The National Insulation Association (NIA), which represents insulation installers, system certificate holders and manufacturers, published its response to the government consultation on extending the ECO4 end date on 8 October 2025.
The consultation asked whether the date by which obligated suppliers may deliver to their ECO4 target, currently 31 March 2026, and other relevant dates, should be extended by 6 to 9 months. The NIA answered no. It said an extension without an increase in the overall obligation would slow delivery, reduce work flowing through the supply chain and risk job losses, while suppliers continued to collect revenues from consumer bills, potentially up to £1 billion across the sector based on the current price cap1.
"If Government decides to extend ECO4, it must include a pro-rata increase in the obligation level so that suppliers are required to deliver more measures over the extension period."
The association also opposed holding the solid wall and EFG minimum requirements at current levels, arguing they should rise pro-rata with the length of any extension. It cited figures showing 90% of solid wall homes in the UK are still uninsulated and 15% of homes remain at EPC E or below1.
On the Great British Insulation Scheme, the NIA agreed the GBIS deadline should remain 31 March 2026, describing GBIS as an ineffective scheme that should not be extended. It supported allowing suppliers to carry over up to 20% of their ECO4 obligation into a future obligation, but said this would only work with a pro-rata increase in the obligation and an optional carry-over allowance1.
The response set out conditions for carry-over to function. It said the ECO4 impact assessment rate was about £17.80, that an estimate of around £18 would let utilities keep contracting at a viable rate of roughly £17, and that an estimate below £14 would mean the economics would not stack up. The estimate must be published by January 2026 at the latest, it said. The NIA also said no measure types should be excluded from carry-over, and agreed with the proposal not to allow new applications for innovation measures or data light measures over the extension period1.
| Consultation question | NIA position |
|---|---|
| Extend ECO4 delivery date by 6 to 9 months | No, unless obligation rises pro-rata |
| Keep GBIS deadline at 31 March 2026 | Yes |
| Allow 20% carry-over into a future obligation | Yes, with a pro-rata obligation increase |
| Hold solid wall and EFG minimums at current levels | No, increase pro-rata |
| Exclude any measure types from carry-over | No |
| Bar new innovation and data light applications | Yes |
Why it matters for households
ECO4 and GBIS are the two supplier-funded routes through which many homes have had insulation installed at reduced or no upfront cost, with the cost recovered through energy bills. The NIA's figures suggest the housing stock still has large gaps: 90% of solid wall homes uninsulated and 15% of homes at EPC E or below1. If delivery slows during a transition, the practical effect for a household is a longer wait for measures that cut heat loss, and continued payment through bills for a scheme delivering fewer installations. The association's point on carry-over is that suppliers will not spend beyond their obligation unless required to, which bears on whether work continues at all between ECO4 and any successor.
What happens next
The NIA said government must give early, binding assurances that a successor obligation will be established with costs recoverable through the price cap, and clarity on eligible measures and scoring. It called for a consultation on the Warm Homes Obligation within the Warm Homes Plan, and for prompt responses to this ECO4 consultation alongside impact assessments. It also said the carry-over estimate must be published by January 2026 at the latest, and pointed to a forthcoming National Audit Office report on the ECO scheme as relevant to consumer protection reforms1. The government's decisions on these points have not been reported.