Compliance / ESOS

ESOS compliance, made practical.

The UK's Energy Savings Opportunity Scheme doesn't have to feel like a tax on your time. We guide qualifying organisations through Phase 4 — from eligibility check to notification — with plain English, practical recommendations, and measurable savings.

Phase04
Compliance period20222026
Deadline05 Dec 2027
Max penalty£90k
Our response time<48h
250+
Employees, or £44m turnover — one threshold triggers ESOS
4th
Compliance phase — the most significant reform yet
£90k
Maximum fine for failing to comply with Phase 4
48h
Our standard response time to every enquiry
01 — ESOS

What ESOS actually is.

No jargon. No acronym soup. Just a clear explanation of the scheme, why it exists, and what's changed for Phase 4.

ESOS is the UK's mandatory energy audit scheme. Every four years, qualifying organisations must measure their energy use, identify cost-effective savings, and prove it to the Environment Agency.

The premise is simple: large organisations use a lot of energy, and most of them could use less if they knew where to look. ESOS forces a structured look at total energy consumption across buildings, transport and industrial processes — then flags the opportunities with the best payback.

Phase 4 has sharper teeth than previous rounds. Tighter audit quality requirements, mandatory action plans, and public disclosure of energy intensity metrics — it's no longer a tick-box exercise.

The aim is not paperwork. Done well, an ESOS assessment typically surfaces 5–15% in recoverable energy costs across an estate. We frame it as an investment, not an obligation.

02 — Do you qualify?

Eligibility at a glance.

You qualify for ESOS if, on 31 December 2026, your UK organisation (or corporate group) meets either of these thresholds — or both parts of the financial test combined.

Threshold A — Headcount
250or more employees

Full-time equivalents across your UK operations. Meet this alone, and ESOS applies.

Threshold B — Turnover
£44mannual turnover

Combined with a balance sheet total exceeding the next threshold — both must be hit.

and
£44m+£38m
Combined financial qualification£44m+ annual turnover and £38m+ balance sheet total together trigger ESOS even when headcount is lower.
Check my eligibility →
03 — The process

From kick-off to notification, in five moves.

We've run this process enough times to make it predictable. Here's what the journey looks like when we run it for you — roughly 12–16 weeks end to end, depending on estate complexity.

01
Week 1–2
Eligibility & scope
Kick-off callScope statement

We confirm your qualification against the Phase 4 thresholds, define the corporate boundary (subsidiaries, JVs, franchises), and agree the sampling approach — saving audit days without compromising the 90% energy coverage rule.

02
Week 2–6
Data collection
Bills, meters, fleet12-month window

We collate 12 months of verifiable energy data — electricity, gas, fuel oil, transport fuel and any on-site generation. Where data is missing, we tell you exactly what to request from whom.

03
Week 6–10
Site audits
Walk-throughsEngineering review

Kiro personally leads audits at representative sites. Lighting, HVAC, compressed air, process heat, BMS set-points, refrigeration, building fabric — every kilowatt gets examined for practical savings.

04
Week 10–14
Report & action plan
Ranked opportunitiesPayback periods

You get a ranked list of cost-saving measures with capex, annual saving, payback period and carbon impact. The mandatory Phase 4 action plan slots in as a natural output — not an afterthought.

05
Week 14–16
Notify & disclose
MESOS submissionBoard sign-off pack

Lead assessor sign-off, a board-ready summary pack, and notification to the Environment Agency via the MESOS portal. Phase 4's new disclosure requirements handled end to end.

Kiro Tamer
Lead Assessor
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04 — The assessor

Every report is signed off by a qualified Lead Assessor.

Kiro Tamer sits on both of the UK's accredited ESOS Lead Assessor registers — ISEP and EMA. That combined credential is held by a minority of practising assessors in the country, and it means your submission clears the Environment Agency's evidence bar without round-trips.

ISEP ESOS Lead Assessor
REG. VERIFIED
EMA ESOS Lead Assessor
REG. VERIFIED
ISO 50001 Lead Auditor
ENERGY MGMT SYSTEMS
Chartered Environmentalist
CENV · SOCIETY FOR THE ENVIRONMENT
05 — Case study

KAB Seating — compliance done quietly.

A UK manufacturer navigating Phase 3 without pausing production. The engagement that became our template for Phase 4.

[site photography]
kab.co.uk

Identified seven-figure savings across a three-site manufacturing estate.

"Placeholder testimonial — a quote from the KAB client praising the clarity of the report and the speed of the engagement goes here."
Annual energy savings identified
Average payback period
Sites audited
06 — Non-compliance
£90k
Maximum civil penalty — per breach

The cost of missing the deadline.

The Environment Agency publishes a non-compliant organisations list every phase. Phase 4 introduces enhanced scrutiny of audit quality — not just whether you notified on time, but whether the underlying work was done to standard.

  • Failure to undertake an assessmentup to £50,000 + £500/day
  • Failure to notify complianceup to £50,000
  • Failure to maintain recordsup to £50,000
  • False or misleading statementup to £50,000
  • Publication on EA non-compliance registerreputational
07 — Coverage

We serve clients across the UK.

KEES is headquartered in Brighton and works the length of the country — from manufacturing sites in the North East to London offices and data centres in the South. All engagements are lead-assessed by Kiro; site visits are scheduled tightly to minimise travel overhead.

  • BrightonHQ
  • LondonSE
  • WokingSE
  • GuildfordSE
  • CrawleySE
  • ReadingSE
  • OxfordSE
  • WorthingSE
  • EastbourneSE
  • ManchesterNW
  • BirminghamW MID
  • NewcastleNE
  • GlasgowSCT
  • EdinburghSCT
08 — FAQ

Good questions, short answers.

The questions we get most often from directors and sustainability leads weighing up their Phase 4 compliance options.

What happens if we miss the ESOS deadline?+

The Environment Agency can issue a civil penalty of up to £50,000 for missing the notification deadline, plus £500 per day of continuing non-compliance (capped at £5,000). Beyond the fine, non-compliant organisations are named on a public register — a reputational cost that often exceeds the financial one.

Can ISO 50001 replace an ESOS audit?+

Yes — a fully certified ISO 50001 energy management system covering 100% of your energy consumption can serve as a complete route to ESOS compliance, without a separate audit. Kiro is accredited as both an ESOS Lead Assessor and an ISO 50001 Lead Auditor.

How long does an ESOS assessment take?+

Typically 12–16 weeks from kick-off to notification for a mid-sized organisation with a handful of sites. The biggest variables are data availability and site access windows.

What's the difference between ESOS Phase 3 and Phase 4?+

Phase 4 introduces mandatory action plans, public disclosure of energy intensity metrics, and stricter audit quality standards.

Do we qualify if we're part of a larger group?+

Probably. ESOS applies at the “highest UK parent” level — if your group as a whole meets the thresholds, all UK subsidiaries are swept in.

How much does an ESOS assessment cost?+

It scales with the size of your estate and the complexity of your energy profile. We quote a fixed fee after the eligibility call.

Let's find out together

30 minutes is all it takes to know where you stand.

A no-pitch eligibility call with Kiro. We'll map your group structure against the Phase 4 thresholds, flag the likely audit scope, and tell you whether ESOS actually applies — before you spend a pound.

Free 30-minute call

Book your ESOS eligibility review

Schedule a call →
Response within 48 hours.