NEWS ROUNDUP: When Driving at Night, Mind the Thermostat

To determine the ultimate driving environment, WPI researcher Shichao Liu has put drivers to the test in some interesting ways.

Liu, an assistant professor in the Department of Civil, Environmental, and Architectural Engineering, has measured the performance of study participants in a driving simulator while outfitting them in caps to image brain activity and exposing them to varying light levels, heat, cold, and even stinky T-shirts.

Now Liu’s lab has published new research showing that when it comes to driving performance at night, the temperature inside a vehicle matters. Study participants who drove in a simulator were less comfortable, sweatier, and more mentally stressed as temperatures rose. They also used the simulator’s accelerator more and drove in a way that would increase the vehicle’s pitch and roll—meaning there would be more car body movement that could make rides feel rougher.

“As the temperature inside the simulator went up, participants drove less steadily and with more variation in their speed,” Liu says. “This has implications for air conditioning operation in vehicles, vehicle design, and, of course, safety.”

The group’s research, which focused on both temperature and lighting, was published in the journal Building and Environment. In addition to Liu, authors were Chao Wang, PhD ’24, a postdoctoral researcher at Harvard Medical School and McLean Hospital; John Elson, a research engineer at Ford Motor Co.; and Yingzi Lin, a professor at Northeastern University. The research was supported by WPI and Ford’s University Research Program.

Both temperature and lighting play a role in what people experience in vehicles, Liu says, and those experiences have implications for a driver’s ability to safely and effectively manage a vehicle, make decisions, and respond quickly to different scenarios. Concentration, cognitive skills, memory, and reaction times are all impacted by temperature and thermal comfort. Light generally can affect alertness, sleep-wake cycles, and mood.

“When the temperatures are very hot or very cold, drivers can feel uncomfortable and annoyed, which impacts their driving,” Liu says. “In addition, studies have shown that during hot summers, drivers drive more aggressively.”

Thermal comfort and optimal lighting conditions also have implications for how vehicles of the future are designed, according to Liu. Commuters using self-driving cars might need temperatures and lighting that allow them to work while traveling. Electric vehicles may need to be designed with sufficient battery power to provide air conditioning for drivers traveling long distances in hot weather.