In January 2025, the UK government suspended 39 insulation companies from taking part in government-backed energy efficiency schemes after uncovering widespread evidence of poor-quality installation work. The decision followed hundreds of homeowner complaints about issues such as damp, mould and inadequate ventilation caused by substandard insulation practices.
The suspensions affect firms working under the Energy Company Obligation 4 (ECO4) and the Great British Insulation Scheme (GBIS), two major national programmes designed to improve energy efficiency and reduce carbon emissions in UK homes. Since 2022, around 65,000 households have received solid wall insulation through these initiatives.
However, routine inspections by TrustMark, the government-endorsed quality assurance body, found widespread failings. In some cases, insulation was left exposed to the elements or installed without proper ventilation, trapping moisture inside walls and creating the perfect environment for mould to grow. These problems not only compromised the energy performance of homes but also raised serious health concerns.
According to The Guardian, the investigation revealed that some installations were so poorly executed they left properties in worse condition than before. In response, Ofgem, the energy regulator, has ordered the responsible companies to carry out remedial work at no additional cost to homeowners. The suspended firms will remain barred from government schemes until they can prove compliance with the required standards.
Miatta Fahnbulleh, Minister for Energy Consumers, said the government takes the issue “extremely seriously” and is working to ensure affected households receive timely repairs. She also confirmed that the government will strengthen quality control measures across national retrofit programmes.
A Reminder of Why Quality and Breathability Matter
This situation highlights the risks of poor-quality installations and the importance of using materials and methods which are suitable to the building and situation. When walls are sealed without adequate ventilation, moisture becomes trapped, leading to damp, condensation and mould.
At Sisalwool, we believe that energy efficiency should never come at the expense of building health or occupant wellbeing. Natural fibre insulation helps regulate humidity and allows moisture to escape, reducing the risk of condensation and maintaining a balanced indoor environment.
As the UK moves towards large-scale retrofit and insulation efforts to meet net zero targets, it is essential that quality and breathability remain at the forefront. The right materials, installed by skilled and accredited professionals, create homes that are not only warm and efficient but also safe, durable and comfortable.
If you are planning an insulation project, make sure your installer understands how to work with natural materials effectively.
To learn more about using natural fibre insulation in retrofit and new build projects, visit our product guides page or explore the full Sisalwool product range.
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