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Freight and retrofit

Clean Vehicle Retrofit Accreditation Scheme

The scheme certifies retrofit technologies that meet UK Government standards.

The Clean Vehicle Retrofit Accreditation Scheme (CVRAS) supports the operation of Clean Air Zones (CAZ) and addresses the air pollution emissions from buses, coaches, heavy goods vehicles, mini-buses, taxis and vans. To learn more about CVRAS, download a free copy of Zemo Partnership’s Clean vehicle retrofit technology guide.


Our guide below will answer many of the questions you might have on the Clean Vehicle Retrofit Accreditation Scheme (CVRAS), Low Emission Zones (LEZ), Clean Air Zones (CAZ) and London’s Ultra Low Emission Zone (ULEZ).

CVRAS Register: approved manufacturers and devices

The CVRAS Register filters which approved companies and emission reduction systems suit your vehicles best, based on make, model and engine type.

This tool contains details of companies and their systems approved under the scheme requirements, along with their contact information and the categories of vehicle to which their systems can be applied in order to make the vehicle CAZ compliant.

Download a full list of approved manufacturers and devices, or a list of products the respective company no longer wants to be listed as available to the market.

CVRAS retrofit vehicle type overview

Energy Saving Trust has withdrawn the Clean Vehicle Retrofit Accreditation Scheme accreditation from GreenUrban Technologies after discrepancies between reported and actual test results were identified during a routine audit.

In total, 16 retrofitted buses belonging to three separate companies have so far been identified as having been affected. Energy Saving Trust is working to identify any other vehicles and companies that may have been affected, and we will work closely with those affected to resolve the issue.

We are supported in this decision by our joint owners of the scheme, Zemo Partnership.

Getting certified

Manufacturers of abatement equipment need to get their equipment accredited by Energy Saving Trust before it can be added to the list of approved devices available to vehicle and CAZ scheme operators. This ensures that approved filters meet minimum technical standards and that vehicles fitting these approved emission reduction systems meet the national CAZ emissions standards.

Potential applicants should be aware that emission reduction systems and technologies will be required to demonstrate robust technical performance in order to be eligible for approval, and manufacturers are required to operate quality management systems to certified standards, for example, ISO 9001. Please see the scheme documentation below for further details.

Scheme documentation and information

Contact our experts

For more information on the Clean Vehicle Retrofit Accreditation Scheme (CVRAS), please contact our transport certification experts on 020 7222 0101. Or get in touch with us via email at

Last updated: 22 July 2022