Energy Savings Opportunity Scheme
Comprehensive ESOS audits, action planning, and reporting support.
What is ESOS?
The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment scheme for large UK organisations, undertaken every four years. It requires qualifying organisations to measure their total energy consumption across buildings, industrial processes and transport before reviewing the areas that account for the majority of their energy use. This assessment, which usually covers at least 95% of total energy consumption, helps identify opportunities to improve efficiency and reduce costs.
For ESOS Phase 4, the qualification date is 31st December 2026 and the final compliance notification deadline is 5th December 2027. The scheme is administered by the Environment Agency, with penalties of up to £50,000 for non-compliance.
ISO 50001 exemption
Organisations with certified ISO 50001 coverage can use it as part of their ESOS compliance route. To avoid appointing an ESOS lead assessor, ISO 50001 must cover 100% of the organisation’s energy supplies.
Where ISO 50001 only covers part of the organisation’s energy use, the remaining consumption must be covered through another approved route, such as an ESOS energy audit. ESOS assessments must account for at least 95% of total energy consumption.
Who qualifies for ESOS?
Organisations qualify for ESOS if they employ 250 or more people, or if they have both an annual turnover above £44 million and a balance sheet total above £38 million.
What the ESOS audit covers
Buildings
Energy use across all buildings in the organisation's estate, including heating, cooling, lighting, and other fixed equipment.
Industrial processes
Energy consumption by production plant, equipment, and process systems, including compressed air, heating, and drives.
Transport
Fuel and energy used by the organisation's fleet and business travel, including both road and any other transport modes.
How Pro Enviro supports you
Pro Enviro's ESOS auditors are Lead Energy Auditors accredited by the Energy Institute. We carry out detailed, high-quality assessments that go beyond minimum compliance requirements and produce action plans that deliver real energy and cost savings - not just tick-box compliance.
What makes a good ESOS action plan?
Following the audit, every qualifying organisation must produce an action plan and report progress against it. The quality of that plan matters — it is made public and shapes your organisation's credibility on energy management. Here is what a strong plan includes:
Your audit will identify multiple energy-saving opportunities. You do not have to implement every one, but you must record your reasons for rejecting any recommendation. All this information belongs in your evidence pack.
For each measure you plan to implement, state the month and year you intend to begin. The audit will suggest timings based on equipment obsolescence, lease renewals, and other factors — use these as a starting point but adapt them to your operational reality.
Progress updates are required 12 months after the action plan deadline and again the following year. These are made public. An over-ambitious plan that is only partially delivered damages credibility — thorough, realistic planning is far more effective.
The plan must include estimated energy savings for each action over the action plan period. Break these down by area of consumption — buildings, industrial processes, and transport — and provide a combined total. State your data sources clearly.
A board-level director must review and sign off the final action plan, ensuring energy reduction commitments are communicated to senior decision-makers. The notification of compliance is then submitted via the MESOS portal.
Get ESOS-ready with Pro Enviro
Our accredited auditors will carry out a thorough assessment and help you build a credible, actionable plan.