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Low-cost and High-efficiency CO2 Mobile Air Conditioning System for Lower Segment Cars

The project aims at developing a new high-efficiency, low-cost air-conditioning system using CO2 as a refrigerant for small cars (A and B segments). Methods to assess performance, annual fuel consumption and environmental impact will be identified, constituting a preliminary step for new EU standards.

Tags: Road


In the Sixth Framework Programme, a specific call was published on “…highly efficient air conditioning systems with near zero greenhouse gas emissions and elimination of hydrofluorocarbon (HFC) …”

This project addresses that call and its main objective focuses on the development of a new low-cost, high-efficiency mobile air conditioning system based on R744 (CO2) working fluid. This is because the application of these systems to the lower segment cars represents a real bottleneck due to the cost and energy consumption constraints. In fact, the state-of-the-art R744 systems are too expensive and sophisticated for the A, B and low priced C-car segments and light commercial vehicles.

For this reason, the system developed in the framework of the B-COOL project will be cost and energy effective so as to allow an easier and more rapid HFC replacement in the automotive sector.

The B-COOL project contributes to the objectives of the Kyoto protocol by:

  • the reduction of CO2 emissions resulting from high efficiency, in comparison to a non-optimised R744 system or the present R134a system
  • the elimination of CFC/HCFC/HFC refrigerants (100% reduction
  • the availability of a low-cost system to allow its diffusion on small and medium-sized cars (70% of the EU market).


The major objective of the project is the development of an innovative low-cost and high-efficiency mobile air conditioning system based on the CO2 (i.e. R744) vapour compressor cycle for low-cost vehicles, integrating the efforts made recently and addressed to higher class vehicles.

This target will be achieved with a systemic approach that starts with the identification of the most suitable system architecture and proceeds with the development of new components and their optimisation, their integration on the system and on the vehicle.

The development will be supported by the technological feasibility analysis that will lead to the realisation of results suitable for rapid exploitation.

Besides this main objective, methods to assess performance, annual fuel consumption and environmental impact will be identified and validated to constitute a preliminary step for new EU standards.

The B-COOL system (low-cost and high-efficiency R744 MAC) will support the EU efforts to reduce resistance to the HFC ban and allow a rapid diffusion of the new system with the related environmental benefits, thus making EU industries more competitive.

Description of work

The work programme is organised following the logical steps required to develop an automotive air-conditioning system. Firstly, the reference vehicle and major system requirements are identified: target performance, cost estimation and technological aspects.

Then common and agreed assessment methods and procedures will be identified, gathering all the partners’ competencies so as to make the system’s real characteristics evident and to be able to estimate the system’s true environmental impact and perceived performance.

The development of the system architecture and components represents the crucial phase of the project. Using advanced system modelling, the most suitable system architecture and component requirements will be defined, taking into account the constraint of the two reference vehicles. Innovative components matching the requirements will then be designed and realised, and the systems assembled and characterised. The compressors will be derived from the ongoing development of the responsible tier one suppliers, as new developments are not compatible with the timing and budget of the project.

Then the systems will be integrated in the demonstrators, tuned and tested following the procedure identified in the project.

The new systems will be compared with the reference systems and with other competitor technologies in terms of environmental impact and cost.


Two demonstration vehicles will be realised, one based on a Fiat Panda with an automatic climate control and one based on a Ford Ka with a manual air conditioning system.

Both vehicles will be equipped with a specific version of the B-COOL system.

The developed systems will have a target cost of about €30 more than the baseline, will be 10% more efficient and will be equivalent to the references for all the other features.

The following experimental and assessment procedures will be also identified in the framework of the project:

  • assess the system efficiency on a bench
  • assess the additional fuel consumption, the associated comfort level and the specification of the testing facility
  • an algorithm to estimate the mean annual fuel consumption due to air conditioning depending on the geographical area
  • estimate the environmental impact (production, usage and maintenance including direct and indirect effects, dismantling).
  • These procedures will be applied to the demonstrator vehicles and to the reference vehicles so as to create an initial database. They will contribute to the definition of the European Standard to assess the MAC system performance and environmental impact.