ESOS Phase 4 Compliance UK & Energy Audits
We deliver ESOS Phase 4 compliance in the UK, including accredited energy audits, reporting and full compliance support for qualifying large organisations.
Avoid costly ESOS penalties and ensure full compliance with expert-led audits and reporting.
The Energy Savings Opportunity Scheme (ESOS) requires large UK organisations to carry out energy audits every four years to improve efficiency. Our accredited ESOS lead assessors help you meet compliance obligations while identifying practical energy and carbon savings.
- Accredited ESOS lead assessors with experience across complex, multi-site organisations
- Full ESOS Phase 4 compliance support from eligibility checks to final notification
- Clear, compliant ESOS audit reports with practical energy efficiency recommendations
- Support for UK-wide property portfolios across multiple sectors
What is ESOS Compliance in the UK?
The Energy Savings Opportunity Scheme (ESOS) is a mandatory UK energy assessment scheme for large organisations. It requires qualifying businesses to conduct energy audits every four years to identify cost-effective measures that allow them to reduce energy consumption and achieve carbon and costs savings.
The audit includes energy used by buildings, industrial processes and transport.
Who needs to comply with ESOS Phase 4?
Your organisation must comply with ESOS Phase 4 if it meets one of the following criteria on the qualification date of 31 December 2026:
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Employ 250 or more people, or
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Have an annual turnover above £44 million and an annual balance sheet total above £38 million, or
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Are part of a corporate group that includes a UK undertaking meeting these thresholds.
There is more to qualifying for ESOS than just meeting the above thresholds on the qualification date, as you might have to look at earlier accounts to determine if you maintained your qualification status or not for at least two consecutive accounting periods.
If you meet any of these criteria, your organisation is legally required to complete an ESOS energy audit and submit a Notification of Compliance before the compliance date.
Not sure if you qualify?
We can carry out a quick ESOS eligibility check based on your latest accounts and group structure and guide you through the full compliance process.
If you are unsure where to start with ESOS Phase 4, talk with one of our ESOS lead assessors to review your position and timelines.
Why choose Smart GreenTech for ESOS compliance
Smart GreenTech Solutions is a multi-award-winning, independent London-based building performance and sustainability consultancy, established in 2011.
Organisations work with us on ESOS because we offer:
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Accredited ESOS lead assessors
Your ESOS consultant is a CIBSE-accredited energy efficiency specialist, registered with the Energy Institute, with deep experience of complex commercial buildings and portfolios. -
Proven energy and cost savings
We focus on realistic, cost-effective measures with clear paybacks that help justify investment and support your wider energy efficiency and carbon reduction strategy. -
Streamlined, low-stress compliance
Our processes and templates significantly reduce internal time spent on data collection, audit coordination and reporting. - Coverage across Greater London, the South East and UK-wide portfolios We support single-site organisations and multi-site estates across Greater London, the South East and the wider UK, including major hubs such as Reading, Slough, Milton Keynes, Oxford and Watford, and can align ESOS audits, TM44 inspections and SECR reporting across your portfolio.
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Clear communication and reporting
We avoid technical jargon and provide concise, board-ready outputs that make it easy to understand the risks, opportunities and next steps.
Choosing the right ESOS lead assessor is critical to ensuring compliance, avoiding penalties and identifying meaningful energy savings.
ESOS Phase 4 key dates and compliance deadlines
ESOS Phase 4 runs from 6 December 2023 to 5 December 2027, with organisations required to complete energy audits and submit their compliance notification before the final deadline.
Key ESOS dates to be aware of are:
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6 December 2023 – Phase 4 compliance period starts
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31 December 2026 – Phase 4 qualification date
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5 December 2027 – deadline to complete your ESOS Phase 4 work and submit your notification of compliance to the Environment Agency
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Action plans and progress updates – if you were in scope for Phase 3, you must submit an ESOS action plan and two annual progress updates tracking delivery of your energy-saving measures.
- Progress against your ESOS Phase 3 action plan commitments must be included in your ESOS Phase 4 assessment.
- You must provide an explanation where action plan commitments have not been met.
- Progress against your ESOS Phase 3 action plan commitments must be included in your ESOS Phase 4 assessment.
Missing these deadlines can result in significant financial penalties and publication of non-compliance.
Explore our guidance on ESOS compliance best practices.
Summary of key Phase 4 changes
The UK Government has made changes to ESOS, which came into force on 22 July 2026, which are summarised below.
