Proof is belief: cutting energy bills the smart way
High energy bills remain a top concern on the UK’s doorsteps, with ever-growing pressure on electricity generation and costs. As the need for practical, long-term solutions grows more urgent, insulation remains one of the most effective measures available, which must not be overlooked, says Sarah Kostense-Winterton, Executive Director of the Mineral Wool Insulation Manufacturers Association (MIMA)
Beyond economics, there's a strong social imperative to cut energy bills. Fuel poverty affects millions, hitting pensioners, low-income families and those with health conditions hardest. Better insulation is a matter of public health, fairness and lower bills.
Insulation is also a “shovel-ready” way to support the UK’s net-zero goals. It acts as an invisible shield in a home, reducing heat loss through roofs, walls and floors. This lowers the energy needed to stay warm in winter or cool in summer, cutting bills and improving year-round comfort for all households.
Insulation is the forgotten fix
The government recognised the importance of well-installed insulation in the recent Energy Company Obligation (ECO4) ‘Pay for Performance’ consultation, which sought to roll out new measurement technology to ensure high quality, while rewarding installers for offering that high quality.
Early signals from the Department for Energy Security and Net Zero suggest ECO5 – its flagship fuel poverty policy set for 2026 – could focus heavily on clean heat technologies such as heat pumps, solar PV and batteries, with less vital insulation being installed in fuel poor homes due to narrowed eligibility criteria and less nuanced assumptions on energy savings.
This shift risks undermining public trust, compromising net-zero goals and driving up household energy costs in the long run. MIMA has issued a clear warning: the UK must course-correct and ensure insulation and heating technologies are treated as equal partners in a joined-up retrofit strategy under the Warm Homes Plan.
The costs of failing to insulate
1. Higher energy bills
An insulation-light approach could mean higher bills, especially for fuel-poor homes. Installing a heat pump without first reducing heat demand can increase costs due to the high price of electricity (to which smart tariffs, shifting levies and other similar interventions provide only a partial solution). Poorly insulated homes remain costlier to heat, whatever the form of heating.
2. Hundreds of billions in avoidable energy costs
Using the UK Green Building Council’s new Home Retrofit Investment Calculator to run illustrative net-zero scenarios shows that combining clean heat and power with a strong drive for home insulation upgrades could cut UK electricity generation costs by around £150bn over 25 years vs a “clean heat only” approach. If coupled with policies to raise the performance of these measures once installed, savings could double – aligning with NESO’s scenarios which assume that one third of 2050’s residential heating demand will come from insulating homes.
The UK must course-correct and ensure insulation and heating technologies are treated as equal partners in a joined-up retrofit strategy under the Warm Homes Plan
3. More expensive heating systems
Without insulation, homes can require larger heat pumps, potentially adding thousands in up-front capital costs, enough to partially, or even fully, cover the cost of an insulation install. Joined-up delivery of good insulation and clean heat is a cost-effective win for the consumer and is an approach that would make the ECO and Boiler Upgrade Scheme spending envelopes go further.
An outcomes-based approach
MIMA urges a performance-led retrofit approach that rewards outcomes, not just installations, in its report on Making Performance-led Home Retrofit a Reality. This includes ‘Pay for Performance’ in ECO5 supported by measured energy savings and verified results.
Consumer confidence must be supported by insulation and clean heat working together, with verified performance once installed. Policy decisions should be based on proven outcomes, not relying on estimates and modelled assumptions. Insulation remains a powerful solution to lower bills, protect vulnerable households, and ease capacity and cost pressure on the grid.
For more information, please contact sarah@mima.info
