Traditionally, cabin comfort assessment depends heavily on testing physical prototypes. Physical testing is very expensive, time-consuming, and inflexible. Solar radiation is a critical component that can be reproduced only to a limited degree in climatic wind tunnels, and measuring surface and fluid temperatures is not sufficient. Passenger comfort is a complex physiological function of temperature, heat transfer rates, air velocity, clothing, body type, body mass, and other factors. With physical testing, such evaluations are very subjective.