92% of government-funded home insulation retrofits have major defects due to uncertified installers

A 2025 National Audit Office review of UK homes fitted with external wall insulation under government grant schemes (ECO4 and GBIS) found that 92% had major technical issues requiring remediation. Problems include trapped moisture causing mold, improper sealing creating cold bridges, and insulation detaching from walls. So what? Homeowners who enrolled in free or subsidized insulation programs to reduce energy bills now face homes that are damper, moldier, and less habitable than before the work was done. So what? Remediation costs range from 5,000 to 20,000 pounds per home, which the homeowner must fight to recover from an accountability chain split between the government program, the accreditation body, and the installer who may have already dissolved their company. So what? Families with respiratory conditions, especially children and elderly residents targeted by these programs due to fuel poverty, experience worsened health outcomes from mold exposure in the very homes that were supposed to be improved. So what? The medical costs from mold-related illness (asthma exacerbation, respiratory infections) fall on the public health system, meaning taxpayers pay twice: once for the botched insulation and again for the health consequences. So what? Future government retrofit programs face public distrust, reducing enrollment and slowing decarbonization of the housing stock which accounts for 15-20% of national carbon emissions. The problem persists because the installer workforce lacks sufficient training, accreditation bodies perform inadequate quality checks, and the incentive structure pays installers per job completed rather than per job verified as defect-free.