The Department for Energy Security and Net Zero (DESNZ) published a consultation on mid-scheme changes to the Energy Company Obligation 4 (ECO4) and the Great British Insulation Scheme (GBIS) on 14 November 2024, with responses due by 12 December 20241. Ofgem, which administers the schemes, published its response to that consultation on 4 February 20252.
The consultation sets out two parts. Part 1 covers mid-scheme changes to current requirements, including deliverability, installation standards and minor policy amendments. Part 2 proposes a voluntary Pay-For-Performance (PFP) mechanism, which would measure and reward actual improvements to a treated home's energy efficiency using Smart Meter Enabled Thermal Efficiency Ratings (SMETERs)1.
On installation standards, DESNZ proposes replacing references to PAS 2035/2030:2019 with PAS 2035/2030:2023 in legislation. The 2023 version of the standard was published in September 2023 and is subject to an 18-month transition process until 30 March 20251. DESNZ states its cost assumption for compliance with PAS 2035/2030:2019 processes is £1,030 per property retrofit, in 2023 prices, for both ECO4 and GBIS, and that it found insufficient evidence to change this assumption in the GBIS Final Impact Assessment1.
The consultation also seeks views on allowing loft and cavity wall insulation to be installed simultaneously as part of a GBIS project, and on allowing smart thermostats to be installed in the low-income group. It proposes that delivery achieved under ECO4 rules counts towards an obligated supplier's GBIS target1. On guarantees, it sets out a proposal to require guarantees of at least 6 years for loft insulation through TrustMark's Framework Operating Requirements, while the two-year guarantee requirement for heating controls would be retained1.
DESNZ gives the following figures for the two schemes:
| Item | ECO4 | GBIS |
|---|---|---|
| Scheme end date | 31 March 2026 | 31 March 2026 |
| Value | £4 billion | £1 billion |
| Average annual heating bill cut | around £430 | around £230 |
The bill figures are based on the most recent energy prices associated with the October 2024 energy price cap set by Ofgem1. DESNZ states that ECO has delivered around 4.1 million measures in around 2.5 million households since it began in 2013, representing just over 9% of homes in Great Britain1.
"We are proposing changes because GBIS is proving more costly to deliver than we originally estimated. Other minor changes are proposed to align GBIS and ECO4 to wider industry changes. We are also proposing to pilot an innovative Pay-For-Performance mechanism in ECO4 and GBIS that could incentivise better quality retrofits."
Why it matters for households
ECO4 and GBIS are the two main routes by which energy suppliers fund insulation and heating measures in homes, so changes to their design affect what work can be installed, to what standard and with what protection. The ECO4 scheme places a legal obligation on larger suppliers to deliver measures to eligible households, while GBIS typically delivers one insulation measure per household and covers a wider pool of homes1.
The proposals touch on practical points for a home's energy independence. Allowing loft and cavity wall insulation in the same GBIS project would permit two fabric measures in one visit rather than one, and counting ECO4 delivery towards GBIS targets could affect how suppliers direct work. The proposed move to PAS 2035/2030:2023 and the discussion of an alternative standard for single loft insulation measures concern the process a home is assessed and installed under, and the cost of that compliance. The guarantee proposals concern what protection remains if a measure later fails. The PFP proposal would, if adopted, base reward on measured heat loss rather than modelled scores1.
The consultation is for England, Scotland and Wales1. DESNZ has not reported in these documents how many households would be affected by each individual proposal.
What happens next
The consultation closed on 12 December 20241. Ofgem published its response on 4 February 20252. Both ECO4 and GBIS are due to end on 31 March 20261. The consultation page was updated on 12 June 2025 and is listed as a consultation outcome1. The consultation process determines how the proposed changes become law, and DESNZ is the department responsible.