The Energy Savings Opportunity Scheme (ESOS) is underway

ESOS – A European Directive

Article 8 (4-6) of the EU Energy Efficiency Directive (2012/27/EU) states that ‘enterprises that are not SMEs* (small and medium enterprises) are required to undertake an energy audit by 5 December 2015, and then at least every four years from the date of the previous energy audit'.

The Energy Savings Opportunity Scheme (ESOS) is the UK Government’s implementation of these requirements and is a mandatory energy assessment scheme for organisations that meet the qualification criteria. The energy audits must include an assessment of energy consumption used for the environmental control of buildings (heating, cooling, ventilation etc.), industrial processes and transport and must include the identification of cost-effective energy saving measures.

An organisation that is not an SME and therefore is required to comply with ESOS is defined as follows:

  • employs at least 250 people
  • employs less than 250 people but has an annual turnover in excess of 50 million euro (£38,937,777), and an annual balance sheet total in excess of 43 million euro (£33,486,489)

It is anticipated that ESOS will affect in the region of 9,000 to 10,000 UK organisations and that measures implemented as a result of ESOS could lead to a net energy saving of £1.6bn for the UK as a whole.

Complying with ESOS

Essentially, ESOS requires that participating organisations carry out 3 main activities:

1. Measure total energy consumption
2. Conduct compliant energy audits or energy management activities, accounting for at least 90% of this energy consumption
3. Declare and report compliance to the Environment Agency (EA) - the scheme administrator.

The latest ESOS Guidance produced by DECC identifies four distinct types of qualifying assessments and management activities that can be utilised in order to comply with ESOS:

  • ESOS Energy Audits – as approved by an ESOS Lead Assessor
  • An ISO 50001 certified Energy Management System;
  • Display Energy Certificates (DECs) and accompanying advisory reports; or
  • Green Deal Assessments.

This means that both Display Energy Certificates (DECs) and Green Deal Assessments can be utilised as a direct, standalone means of complying with the assessment of building energy for ESOS reporting. The advent of ESOS may, therefore, increase the market requirements for these report types.

Irrespective of the methodology utilised, for an ESOS assessment to be compliant with the EA’s requirements, it must be authorised by a registered ESOS Lead Assessor. Organisations will, therefore, need to appoint an ESOS Lead Assessor to ‘sign off’ their assessment process. ESOS Lead Assessors can be internal staff members or external contractors but must be a member of an approved professional body register. National Energy Services are approved and will be operating such a register.

ESOS Energy Audits
Whilst the use of reports such as DECs offer a minimum route to ESOS compliance there are limitations to the Advisory Report and organisations may opt to obtain more detail in the form of a ‘DEC plus’ report or a fully compliant ESOS Energy Audit. Both of these reports will include more detailed information regarding costed energy efficiency measures and associated payback periods and both will require to be managed by a registered ESOS Lead Assessor.

The ESOS Lead Assessor will also have overall responsibility for the assessment of all identified energy consumption, including that used for processes and transportation.

Need to know more?
The government's ESOS guidance is available here.

DECC's detailed ESOS guidance document can be obtained here.

If you are a qualified DEC Assessor (PBEA/Operational Ratings Assessor), Green Deal Advisor or ESOS Lead Assessor and would like to accredit with NES and become involved in the delivery of ESOS, please contact the Membership team at or click here for more information.

If you are a Non Domestic Energy Assessor and would like to train as a DEC Assessor to carry out ESOS assessments, please click here for course details or contact the training team at for details.

For details on our ESOS lead assessor training, please click here