TrustMark Quality Assurance

TrustMark Quality Assurance encompasses all work(s) for government funded schemes that require mandated lodgement into the TrustMark Data Warehouse including, but not limited to:

• Energy Company Obligation (ECO)
• Great British Insulation Scheme (GBIS)
• Warm Homes Discount (WHD)
• Warm Homes Plan (WHP)

TrustMark uses a variety of methods to conduct the Quality Assurance of measures lodged in the Data Warehouse. These include a blend of onsite and desktop audits. TrustMark works in collaboration with its Scheme Providers through the sharing of data recorded within the Data Warehouse. This data includes but is not limited to:

• Registered Business performance
• Volumes of work lodged across government schemes

These documents are applicable for work installed under the current version of PAS:2035, PAS:2030, Microgeneration Certification Scheme (MCS) standards delivered under associated government schemes where TrustMark is mandated.

The TrustMark Certification of Lodgement (CoL) (void) process is now live. Any measure where the CoL has been removed will now be referred to Ofgem. Please see the Ofgem guidance for further information on the next steps - 16th April 2026

If a measure is identified as non-compliant before 1st January 2026, the remediation timeframe will start on 1^st January 2026. This process does not currently include audits undertaken directly by Certification Bodies.

For measures identified as non-compliant on or after 1st January 2026, the remediation timeframe will begin from the date the Registered Business is notified of the non-compliance.

Remediations will be valid only if they occur before the relevant deadline. TrustMark will not accept late remediations as valid.

As of 1^st January 2026, the CoL voiding process is now live, taking effect when remediation deadlines have not been met. 

Remediation Deadline:

A remediation deadline extension option will be available for legitimate circumstances. Options can include:

• Installer actively trying to remediate and is engaging in the process
• Large numbers of non-compliances generate a backlog for the installer 
• Alternative RC / Installer being sought by the supply chain
• Guarantee provider is engaged 

All extensions will be capped by remediation deadlines for the relevant scheme. See the table below.

Extensions will only be agreed on a case-by-case basis by TrustMark.

TrustMark will void where remediation was not successful due to non-access, even if the no-access policy is evidenced.

Key fixed dates below:

Ofgem has published new versions of their ECO4 and GBIS guidance documents. A full list of changes is available in the summary of updates document on each publication page:

ECO4 Delivery Guidance

ECO4 Supplier Administration Guidance

GBIS Delivery Guidance

GBIS Supplier Administration Guidance

Q&As:

Why are Certificate of Lodgements being voided? 

TrustMark will implement the voiding of the Certificate of Lodgement (CoL) for any non-compliant measures that have not been remediated in the required timescales.

As per the ECO4 Guidance Delivery (4.19 and 4.55), this will result in Ofgem referring the project or measures to their rejections process to ensure only compliant projects are accepted within the obligation. 

Does “No Access” remove the requirement to evidence remediation compliance under ECO4/GBIS? 

No. “No Access” does not remove the obligation to provide the required remediation evidence. If evidence cannot be provided, the Certificate of Lodgement cannot be considered valid. 

Under ECO4/GBIS, a measure is eligible where it is supported by a valid Certificate of Lodgement, and TrustMark will only issue / maintain a Certificate of Lodgement where the measure meets the requirements set out in PAS:2030/PAS:2035 and satisfies TrustMark Quality Assurance requirements.

Why is a measure still non-compliant if the installer could not gain access to remediate and supply required evidence? 

ECO4 legislation requires that an insulation measure has a valid Certificate of Lodgement issued by TrustMark. For a Certificate of Lodgement to be in place, the measure must be installed subject to the quality assurance and consumer protection requirements under TrustMark registration. This includes relevant installation standards, arrangements for repairs and other remedies and consumer financial protection. If the required remediation cannot be completed and compliance cannot be evidenced - regardless of consumer refusal or access issues - then the Certificate of Lodgement is not valid. 

Live from 18/11/24

This document outlines the responsibilities and requirements for Retrofit Coordinators (RC) and other qualified professionals overseeing energy efficiency installations under Publicly Available Specification (PAS) 2030:2023.

It emphasises a risk-based approach, mandatory site visits for measures such as External Wall Insulation (EWI), Internal Wall Insulation (IWI), Room-in-Roof Insulation (RIRI), Underfloor Insulation (UFI), Park Home Insulation (PHI), and Flat Roof Insulation (FRI), and the qualifications needed for those conducting site visits.

It also details the use of digital evidence, conditions under which physical inspections are required, and the process for confirming sufficient evidence before project lodgement.

Live from 23/09/25

The EPR Conventions Working Group, comprising of TrustMark, Ofgem, Retrofit Assessment Scheme Providers (Elmhurst, ECMK, Quidos, Sterling), and wider industry stakeholders has updated the Energy Performance Report (EPR) Variation Convention to reflect the transition from RdSAP 9.94 to RdSAP 10.

These changes will apply only to new projects with retrofit assessments conducted on or after 10th November 2025

Key updates include revised requirements for the pre- and post-installation recording of ventilation, aligned with the latest ECO4 and GBIS regulations. These changes are designed to ensure consistency, compliance, and improved quality across retrofit assessments.

We strongly encourage all assessors to familiarise themselves with the updated conventions to ensure readiness ahead of the implementation date.

Ventilation Upgrades

Where ventilation in a property has been upgraded as a part of the project, then the updated ventilation system must be reflected in the post EPR, even though Ventilation is not an ECO4/GBIS eligible measure.

Air Tightness Testing

All airtightness testing must be conducted by an appropriately trained Level 1 or Level 2 airtightness tester who is registered with a government-approved Competent Person's Scheme.

The testing itself must be carried out using calibrated equipment in accordance with CIBSE TM23. The building preparation and testing procedure to be used is also detailed in CIBSE TM23.

For an airtightness test to be valid and used within an RdSAP lodgement, it must be lodged to the registered Competent Person's Scheme, with the resultant certificate provided as documentary evidence for audit purposes.

Where an airtightness test is used in an ECO4/GBIS project, this must be done for both the pre and post EPR.  If only used on the Pre or Post EPR, the project will be non-compliant.

If you have any questions, please contact your Retrofit Assessor Scheme Provider.

Live from 01/02/23

In December 2022, TrustMark (on behalf of Retrofit Assessor Scheme Providers) published the Energy Performance Report (EPR) conventions to be applied specifically to ECO4 & GBIS projects.