What is ESOS? Avoid costly business energy compliance mistakes

Keeping up with the latest business energy regulations can feel like a full-time job.

You don’t have time to wrangle with the newest acronyms - but making sure you remain compliant is non-negotiable. It must be done.

Failure to comply with updated regulations, such as the Energy Savings Opportunity Scheme (ESOS), can prove costly to your business on multiple fronts.

The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment scheme that requires large businesses and organisations to audit their energy usage and identify opportunities for improved efficiency.

We’re here to walk you through ESOS, what it is, who it’s for and why it matters, so you can remain compliant and potentially discover ways to reduce your business energy costs in the process.

In this article:

• Learn what the Energy Savings Opportunity Scheme (ESOS) is.
• Understand how ESOS impacts businesses, and who is required to be compliant.
• Discover the consequences of failure to comply with ESOS.

What is the Energy Savings Opportunity Scheme (ESOS)?

The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment scheme that requires qualifying businesses to measure their usage every four years.

ESOS identifies opportunities to boost energy efficiency and reduce carbon emissions, which should lead to lower costs and lower environmental impact.

The audit is part of a nationwide effort to reduce unnecessary energy usage, which hurts businesses in terms of their bottom line and the environment through greenhouse gas emissions.

Which businesses need to comply with ESOS?

Not every business is required to comply with ESOS.

Typically, your business must comply with the scheme if it:

• Employs 250 or more people; or
• Has an annual turnover exceeding £44 million and a balance sheet total exceeding £38 million.

If your business is approaching the qualification thresholds, we recommend that you review the latest ESOS guidance early to avoid being caught out by future growth.

How does an ESOS audit work?

1. Calculate total energy usage: review energy use across all buildings, transport (including fuel) and industrial processes used by the business or organisation over the last 12-month period.
2. Identify main energy requirements: highlight the areas of your business that use at least 95% of your total energy consumption.
3. Calculate energy intensity ratios: you must calculate energy intensity ratios for buildings, transport, industrial processes and remaining energy uses.
4. Appoint a lead assessor: an ESOS lead assessor is an approved energy professional responsible for reviewing audit findings and ensuring compliance with scheme requirements.
5. Carry out ESOS audit: GOV.UK states an ESOS compliant energy audit must:
   - Be based on 12 months’ verifiable data.
   - Analyse the participant’s energy consumption and energy efficiency.
   - Identify energy saving opportunities.
   - Include site visits.
6. Complete the ESOS report: the final report should be completed and shared with the corporate group your business is part of, if required.
7. Notify the Environment Agency (EA): the notification must include details about your organisation, how it has complied, energy consumption information and energy savings opportunities identified. It must be received by the deadline for the compliance period.

When is the ESOS deadline?

ESOS operates in cyclical compliance phases, each with its own qualification and reporting deadlines.

Businesses should always check the latest government guidance to confirm the current phase requirements.

The next window is Phase 4. The qualification deadline is 31^st December 2026.

If your business meets the criteria for eligibility on that date, you will be required to comply with ESOS.

The final assessment completion date for Phase 4 is 5^th December 2027.

What happens if I don’t comply with ESOS?

Compliance is legally required.

The Environment Agency has the power to issue financial penalties and publish details of organisations that fail to comply with ESOS requirements.

The assessment may also identify opportunities to reduce energy waste, lower your costs and improve efficiency, so you also risk missing out on a range of benefits.

How we can help

Many businesses struggle with collecting the right type of data for ESOS. It’s a lot. We get it.

We can help identify what you should be monitoring and implement granular level data collection to drive efficiency and reporting.

Troo exists to help businesses like yours make sense of their energy needs, simplify complex information and make smart decisions that lead to real change and reduced costs.

We are not here to sell you a quick fix. We're here to understand what matters to you, offer clear advice, and take ownership of the hard parts, so energy becomes one less thing to worry about.

Book a free energy health check today for practical guidance on your business electricity, gas or water bills.