Organisations that qualify for ESOS are legally required to carry out mandatory energy assessments every four years.
These assessments review how energy is used across buildings, industrial processes and transport, identifying cost-effective opportunities to reduce consumption, cut costs and lower emissions.
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With the right support, ESOS can be more than a compliance exercise. It can be a valuable step towards long-term energy-efficiency and carbon reduction.
What is ESOS?
The Energy Savings Opportunity Scheme (ESOS) is a mandatory UK government scheme administered by the Environment Agency (EA). It was introduced to encourage large organisations to identify energy-saving opportunities and reduce carbon emissions as part of the UK’s journey to net zero by 2050.
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Under ESOS, qualifying organisations must complete an energy assessment covering the majority of their energy use and produce recommendations to improve efficiency. These assessments must be completed over a 12-month period and repeated every four years.
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Who Needs to Comply with ESOS?
Large organisations, as defined by the Companies Act 2006, must comply with ESOS if they meet one or both of the following criteria:
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More than 250 employees in the UK
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A turnover exceeding £44.1m and a balance sheet total exceeding £37.9m for two consecutive years on or before 31 December 2026
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If your organisation qualifies, you must report on at least 90% of your total energy consumption.
When is the Next ESOS Submission Date?
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If your organisation is in scope for ESOS Phase 4, the following dates apply.​
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Qualification date
31 December 2026
Compliance period
From August 2025 to
5 June 2028
Compliance deadline
5 December 2027
During this period, organisations must survey their sites, analyse 12 months of energy data, identify savings opportunities and notify compliance to the Environment Agency by 5 June 2028.​
Many organisations in scope of ESOS also have SECR obligations. With smart planning, ESOS data can be seamlessly transitioned into SECR reporting, reducing duplication and saving time and cost.
If your organisation operates a certified ISO 50001 energy management system covering all energy use, you are exempt from completing an ESOS assessment and only need to submit a notification to the regulator.​
​What do the Energy Assessments Involve?
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An ESOS assessment provides a clear, detailed picture of how your organisation uses energy and where improvements can be made.
To comply, organisations must:
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Measure 12 months of total energy consumption (buildings, processes and transport)
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Identify significant areas accounting for at least 95% of total use
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Conduct energy audits to identify cost-effective energy-saving measures
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Appoint a qualified ESOS Lead Energy Assessor to review and verify the assessment
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Submit compliance notification via the EA’s online portal by the 5 June 2028
​Penalties for Missing the ESOS Deadline
The Environment Agency has wide enforcement powers and is actively taking action against organisations that fail to comply.
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Potential penalties include:
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Fixed Penalty: Up to £50,000 for failing to complete an ESOS assessment
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Daily Penalty: £500 per day of non-compliance (up to 80 working days = £40,000)
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Record Keeping Penalty: Up to £5,000 for poor or missing records
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Public Disclosure: Non-compliant organisations may be named on the EA’s website
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Enforcement Notices: Formal instructions requiring organisations to achieve compliance within a set timeframe
​Total fines can reach up to £90,000 depending on the duration and nature of the breach.
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Before starting any assessment, we’ll verify whether your organisation is genuinely required to comply. In some cases, corporate structure or financial arrangements can affect eligibility. If you are exempt, we’ll prepare the necessary documentation and support communication with the Environment Agency.
​Appointing a Qualified ESOS Lead Assessor
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Unless fully compliant through ISO 50001 certification, organisations must appoint a government-approved ESOS Lead Assessor.
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An ESOS Lead Assessor is responsible for:
✔ Being registered with an approved professional body
✔ Meeting strict competency requirements
✔ Reviewing and signing off ESOS assessments
✔ Confirming that ESOS compliance requirements have been met
​Our Approved ESOS Lead Assessor
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We provide a cradle-to-grave ESOS Phase 4 service, ensuring your assessment is compliant, complete and defensible.
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Our in-house ESOS Lead Assessor, Jason Martin, is approved by the Energy Managers Association (EMA). With extensive experience in energy management and engineering, Jason has helped organisations optimise building performance, reduce energy consumption and deliver meaningful efficiency improvements.
Why Choose Our ESOS Specialists
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Our team offers far more than a tick-box approach to compliance. We support organisations at every stage — from eligibility checks to submission — protecting you from financial penalties and reputational risk.
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We can deliver:
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Standalone ESOS assessments, or
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A tailored Energy Efficiency & Compliance Plan that embeds ESOS into a long-term strategy​
​Our ongoing approach provides continuous monitoring, regular data review, proactive regulatory updates and a dedicated Energy Manager to ensure compliance is maintained all year-round, not just at reporting deadlines. It also ensures priority access to our Lead Assessor when submission time comes.
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By embedding compliance into a structured, long-term energy strategy, you reduce risk, improve efficiency and stay ahead of changing legislation.
Energy Management Services
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Helping businesses identify opportunities to improve energy efficiency, reduce carbon, and explore potential savings whilst ensuring compliance and avoiding penalties.
Expert support with the implementation of energy reduction solutions and technology. A turnkey solution for power, heating, compressed air, EV charging, lighting & building controls.
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Ongoing support for the implementation of energy efficiency measures, planning and executing a Net Zero roadmap whilst capitalising on available grants and funding.