Clean air zone retrofit accreditation scheme launched

A Clean Vehicle Retrofit Accreditation Scheme (CVRAS) has been launched today (3 August) to provide a standard for emission technology to meet requirements in the government’s Clean Air Zone Framework.

Developed jointly by the Low Carbon Vehicle Partnership (LowCVP) and the Energy Saving Trust (EST), the scheme is designed to provide independent evidence that a vehicle retrofit technology will deliver expected emissions reductions and air quality benefits in real world operation.

Retrofit systems can be used to reduce emissions from vehicles including buses

The scheme will initially apply to technology used to reduce emissions from buses, but will be extended to apply to a wider range of vehicles.

Within its Clean Air Zone Framework, the government states that buses and other large vehicles must meet the Euro 6 standard in order to operate within a Clean Air Zone, which will be introduced in a number of towns and cities across the country to address pollution emissions.

Whilst vehicle operators — in particular local and transport authorities operating large bus fleets — may not be able to invest in new vehicles to replace older, more polluting fleets in a short space of time, retrofit options are seen as a cheaper and speedier method of reducing emissions.


According to the developers, the scheme will enable drivers, technology manufacturers, businesses and local authorities to be confident that verified and accredited technologies provide the appropriate emissions reductions to meet the standards in the Framework.

The retrofit accreditation process will be technology-neutral and designed to allow all potential suppliers of eligible, credible emission reduction technology to apply for accreditation.

Technologies already potentially identified and in common use include: SCR (Selective Catalytic Reduction) fitted to exhaust systems, hybrid powertrain systems and engine repowers with gas (LPG or CNG).

New technologies will need to provide robust, independent relevant test data of the performance, prior to being considered for CVRAS accreditation, LowCVP and EST have said.


Commenting on the scheme, LowCVP’s managing director, Andy Eastlake said: “The most effective retrofit technologies can cut polluting emissions by over 95%. But it is critical that these systems are properly calibrated and matched to the vehicle and its operation and that we have a common and robust approval system.

“By making sure that we fit a range of the most appropriate technologies to the right vehicles, retrofitting can make a very significant, immediate impact on our air quality problems, supporting the complementary strategy to adopt new vehicles as quickly as economically viable.

Buses, vans and HGVs are thought to contribute over half of UK national average roadside concentration of nitrogen dioxide

“As you would expect from the LowCVP, our accreditation process will also ensure that there is no adverse impact on fuel efficiency or carbon emissions and aims to maximise the simultaneous benefits for both the environment and climate”

Larger vehicles (buses, vans and HGVs) contribute over half of UK national average roadside concentration of nitrogen dioxide according to Defra’s air quality analysis.


The initial objectives of the scheme, are to develop a set of test protocol to accredit retrofit technologies which will deliver on road emission levels equivalent to. Euro 6, based on the best available data.

EST’s transport certification manager, Colin Smith said: “By appropriately retrofitting the legacy fleet will bring immediate benefits. However, having confidence in which systems to fit and which solutions work is key for both vehicle operators and the local authorities implementing CAZs”.

“This is where a robust certification scheme will play a vital role and give assurance to stakeholders in verifying the emission reduction technologies and those that supply them in a consistent, comparable and trusted manner. As the scheme has been set up as technology neutral, any new technology can also be tested in a consistent a comparable way ensuring that real emissions reductions are achieved and air quality is improved for all.”

Related Links

Clean Vehicle Retrofit Accreditation Scheme


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