Recently, eco-friendly vehicles such as electric vehicles or hybrid electric vehicles have been brought to public attention. However, the deterioration of energy efficiency when the heater system is operated represents a potential problem for these vehicles. The vehicle cabin environment thus needs to be designed to be comfortable using less heater energy. As a technical solution, a heated seat was focused on. In the present study, the effects of regional heating by a heated seat on thermal sensation were investigated at 15°C. Eight subjects participated in a subjective experiment. The experimental conditions were designed in terms of different heated areas: none (unheated), seat back, buttocks, thigh and seat cushion (buttocks & thigh). Subjects were exposed to each condition for 30 min with an air temperature of 15°C and clo value of 1.0. The heating of a seat cushion was more effective than that of a seat back to improve overall thermal sensation. The main reasons for this were as follows: (1) The area of the seat cushion was larger than that of the seat back. Thus, the power for heating the body was greater with seat cushion heating. (2) Buttocks and thigh sensed warmth with a lower skin temperature than back. The difference of skin temperature between seat back and seat cushion to sense the same thermal sensation was about 1°C. (3) The heating of the seat cushion could increase thermal sensation not only in the heated body part but also in unheated parts such as hand or foot. Conversely, the heating of the seat back increased only the thermal sensation of the back.

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The purpose of this study was to compare the effects of three different intensities (low, medium, high) of two different wavelengths of light (red and blue) on cardiovascular responses by assessing the responses to an auditory task, and to evaluate the possible correlation between the monochromatic light and the personality traits (anxiety) of subjects. The sessions consisted of 5 minutes of baseline, and 10 minutes of s1-s2 reaction time task during exposure to the red or blue light, with 10-minute recovery periods. As for the results, the influence of wavelength of the monochromatic light was observed in the performance of an auditory task, which revealed that the reaction time for the blue was significantly shorter than that for the red. The influence of intensity of monochromatic light was observed in the blood pressure, especially during the recovery periods, which show that while blood pressure increased up to the medium level of light intensity, it decreased at high intensity. In addition, during the task periods, a significant correlation was found only between change score of mean arterial pressure and changes score of cardiac output, which suggests that under the blue light exposure caused a clear cardiac response. Furthermore, our results suggest that trait anxiety may have an impact on blood pressure responses following lower-irradiance short-wavelength light conditions.

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This paper reports our research findings of a joint influence of several environmental factors -sunlight, outdoor view, privacy, and control- on room occupants’ cognitive performance. An experiment with one hundred subjects showed that the amount of daylight and sunlight alone was not evident for subjects’ cognitive performance; instead, multiple environmental factors have significant effects. The combined effect of the above environmental factors at a level of sixty percent was optimal for performance. This finding is in agreement with the optimal arousal theory, which suggests that an optimal level of arousal is at a certain moderate value for most day-to-day activities. It suggests that the commonly believed benefits of daylighting on improving building occupants’ performance may only take effect on condition that the other factors are in an optimal range. This study, for the first time, reveals the importance of non-luminous factors, privacy and control, in daylighting design.

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