TrustMark and the Delivery of PAS2035


TrustMark has incorporated the new specification, the requirements for registration of the Retrofit Roles and the agreed transitional arrangements into Annex B of our Framework Operating Requirements, so that going forward, where a consumer engages with a TrustMark Registered Business about the installation of energy efficiency measures, they can have confidence that the work is delivered to improved, recognised specifications and is underpinned by a compliance regime. 

Ventilation & Air Tightness Testing

We have approved a process for background Ventilation and Air Tightness Testing following a period of evaluation by our compliance team. The process was developed by The IAA and offers an approach to measure and address background ventilation requirements under pathways A and B of PAS 2035 and provides an alternative for pathway C whilst not replacing the airtightness testing requirements.


It is important to understand that when a business becomes PAS 2030:2019 certified, then they must adhere to the PAS 2035:2019 requirements for a project, which must be overseen and lodged into the TrustMark Data Warehouse by a TrustMark registered Retrofit Coordinator.

PAS 2035:2019 Retrofit Roles


PAS 2035 specifies the retrofit roles as follows:

  • Retrofit Advisor
  • Retrofit Assessor
  • Retrofit Coordinator
  • Retrofit Designer
  • Retrofit Evaluator

Further information on the retrofit roles and qualifications can be found here. 

Further Resources


If you would like to learn more about why PAS 2035 was created and how it works, visit the following external links:

PAS 2035: An interview with Dr. Peter Rickaby (the technical author of PAS 2035)

The Retrofit Academy

Retrofit Works - Model


PAS 2035:2019 Retrofitting Dwellings for Improved Energy Efficiency


PAS 2035:2019 was sponsored by the UK Government's Department for Business, Energy and Industrial Strategy (BEIS). This is the key document in a framework of new and existing standards on how to conduct effective energy retrofits of existing buildings, it covers how to access dwellings for retrofit, identify improvement options, design and specify Energy Efficiency Measures (EEM) and monitor retrofit projects.

The standard drives the 'whole house approach' including the 'fabric first' methodology. It defines the qualifications and responsibilities of individual retrofit roles and respective activities required prior to and post EEM installation.  It also includes a risk assessment process that builds incrementally robust requirements depending on what requirement path (A, B, or C) the retrofit project is assessed to fall within.

It is not possible to be certified to PAS 2035:2019 in the way that it is with PAS:2030. In the case of PAS 2035:2019. TrustMark Registered Businesses carrying out work within its scope are required to be compliant with its requirements; subject to the transition arrangements outlined below.

PAS 2035 is inextricably linked to PAS 2030:2019, the new industry specification to replace PAS 2030:2017 and is the standard to which all energy efficiency installers must be certified and compliant.

The specifications are available from the BSI Shop.

PAS 2035 Retrofit Assessor and Retrofit Coordinator Scheme Requirements Documents


The publication of PAS 2035 and the updated PAS 2030 standard signalled a major change to the domestic property retrofit and energy assessment industry. The PAS 2035 standard introduced newly defined and qualified roles including the Retrofit Assessor and Retrofit Coordinator. It was therefore important to support the launch and ongoing improvement of these roles, so TrustMark Scheme Providers involved with the registration and on-going monitoring of Retrofit Assessors and Retrofit Coordinators collaborated to produce standardised approaches and requirements of these organisations and the businesses that they register. 

To achieve this goal, two groups were formed; a Retrofit Assessor Scheme working group and Retrofit Coordinator Scheme working group. Both had a similar remit; to produce an overarching ‘Scheme Requirements’ document to bring consistency to the Scheme deliveries.  

Both groups have created, evolved, and adopted the Scheme Requirements documents which bring together the obligations of PAS 2035 and the TrustMark Framework Operating Requirements, supported with existing requirements of the schemes.

It has been agreed that the Scheme Requirements documents should be hosted in one location, that being the TrustMark website. The working groups have also agreed a review and approval process via their regular meetings and are committed to keeping these documents updated as and when required. As a result, the latest version of the documents will be available via the TrustMark website. 

Whilst TrustMark has a place at both the Retrofit Assessor and Retrofit Coordinator working groups, it is not the owner or custodian of the Scheme Requirements documents and to that end questions related to them should be directed to the respective retrofit Schemes.  Where TrustMark received direct inquiries, as appropriate they will be directed into the applicable Scheme working group.

The Retrofit Assessor and Retrofit Coordinator Scheme Requirements documents can be viewed here:

Retrofit Coordinator Scheme Requirements V1.2

Retrofit Assessor Scheme Requirements V1.021

PAS 2035:2019 - Reduction of Inherent Technical Risk Scores of Energy Efficiency Measures Through the Use of TrustMark Recognised Industry Quality Assurance Schemes


Annex B of PAS2035 provides the ability for installers working under an Approved Industry Quality Assurance Scheme (IQAS) to reduce the Inherent Technical Risk (ITR) of a measure for the purposes of assessing the PAS2035 risk pathway providing the installer complies with the IQAS requirements under the PAS.

Currently, there are only two approved IQAS that requires installers to be operating under an end-to-end offer and applies only to approved systems under an Agrément Certificate.

Guarantee Under The Quality Assurance Framework Of The IAA

Non-Standard System Approval Process for Loft, UFI, IWI and RIRI insulation measures (installations) 
Standard System Approval Process for Cavity Wall insulation measures (installations)
Use online application or website contact details


This list provides details of Systems for which the ITR can be reduced under PAS2035 and indicates those installers approved for the system. If an installer does not appear against the proposed system, then the ITR should not be permitted to be reduced. Equally, if a system does not appear on the list then the ITR should not be permitted to be reduced.

This list will be updated on an ongoing basis and Retrofit Participants and their Scheme Providers / Certification bodies are advised to check the list before permitting the reduction in the ITR.

SWIGA Guarantee - Use application or website contact details

Should your organisation operate an industry quality assurance scheme as described in PAS 2035:2019 and you require to be considered for TrustMark recognition, you can obtain the recognition criteria by contacting TrustMark directly.

A further opportunity to reduce the inherent technical risk score for a measure (without being subject to a recognised quality assurance scheme) is afforded by the following extract from PAS 2035 Annex B.3. Where a measure complies with the MCS standards, [N7], [N8] and is installed by an MCS certified installer the inherent technical risk score for that measure in Table B.2 may be reduced by one.

[N7] Microgeneration Certification Scheme (MCS) Product Standards at

[N8] Microgeneration Certification Scheme (MCS) Installer Standards at 

Energy Efficiency Measures for Older and Traditional Buildings: 2-day Course - Level 3 Award Qualification


This qualification is a way of meeting part of the requirements for Retrofit Assessors working under PAS 2035:2019 in respect of some building type categories (please see PAS 2035:2019 for further information). This course is about the energy efficiency and retrofit of traditional buildings, classified as those with the construction of solid brick or stone external walls or pre 1919 timber-framed external walls with any infill, which make up about 35% of UK building stock.

It is delivered by retrofit expert Professor John Edwards, a member of the BSI Retrofit Standards Task Group and the lead author of BS7913: 2013, the British Standard for traditional and historic buildings; also a member of the Steering Groups for PAS2030:2019 and PAS2035:2019.

At the end of this course, participants will increase their familiarity with issues concerning traditional buildings and understand their retrofit requirements more readily.

The course is available for individuals to book a place and for in house group bookings for which there is a substantial discount offered - click here for further details.