Don't leave Phase 4 until 2027.
Mandatory four-yearly energy audits for UK businesses with 250+ employees or £44m+ turnover. We handle the full Phase 4 process - from data foundation to Lead Assessor sign-off to submission.
What ESOS is. Who has to do it.
The Energy Savings Opportunity Scheme is a mandatory UK programme requiring qualifying organisations to conduct a comprehensive energy audit every four years. The audit covers buildings, transport, and industrial processes, identifies cost-effective energy savings opportunities, and is signed off by a qualified Lead Assessor before submission to the Environment Agency.
ESOS Phase 4 covers the four-year period to December 2027. The audit must analyse at least 95% of total energy consumption, identify cost-effective savings opportunities with payback periods, and include board-level sign-off before going to the Environment Agency.
Non-compliance carries penalties of up to £50,000 plus daily fines for ongoing breach - and non-compliance is published, which creates reputational exposure with customers, investors, and procurement teams.
Phase 4 has tighter requirements than previous phases. The audit must include action plans for cost-effective recommendations, with progress reporting against those actions in subsequent phases. ESOS is no longer just a tick-box - the recommendations are expected to be implemented and tracked.
Who must comply
- 250 or more employeesUK headcount across the corporate group, calculated at the qualification date.
- Annual turnover above £44mAND balance sheet above £38m. Both thresholds must be met.
- Part of a qualifying corporate groupSubsidiaries of large groups are typically in scope, even when they don't independently meet the thresholds.
- Franchises that meet thresholdsFranchise structures need careful assessment - the rules differ depending on franchisor/franchisee relationship.
Five stages, one team.
From qualification assessment through to Environment Agency submission. The full Phase 4 programme delivered by Lead Assessors who've run hundreds of audits across the previous phases.
Qualification & scope
We confirm whether ESOS applies to you, identify the responsible undertaking, and define the scope of energy consumption that must be audited. Group structures, franchises, and joint ventures handled.
Data foundation
We gather 12 months of energy consumption data across buildings, transport, and processes - via supplier requests, your accounts, and the elexi platform. The data covers at least 95% of total consumption.
Site-level energy audits
Our auditors run on-site assessments of your significant energy-consuming sites. Cost-effective savings opportunities identified with payback periods, capex requirements, and carbon impact quantified.
Lead Assessor sign-off
Our qualified Lead Assessor reviews and signs off the full Phase 4 audit pack. Action plan documented for cost-effective recommendations - the new Phase 4 requirement.
Board approval & submission
Board sign-off pack prepared. Notification submitted to the Environment Agency before the 5 December 2027 deadline. Compliance evidence packaged for ongoing PPN 06/21 supply chain requirements.
The cost of getting Phase 4 wrong.
Non-compliance with ESOS isn't a private matter between you and the Environment Agency. It's a public record that affects procurement eligibility, customer relationships, and board liability.
Financial penalties up to £50,000
Plus daily fines for ongoing non-compliance. Quickly compounds to materially significant numbers for repeat or extended breaches.
Public non-compliance record
Non-compliance is published on the Environment Agency's public register. Visible to customers, investors, ESG ratings, and competitors.
Lost public sector procurement eligibility
PPN 06/21 and similar procurement frameworks require ESOS evidence. Non-compliance can disqualify you from public contracts.
Late-stage scramble = Lead Assessor shortage
Lead Assessor capacity tightens dramatically through 2027. Organisations leaving it late often cannot find a Lead Assessor in time, which is itself a route to non-compliance.
Phase 4 sorted. Operational improvements found.
Book a 15-minute Phase 4 review. We'll confirm your obligation, scope the work, and tell you exactly what we'd handle on your behalf - including the savings we'd expect to identify along the way.