Measuring human physiological indices for thermal comfort assessment through wearable devices: A review

Thermal comfort is defined as the condition of mind that expresses satisfaction with the thermal environment and it is assessed by subjective evaluation. Achieving comfortable environments is essential for human health, productivity, learning performance and energy efficiency. The measurement of thermal comfort requires an indirect process involving several domains: thermal environment, physiology and psychology. Four physiological signals were reviewed, considering their relevance in the context of measuring indoor thermal comfort. The measurement approaches for investigating electroencephalography, electrocardiograph, skin temperature and galvanic skin response signals in the field of thermal comfort are presented. This paper introduces an overview on the application of wearable sensors for recording physiological parameters and extracting features potentially correlated with thermal comfort, together with a discussion about their reliability. The review shows the state of the art, the identification of existing knowledge gaps in this area and the corresponding needs for future research and dedicated methodological efforts.