Energy Saving Opportunity Scheme

Compliance audits

Where audits are required, they can take place any time during the ESOS compliance period. This means organisations can plan a rolling audit programme. Audits already carried out before ESOS was introduced can contribute to its implementation as long as they meet the scheme's requirements.

An ESOS-compliant energy audit is one that:

  • is based on 12 months’ verifiable data for a continuous period, beginning no earlier than 6 December 2010 for the first compliance period and no more than 24 months before the start of the audit (the data also may not have been used for an energy audit in a previous compliance period)
  • analyses the organisation’s energy consumption and energy efficiency
  • identifies practicable ways to improve their energy efficiency
  • recommends cost-effective energy saving opportunities
  • identifies the estimated costs and benefits of the energy saving opportunities recommended


ESOS audits and assessments must be undertaken, overseen or signed-off by a qualified ESOS Lead Assessor.

It will be for each organisation to determine what it wants to do as a result of the assessment. ESOS is intended to identify cost-effective energy saving opportunities that will be in organisations' own interests to apply.

There is no regulatory requirement to implement the recommended measures.

Lead assessors can be employees of the organisation or external contractors, as long as they are on an approved register. IChemE is an ‘ESOS Approved Competent Authority’ appointed by the Environment Agency to deliver the required level of training and maintain to a register of qualified ESOS Lead Energy Assessors.

Use these links to find out more about becoming an ESOS Lead Energy Assessor and book onto the IChemE - ESOS training course.


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