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Delphi Harrison Thermal System's comfort model can be used to predict the local thermal comfort level of an occupant in the highly non-uniform thermal environment of a vehicle cabin. This model is based on the concept of Equivalent Homogeneous Temperature (EHT) to assess the local comfort of 16 body segments as a function of air temperature, surrounding surface temperatures, air velocity, humidity, direct solar flux, as well as the level of activity and clothing type of each individual. Although EHT has been accepted by some European automotive industries, OEMs in North America have their own comfort scales. In the present study, we developed a model to correlate our EHT scale to an OEM's comfort scale. The current comfort model based on EHT produced excellent agreements with human subject data based on an OEM's comfort scale for both summer and winter rides.

An ultrasonic air temperature sensor, intended to help improve automatic climate control (ACC), has been demonstrated in a vehicle. Ideally, ACC should be based on inputs correlated with thermal comfort. Current ACC systems do not measure the air temperature best correlated to thermal comfort - at breath level in front of an occupant. This limits the thermal comfort that ACC can provide under transient conditions. An ultrasonic sensor measures the bulk air temperature, is transparent to the driver, and can use commercially available components. In a proof-of-concept test, we monitored the thermal transients in a vehicle during cool-down after a hot soak and also during warm-up after a cold soak. The ultrasonic path was along the roof console. The ultrasonic temperature always agreed to ±1 °C with the air temperature measured by a thermocouple at the midpoint of the ultrasonic path.