Energy Company Obligation (ECO)

Supply Chain

How can Installers get involved with ECO?

ECO4 focuses on insulation and heating measures that support vulnerable consumer groups. If you are an installer and interested in delivering ECO measures, you need to contact an obligated supplier. To be eligible to deliver measures under ECO4, all installers must be a TrustMark registered business. The exception would be installers of district heating connections not connected to a shared ground loop.

What measures can be installed?

There are a wide range of energy efficiency measures that can be installed under ECO4 including insulation measures, heating measures and connections to district heating systems. 

The ECO4 measures table provides information on eligible energy efficiency measures which suppliers can use to meet their ECO4 obligations. The list of measures is non-exhaustive. Other measures may qualify, subject to review by us, on a case-by-case basis.

Evidencing measures

The Great British Insulation Scheme and ECO4 forms are used to collect and provide evidence of measure eligibility, all forms can be found on the Energy Company Obligation Forms and Tables page.


ECO4 adopts a whole-house approach to energy efficiency improvement, as set out in Publicly Available Specification (PAS) 2035:2019, whereby multiple measures are installed in a property following a full assessment of the home’s needs. ECO4 projects which involve one or more measures referred to in PAS should follow the domestic retrofit process required by PAS 2035:2019. ECO4 further introduces a minimum requirement for a property’s Standard Assessment Procedure (SAP) rating to be increased. To meet the minimum requirement, any starting SAP band F or G property treated must be improved to at least a band D. Any starting SAP band D or E property treated must be improved to at least a band C.

A pre-retrofit assessment is the start of the lifecycle of a project and determines the starting SAP rating of the property.

Innovation opportunities

ECO4 includes incentives designed to support the delivery of innovative measures that can provide further energy efficiency improvements, or that offer additional benefits, via the new measures and products (NMAP) routes. Only obligated suppliers can apply under the innovation routes. If you have a new or innovative product or system you wish to have supported under ECO4 you need to work with an obligated supplier who will liaise with and submit the application to Ofgem. More information on ECO4 innovation is outlined in the ECO4 Guidance: New Measures and Products. Further information, including application forms for the innovation routes, is available on the ECO4 innovation page.

Appropriate guarantees 

Ofgem no longer administers appropriate guarantees or financial protection. The current list of appropriate guarantees can be found on the TrustMark website and any queries regarding these should be directed to TrustMark (

How we engage with stakeholders

We believe that engaging with stakeholders when designing and delivering schemes brings real benefits. We do this via forums and working groups which gather contributions from a range of stakeholders on the main operational and delivery issues in ECO.

To find out more see the section dedicated to stakeholder engagement