The Department for Energy Security and Net Zero has set out mid-scheme changes to the Great British Insulation Scheme (GBIS) and Energy Company Obligation 4 (ECO4), with the intention that they apply from the date the consultation was published, 14 November 2024. The changes are: allowing two measures out of floor, loft and cavity wall insulation to be installed simultaneously in one GBIS project; allowing smart thermostats to be installed in the low-income group; and allowing delivery achieved under ECO4 rules to count towards an obligated supplier's GBIS target1.
The department states the intention is to legislate so these changes are allowed from the date of the consultation publication, 14 November 20241. The preferred option will be given effect via secondary legislation, due to be laid in May and come into force from July 20251. The consultation, carried out in November 2024, received 122 responses1.
Under the original GBIS policy, only a single measure could be installed in one household, smart thermostats were not allowed in the low-income group, and ECO4 annual bill savings had no contribution towards the GBIS target1. GBIS was estimated to be a £1 billion obligation on energy suppliers, running between Spring 2023 and March 2026, and originally aimed to deliver 55,998,000 in annual bill savings1. The scheme covers EPC D to G properties across a low-income group and a general group1.
Delivery figures from the Household Energy Efficiency National Statistics, as at the end of December 2024, were1:
| Metric | Count |
|---|---|
| Total number of homes | 46,887 |
| Low-income group | 17,111 |
| General group | 29,579 |
| Total number of measures | 58,975 |
| Loft insulation | 16,295 |
| Cavity wall insulation | 24,778 |
| Under floor insulation | 144 |
| Solid wall insulation | 3,254 |
| Heating controls | 12,093 |
The department says GBIS is proving more difficult and costly to deliver than originally estimated, with Ofgem reporting installation rates lower than expected and suppliers reporting higher costs and supply chain constraints1. The average GBIS cost is reported by suppliers to be £26.03 per annual bill saving, higher than assumed in the original impact assessment1.
"The intention is to legislate so these changes are allowed from the date of the consultation publication, 14 November 2024."
Why it matters for households
The change to two measures per project matters most for homes that need both loft insulation and cavity wall insulation, since these can now be delivered together rather than one at a time. Loft and cavity wall insulation are described as the most popular and cost-effective measures in GBIS, and installing both where possible is said to produce better outcomes for installers and householders1. Spreading fixed compliance costs across more measures is intended to reduce the cost of delivering annual bill savings1.
For the low-income group, smart thermostats become an eligible secondary measure, broadening the range of measures on offer. Heating controls, of which smart thermostats form a part, can reduce heating hours when heat is not required, and smart thermostats allow remote control of home temperature by tablet, smartphone or desktop1.
The department notes that allowing two measures theoretically reduces the number of homes that could be treated compared with the original assumption, but should enable more delivery overall than would take place without the change1. Whether a household qualifies depends on the eligibility rules and how the scheme compares with ECO4 and the Warm Homes: Local Grant.
What happens next
The secondary legislation is due to be laid in May and come into force from July 20251. GBIS and ECO4 are due to end on 31 March 2026, with final reconciliation to be done at the end of the scheme in March 20261. The department says the increase in delivery will be measured by Ofgem, the scheme administrators1.