ESOS Phase 4 is approaching, and the requirements have changed.
The government has introduced a number of changes to the Energy Savings Opportunity Scheme (ESOS), which came into force on 22 July 2026.
For organisations that qualify for Phase 4 on 31 December 2026, the deadline for submitting their Phase 4 compliance notification is 5 December 2027.
With the final Phase 3 Progress Update also due on 5 December 2026, organisations should now be reviewing their current position, understanding the new requirements and preparing for the next compliance period.
What is ESOS?
The Energy Savings Opportunity Scheme (ESOS) is a mandatory UK energy assessment scheme for large organisations.
It requires qualifying businesses to measure their energy consumption, assess energy performance and identify opportunities to improve energy efficiency.
While ESOS is a compliance requirement, it can also provide valuable insight into where organisations can reduce energy consumption, lower costs and support wider carbon reduction and Net Zero objectives.
What has changed for ESOS Phase 4?
Several important changes have been introduced for the fourth compliance period.
- DECs and GDAs are no longer compliance routes
Display Energy Certificates (DECs) and Green Deal Assessments (GDAs) have been removed as ESOS compliance routes.
From Phase 4, organisations must use energy audits and/or ISO 50001 certification to comply with ESOS.
There have also been changes to the ISO 50001 compliance route. Organisations with ISO 50001 covering either their Total Energy Consumption (TEC) or Significant Energy Consumption (SEC) can be exempt from appointing a Lead Assessor and completing an ESOS report.
- Phase 3 Action Plans must now be reviewed
Organisations that were required to submit a Phase 3 Action Plan will need to review their progress as part of their Phase 4 assessment.
This includes providing details of:
- Measures that have been implemented
- Energy savings achieved through those measures
- The energy-saving category of each measure, such as behaviour change, training or capital investment
This means organisations should start gathering evidence of the action they have taken and the savings achieved.
- Unimplemented measures must be explained
If measures included in a Phase 3 Action Plan have not been implemented, organisations will need to provide an explanation for why they were not taken forward.
Reviewing previous ESOS recommendations now will help organisations understand what has been delivered, what remains outstanding and what evidence may be required for Phase 4.
- Additional information will be required
Phase 4 also introduces additional reporting requirements, including:
- The total number of sites covered by energy audits
- ISO 50001 certification details
- UK SIC codes
- Improved recording of the methods and data used for calculations
These changes place greater emphasis on the quality, accuracy and transparency of the information submitted as part of the ESOS process.
Don’t forget the Phase 3 Progress Update
Before preparing for Phase 4, there is still an important Phase 3 requirement to complete.
The second and final Phase 3 Progress Update is due by 5 December 2026 and requires organisations to report on progress against their Phase 3 Action Plan.
This means organisations should already be reviewing which recommendations have been implemented, what savings have been achieved and which actions remain outstanding.
Starting this process early can help avoid a last-minute scramble for data, evidence and internal sign-off.
How can organisations prepare for Phase 4?
Review your Phase 3 Action Plan
Understand which measures have been implemented, quantify the savings achieved and identify any recommendations that have not been taken forward.
Check your energy data
Make sure your energy consumption data, metering information and monitoring systems are accurate and complete across your organisation.
Reliable data will be essential for demonstrating energy performance and supporting future assessments.
Review your compliance route
If your organisation previously relied on a DEC or GDA, this will no longer be sufficient for Phase 4.
Consider whether energy audits, ISO 50001 or a combination of both is the most appropriate route for your organisation.
Strengthen energy management
Regular monitoring, reporting and performance reviews can make future ESOS assessments easier while helping organisations identify and act on energy-saving opportunities throughout the compliance cycle.
Look beyond compliance
The most effective organisations use ESOS as more than a reporting exercise.
The process can help identify practical opportunities to reduce energy costs, improve efficiency, reduce carbon emissions and support wider Net Zero objectives.
Rather than viewing ESOS as another regulatory burden, organisations can use Phase 4 as an opportunity to turn previous recommendations into measurable action.
How TEST can help
At TEST, we support organisations throughout the ESOS process, from qualification and energy audits to Progress Updates, reporting and ongoing energy management.
Our data-led approach helps organisations understand their energy performance, identify practical opportunities for improvement and turn ESOS recommendations into measurable action.
We can help organisations understand the new Phase 4 requirements, review their previous Action Plans, gather the necessary evidence and develop a clear route towards compliance.
With the final Phase 3 Progress Update due on 5 December 2026, and the Phase 4 qualification date just weeks later on 31 December 2026, now is the time to start preparing.
If your organisation needs support with ESOS Phase 3 or Phase 4, contact the TEST team to discuss how we can help.
Tel: 0113 467 7650
Email: enquiries@test-consulting.co.uk
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