Investigation of bio-signal changes of occupants resting in buildings using local cooling and heating seats

The electroencephalogram (EEG), photoplethysmography (PPG), subjective questionnaires, surface temperature, and concentration of subjects for various resting conditions in the building under cooling and heating conditions were investigated to improve their quality of rest and examine the effect of environmental changes on various biosignals comprehensively. As a result, the use of a cold water seat during a rest under cooling condition activated θ wave and α wave in the subjects and decreased low frequency/high frequency (LF/HF) ratio and stress. In addition, the hot water seat used during a rest under heating conditions provided subjects with a stable rest environment because it activated the PPG and θ wave of the subjects and decreased the LF/HF ratio. However, the stress index of the subjects was slightly higher when electric heating and hot water seats were used. The subjective questionnaire showed that the use of an electric heating seat provided subjects with a comfortable environment and high concentration compared to those of other seat types.