Relationships between EEG and thermal comfort of elderly adults in outdoor open spaces

We investigated the relationship between variation in EEG signal characteristics (alpha, beta, theta and delta frequency bands) of elderly adults and their thermal perceptions in outdoor environments in Xi'an, China using meteorological measurement, subjective questionnaire survey and EEG signal monitoring. We found that: 1) the delta, theta and beta relative powers of the frontal lobe were significantly correlated with physiological equivalent temperature (PET), globe temperature (Tg), wind speed (Va), mean radiant temperature (Tmrt) and global radiation (G). The alpha, delta and beta relative powers of parietal lobe were significantly correlated with PET, Tg, air temperature (Ta) and relative humidity (RH). 2) The alpha relative power of the frontal lobe varied with an inverted U-shape with an increase in thermal sensation. The alpha wave of the frontal lobe was the most accurate index to evaluate elderly adults' thermal sensation. 3) The alpha wave of the right cerebral hemisphere can be used to identify elderly adults' thermal comfort, particularly the O2 channel of the occipital lobe. 4) Ta and Va were dominant influences of the EEG among elderly adults. The meteorological factors that affected the EEG changed as thermal stress fluctuated; most meteorological factors were positively related to thermal stress. Our results provide theoretical evidence of the predictive accuracy of outdoor thermal comfort models for elderly adults and contribute to the practical bioclimatic design of outdoor open spaces for vulnerable groups.