Trials conducted by the German environmental agency Umweltbundesamt (UBA) are said to have shown shown that the energy consumption of a CO2 system during a normal European summer is lower than that of a similar car with an R134a system.
Until 2009 and the rise of R1234yf, CO2 had been the refrigerant of choice of the German car industry as Europe sought a replacement for R134a, a refrigerant banned under the European MAC directive. The subsequent global acceptance of R1234yf forced the German car makers to conform, some reluctantly.
Since 2009, the UBA has been continuing to trial CO2 in a VW people carrier, as part of a research project of the German Federal Environment Ministry.
After 165,000km the energy consumption of the vehicle’s CO2 air conditioning system is reported to have been even lower than that of an R134a system. The air conditioning system was upgraded last summer with a new CO2 compressor and a replacement heat exchanger, as the prototype was exhibiting external corrosion.
Higher costs due to CO2’s higher pressures have delayed introduction but the UBA says that systems will be available from next year. Meanwhile, prototypes of CO2 compressors for use in electric passenger car are also being developed.