Investigation of drivers' thermal comfort based on selective cooling seats with air conditioner in summer using biosignals and subjective survey

In this study, biosignals (skin temperature, heart rate variability (HRV), and electroencephalogram (EEG)) as objective indices and questionnaires as subjective indices of the subjects were investigated and compared to study the changes in the thermal comfort of drivers during driving by applying various cooling seats with air conditioner (AC) operation. The HRV analysis showed that the stress index (SI) was reduced by up to 8.2 % and 28.6 % for AC with a ventilation seat (AC-VS) and AC with a water cooling seat (AC-WCS), respectively, compared to the AC mode alone. In addition, EEG showed that the attention index (AI) was reduced by up to 4.2 % and 17.9 % for AC-VS and AC-WCS, respectively, compared with the AC mode only. In particular, owing to the direct contact cooling, the AC-WCS showed a greater improvement in thermal sensation vote (TSV) in the early driving state than the other cooling modes, but the driver felt cold, and the thermal comfort vote (TCV) increased. Therefore, using an AC-WCS in the early driving stages of a hot summer significantly contributes to improving thermal comfort. This confirms that reasonable thermal comfort can be maintained using the AC-VS. It was concluded that the appropriate use of the VS and WCS with AC will reduce vehicle cooling load. Proper use of VS and WCS with AC systems in the automobile is expected to lead to reduced vehicle fuel consumption, resulting in energy savings and reduced environmental pollution owing to the optimized operating control of HVAC.