UK Energy Savings Opportunity Scheme Phase 4 is here

ESOS Phase 4: turn your energy assessment into a plan for savings.

The Phase 4 compliance deadline is 5 December 2027. Start now to understand your obligations, organise your energy data and identify opportunities to cut costs.

The Energy Savings Opportunity Scheme (ESOS) requires qualifying UK organisations to assess their energy use every four years. A useful assessment does more than meet a reporting requirement: it shows where energy is being wasted across buildings, processes and transport, and which changes could deliver worthwhile savings.

Does your organisation need to comply?

Your organisation may qualify for Phase 4 if, on 31 December 2026, it has 250 or more employees, or both annual turnover above £44 million and an annual balance sheet total above £38 million. Corporate groups may also qualify if a UK group member meets the criteria.

If you are close to a threshold, have grown since Phase 3, or are unsure how your group should be assessed, Carbon Lens can help you establish your position.

What is different in Phase 4?

Phase 4 puts greater emphasis on what happened after the previous assessment. Qualifying organisations must review their earlier action plan, report energy savings achieved and explain why any planned measures were not implemented.

Your assessment must account for your total energy consumption and cover at least 95% through energy audits or an eligible alternative compliance route.

How Carbon Lens can help

We can help you plan the work, bring together energy data from across your organisation, identify significant energy use and develop practical, costed recommendations. We can also support your action plan review and prepare the information needed for your ESOS report and compliance notification, working with a qualified ESOS lead assessor where required.

The aim is a clear picture of your obligations and a set of actions your business can use to reduce energy costs and emissions.

Why start now?

An ESOS energy audit normally needs 12 months of energy data. If you start collecting it now, that period will run to September 2027, leaving only around two months before the 5 December compliance deadline to complete the assessment, obtain sign-off and submit your notification. Starting now also lets us check whether suitable existing data can be used, identify gaps early and plan audits while there is still time to act on the findings.

Start with a conversation

Unsure whether you qualify, or need to get Phase 4 underway? Tell us about your organisation and your previous ESOS assessment. We’ll discuss what needs to happen next and how Carbon Lens can support you.

Enquire about ESOS Phase 4

Email info@carbonlens.systems.

The qualification criteria, 95% coverage, Phase 4 deadline and reporting changes above follow the current Environment Agency guidance.

Qualified for ESOS Phase 3? Your second progress update on your Phase 3 action plan is due by 5 December 2026. Contact Carbon Lens if you need help preparing it.