ESOS – Energy Savings Opportunity Scheme

This is a mandatory energy assessment scheme for large organisations in the UK. It helps businesses identify energy-saving opportunities across their operations.

Who Must Comply?

Organisations that meet any of the following (as of the 31st December 2026 qualification date) :

250+ employees, or
Annual turnover > £44 million and balance sheet > £38 million

Key Requirements:

Measure total energy consumption (buildings, transport, industrial processes) and identify significant energy consumption (at least 95% of total consumption must be audited).
Conduct site energy audits or use alternative routes (e.g. ISO 50001 certification).
Identify cost-effective energy-saving opportunities.
Have assessment reviewed by a qualified ESOS Lead Assessor and signed-off by a board-level director.
Notify the Environment Agency (or relevant regulator) of compliance by 5th December 2027, via the government's ESOS portal.

ESOS Phase 4 Deadlines:

The Phase 4 compliance period runs from 6th December 2023 to 5th December 2027.

The Total Energy Consumption must be reported on a 12 month period that includes the 31st December 2026.

An Action Plan needs to be produced within 12 months of the compliance deadline, showing the estimated kWh savings that will be introduced from energy savings measures over the following 4 years.

What Are The Benefits of ESOS?

Helps identify energy cost savings.
Promotes energy efficiency investment.
Can improve corporate sustainability and reduce emissions.

Penalties for Non-Compliance:

Up to £50,000 fixed fine, plus
£500 per day for ongoing failure (max 80 days).

Organisations fully covered by ISO 50001 (certified) do not need to carry out separate site audits, however they still need to produce an overarching report that is signed-off by a Lead Assessor.