The letter landed on the Serious Fraud Office’s desk last week: a cross-party group of MPs demanding a criminal investigation into the UK home insulation industry. The allegation is systematic fraud, incompetence, mis-sold materials, falsified paperwork, and public money spent on work that does nothing to cut bills.
As reported by The Guardian, the MPs’ intervention follows years of complaints from homeowners who paid for cavity-wall or loft insulation under government schemes, only to find damp, mould, and no reduction in their heating bills.
Why this matters to your heating bill
Insulation is the bedrock of the UK’s energy-efficiency strategy. The Climate Change Committee says 19 million homes need upgrading by 2050. The Great British Insulation Scheme, launched in 2023, earmarked £1 billion of taxpayer money to do it. But if the work is shoddy, the maths falls apart.
A typical semi-detached house with 270mm of loft insulation saves about £300 a year on gas, according to Energy Saving Trust figures. But that saving disappears if the insulation is installed with gaps, compressed, or left to absorb moisture from unsealed leaks. Worse, poor cavity-wall insulation can trap water, causing structural damage that costs thousands to fix.
The MPs’ letter cites cases where installers claimed grants for work never done, or used materials that failed within months. Ofgem, which administers the schemes, has already suspended several firms. But the MPs argue that only a criminal investigation can root out what they call a systemic problem.
Who qualifies, and who doesn’t
The Great British Insulation Scheme targets households in lower council-tax bands, A through D in England, A through E in Scotland and Wales, and those with an EPC rating below C. But eligibility has been a mess. Homeowners on the wrong tax band or in off-gas-grid properties have been turned away, while others have been signed up by doorstep salespeople promising free upgrades that never materialise.
The catch is that the scheme relies on approved installers, but approval has been self-certified in many cases. The MPs want the SFO to examine whether the accreditation bodies, often industry-funded, did enough to police their members.
For the homeowner, the immediate lesson is: never accept an insulation grant without checking the installer’s track record. The National Insulation Association has a list of certified members. Citizens Advice has a template for asking for references. And the Energy Ombudsman handles complaints about work done under ECO and GBIS schemes.
What a criminal probe could change
A full SFO investigation would be slow, typically two to five years, and would focus on the largest operators. But the ripple effects would arrive sooner. Ofgem has already tightened its audit rules for the 2024–25 scheme year. More firms will likely be suspended. Grant applications may face longer waits as checks intensify.
But there is an upside for homeowners. If the SFO finds evidence of fraud on a wide scale, the government may redesign the grant system to prioritise quality over volume. That could mean fewer cowboy installers, better warranties, and mandatory post-installation inspections before payment is released.
Until then, the advice is defensive. If you are offered a free insulation survey, treat it like a boiler service: ask for the installer’s Gas Safe or TrustMark registration, get the scope of work in writing, and photograph every stage of the installation. Your EPC rating, and your heating bill, depend on it.
Frequently Asked Questions
Use the TrustMark website or the National Insulation Association's member directory. Both list firms vetted by industry schemes. Avoid installers who cannot provide a Gas Safe or TrustMark registration number on request.
Yes, but the process depends on the scheme. For ECO or GBIS work, contact the installer first, then escalate to the Energy Ombudsman if unresolved. Ofgem can also investigate complaints about grant-funded installations.
