Energy Company Obligation (ECO3) Final Determination Report

Reports, plans and updates

The Energy Company Obligation (ECO), first introduced in 2013, is a government energy efficiency scheme for Great Britain. ECO places legal obligations on larger energy suppliers to deliver energy efficiency measures to low income and vulnerable households. ECO is intended to assist in reducing fuel poverty, help to maintain security of energy supply and reduce household carbon emissions - a critical component of achieving our Net Zero ambitions.

ECO3 which ran from October 2018 to March 2022, was the third iteration of ECO and consisted of one distinct obligation. Under the Home Heating Cost Reduction Obligation (HHCRO) obligated suppliers promoted measures that reduced the energy costs for low-income, fuel-poor and vulnerable households. With a focus on insulation and heating measures, estimated lifetime bill savings of £8.253 billion had to be achieved. There were also sub-obligation targets to achieve a proportion of these savings from households in rural areas and from households with harder to insulate solid wall construction.

The ECO3 final determination report provides details on overall scheme performance and our final determinations of energy suppliers’ achievement against their obligations.


  • The overall bill saving target for the HHCRO obligation was exceeded with lifetime bill savings of £8.547 billion achieved.
  • All but one active supplier successfully met their HHCRO obligation and sub-obligation lifetime bill saving targets.
  • 1.03 million energy saving measures were installed over the course of ECO3. This included:
    • Broken down or energy inefficient boilers being replaced in 251,741 households with energy efficient condensing boilers or low carbon heating alternatives
    • Cavity wall insulation installed in 152,938 households
    • Underfloor insulation installed in 133,173 households
    • Loft insulation installed in 88,588 households.
  • It is estimated that measures installed since the first ECO scheme was introduced in 2013 will provide lifetime carbon savings of around 58.2 MtCO2e. This is equivalent to the amount of carbon absorbed by 264 million mature trees over 10 years.

Please note: For those who wish to look at the data used in the report in more detail, a spreadsheet with this information is published below.