Evaluation of Advanced Automotive Seats to Improve Thermal Comfort and Fuel Economy

Automotive ancillary loads have a significant impact on the fuel economy of both conventional and advanced vehicles. Improving the delivery methods for conditioned air is an effective way to increase thermal comfort at little energy cost, resulting in reduced air-conditioning needs and fuel use. Automotive seats are well suited for effective delivery of conditioned air due to their large contact area with and close proximity to the occupants. Normally a seat acts as a thermal insulator, increasing skin temperatures and reducing evaporative cooling of sweat. Ventilating a seat has low energy costs and eliminates this insulating effect while increasing evaporative cooling. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has applied a combination of experimental testing and modeling to quantify improved thermal comfort and potential fuel savings by using a ventilated seat. The thermal comfort improvement can be used to reduce the A/C heat capacity by 4%, resulting in a predicted A/C fuel use reduction of 2.8% on an EPA highway cycle and 4.5% on an EPA city cycle. This is a 0.3%-0.5% reduction in total vehicle fuel use when the A/C system is on; while modest for an individual car, the potential fuel savings is significant on a national level.