Predicting thermal sensation through local body skin temperatures to assess thermal comfort: a short systematic review

Introduction: The skin plays a substantive role in the thermoregulatory process. The maintenance of a constant internal body temperature by the thermoregulatory system, partially achieved by vasoconstriction and vasodilation, makes the skin temperature an important mechanism to indicate the thermal state of the comfort of a given subject. However, this parameter is still little considered in studies that evaluate thermal comfort. Therefore, this work aims to investigate the use of skin temperatures as a predictor of thermal sensation to assess thermal comfort. Methodology: A short systematic review based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was performed to assess scientific publications that evaluated thermal comfort considering the skin temperature as a predictor. The review search strategy considered the use of "thermal comfort" and "skin temperature" as keywords in the ‘Web of Science’, ‘Scopus’, ‘PubMed’, and ‘Academic Search Ultimate’, ‘Taylor and Francis’ and ‘Sage Journals’ databases. Eligibility criteria considered articles that conducted experiments under steady-state environmental conditions and that considered skin temperature measurements in the assessment of thermal comfort. Results and Discussion: The search resulted in the identification of 73 articles, from which five were considered suitable for the systematic review. Skin temperatures were measured at a variety of measurement points throughout the reviewed articles. Overall, the mean skin temperature of female subjects was lower than the mean skin temperature of male subjects at each experimental temperature, at the same level of thermal comfort. Forehead, chest and abdomen were evidenced as the best measuring points and presented the highest correlation between thermal sensation and skin temperature. Conclusion: The systematic review has shown that the comparison between the selected articles is hampered by the lack of uniformity in the adopted experimental procedures. There seems to be a relationship between thermal sensation and skin temperature responses. Future studies should consider more uniform experimental procedures. Besides, there is the need of increasing the size of the experimental sample and to consider different target groups (such as children or the elderly) to verify if the prediction of thermal comfort based on skin temperature exhibits the same trends when compared to healthy adults.