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Removal of Display Energy Certificates (DECs) and Green Deal Assessments (GDAs) as compliance routes.
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Progress against Phase 3 action plan commitments must be included in the ESOS Phase 4 assessment
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Where action plan commitments have not been met, participants must provide an explanation.
- Participants with ISO 50001 Energy Management System covering either the total energy consumption (TEC) or significant energy consumption (SEC) are exempt from:
- appointing a lead assessor
- completing an ESOS report
- Lead assessors are now required to notify their professional body of each ESOS assessment the complete/review, along with the ESOS participants contact details.
- This is to allow the professional body to seek the ESOS participants consent to share its ESOS report so that the professional body can carry out quality checks
What happens if you do not comply with ESOS?
Organisations that fail to comply with the Energy Savings Opportunity Scheme (ESOS) may face enforcement action from the Environment Agency. Civil penalties can include significant financial fines, enforcement notices and public disclosure of non-compliance.
Depending on the nature of the breach, penalties may include:
- A fixed penalty of up to £50,000 for failing to carry out an ESOS energy audit
- Additional daily penalties of up to £500 per day until compliance is achieved
- Further penalties for failing to notify compliance, maintain records or respond to enforcement notices
- Publication of the organisation’s name on a public register of non-compliance
In some cases, total penalties can reach up to £90,000 depending on the breach and the duration of non-compliance.
For a full breakdown of enforcement actions, penalties and how regulators apply them, read our guide to approved changes to ESOS and compliance enforcement.
What’s included in our ESOS compliance service
Our end-to-end ESOS compliance service covers every stage of the process, from initial eligibility checks through to audit delivery, reporting, final submission via MESOS and ongoing support.
We manage the entire ESOS process for you, reducing internal workload, ensuring compliance and identifying practical energy and cost savings.
Step 1 – ESOS eligibility check and scoping
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Review your group structure, accounts and previous ESOS status
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Confirm whether you qualify for ESOS Phase 4
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Agree the most suitable route to compliance (audits or ISO 50001)
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Define the scope of work, sites to be included and timescales.
Read our article on understanding the ESOS Phase 4 qualification thresholds and criteria
Step 2 – Energy data collection and analysis
We work with your team to gather and validate energy data across:
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Buildings and facilities
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Transport (fleet and business mileage where applicable)
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Industrial processes and other significant energy uses
Our user-friendly templates and processes streamline data collection and help ensure that at least 95% of your total energy consumption is assessed, in line with strengthened ESOS requirements.
Step 3 – Site surveys and ESOS energy audits
Our CIBSE-accredited energy and sustainability consultants carry out on-site ESOS energy audits across your portfolio of buildings.
We identify:
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Operational and control issues in HVAC, lighting and building services
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Opportunities for low-cost behavioural and control improvements
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Cost-effective fabric and plant upgrades
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Measures that support your wider net-zero and carbon reduction plans
Where appropriate, we use relevant standards and good-practice benchmarks to quantify savings and paybacks.
Step 4 – ESOS compliance reporting, sign-off and submission
We then produce your ESOS compliant report and supporting documentation, including:
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Overview of total energy consumption and significant energy uses
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Site-level findings, recommendations and savings estimates
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Energy intensity metrics required under ESOS strengthening measures
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Evidence of board-level review and sign-off and supporting Evidence Pack
We support you through to submission via the MESOS reporting system and notification of compliance to the Environment Agency.
Step 5 – ESOS action plans and ongoing compliance support
For organisations that were in scope for ESOS Phase 3, we also help to:
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Develop your ESOS action plan setting out which measures you intend to implement and when
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Quantify expected energy and carbon savings
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Prepare the two required annual progress updates, explaining achievements and any variances from the plan
This turns ESOS into a practical roadmap for ongoing improvement rather than just a one-off compliance exercise.
Need support with your ESOS compliance? Speak to one of our accredited lead assessors today.
ESOS Compliance FAQs
Our Industry Accreditations & Registrations
Check out our ESOS compliance and related articles
Our articles include guidance on ESOS compliance, audits and reporting and how to improve your buildings energy efficiency.
Ready to talk about ESOS?
Whether you need help confirming if you qualify for ESOS Phase 4, want to make sense of new guidance, or are ready to plan audits across your estate, we’re here to help.
Call us: +44 (0) 3300 881451
Email:
Or: complete our short form to request a free ESOS consultation
We’ll review your situation, outline the likely scope of work and timescales, and propose a practical plan to achieve ESOS compliance and long-term energy savings.