On the improvement of thermal comfort of university students by using electrically and chemically heated clothing in a cold classroom environment

This study aimed to examine the effectiveness of two types of heated clothing (i.e., electrically and chemically heated clothing) in improving thermal comfort of university students while sitting in a simulated cold classroom environment. Eight male subjects performed three 90-min trials and three test scenarios were selected: EHC (i.e., electrically heated clothing), CHC (i.e., chemically heated clothing) and CON (i.e., the control, no heating). The trials were conducted in a climate chamber where the air temperature was 8.0 °C, RH = 80% and the air velocity was 0.17 m/s. Significantly higher mean skin (in both EHC and CHC) and body temperatures (in CHC) were found in the heated clothing compared to CON throughout the entire trials (p < 0.05). The whole-, upper- and lower-body thermal (TS) and comfort sensations (CS) were improved in the heated clothing (rated 'Neutral' and 'Comfortable', respectively, throughout the test) than CON (aggravated with time) (p < 0.05). Significantly higher finger temperatures (the 65-90th min, p < 0.05), finger blood flow (the 2-5th min in EHC and the 2-10th min in CHC, p < 0.05) and remarkably improved TSs at the hands and feet were detected in EHC and CHC than CON (p < 0.05). Finger dexterity was improved in CHC at the end of the test than the beginning (p < 0.05). CHC offered more heating benefits than EHC in terms of local skin temperature elevation at the trunk (p < 0.05). In summary, the heated clothing could serve as an effective method to improve both local- and whole-body thermal comfort of university students while sitting in cold classrooms.