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ESOS Phase 4: we'll get you compliant, then show you which savings are worth having.
An ESOS consultant for UK organisations that qualify as large undertakings. Energy audits, the notification, the new action plan and the yearly updates, with every audit signed off by a registered lead assessor. Fixed fees from £7,500 + VAT.
What is ESOS?
ESOS, the Energy Savings Opportunity Scheme, is the UK's mandatory energy assessment scheme for large organisations. Every four years, qualifying organisations must measure their total energy use, audit it, notify the regulator that they have complied and set out an action plan for the savings they will make. The name says what it is for: finding energy savings opportunities.
Do you qualify?
You're in Phase 4 of the Energy Savings Opportunity Scheme if, on 31 December 2026, your UK undertaking has 250 or more employees, or turnover above £44 million and a balance sheet above £38 million. Both financial tests must be met. If one UK company in your group qualifies, the whole UK group is in.
ESOS covers England, Wales, Scotland and Northern Ireland. It doesn't apply in the Republic of Ireland.
Phase 4 deadlines
| What | Due |
|---|---|
| Qualification date | 31 December 2026 |
| Notification of compliance | 5 December 2027 |
| Action plan | 5 December 2028 |
| Progress updates | December 2029, 2030 and 2031 |
What you have to do
Measure your total energy use over 12 consecutive months, then cover at least 95% of it with an energy audit or an ISO 50001 certificate. Display Energy Certificates and Green Deal assessments no longer count. A lead assessor on an approved register reviews the work, and board-level directors sign off the report.
The action plan is where ESOS has changed most. You commit to the energy saving measures you'll actually carry out, then report progress each year and explain any you've dropped.
What happens if you miss it?
Under the ESOS Regulations, failing to carry out an energy audit can cost up to £50,000 plus £500 a working day. Failing to notify can cost up to £5,000 plus £500 a day. Regulators can also publish the names of those penalised.
Why the savings come first
Most ESOS reports list savings that nobody acts on. Ours rank each measure by payback and show where other companies made the same change and what it earned them, drawing on our evidence base of more than 2,000 projects. That makes the action plan easier to commit to, and the numbers feed straight into your Carbon Reduction Plan or EcoVadis evidence.
When you want to go beyond energy, Sustainability Opportunity Discovery applies the same method to materials, waste and freight.
Fees
| Service | Fee |
|---|---|
| ESOS Phase 4 compliance, up to three sites | From £7,500 + VAT |
| Action plan and yearly progress updates | £1,500 + VAT a year |
| Larger estates and manufacturing sites | Quoted after a call |
Questions organisations ask
Does ISO 50001 mean we don't need an ESOS audit?
If an ISO 50001 certificate covers all your significant energy use, it can be your route to compliance and you won't need a lead assessor. You still need to notify and produce the action plan.
Can our own staff be the lead assessor?
Yes, if they're on an approved register. With an internal lead assessor, two directors must sign off instead of one.
When should we start?
Early 2027. The audit needs 12 months of data, site visits and director time, and assessors get busy close to December.