Scoping & specifying ESOS energy audits.

Part of the problem is that this is the first time that we have undertaken ESOS audits, another is that the guidance is mixed. A typical response that I have had from the Environment Agency when asking questions is “that is a matter for the Lead Assessor to determine using their professional judgement”.

So, to an extent we are making this up as we go along!

For ESOS purposes the scope of the audit (i.e. what energy use it needs to look at) should be determined, at a high level, from the assessment of the total energy use of the organization. Ideally this will have been undertaken, or approved, by your Lead Assessor.

So, at this point you might know that, for example, you need to cover transport and two main sites, or that you need to cover 90 branches and can exclude transport.

In the first option the way forward is clear – a transport audit plus an audit of at least one of the two main sites – assuming they are similar – if not, then both sites will need to be audited.

In the second option you are not going to audit 90 sites. Here a sampling approach is acceptable and needed! There is no official guidance on sampling – again it is left up to the Lead Assessor.


At this point you now know what you need to audit but you have not specified the audit(s). The official guidance is in fact very loose on what the audit is. For example, an audit to ISO 50002 could be a walk through or an in-depth audit.

If we look to the guidance then section 5.4.1 is the ESOS audit ‘specification’.

5.4.1. Minimum energy audit requirements

The data used in any ESOS energy audits must:

  • detail a period of 12 consecutive months’ energy use for the asset or activity
  • begin no earlier than 12 months before the start of the compliance period (for the first compliance period they must begin no earlier than 6 December 2010)
  • begin no earlier than 24 months before the start of the ESOS energy audit by the participant in the compliance period (for example, for an ESOS energy audit on say 1 April 2015, data must begin no earlier than 1 April 2013)
  • not extend beyond the compliance date (that is, not extend beyond 5 December 2015 for the first compliance period)
  • not have been included in energy audits for a previous compliance period

The energy audit must, so far as reasonably practicable:

  • analyse your organisation’s energy consumption and energy efficiency
  • identify any way in which you can improve your organisation’s energy efficiency
  • recommend practical and cost effective energy saving measures for your organisation
  • identify the estimated costs and benefits of any energy saving opportunity.

The language here could cause issues at a later date – for example, exactly what does “identify any way in which you can improve your organisation’s energy efficiency” mean? At least it does not say all ways!

Ideally the specification for an audit should be worked out in partnership with the auditor – but this can be difficult if you have to seek competitive tenders. If you are seeking competitive quotes, then you really need to understand your energy auditing needs before drafting the tender documents. One way would be to use your Lead Assessor to specify the audit – but if you do you then may exclude the Lead Assessor from undertaking audits.

An audit as such will not save you any energy or money – what it will do is ‘diagnose’ your energy issues and suggest treatments. Think of this like going to the doctor. Do you go to the doctor knowing exactly what is wrong with you? In some simple cases you might, but in more complex cases you will have an initial diagnosis then an appointment with a consultant and then treatment.

I come back to an earlier post – in energy auditing, as in life, all things being equal, you tend to get what you pay for.