The Energy Company Obligation (ECO 4) is a government energy-efficiency scheme in Great Britain, designed to tackle fuel poverty and help reduce carbon emissions. ECO is an obligation placed on energy companies to deliver energy efficiency measures to domestic premises. ECO is not a grant scheme; it is up to the energy companies to determine which retrofit projects they choose to fund, the level of funding they provide, and the Retrofit Coordinator and installers that they choose to work with.

ECO 4 measures were able to be delivered from the 1st April 2022. The ECO 4 scheme will run until 31 March 2026.

ECO 4 focuses on improving the least energy efficient homes and households in fuel poverty, as only properties in bands D-G can be treated. It also aims to deliver a more complete upgrade of those homes, shifting to a multi-measure whole-house retrofit approach. Furthermore, a minimum number of private tenure homes in energy efficiency rating band E, F and G must be upgraded throughout ECO 4, ensuring the least efficient homes are treated.

There is a new Minimum Requirement (MR) to improve the energy efficiency rating of band D and E homes to at least a band C and band F and G homes to at least a band D. ECO 4 aims to encourage the installation of various energy efficient measures such as insulation measures, first time central heating, renewable heating, and district heating connections.