Effect of local exposure on human responses

At room temperatures ranging from 28 to 35 °C, the three sensitive body parts face, chest and back were exposed to local cooling airflow, whose temperatures ranged from 22 to 28 °C. Dressed in shorts, 30 randomly selected male subjects were exposed to each condition for 30 min and reported their local thermal sensations of all body parts, overall thermal sensation and thermal acceptability on voting scales at regular intervals. It was shown that local exposure affected local thermal sensations of the unexposed body parts significantly, based on which a new influencing factor method was proposed. Influencing factor and weighting factor for each body part are unaffected by room or cooling air temperatures under steady state and the predictive model of overall thermal sensation was obtained using influencing and weighting factors. Taking the maximum thermal sensation difference between body parts to represent non-uniformity of thermal sensation, a new assessment model for non-uniform thermal environment was proposed. The model shows that the upper boundary of the acceptable room temperature range can be shifted from 26 to 30.5 °C while face cooling is provided.