Environment Agency: ESOS Mandatory Scheme Compliance Guidance

We use some essential cookies to make this website work. We’d like to set additional cookies to understand how you use GOV.UK, remember your settings and improve government services. We also use cookies set by other sites to help us deliver content from their services. You have accepted additional cookies. You can change your cookie settings at any time. You have rejected additional cookies. You can change your cookie settings at any time. Find out if you qualify for the energy savings opportunity scheme (ESOS) and how to meet the requirements to make your business more energy efficient. Get emails about this page Print this page The energy savings opportunity scheme ( ESOS ) is a mandatory energy assessment scheme for organisations in the UK that meet the qualification criteria. Organisations that qualify for ESOS must carry out an assessment every 4 years. The assessment includes an audit of the energy used by their buildings, industrial processes and transport. The ESOS assessment is designed to identify tailored and cost-effective measures that allow participating businesses to save energy and achieve carbon and cost savings. The costs of an ESOS assessment are estimated to be significantly outweighed by the savings from implementing the recommendations. For full details of how to comply with ESOS requirements see: This guidance works alongside the legislation to help you understand the requirements of the scheme. The government has amended the Energy Savings Opportunity Scheme Regulations 2014 ahead of the fourth compliance period, also known as ESOS phase 4. This means that: Participants in phase 4 can voluntarily include net zero considerations in their ESOS assessment using the following British Standards Institution (BSI) standards: These standards combine the process and lead assessor competence standards required for the mandatory energy assessment for ESOS and a decarbonisation assessment. The existing competency standard, PAS 51215:2014 Energy efficiency assessment: Competence of a lead energy assessor , remains the competency standard for ESOS lead assessors. Manage your Energy Savings Opportunity Scheme Reporting ( MESOS ) is the online system for reporting compliance with the ESOS requirements. MESOS does not allow reporting of any voluntary decarbonisation assessments, although the Department for Energy Security and Net Zero (DESNZ) is considering this for potential future changes to the online system. Organisations may wish to publish this information via their own reports or websites. If you qualified for ESOS in the third compliance period, also known as ESOS phase 3, between 6 December 2019 and 5 December 2023, an annual progress update is due to be submitted by 5 December 2026 in relation to the action plan you submitted. The progress update must be signed off by a board level director (or equivalent) and submitted via MESOS . For full details of how to complete ESOS annual progress updates, see section 14 of the guidance on how to comply with ESOS phase 4 . If you have not yet submitted an action plan you should contact the Environment Agency. ESOS applies to large UK undertakings and their corporate groups. It mainly affects businesses but can also apply to not-for-profit bodies and any other non-public sector undertakings that are large enough to meet the qualification criteria. Your organisation qualifies for ESOS phase 4 if, on 31 December 2026, it meets the ESOS definition of a large undertaking . The deadline for submitting a notification of compliance for phase 4 of ESOS is 5 December 2027 . Organisations that qualify for ESOS must comply with their ESOS obligations, via MESOS . For phase 3, the qualification date was 31 December 2022. Corporate groups qualify if at least one UK group member meets the ESOS definition of a large undertaking. UK registered establishments of an overseas company also need to take part in ESOS (regardless of their size) if any other part of their global corporate group