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ADAC proves Air Conditioning testing feasible |
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Using air conditioning can increase a car's fuel consumption by up to 20%, according to Europe's biggest automobile club. Its simple testing method confirms that measuring the AC system's fuel consumption is possible and urgently needed to minimise this additional fuel use.
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2007-06-19
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According to the German automobile club ADAC, an additional 2.47 to 4.15 litres / 100 km of fuel will be needed to cool down a car from 31°C to 22°C after its parking in the sun. After this first cool-down phase, the constantly operating Mobile Air Conditioning (MAC) will raise the fuel consumption by up to 2 litres/100 km. Depending on vehicle type and design of the cooling system this could cost the driver at least an extra 5-8 € for an 8 hours' summer drive, with even higher fuel costs expected for less efficient systems and higher ambient temperatures.
These are key results from test cycles performed by Europe's biggest automobile club, ADAC, that have also confirmed the impact of the air conditioner's compressor design on the whole system efficiency and therefore on additional fuel consumption.
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ADAC test results
Taking as an example a Ford Fiesta equipped with a manually controlled fixed displacement compressor, the results showed an additional fuel use of up to 20% due to the simple low-cost air conditioning system. More sophisticated variable displacement compressors with electronic control, however, could limit the extra fuel use to 6%.
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Facing these enormous differences in the economic and environmental performance of MAC systems, and given that 90% of all new cars in Germany are equipped with MAC, the ADAC has intensified its call for a standardized test procedure for MAC to be part of a revised type approval.
Testing of MAC is possible and needed
So far carmakers are not obliged to indicate the additional fuel consumption from the MAC system on any sales documents or data sheet. In addition, the performance of MAC is not included in the common European type approval procedure. The European Commission and the car industry have also claimed that the implementation of standard tests for MAC would be highly difficult. The simple and reliable test methods from the ADAC now offer one possible way to quantify the impact of MAC on the indirect emissions of a car, thereby clearly challenging this long-held argument.
Based on the New European Driving Cycle (NEDC), the ADAC test vehicles’ passenger compartment is cooled down from an ambient temperature of 28°C to a constant inside temperature of 22°C while driving in the city and on the highway. The constant sun load is imitated by a calibrated 750W radiant heater avoiding the investment in expensive solar load equipment for the vehicle type approval test chambers.
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More information:
› Find the original article on the ADAC website (GERMAN)
› See the ADAC video explaining the test procedures and results (GERMAN)
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