ESOS compliance starts with knowing where your energy goes
The Energy Savings Opportunity Scheme (ESOS) requires large UK undertakings to measure their total energy consumption, audit their areas of significant energy use, identify savings opportunities and notify the Environment Agency, with a lead assessor's review and director sign-off. Aqueduct supplies the measured inputs: metered energy by site and use, significant energy uses ranked and savings verified at the meter.
What ESOS is and who it applies to
ESOS is a mandatory UK energy assessment scheme administered by the Environment Agency, with other UK regulators covering Scotland, Wales and Northern Ireland. It applies to large undertakings and their corporate groups, defined by employee numbers, turnover and balance sheet tests. The scheme runs in compliance phases. In each phase, a qualifying organization measures its total energy consumption across buildings, industrial processes and transport, identifies its areas of significant energy consumption and audits them to find cost-effective savings.
A registered lead assessor reviews the work, board-level directors confirm it and the organization notifies the regulator. Recent phases added requirements such as action plans and progress updates. Certification to ISO 50001 covering the organization's energy can be a route to compliance. Qualification tests, deadlines and phase rules change, so check current Environment Agency guidance before you plan.
ESOS requirements and the evidence Aqueduct supplies
Aqueduct supplies measured energy data for buildings and processes. Your lead assessor and directors own the assessment.
| Requirement | Evidence needed | How Aqueduct supplies it |
|---|---|---|
| Total energy consumption | Energy across buildings, processes and transport for the reference period | Metered electricity, gas and other fuels by site in one dataset, with bills uploaded where meters are not yet live; transport fuel stays with your fleet data |
| Areas of significant energy consumption | Which sites and uses make up most of the total | Sites and sub-metered loads ranked by share of consumption, using load disaggregation where sub-meters are sparse |
| Energy audits | Analysis of consumption profiles and savings opportunities | Half-hourly and finer profiles, after-hours base load, peak demand and equipment faults per site |
| Savings opportunities | Costed measures with expected savings | Measured baselines that make estimates credible, and fault findings with the equipment and time named |
| Action plan | Measures the organization intends to take | A list of identified opportunities your team can adopt, with the meters that will verify them |
| Progress updates | Evidence of what was done and what changed | Savings verified at the meter against a weather-normalized baseline |
| Evidence pack | Records the regulator can request | Exports by site and period, meter registers and device health |
How to prepare for an ESOS phase
Confirm qualification and the group
Check the qualification tests against current guidance and agree which entities are in the group.
Measure total energy
Pull a full year of energy for every site and fuel. Aqueduct consolidates metered and billed data so nothing is counted twice.
Find significant energy consumption
Rank sites and end uses, then decide with your lead assessor which areas to audit.
Audit with measured profiles
Use interval data to find base load, out-of-hours running and faults, and cost the opportunities from real consumption.
Plan, notify and verify
Agree the action plan, complete the notification with director sign-off and use the meters to evidence progress between phases.
What stays with your lead assessor and board
ESOS is a legal obligation for the organization. Aqueduct supplies data.
Lead assessor review
A registered lead assessor carries out or reviews the assessment and signs off.
Director confirmation
Board-level directors confirm the assessment and the organization notifies the regulator.
Transport and other energy
Fleet fuel and energy outside metered sites come from your own records.
sites in 21 countries run on Aqueduct.
and 9 clinics in one of India’s top hospital chains.
US airport running water intelligence on Aqueduct.
of commercial real estate under Aqueduct.
FMCG manufacturing campus.
operations run on Aqueduct.
Related
Common questions
ESOS is the UK's Energy Savings Opportunity Scheme. Large undertakings must measure total energy, audit significant energy uses, identify savings opportunities and notify the regulator in each compliance phase. Aqueduct supplies metered energy data and verified savings.
ESOS does not mandate a meter count, but audits need enough data to understand where energy goes. Sub-metering and load disaggregation make the analysis faster and more credible.
Certification to ISO 50001 covering the organization's energy can be a compliance route. Check current guidance on the conditions, and see our ISO 50001 page for the data it needs.
No. A registered lead assessor must carry out or review the assessment. Aqueduct supplies the measured data they work from.
ESOS is an energy audit scheme with phases, while SECR is annual energy and carbon reporting in company accounts. Many organizations meet both from the same metered dataset.
Aqueduct measures energy at sites. Transport fuel comes from your fleet and fuel card records, which your assessor combines with site data.
Recent phases expect organizations to plan measures and report progress, so the work no longer stops at notification. Continuous metering lets you show what changed between phases, verified against a weather-normalized baseline rather than estimated.
See Aqueduct on your own facility.
Bring a site, a utility bill or a question. We will show you where the loss is.