Wednesday 8 March 2023

What is an ESOS audit and what rules do you have to follow?

What is an ESOS audit and what rules do you have to follow?

What does that look like in practice and what will your assessor look for? Take a closer look at the process with the help of Energise’s ESOS specialists.

An audit is so much more than a short visit on site, and starts earlier than you might think. A fair amount of work goes into preparing your compliance before the site surveys can even take place, and you should factor this into your timeline of compliance. Here are just some of first steps:

  • Identify your areas of significant consumption;
  • Create a process around sampling 95% of your energy consumption;
  • Determine the number of visits necessary to meet your sampling approach;
  • Consult with key staff members responsible for the sites, as well as those colleagues who will be able to provide significant detail around operational behaviours and patterns;
  • Consider if there is already data available to you from other compliance activities, but note that Phase 3 of ESOS has eliminated some compliance routes you were familiar with – you’ll need to look carefully into which are still acceptable. ISO50001 is one of them.

Ensuring everybody is able to cooperate will make the journey to compliance easier, but it is important to allocate time to this process before your assessors head out on visits. Keeping track of your methodology is actually a critical part of meeting compliance requirements, as it forms the basis of the ESOS Evidence Pack.

What do you need to look out for during a visit?

The first thing the auditor will do when arriving at the site is to connect with the key member of staff identified in the pre-visit conversations. It’s important that this person has set some time aside in their day to be available for the auditor, there’s no need to stay with the auditor all day, unless you want to, or it is in your site Health and Safety policy that visitors should be accompanied. While on site the auditor will:

  • Complete an initial tour of the facility with the key contact, covering all the key areas, location of energy consuming equipment (e.g. plant rooms) and any access requirements;
  • Talk with the key contact about the operational patterns of the site and other key drivers of the energy consumption such as maintenance and management procedures for key energy consuming equipment;
  • Review the energy consumers on site, potentially taking non-invasive measurements on key equipment;
  • Take photographs to support the findings and the commentary in the audit report;
  • Develop an understanding of how the site operates.


Does ESOS require you to audit your fleet?

ESOS also includes a requirement to audit transportation assets where they meet the significance threshold. These fleet audits largely follow the same pattern as a site visit for a building audit, except for some key adjustments. It is important that the required types of vehicles to meet the sample, and their drivers, at the depot in order to be physically assessed. The auditor will work with you to time this in order to limit disruption to normal operations as much as possible.

Each vehicle takes around 10-15 minutes to have its assessment and can then be on its way. We will review:

  • Telematics data (if available);
  • Onboard computers for efficiency metrics and trip computers;
  • Physical review of the vehicles maintenance and features;
  • Talk with the driver to understand their vehicle operation and user experience.

Making your ESOS assessment work harder

Our qualified Lead Assessors run comprehensive ESOS energy audits that ensure your business goes beyond meeting the requirements, to lay the foundations for your carbon reduction journey. The detail we collect on site will form a comprehensive set of notes in order to identify where improvements in energy efficiency and carbon reduction could be made. These are scaled up across the whole organisation to create a company-wide assessment of your opportunities.


You can get in touch with Energise’s Lead Assessors at to find out more or book in a complimentary consultation.


Written by

Bruna Pinhoni

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