B2.10.2.6 Energy Savings Opportunity Scheme Regulations 2014 (ESOS Regulations).



The Energy Savings Opportunity Scheme Regulations 2014 (ESOS Regulations) establish the Energy Savings Opportunity Scheme (ESOS). This is an energy assessment and energy saving scheme that applies to large undertakings and groups containing large undertakings in the UK.


An undertaking, as defined in the Companies Act 2006, is:

  • a corporate body or partnership
  • an unincorporated association carrying on a trade or business, with or without a view to profit


A large undertaking is any UK undertaking that meets either one or both of the conditions below:

  • it employs 250 or more people
  • it 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)


You also must take part in ESOS if your undertaking is part of a corporate group which includes another UK undertaking that meets either of these conditions. Where a corporate group participates in ESOS, unless otherwise agreed the highest UK parent will act as a ‘responsible undertaking’ and be responsible for ensuring the group as a whole complies.

Qualification is based on the status of your organisation on 31 December 2014, and every four years after that for each subsequent compliance period.

If your organisation qualifies, you must participate in ESOS and notify compliance to the Environment Agency by the last date of each compliance period (‘the compliance date’).

The table below shows the qualification dates, compliance periods and compliance dates.

B2.10.2.6 Table

To comply with the regulations, a ‘Lead Energy Assessor’ will need to conduct an ESOS Assessment to:

  • Measure your total energy consumption for buildings, industrial processes and transport
  • Identify areas of significant energy consumption, accounting for at least 90% of your total energy consumption
  • Identify cost-effective energy efficiency recommendations for areas of significant energy consumption
  • Report compliance to the Environment Agency


Organisations may not need to undertake the Assessment if are certified to ISO 50001.

Complying with the Energy Savings Opportunity Scheme Environment Agency Version 4.0 is available here: ESOS Guide v4