Reducing fuel consumption by air conditioning systems is the focus of Vehicle Ancillary Loads Reduction (VALR) activities at NREL. About 7 billion gallons of fuel—about 5.5% of total national light-duty vehicle fuel use—are used annually just to cool light-duty vehicles in the United States. That's why our VALR team works with industry to help increase fuel economy and reduce tailpipe emissions by reducing the ancillary loads requirements in vehicles while maintaining the thermal comfort of the passengers. Approaches include improved cabin insulation, advanced window systems, advanced cooling and venting systems, and heat generated cooling.
Another focus of the VALR project is ADAM, the ADvanced Automotive Manikin (pictured at right). We use ADAM to assess human thermal comfort in automobiles. ADAM is essentially a human-body-shaped surface sensor that measures heat loss. As ADAM "sweats" and "shivers," corresponding data is delivered to a model that simulates the internal thermal physiological systems of humans and their thermoregulatory responses. This model then returns predicted human skin temperatures to the manikin. Information is also sent to a psychological model that predicts human thermal comfort.
Using a thermal manikin is more efficient than using human test subjects. It enables the repeatable quantification of thermal comfort. This way of predicting human responses can be used in a variety of testing environments including automobiles, aircraft, military vehicles, hazardous materials suits, flight suits, military uniforms using gas masks, and more.
NREL's vehicle ancillary loads reduction research supports many NREL programs and is led by the Center for Transportation Technologies and Systems.