In recent years, there has been growing interest in extending healthy life expectancy. Even though the thermal environment inside a house has a significant impact on the health and comfort of its occupants, the air conditioning in most houses is controlled to maintain a constant room temperature, and the risk of decline in the adaptive functions of the occupants is not taken into consideration. Therefore, we hypothesized that room temperature fluctuations that provide an appropriate load to the autonomic nervous system, within a range that does not cause discomfort to the user, can be expected to prevent any decline in the user’s adaptive function. In this study, we conducted a subjective experiment to compare and verify the physiological and psychological quantities at different rates of decrease in room temperature, targeting the process of room temperature decrease after a gradual increase in room temperature from a thermally neutral state. The results showed that there were large individual differences in the sensation of heat and cold and in the fluctuation of physiological indices; however, the room temperature at which thermal neutrality was felt was higher when the room temperature descended at a slower rate after the room temperature rose than when the room temperature descended at a faster rate. The room temperature at which the sensation of coolness or coldness began was slightly higher when the room temperature descended more rapidly, although significant differences were not observed. However, it was confirmed that the difference in physiological and psychological quantities due to the difference in the rate of decrease in room temperature after the increase in room temperature was small compared to the difference when the room temperature rose. Next, we analyzed the differences in warming and cooling sensations and physiological responses before and after the increase in room temperature. It was confirmed that regardless of the rate of decrease in room temperature, the room temperature at which thermal neutrality was felt was higher when descending after an increase in room temperature compared to that when ascending. In addition, the physiological indices of the surface of the body changed as the room temperature increased, and in the case of a gradual decrease in room temperature, an increase in deep body temperature was also observed. This experiment showed that a gradual fluctuation of room temperature can increase the receptivity to heat and stimulate both the surface and deep physiological mechanisms of the human body appropriately. In the future, we would like to compare room temperature fluctuation control with conventional steady-state control and verify whether it can stimulate physiological mechanisms without causing discomfort.

In pathology laboratories, it is crucial to prevent exposure to formaldehyde emitted from specimens during dissection tasks. However, adopting partial enclosure fume hoods is often challenging. Several studies have shown that the risk of exposure remains high even when using push-pull ventilation systems or other local exhaust ventilation systems. We developed an airflow control device that forms a U-shaped airflow to eject contaminants and performed CFD analysis to verify the effectiveness of this device in preventing contaminant diffusion when compared to conventional equipment. The results revealed that conventional push-pull ventilation systems with downward airflow could diffuse contaminants if the cutting board covers the exhaust vent. Furthermore, it was confirmed that the device we developed has the same or better efficiency in preventing contaminant diffusion as capturing hoods with the same exhaust volume.

This study developed and validated ZEF (net Zero Energy Factory) as a new energy performance evaluation framework for manufacturing facilities. ZEF overcomes the limitations of conventional ZEB (net Zero Energy Building) by enabling comprehensive evaluations that include air conditioning, ventilation, and lighting in production areas. In a manufacturing facility designed based on this concept, the ZEF baseline value was set at 1,389 MJ/m², approximately 4.4 times higher than the ZEB baseline value of 313 MJ/m². Operational performance data confirmed that the facility achieved Nearly ZEF (BEI=0.06). This study demonstrates the validity of using ZEF as a universal evaluation framework for visualizing total energy consumption and enabling comparisons across manufacturing facilities.