Get free ESOS guidance with our video series
You’ll learn:
What organisations should know about ESOS Phase 4
Where is the real value of ESOS Phase 4
How to get started with ESOS Phase 4
Why ESOS Phase 4 is important and how to get started
ESOS Phase 4 brings new requirements, stricter expectations and a much greater focus on action. It’s important for organisations to start preparing now to avoid fines of up to £50,000 and additional daily penalties for continued non‑compliance. Beyond the legal requirement, ESOS Phase 4 offers a real opportunity to understand how your organisation uses energy, where it is being wasted and how to reduce both cost and carbon.
If you want free guidance on where to begin, you can sign up to receive our ESOS video series, featuring insights from our in-house ESOS expert, John Tarbet.
What is ESOS Phase 4?
ESOS (the Energy Savings Opportunity Scheme) makes energy audits mandatory for large organisations in the UK. It provides a clear view of your total energy footprint and identifies opportunities to reduce waste and cut costs.
ESOS Phase 4 is the fourth mandatory compliance period, covering:
6 December 2023 – 5 December 2027
Phase 4 reinforces the purpose of ESOS helping organisations reduce energy use and emissions by adding stricter reporting expectations, new requirements and greater accountability.
Key differences: ESOS Phase 3 vs. Phase 4
Action Plan accountability
Phase 4 requires participants to report on progress made against their Phase 3 action plan commitments and explain any unmet goals.
Increased enforcement
The Environment Agency will take a more rigorous approach to checks and penalties.
Stricter standards
Phase 4 removes Display Energy Certificates (DECs) and Green Deal Assessments (GDAs) as compliance routes. Energy audits must now follow recognised standards such as ISO50002 or EN 16247.
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When should organisations start preparing for Phase 4?
The best time to start is now. Although the compliance deadline is 5 December 2027, Phase 4 requires progress reporting and the delivery of an Action Plan, so organisations benefit from conducting audits and preparing their evidence early.
Who should comply with ESOS Phase 4?
UK companies that meet either of these criteria: have 250 or more employees or have an annual turnover over £44 million and a balance sheet over £38 million.
ESOS steps
Start with a consultation
To start, you’ll have a consultation with our carbon management experts. We’ll discuss everything from your energy usage goals to your organisation’s requirements, and also give you the chance to learn more about the process of undergoing an ESOS audit.
Measure your site’s energy
Next, we will review and analyse all relevant energy consumption data across applicable sites and conduct physical energy surveys at each pre‑agreed location. Using insights from the initial assessment and site reports, we will draft your ESOS Summary Report, consolidating key findings and recommendations. This report will then be shared with the Board for review.
Define your sustainability roadmap
Finally, we’ll develop an ESOS report that highlights your energy usage and recommends savings. This is designed to enable the efficient transfer of all required data into the MESOS portal, which we will fully support with.
FAQS
I am already working with an ESOS provider but unsure what I am actually getting
For many organisations, ESOS becomes a tick-box exercise where a report is delivered, signed off and forgotten. But ESOS should be far more than compliance. It should give you a clear view of energy use, highlight waste, and reveal practical savings opportunities. ESOS outputs can also directly support your wider carbon reduction and transition planning.
We typically identify 10–30% of an organisation’s energy savings through ESOS when it’s done properly. With Phase 4 including Action Plans and mandatory progress reporting, there is now greater pressure and greater opportunity to demonstrate real change.
If you want more hands-on direction, you can book a free ESOS consultation to understand where you stand and what to do next.
What happens if my organisation does not comply with ESOS Phase 4?
Non‑compliance can lead to penalties of up to £50,000, plus additional daily fines until you submit a compliant assessment. Phase 4 enforcement is expected to be stricter than previous phases, so it is important to act early and keep records that demonstrate meaningful progress.
What information do we need to complete ESOS Phase 4?
You will need access to your organisation’s electricity, gas, fuel and transport data, information on building usage, operational activity and any previous ESOS records. ESOS Lead Assessors can help you identify data gaps and prepare compliant submissions.
Do we need an ESOS Lead Assessor for Phase 4?
Yes. All ESOS Phase 4 audits must be reviewed and approved by a qualified , like Planet Mark. They ensure that audits meet ISO 50002 or EN 16247 standards and that your submission is compliant.
Can ESOS Phase 4 help reduce our energy costs?
Yes. When completed properly, ESOS typically identifies 10–30% in potential energy‑saving opportunities. These insights can help organisations cut energy waste, lower bills and invest savings into wider sustainability efforts.
How long does an ESOS audit take?
This depends on the size and complexity of your organisation. In an initial call with us, we’ll be able to give you an idea of how long it might take for you. Most organisations should allow several months for data collection, audits, internal approvals and Assessor signoff. Starting early avoids last-minute stress and reduces the risk of errors.
What is an ESOS Action Plan?
An ESOS Action Plan outlines how your organisation intends to implement the recommendations from your ESOS audit. In Phase 4, you must also report annually on your progress, including any missed targets and reasons for them.
Can ESOS Phase 4 be completed remotely?
Some parts such as data review and analysis can be completed remotely. However, site visits are still required to ensure audits meet EN 16247 or ISO 50002 standards.
Do public sector bodies need to comply with ESOS?
Most public bodies are excluded, but organisations that operate commercially or sit outside the public sector definitions may still qualify. If you are unsure, it’s best to check your eligibility early.
Is ESOS the same as SECR or ISO 50001?
No. ESOS is an energy audit scheme. SECR is a reporting requirement. ISO 50001 is a full energy management system. However, ISO 50001 certification can be used to comply with ESOS. If you’re confused about which of these you should be complying with, book a call with our team to chat.
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Book your free ESOS compliance consultation
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