ESOS: Is Your Organisation Prepared?

For large UK organisations, ESOS is an important part of understanding and improving energy efficiency. With the next deadlines approaching, now is the time to check whether your organisation qualifies and start preparing.

What Is ESOS?

ESOS stands for the Energy Savings Opportunity Scheme.

It is a mandatory energy assessment scheme for large UK organisations, designed to help businesses understand their energy use and identify opportunities to improve efficiency and reduce consumption.

While ESOS is a compliance requirement, it can also highlight practical ways to reduce energy costs and improve performance.

Who Does ESOS Apply To?

ESOS generally applies to organisations with:

• 250 or more employees, or
• Annual turnover above £44 million and a balance sheet total above £38 million

Corporate structures also matter. If one UK undertaking qualifies, other UK entities within the same group may also fall within scope.

Key ESOS Dates

5 December 2026 – Phase 3 second progress update deadline

31 December 2026 – Phase 4 qualification date

5 December 2027 – Phase 4 compliance deadline

Organisations that participated in Phase 3 must report on the energy-saving measures they have implemented, those delayed or not completed, estimated savings and how these savings were calculated.

Preparing for Phase 4

Businesses should start preparing by:

• Confirming whether they qualify
• Reviewing their group structure
• Gathering accurate energy data
• Identifying relevant sites and activities
• Reviewing energy-saving opportunities

Starting early can make compliance easier and help businesses get more value from the process.

How GLEG Can Help

GLEG can support businesses with:

• ESOS qualification and group assessments
• Phase 3 progress updates
• Energy data collection and validation
• Site surveys and energy audits
• Evidence packs and director approval
• Phase 4 compliance and submission
• Delivery of identified energy-saving opportunities

Don’t leave ESOS until the deadline. If you’re unsure whether your organisation qualifies or want to start preparing for Phase 4, contact the GLEG team at hello@gleg.co.uk.