3 December 2025

ESOS Stage 3: The Requirements

Understanding ESOS Phase 3: Key Requirements for Businesses


What is ESOS?

The Energy Savings Opportunity Scheme (ESOS) is a mandatory program in the UK targeting large businesses. It requires them to assess their energy consumption, identify areas for improvement, and implement measures to become more energy-efficient. This not only benefits the environment by reducing carbon emissions but also translates to cost savings for the businesses involved.


Who Needs to Comply?

Large undertakings as defined on December 31, 2022 are required to comply with ESOS. This applies to:

• Companies employing 250 or more people.

• Companies with an annual turnover exceeding £44 million and a balance sheet exceeding £38 million.


What Actions are Required in Phase 3?

Phase 3, currently ongoing, introduced stricter regulations compared to previous phases. Here's a breakdown of the key requirements:

1. Appoint a Qualified Lead Assessor: An approved professional must review and sign off on the energy audit report.

2. Measure Total Energy Consumption: This covers a 12-month reference period ending before June 5, 2024.

It includes energy used in:

o Buildings (heating, lighting, etc.)

o Industrial processes

o Transportation (company vehicles)

3. "De Minimis Exemptions" (Optional): Businesses can exclude up to 5% of their energy consumption from the report.

4. Calculate Energy Intensity Ratios: This involves expressing energy use in relation to:

o Buildings: kWh per square meter

o Transport: kWh per mile travelled

o Industrial processes: Energy consumed per unit of output


Reporting and Action Plan:

• Completion of the Report: Analyse your organization's energy consumption and efficiency.

• Recommendations for Improvement: Identify cost-effective measures to reduce energy use.

• Board-Level Sign-off: Get the report approved by a director.

• Develop an Action Plan: Outline specific actions to achieve energy savings over the next four years. This includes:

o Planned measures to reduce energy consumption

o Timeline for implementation

o Expected energy savings

o Method used to estimate savings


Key Deadlines:

• Compliance Notification: Submit to the Environment Agency by June 5, 2024 (previously December 5, 2023).

• Action Plan Submission: December 5, 2024.


Additional Information:

• Businesses that qualified for Phase 2 but not Phase 3 should inform the Environment Agency.

• The Environment Agency website provides further details and resources: https://www.gov.uk/guidance/energy-savings-opportunity-scheme-esos



If you require assistance with your ESOS compliance, contact us today to see how we can assist you ahead of the deadline.

by Craig Watson 27 March 2026
With consumer spending declining and OFGEM raising their price cap, you would be forgiven for seeing February as a month where negative news was at the forefront, but in the energy markets, this was not the case.
by Craig Watson 27 March 2026
In a year that began with falling energy prices, there were recurring catalysts that led to prices climbing steadily higher. Geopolitical uncertainty and the perennial threat of escalating conflicts meant fear would maintain a constant presence in the wholesale markets. We will look back at the key energy stories from 2024, and how the energy markets are likely to shape up in 2025. Quarter 1  The year began with cautious optimism as the UK’s gas reserve levels were healthy and prices for the Summer’24 season were in freefall. In February, prices pulled back to their lowest levels since 2021, and for the first time in a while, we identified that there was greater potential for upside risk than for further downward price movement: “ there now (exists) an asymmetrical element of risk should the market encounter a supply-side problem of significance. ” During February we had advised customers on flexible contracts that this was an ideal time for making purchases. March would see prices begin to ascend again as international conflict would create problems with LNG imports, and we would highlight the geopolitical risks as an area for concern moving forwards: “ fears remain and there are potential negative catalysts that could lead to prices rising further, with the main factors to watch out for being based on geopolitical unrest. “ For a business that purchases their energy in advance, this quarter was the optimal time for purchasing during 2024. In February, electricity prices for Winter’25 were down to 7.75p/Kwh, and as low as 6.05p/Kwh for Summer’25. Winter’25 ended the year with prices above 11.1p/Kwh, with Summer’25 prices exceeding 9p/Kwh. For a company that uses 500,000Kwh of electricity per month, the difference between buying at the February low point compared to today’s prices would represent a yearly saving of over £200,000.
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