To limit further faulty installations, the Department asked the certification bodies and scheme providers, via TrustMark, to suspend installer businesses based on their failure rate. By the end of January 2025, 38 installers had been suspended, preventing them from carrying out new work of this kind under government schemes.22 The Department told us this represented 81% of the external wall insulation market and that 22 installers had been re-instated by the time we took oral evidence in November 2022, 16 C&AG’s Report, para 2.3 and Figure 10 17 C&AG’s Report, para 2.6 18 Q 75 19 C&AG’s Report, Figure 7 20 FEE0003, FEE0021 21 Energy Security and Net Zero Committee Oral evidence: Retrofitting homes for net zero, HC 453, 12 February 2025 22 C&AG’s Report, para 2.13 12 after having fixed the identified defects for which they were responsible.23 However, this reinstatement process only covers remediation work identified by the audit of 1,109 external wall insulation installations, before it was understood how widespread the major failures against the quality standard were.24