Conference Year



mobile AC system, energy saving, LCCP, fuel economy, default cabin air recirculation


The climate control load is the most significant auxiliary loads present in vehicles today. The peak climate control load of an AC system in sedan can be as large as the engine input power. As the attention on vehicle energy economy is rising worldwide, the energy-saving of mobile air conditioning is becoming more and more important. Most mobile AC systems nowadays draw air from outside the vehicle and cool it to the desired comfort level inside the vehicle. Lots of energy is wasted during this process due to continuously cooling the hotter outside air instead of cooling the “cooler” inside air. Compared to that, defaulting to recirculated cabin air will certainly be energy-saving. Though some studies have revealed the energy saving effectiveness under bench test conditions, it is still unclear how much energy can be saved when mobile AC systems are operated in different climates and driving patterns. The GREEN-MAC-LCCP tool is modelled to evaluate the life cycle climate performance of mobile AC system, and it is well-accepted. This tool is capable of analysing the full cycle of greenhouse gas emissions (GHG) of alternative refrigerant systems and different system structures. In this article, the energy-saving effect of defaulting to recirculated cabin air is evaluated using GREEN-MAC-LCCP. It is found that 7%-48% of energy saving can be achieved under the calculated climate conditions.