review to delivery.
Legislation and guidance
Check the framework and sources behind the requirements.
BNG locations
Find the appropriate England, regional and local guidance.
For topical updates and practical coordination checklists, visit Insights & Guidance.
Your questions
Biodiversity Net Gain FAQs
Is Biodiversity Net Gain mandatory?
For non-exempt development in England, mandatory BNG applies through the relevant planning framework. Check the current exemptions, application date and planning route before deciding what your site needs.
When should a Biodiversity Net Gain assessment be completed?
Biodiversity Net Gain should be considered at the earliest stages of project design. As a result, early ecological advice can inform the site layout and identify planning risks before you submit an application.
What documents are usually required?
Requirements vary between developments but commonly include habitat surveys, biodiversity metric calculations, Biodiversity Gain Plans, Habitat Management & Monitoring Plans and planning reports.
Can Biodiversity Net Gain be achieved off-site?
Yes, off-site delivery can form part of the strategy. The applicable hierarchy and metric requirements still matter. See our off-site biodiversity units guidance and current government guidance for the route relevant to your development.
How long must Biodiversity Net Gain habitats be managed?
Off-site gains and significant on-site gains must be maintained for at least 30 years. The relevant plans and agreements should set out the responsibilities and monitoring arrangements.
How much does Biodiversity Net Gain cost?
Costs vary depending on the size of the development, existing habitats, planning stage and the documentation required. Early ecological advice often reduces overall project costs by identifying practical biodiversity enhancements before planning applications are submitted.
Do all developments require Biodiversity Net Gain?
No. Exemptions and transitional arrangements can apply. Eligibility for the Small Sites Metric is a separate question and does not itself establish an exemption.
Can ACP Consultants help throughout the planning process?
Yes. We provide planning-focused Biodiversity Net Gain support from early feasibility through to planning approval and post-permission requirements, including habitat surveys, biodiversity metric calculations, Biodiversity Gain Plans, Habitat Management & Monitoring Plans and ongoing ecological advice.
Can Biodiversity Net Gain delay planning permission?
Incomplete evidence, unresolved design changes or seasonal survey constraints can affect a programme. Early ecological input helps identify those risks, but it cannot guarantee a planning decision or timescale.
Can Biodiversity Net Gain be designed into a development?
Yes. The most successful developments consider Biodiversity Net Gain during the earliest design stages. Retaining existing habitats, improving habitat connectivity and incorporating new ecological features into the layout often provides better biodiversity outcomes while reducing planning risk and the need for costly redesigns.
Who prepares Biodiversity Net Gain reports?
Biodiversity Net Gain reports should be prepared by experienced ecologists familiar with the Statutory Biodiversity Metric, UKHab habitat classification, planning policy and current Biodiversity Net Gain guidance. Reports should provide proportionate technical evidence that supports planning applications and demonstrates compliance with statutory requirements.
How long does a Biodiversity Net Gain assessment take?
Timescales and costs vary depending on the size of the site, habitat complexity, seasonal survey requirements and the planning stage. Smaller developments can often be assessed quickly, while larger or more complex sites may require additional ecological surveys and supporting documentation. Seeking advice early helps avoid unnecessary delays and ensures the correct information is available before planning submission.
Let’s discuss your site
Get practical BNG advice for your project
Tell us the site location, what you are proposing and where you are in the planning process. We can then discuss the relevant BNG work.
Useful starting information includes your red-line plan, proposed layout, existing ecology reports and any planning correspondence.
Sources and scope
Useful BNG references
- GOV.UK: understanding biodiversity net gain
- GOV.UK: exempt developments
- Planning practice guidance: biodiversity net gain
Disclaimer date: October 2026
Disclaimer: The information on this page has been prepared by ACP Consultants’ in-house specialists using current legislation, published guidance, recognised industry standards and environmental best practice available at the time of writing. It is provided for general information only and should not be relied upon as a substitute for project-specific professional advice. Planning legislation, Biodiversity Net Gain requirements, local validation criteria and planning authority guidance may change over time and can vary between local planning authorities. Every development site is different and may require different surveys, assessments, calculations or mitigation measures depending on its individual characteristics. While every reasonable effort is made to keep this information accurate and up to date, ACP Consultants accepts no responsibility or liability for any loss, damage, planning outcome or decision arising from reliance on this information without first obtaining project-specific professional advice.