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Energy Savings Opportunity Scheme - ESOS

What is ESOS?
How the scheme works
How can CIBSE help?

What is ESOS?

ESOS (Energy Savings Opportunity Scheme) is an energy assessment scheme that is mandatory for large organisations in the UK with more than 250 employees, turnover in excess of €50m and an annual balance sheet total of €43m. The Environment Agency is the UK scheme administrator.

CIBSE Certification Guide to ESOSView the CIBSE Certification Guide to ESOS


On 26 June 2014, following a consultation process in 2013, the Department for Energy and Climate Change (DECC) published the ESOS Regulations 2014, which give effect to the scheme.

  • The full suite of supporting documents and associated guidance can be viewed at UK Government Website.

  • Download Philip Douglas' (Head of Energy Efficiency & Community Energy Strategy team at DECC) presentation on Energy Savings Opportunity Scheme (ESOS) delivered at the CIBSE Leadership in Building Performance Conference and Exhibition Drinks Reception, 28 Oct 2014.

How the scheme works

An ESOS Assessment requires participants to do three things:

  • 1. Measure total energy consumption
    • Measure total energy consumption across buildings, transport and industrial activities.
  • 2. Conduct energy audits to identify cost-effective energy efficiency recommendations.
    • Ensure that at least 90% of your total energy consumption is subject to an ESOS compliant energy audit, a Display Energy Certificate, a Green Deal Assessment or a certified ISO 50001 Energy Management System during each phase of the scheme.
    • For the first phase of the scheme, any energy auditing activity dating back to December 2011 may be used to support compliance provided that it meets the minimum standards required of ESOS Energy Audits.
  • 3. Report compliance to the Environment Agency
    • By 5 December 2015, participants must notify the Environment Agency (as the scheme administrator) of compliance with the scheme. The Assessment must have been reviewed by a Board-level Director and approved by a Lead Assessor. (Participants are not required to implement energy efficiency recommendations identified by their ESOS Assessments. However, they will only achieve the financial benefits that arise from avoiding energy waste if they do implement cost-effective recommendations identified.)

More detailed guidance is available in the summary document on the UK Government website.


ESOS will operate in four-yearly compliance phases. Organisations in the UK must assess whether or not they are required to participate in ESOS on the qualification date of each phase. The qualification date for the first phase is 31 December 2014.


Qualification date

Four-year compliance phase

Compliance date

Phase 1 31 Dec 2014 6 Dec 2011 – 5 Dec 2015 5 Dec 2015
Phase 2 31 Dec 2018 6 Dec 2015 – 5 Dec 2019 5 Dec 2019
Phase 3 31 Dec 2022 6 Dec 2019 – 5 Dec 2023 5 Dec 2023

How can CIBSE help?

CIBSE Certification Ltd is one of the first to be approved by the Environment Agency to operate a register of ESOS Lead Assessors.