“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.” So says Industry expert Colin King in support of an updated INCA report.

 

First published in September 2025 the revised, evidenced based report from INCA, the recognised trade association for the external wall insulation industry, entitled “Why Fabric First Is Right” now includes a foreword from Colin who goes on to say:

 

“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.”

 

About Colin King:

 

Through his own consultancy CKC, Colin provides technical support to housing providers, and government on hard-to-treat (HTT) buildings, working in particular with DESNZ on the decarbonisation of social housing and MHCLG where he delivered a review of the Housing Health and Safety Rating System on housing standards in the rented sector.

 

A former director at BRE where he led work on retrofit energy performance and hydrothermal analysis, Colin currently sits on the Retrofit Task Force, Chairs CB401 for the BSI on new Energy Standards and BS5250 Management of Moisture in Buildings Steering Groups for Part C, F and L of the Building Regulations in England and Wales. He also acts as Expert Witness, trains Retrofit Co-Ordinators, provides technical support to warranty providers and remains active across numerous other leading technical and research groups.

 

Why Fabric First

 

With the Warm Homes Plan now published it’s abundantly clear that, whilst external wall insulation has not been completely abandoned, the main domestic retrofit focus is on heat pumps, solar PV and battery storage. But, according to the latest Government statistics, at the end of December 2025, there were an estimated 8.5 million homes with solid walls in Great Britain. Of these, it is estimated that only 909,000 (11%) had solid wall insulation and 7.6 million (89%) were uninsulated.

 

So, the shocking facts are that there are still families living in around 7.6 million solid wall properties which are completely uninsulated. These are old houses, some of them of non-traditional post war construction and thermally inefficient. They leak energy and installing a heat pump, solar PV or battery storage is not going to solve the problem – it will just mean that more efficiently produced energy will be wasted!

 

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 findings were clear – that solid wall insulation (SWI) is the most impactful single measure for older, uninsulated properties, reducing whole-house heat losses by 19% to 55%.

 

And they’re not alone … the Committee on Fuel Poverty state the “the best path toward sustainability for low-income households has to be a fabric first – insulation, insulation, insulation – approach”. The Heat and Buildings Strategy says, “improving energy efficiency by adopting a fabric-first approach is key in ensuring the transition to low-carbon is cost-effective and resilient”. Even Ofgem, in their Boiler Upgrade Scheme guidance agrees that “heat pumps perform best in a well-insulated home”.

 

INCA therefore call on Government to reconsider their approach to domestic retrofit as 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.