Differences between EEG during thermal discomfort and thermal displeasure

This study used electroencephalograms (EEGs) to investigate thermal discomfort. The thermal discomfort defined in this study considers both thermal displeasure induced by step-changes and thermal discomfort induced by temperature ramping. A total of 108 people in their 20s and 30s participated in the experiments. The subjects experienced uncomfortable thermal environmental changes and changes in EEG were measured accordingly. The EEG data were divided into four frequency bands, namely; theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and gamma (30-40 Hz) waves for analysis. By examining the thermal-displeasure EEGs, we observed that when thermal displeasure was induced by heat, the relative theta power decreased and the relative beta and gamma powers increase. Furthermore, the relative theta power decreased when thermal displeasure was induced by cold. By examining the thermal-discomfort EEGs, we observed that all the EEG power values increase when thermal discomfort results from either heat or cold. Based on these experimental results, the brainwaves can be utilized to increase the prediction accuracy of individual thermal comfort by the conventional comfort model that is based on physical quantities, such as, temperature, humidity, air velocity, metabolic rate, and clothing insulation.