ESOS Compliance: What your organisation needs to do for Phase 4

With ESOS Phase 3 now concluded, organisations must shift their focus towards ongoing obligations and preparing for ESOS Phase 4.

The Energy Savings Opportunity Scheme (ESOS), regulated by the Environment Agency, requires qualifying UK organisations to assess and report their energy use every four years, forming a core part of their ESOS compliance obligations. As outlined in the official GOV.UK guidance, organisations will need to comply if either of the following applies:

• Employs 250+ members of staff
• Annual turnover exceeds £44 million and annual balance sheet total exceeds £38 million

What has changed since ESOS Phase 3?

ESOS Phase 3 introduced more rigorous requirements designed to improve accountability and transparency. The introduction of action plans and mandatory progress updates marks a long-term shift in how organisatons approach ESOS compliance, moving from one-off audits to continuous improvement.

According to GOV.UK guidance on ESOS action plans and progress updates, organisations were required to:

• Submit a notification of compliance
• Produce a board-approved action plan
• Deliver ongoing ESOS reporting through annual progress updates

These requirements now form the foundation for ESOS Phase 4, where organisations are expected to demonstrate measurable progress against their commitments.

What to expect from ESOS Phase 4

While ESOS guidance continues to evolve, the direction is clear based on current regulatory requirements.

The GOV.UK ESOS framework indicates that organisations must not only identify energy-saving opportunities but also track and report on implementation:

For ESOS Phase 4, organisations should expect:

• Continued mandatory ESOS reporting on energy-saving actions
• Increased scrutiny on whether identified opportunities are implemented
• Greater board-level accountability
• Stronger alignment with net zero and carbon reduction strategies

This reinforces that ESOS compliance is now an ongoing operational framework, not a periodic exercise.

Your ongoing ESOS compliance requirements

Although Phase 3 has ended, organisations must continue meeting their obligations.
This means you are required to:

• Submit annual progress updates (typically 12 months after your action plan deadline)
• Report on implemented and unimplemented energy-saving actions
• Provide evidence and data supporting energy savings
• Maintain transparency in ESOS reporting

Failure to submit updates may result in non-compliance being recorded and published by the Environment Agency.

Maintaining consistent ESOS compliance now will ensure a smoother transition into ESOS Phase 4.

Why early preparation for ESOS Phase 4 matters

It is essential that organisations don’t leave compliance until the last minute, risking ESOS assessor shortages. The Energy Savings Opportunity Scheme (ESOS) Phase 4 compliance deadline is 5 December 2027. If you qualify, you must submit your notification of compliance by this date, with the qualification date for inclusion being 31 December 2026.

Organisations that take action now will be better positioned to:

• Reduce operational energy costs
• Strengthen ESG and sustainability reporting
• Avoid compliance risks and enforcement action
• Demonstrate measurable progress to stakeholders

The direction of travel is clear from GOV.UK guidance: implementation and accountability are now central to ESOS.

How Zenergi supports your ESOS compliance journey

Zenergi supports organisations in navigating the increasing complexity of ESOS compliance, particularly as requirements evolve in ESOS Phase 4. Our services include:

• End-to-end management of ESOS reporting
• Action plan development and implementation support
• Energy data collection, validation, and analysis
• Identification of cost-effective energy-saving opportunities
• Ongoing compliance tracking aligned with regulatory expectations

Our accredited ESOS Lead Assessors ensure your organisation meets all Environment Agency requirements while unlocking tangible cost and carbon savings.

Prepare for ESOS Phase 4 with confidence using our ESOS Lite service

As organisations transition from ESOS Phase 3 to Phase 4, the focus has shifted from one-off compliance to continuous improvement, accountability, and measurable progress. Zenergi’s ESOS Lite service aligns with this evolving framework, offering a streamlined, cost-effective way to maintain compliance while preparing for stricter reporting and governance requirements.

By simplifying data collection, supporting ongoing obligations, and providing expert-led assessments, ESOS Lite helps organisations stay compliant, reduce energy costs, and confidently meet the demands of Phase 4.