What is an ESOS Lead Assessor And Why Do You Need One?

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The Energy Savings and Opportunities Scheme (ESOS) is aimed at making energy audits mandatory for UK businesses of a certain size. Under ESOS legislation, all businesses meeting the following qualification criteria must carry out a compliance programme and produce a detailed audit of their energy usage:

  • more than 250 employees.


  • an annual turnover exceeding £44m+ and a balance sheet exceeding £38m+ on 31st December 2022.

For UK corporate groups, if one group member meets the criteria, the entire UK group must comply.

To perform the audits and sign off the programme as compliant, you’ll need an ESOS Lead Assessor. This person is a professional who is accredited to an approved ESOS Lead Assessor register on the Government’s website. This is mandatory – part of the ESOS compliance requirements states that you must appoint a Lead Assessor and that the assessor will not be held responsible for compliance by regulators.

What is an ESOS Lead Assessor?

An ESOS Lead Assessor (LA) is someone who meets the approval criteria set out by the Government and is therefore registered on the ESOS page of the Gov.uk site.

An ESOS LA is necessary for every ESOS compliance programme as any ESOS assessment must be reviewed and approved by one for it to be accepted by the government.

ESOS LA’s review the following parts of your ESOS audit to ensure they meet compliance requirements:

  • Total energy consumption
  • The determination of your assets and activities that account for your significant energy consumption (at least 90%)
  • Confirming the necessary certifications and evidence that must exist for alternative routes to compliance
  • Review the competency and experience of those involved in the audit (provided it was not done by the LA themselves)
  • Reviewing all audits undertaken to meet ESOS compliance criteria

LA’s do not have to carry out the ESOS audit themselves, though it is often more efficient in terms of time and resources to hire an LA with energy auditing experience to deliver a ‘one-stop-shop’ service to take care of ESOS. However, some businesses may instead choose to perform their audits and have the LA review them.

In all cases, the assessor will review your total energy consumption calculations, review the certifications and evidence you may need to meet compliance and review the audits against the minimum requirements for ESOS.

If you’ve produced the report yourself, the LA will have to perform more intensive checks on the experience of those involved in the report, the actual activities used during the audit (how many site visits etc), the framework you have for future audits and other factors. Ultimately, the LA is likely to act as more than just a stamp of approval – they will add value to your ESOS process.

Why an ESOS Lead Assessor should perform your audit

ESOS LAs are not only capable of performing audits, they are also more experienced in the requirements of the auditing activities required and framework demanded by the government. As such, hiring an ESOS LA as your auditor and the final stamp of approval is usually the most effective route for your business from a time and cost perspective.

The right ESOS lead assessor will be able to perform the following tasks on your behalf:

  • Determining energy use profiles.
  • Identifying energy-saving methods and recommendations for future efficiency gains.
  • Calculating the cost savings associated with any energy-saving methods.
  • Developing a sampling approach, audit timetable, site visit schedule and even the ongoing process for future audits.

Training someone in-house to both perform all of these audit activities to ESOS standards and also achieve LA status is time, cost and labour-intensive. Hiring an experienced professional to carry out all of the work on your behalf saves time and, ultimately, money. Using an external LA means only one director of your business must review the LA’s final assessment and any recommendations it makes. Choosing to use an in-house assessor means you’ll need two directors to assess and sign off the report.


Make your ESOS compliance easy with Integral Energy

If you’d like to make ESOS as simple as possible, work with Integral Energy. We have a UK-wide network of qualified ESOS energy auditors and Lead Assessors of all disciplines who can complete all aspects of your ESOS compliance requirements for Phase 3 and any future phases.

You’ll have to act quickly, however, as many businesses are now playing catch-up for ESOS, and capacity will be at a premium throughout 2023. Get in touch today to discuss your reporting requirements and ESOS programme as a whole.

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