Physiological activity in calm thermal indoor environments

Abstract

Indoor environmental comfort has previously been quantified based on the subjective assessment of thermal physical parameters, such as temperature, humidity, and airflow velocity. However, the relationship of these parameters to brain activity remains poorly understood. The objective of this study was to determine the effect of airflow on brain activity using electroencephalograms (EEG) of participants in a living environment under different airflow conditions. Before the recording, the room was set to a standardised air temperature and humidity. During the recording, each participant was required to perform a simple time-perception task that involved pressing buttons after estimating a 10-second interval. Cooling and heating experiments were conducted in summer and winter, respectively. A frequency analysis of the EEGs revealed that gamma and beta activities showed lower amplitudes under conditions without airflow than with airflow, regardless of the season (i.e., cooling or heating). Our results reveal new neurophysiological markers of the response to airflow sensation. Further, based on the literature linking gamma and beta waves to less anxious states in calm environments, we suggest that airflow may alter the feelings of the participants.

Physiological and subjective comfort evaluation under different airflow directions in a cooling environment

“…In the EEG analysis, we focused on beta and gamma frequency bands since our previous study showed a relationship between these bands and airflow sensations [ 17 ]. The amplitudes were analyzed by each session and frequency band.…”

“…Some components of EEG signals are known to reflect mental states directly [ 15 , 16 ]. For example, beta and gamma amplitudes were found to be lower under a no-airflow condition than under a direct-airflow condition in a showhouse [ 17 ]. These amplitudes are useful indicators to evaluate comfort feelings with different airflow directions.…”

“…The physiological responses were measured under two airflow directions: direct and indirect cool air to the face. For EEG analysis, beta and gamma activities were extracted as per our previous report [ 17 ] as responses of the central nervous system. For ECG analysis, HF and LF/HF were calculated as responses of the autonomic nervous system.…”

Study of Human Thermal Comfort for Cyber–Physical Human Centric System in Smart Homes

“…The result of this study suggests that it could be possible to design automatic real-time thermal comfort controllers based on people's HRV. Both research teams from Nkurikiyeyezu et al [10] and Zhu et al [11] have been studied on the Electrocardiogram (ECG) data. The frequency-domain method is adopted to obtain the HRV results and to explore the human thermal comfort under different environments.…”

“…Additionally, the relationships between the LF/HF, the thermal sensation and the thermal comfort are also revealed. Hasan et al [12] propose the sensitivity of the PMV thermal comfort model with relative to its environmental factors and personal parameters using the wearable devices. It is found that the expected error range of PMV is high when the other parameters are ignored, such as clothing and metabolic rate.…”