Observations of upper-extremity skin temperature and corresponding overall-body thermal sensations and comfort

This paper explores how upper extremity skin temperatures correlate with overall-body thermal sensation and comfort. The study’s motivation was that skin temperature measurements of the finger, hand, and forearm might be useful in monitoring and predicting people’s thermal state. Subjects in a range of test chamber temperatures had their subjective perceptions of overall thermal sensation and comfort collected by repeated surveys. A positive temperature gradient (finger warmer than the forearm) of as much as 2 K was seen when subjects felt warm and hot, while a negative temperature gradient (finger colder than the forearm) as much as 8.5 K was seen for cool and cold subjects. A useful warm/cold boundary was found at a finger temperature of 30°C, for both steady state and transient conditions. When finger temperature was above 30°C, or finger-forearm skin temperature gradient was above 0 K, there was no cool discomfort. When finger temperature was below 30°C, or the finger-forearm skin temperature gradient was less than 0 K, cool discomfort was a possibility. Finger temperature and finger-forearm temperature gradient are very similar in their correlation to overall sensation. We also examine how overall sensation is affected by actively manipulating the hand’s temperature