Ofgem published its final decision on the administration of mid-scheme changes to the Energy Company Obligation 4 (ECO4) and the Great British Insulation Scheme (GBIS) on 26 June 20251. The regulator, which is the scheme administrator for both schemes, consulted on how it would administer changes set out by the Department for Energy Security and Net Zero (DESNZ)1.
Ofgem received 18 responses in total, including from 9 suppliers, 5 installers and 4 from related industry bodies and consumers1.
"We received 18 responses to the consultation in total"
On multiple insulation measures under GBIS, Ofgem will require that secondary insulation is promoted by the same supplier as the first insulation measure, and that both measures take place in the same retrofit1. A second insulation measure promoted by a different supplier from the first will be ineligible and face rejection1. Ofgem said it will use an existing field, the TrustMark project reference number, on the notification template rather than introducing a new one1.
For smart thermostats, only those completed on or after 14 November 2024 are eligible to be notified as smart thermostat measures1. Products must incorporate automation and optimisation alongside wider connectivity for remote control of the central heating system, and will only score where the specific product is listed in the Product Characteristics Database for use with the heat source of the home where it is installed1.
Ofgem also confirmed that annual targets will not be removed1. On rural area definitions, it noted that the Scottish Urban Rural Classification 2022 was published by the Scottish Government in December 2024, the 2021 Rural Urban Classification for England and Wales was published by the Office for National Statistics in March 2025, and the ONS Postcode Directory included England and Wales data in May 20251.
Why it matters for households
ECO4 and GBIS are the two main routes through which energy suppliers fund insulation and heating measures in homes, so the administrative rules Ofgem has settled determine which installations can be notified, scored and paid for. The requirement that both insulation measures in a GBIS project come from the same supplier narrows the routes by which a loft and cavity wall measure can be delivered together, and two consultation respondents said this went against the policy intent of increasing GBIS delivery1. For a household, the practical effect is on whether a project can proceed as a single job or has to be split.
The smart thermostat rules tie eligibility to the date of completion and to product listing for the specific heat source, which affects whether a thermostat installed alongside other work can count towards a supplier's obligation. Ofgem said measures will remain with "On Hold" status until the legislative changes come into effect, and that suppliers are now able to notify the measure to Ofgem1. The draft legislative amendment laid on 11 June 2025 sets out the changes required, and Ofgem alerted suppliers by email on 13 June 20251.
What happens next
Ofgem said final guidance will be published in due course, and that the draft guidance issued alongside the consultation is not the final version1. Measures notified under the new arrangements will remain with "On Hold" status until the legislative changes come into effect1. DESNZ published a clarification on 12 June 2025 covering GBIS annual targets and the rural area definition, which Ofgem said it has taken into account1.