The consultation on extending the ECO4 end date closed on 25 September 2025, with the National Insulation Association (NIA) among the bodies submitting a response1. The proposals covered the date by which obligated suppliers may deliver to their ECO4 target, currently 31 March 2026, the equivalent date for the Great British Insulation Scheme (GBIS), carry-over of up to 20 per cent of an ECO4 obligation into a future obligation, and additional consumer protection measures1.
The government asked whether the ECO4 delivery date and other relevant dates should be extended by 6 to 9 months1. The NIA said it does not support an extension in its current form, arguing that extending the scheme without increasing the overall obligation would slow delivery and risk job losses in the insulation industry1. It said that during such an extension, obligated suppliers would continue to collect revenues from consumer bills, potentially up to £1 billion across the sector based on the current price cap, without any corresponding obligation to increase the volume of installations1. The NIA called for a pro-rata increase in the obligation alongside any extension, and for the solid wall and EFG minimum requirements to be raised on the same basis1.
On GBIS, the NIA agreed the deadline should remain 31 March 2026, describing GBIS as an ineffective scheme that should not be extended1. On carry-over, it supported allowing suppliers to carry over up to 20 per cent of their ECO4 obligation, but said the conversion estimate must be set at a commercially realistic level and published early, by January 2026 at the latest1. It cited the ECO4 impact assessment rate of about £17.80, saying an estimate of around £18 would let utilities continue contracting at a viable rate of about £17, while an estimate below £14 would mean carry-over would not take place1. It said no measure types should be excluded from carry-over1.
The NIA also agreed with the proposal not to allow new applications for innovation measures or data light measures over the extension period1. On consumer protection, it said the certification bodies overseeing ECO delivery must themselves be subject to greater scrutiny, including a review of potential conflicts of interest where organisations both install and audit measures, and pointed to the forthcoming National Audit Office report on the ECO scheme1.
"The NIA agrees the GBIS deadline should remain 31 March 2026. GBIS has been an ineffective scheme, therefore we do not think it should be extended."
The NIA cited figures on the housing stock: 90 per cent of solid wall homes in the UK are still uninsulated, and 15 per cent of homes remain at EPC E or below1. It also cited an Insulation Assurance Authority Federation survey finding that 91 per cent of employers said that, without timely confirmation of an ECO4 extension, they would face difficult choices including potential staff redundancies1.
| Proposal | NIA position |
|---|---|
| Extend ECO4 delivery date by 6 to 9 months | No, unless the obligation is increased pro-rata |
| Keep GBIS deadline at 31 March 2026 | Yes |
| Allow carry-over of up to 20 per cent of ECO4 obligation | Yes, with a pro-rata increase and an early, realistic conversion estimate |
| Keep solid wall and EFG minimum requirements at current levels | No, they should rise pro-rata with any extension |
| Exclude any measure types from carry-over | No |
| Bar new innovation and data light measure applications over the extension | Yes |
Why it matters for households
ECO4 and GBIS are the routes through which energy suppliers fund insulation and other efficiency measures in homes, with the cost recovered through consumer bills. The consultation outcome therefore bears on what work can be funded, and for how long, in homes that qualify. The NIA's figures indicate the scale of what remains: 90 per cent of solid wall homes uninsulated and 15 per cent of homes at EPC E or below1. For a household in a hard-to-treat property, the practical question is whether funding routes continue without a gap between ECO4 and whatever replaces it. The NIA warned that without early certainty on a successor obligation and on how ECO4 work would count towards future targets, suppliers would withhold investment and delivery would fall away1. It also said the conversion estimate for carry-over must be published by January 2026 at the latest, warning that clarity arriving in March 2026 or later would be of little practical value as the industry would already be winding down1.
What happens next
The consultation closed on 25 September 20251. The NIA called for prompt government responses to the consultation alongside impact assessments, and for a consultation on the Warm Homes Obligation within the Warm Homes Plan1. It said the carry-over conversion estimate must be published by January 2026 at the latest1. The government's response to the consultation has not been reported.