ESOS Audits
mandatory assessment
Energy Savings Opportunity Scheme
An ESOS (Energy Savings Opportunity Scheme) audit is a mandatory energy assessment for large organisations in the UK. It analyses energy use across buildings, industrial processes, and transport to identify practical, cost-effective opportunities to reduce consumption and cut carbon emissions.
Qualifying organisations must complete an ESOS assessment every four years, signed off by a certified Lead Assessor and a board-level director.
criteria
Do you need an ESOS audit?
Qualifying businesses:
- Employ 250 or more people
- Have an annual turnover exceeding £44 million and an annual balance sheet total exceeding £30 million. Corporate groups that include at least one large UK undertaking also fall within scope
Current position for qualifying businesses:
- Eligible UK businesses are currently working through Phase 4 of the Scheme, Data Collection & Auditing which runs until 05/12/2027.
- Organisations are gathering 12 months of energy data to prepare for the 31/12/2026 qualification date, whilst also preparing to submit their final Phase 3 progress report by 05/12/2026.
- Preparing for the Qualification Date: Companies are assessing their workforce and financials to see if they will meet the ESOS criteria by 31/12/2026.
- Completing Phase 3 Obligations: Businesses that were in scope for Phase 3, will have already submitted their Action Plan and the first progress report. They must submit their second progress report by 05/12/2026.
energy consumption
What the audit covers
An ESOS audit must account for at least 95% of your organisation's total energy consumption. The process typically includes:
- Data profiling: Analysing 12 months of verifiable energy data to identify usage patterns and high-consumption areas.
- Site walk-throughs: Physical assessments of buildings, plant rooms, and operational processes.
- Transport review: Assessing fuel use from company vehicles, commercial fleets, and business travel.
- Recommendations: Delivering costed recommendations that quantify how much energy and money could be saved through specific improvements.
energy management
Alternatives to a full audit
Organisations with certain energy management systems already in place may not need to complete a full ESOS audit. The main alternatives include:
- ISO 50001 Certification: A fully certified Energy Management System covering all energy use can satisfy ESOS requirements.
- Display Energy Certificates (DECs) or Green Deal Assessments: These can be used for specific building types in certain circumstances.
If you're unsure whether an alternative applies to your organisation, we can help you work through the options.
secr
Related compliance requirement
Alongside ESOS, some businesses will also have obligations under Streamlined Energy and Carbon Reporting (SECR) – a separate requirement that applies to quoted companies of any size, and to large unquoted companies and LLPs meeting at least two of the following thresholds: more than 250 employees, annual turnover above £36 million, or a balance sheet total above £38 million.
Where ESOS requires a private assessment every four years, SECR requires eligible businesses to publicly disclose their energy use and greenhouse gas emissions annually, within their Directors' Report.
The data gathered through an ESOS audit – energy consumption figures, emissions calculations, and efficiency recommendations – often provides a strong foundation for SECR reporting. If you're subject to both obligations, we can help you understand how the two fit together and point you towards specialist support for the reporting process itself.
notification of compliance
Compliance and penalties
Once the assessment is complete, organisations must submit a notification of compliance to the relevant UK environmental regulator – the Environment Agency in England, or the equivalent body in Scotland, Wales, and Northern Ireland. Missing the deadline or failing to comply can result in significant financial penalties.
For official guidance on deadlines, registration, and compliance requirements, the UK Government publishes an ESOS guidance hub.
practical energy solutions
How we can help
An ESOS audit is a legal obligation – but it's also a genuine opportunity to understand where your energy spend is going and identify improvements that deliver real financial and carbon savings.
We support organisations through the audit process and, where relevant, help translate the findings into a practical energy strategy – identifying which recommendations are worth acting on, in what order, and how they fit within your wider plans.