The INCA (Insulated Render and Cladding Association) has released an updated version of a research report released in 2025, Why Fabric First Is Right, raising concern over the lack of insulated buildings as the government places it’s focus on green upgrades such as heat pumps.
The government’s Warm Homes Plan released earlier this year, unveiling a raft of measures aimed at tackling fuel poverty and bringing warm, healthy homes into reach for families on lower incomes. The plan was mostly built around subsidies and incentives for green upgrades, such as heat pumps, solar panels and batteries. However, industry voices were concerned about high running costs, something that the INCA have also raised, claiming that without the correct insulation, upgrades such as heat pumps will never function effectively.
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Colin King, an insulation expert with significant experience in the social housing sector, has thrown his backing behind the report and is featured as the foreword to the report. King agreed that fabric first is the most effective and accessible solution to widespread fuel poverty:
“In these days of increased tensions and pressure over fuel security and rising fuel poverty, adoption of a fabric first approach to retrofit remains a sensible strategy for a fundamental reason: the most affordable, clean and dependable energy is the energy you never have to use.”
“All other solutions—such as heat pumps, solar panels, batteries, and smart controls—perform more efficiently after the building envelope has been properly addressed, and energy demand reduced.
“A fabric first strategy, which focuses on insulation, airtightness, and minimising thermal bridging, remains the most economical and future proof method to decrease energy demand, lower emissions, and enhance comfort, regardless of technological advancements.
“A fabric first approach aligns with building physics and reduces energy demand to a level where electrification of heat makes sense in terms of running cost and national capacity.”
According to the latest Government statistics, at the end of December 2025, there were an estimated 8.5M homes with solid walls in Great Britain. Of these, it is estimated that only 909,000 (11%) had solid wall insulation and 7.6M (89%) were uninsulated.
Of these 7.6M homes without insulation, many will be old homes, some of them of non-traditional post war construction and thermally inefficient. Without efficient insulation, the INCA claim, installing a heat pump, solar PV or battery storage is not going to solve the problem, simply leading to wasted energy.
Back in 2024 the Department for Energy Security and Net Zero published a report based on the findings of the Demonstration of Energy Efficiency Potential (DEEP) project. Commissioned by DESNZ this was one of the UK’s largest research projects into retrofitting solid walled homes and has expertise from three universities. The report highlighted the benefits of solid wall insulation, showing that for older, uninsulated properties, it was the single most impactful measure, reducing whole-house heat losses by 19% to 55%.
The INCA have called on the government to reconsider their approach to domestic retrofit, and said: “addressing the fabric first is the most effective way to reduce fuel consumption, improve comfort, health and quality of life and to help residents out of fuel poverty – and there’s 7.6 million families living in old, uninsulated solid wall properties in desperate need of solid wall insulation”
