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ESOS Lead Assessors

CIBSE Certification is an approved ESOS Lead Assessor register under the Environment Agency scheme.

What is ESOS?

The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment scheme for large UK organisations. Qualifying businesses must carry out energy audits every four years and report compliance through an approved Lead Assessor.

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What is an ESOS Lead Assessor? 

In 2015 CIBSE Certification were approved to operate an ESOS Lead Assessor register in support of the ESOS Regulations. ESOS reports identifying the total energy use and energy savings opportunities for large organisations must be signed off by a registered ESOS Lead Assessor.  You need to be an LCC to become an ESOS Lead Assessor. 

The ESOS regulations require that ESOS Lead Assessors be sourced from approved existing schemes run by professional bodies, such as the CIBSE Certification Low Carbon Consultants register. Therefore CIBSE Certification ESOS Lead Assessor applicants are required to be registered as a CIBSE Certification Low Carbon Consultant.

The ESOS Lead Assessor certification scheme is open to anyone that can meet the entry requirements of competence, a minimum of two years of professional energy assessment and energy audit experience relevant to PAS 51215.

What Does an ESOS Lead Assessor Do?

ESOS Lead Assessors are responsible for:

  • Overseeing ESOS energy audits
  • Signing off compliance reports
  • Ensuring assessments meet legal and technical requirements
  • Submitting reports to the Environment Agency (or devolved equivalents)

You can act as a sole assessor or work with an internal team to deliver compliance.

Why Become a certified ESOS Lead Assessor?

  • Be listed on the official CIBSE Certification ESOS Register
  • Demonstrate your technical competence and understanding of energy assessment
  • Open new consultancy opportunities under ESOS Phase 3 and future phases
  • Access updates, technical guidance and audit tools
  • Benefit from the support of a UKAS-accredited certification body

Who Can Apply?

Applicants must demonstrate:

  • A strong technical understanding of building energy use and systems
  • Experience in conducting energy audits or similar assessments
  • Relevant qualifications or professional registration
  • Completion of ESOS-specific training (recommended but not mandatory)
  • Evidence of recent CPD and appropriate insurance

How to Apply

  1. Register as a Low Carbon Consultant (LCC) if not yet registered 
  2. Download and complete the ESOS Lead Assessor application pack
  3. Submit your application, supporting documents, and signed Code of Conduct to:
    epc@cibsecertification.org
  4. Pay the applicable certification fee

Download application pack →

Need Help?

If you have questions about becoming an ESOS Lead Assessor, contact our Certification team:

Useful Information

BEIS have published their consultation response regarding changes to ESOS for Phase 3 & 4. These changes are set out below.

Regulations for the Phase 3 changes are intended to be brought into force ahead of the 5 December 2023 compliance deadline. BEIS and the Environment Agency will work with Professional Bodies, assessors and participants as they move towards this.

These changes are set out in the response to questions 2, 3, 8, 15, 20 and 21 in the Government Response and relate to:

  • A standardised template for including compliance information in the ESOS report, generally comprising ESOS information the participant should already have available
  • The reduction of the 10% de minimise exemption to up to 5%
  • The addition of an energy intensity metric in ESOS reports
  • Requirement to share ESOS reports with subsidiaries
  • Requirement for ESOS reports to provide more information on next steps for implementing recommendations
  • Requirement for participants to set a target or action plan following the Phase 3 compliance deadline, on which they will be required to report against for Phase 4
  • Collection of additional data for compliance monitoring and enforcement

It should be noted that implementation of these requirements is subject to the Parliamentary timetable and scrutiny of the necessary primary and secondary legislation.

The remainder of the changes set out in the government response will be introduced in Phase 4, including the new requirements for net zero which will be based on the ESOS PAS currently under development.