Aquifer thermal storage systems utilize groundwater, and thus, it is necessary to balance the heat and material in the ground within one year from the perspective of environment and long-term operation. In this study, two methods of free cooling or cold storage using a turbo heat pump were considered as countermeasures against the heating and cooling imbalance of heat load in warm regions of Japan. The system coefficient of performance (SCOP) was compared under the meteorological conditions of Osaka. According to the results of numerical simulations, the turbo heat pump model could reproduce the performance accurately in proportion to cold water temperature, cooling water temperature, load factor, and inverter frequency as a result of preparing its characteristic equation in proportion to the actual machine. The simulations clarified that the free cooling cold storage system had a high SCOP in the region where the wet bulb temperature was 13°C or lower.

This study investigated the effect of cold stimulus using a personal air supply device on cognitive task performance and physiological and subjective responses. Eighteen healthy adult participants performed a cognitive task in a sitting position for 90 min in a private work booth (approximately 26°C). Each participant was subjected to two experimental conditions, with or without an airflow (approximately 22°C) supplied from a personal air supply device, on separate days. The participants were asked to change the airflow direction as they preferred every 5 min. During the experiment, the heart rate and skin temperature were measured. Additionally, thermal sensation and comfort, subjective fatigue, and blood pressure were assessed three times during the protocol. The result showed that, in the airflow condition, the mean skin temperature and dorsal hand temperature decreased, and the back-dorsal hand skin temperature gradient increased. Moreover, the task performance was higher in the airflow condition than in the no airflow condition. The preferred airflow direction was toward the face, followed by that toward the hands. It was observed that the higher the usage rate of air supply toward the hands was, the more the sympathetic nerves were activated, as indicated by the heart rate variability. These results suggested that a mild cold stimulus induced by airflow could enhance peripheral vasoconstriction and sympathetic nerve activity. Therefore, the use of a personal air supply system in a private work booth is expected to maintain arousal level and improve working performance.

In this study, low-cost Ni–carbon nano-onion (CNO) catalytic electrodes were applied to a proton exchange membrane (PEM) electrolyzer. Fullerene in the electrodes prevented the degradation of Ni, allowing for a significant cost reduction compared to Pt–Ru/C catalysts. To develop a membrane electrolyte assembly (MEA) using Ni–CNO electrodes, we introduced an orthogonal array and investigated the influence of process parameters examined in our previous study. It is known that the conversion efficiency of a conventional PEM electrolyzer decreases due to the effect of variable renewable energy (VRE). The energy conversion efficiency of the Ni–CNO electrode was investigated experimentally with the Pt electrode, and the results showed that a PEM electrolyzer with a Ni–CNO catalytic electrode is an economically viable alternative for water electrolysis applications.　

In this study, an optimum control was developed system for an air-conditioning system with multiple variable refrigerant flow (VRF) air-conditioning systems in a single room to minimize the energy consumption of the complete air-conditioning system. The developed control system was installed in an actual building to verify the control system and the indoor environment. It was confirmed that the control system reproduced the ideal control well and that the indoor dry temperature and relative humidity were within 23~26°C and 50~70%, respectively. Furthermore, the total system COP of the multiple VRF air-conditioning system with the optimum control system was improved by 13% and 3% compared to the total system COP of the VRF air-conditioning system without the optimum control system and with the optimum control system for a single VRF air-conditioning system, respectively. The results confirmed that the optimum control system improved the total system COP.　

When establishing countermeasures against viral infections using unidirectional airflow, if the field of the unidirectional airflow cannot be maintained due to disturbances caused by human movement, the ability to prevent viral spread and transport may be reduced. It is very important to construct an appropriate indoor environment when developing such countermeasures after verifying it in advance by an actual flow evaluation. In this study, we measured the time variation of the unidirectional airflow formed between partitioned air purifiers in terms of air velocity in three axial directions against a disturbance simulating the case in which the direction of human movement is parallel to the unidirectional airflow. As a result, it was confirmed that there were significant differences in the air velocity of the unidirectional airflow depending on the air flowrate setting of the air purifier, the distance between the air purifiers, and the setting of the direction of movement of the test plate. In particular, the vertical air velocity component was found to be more robust against disturbances caused by human movement than other air velocity components.

A simulation was performed to investigate the reduction in residual chlorine concentration in rainwater considering the piping of water supply of an existing building as the model. This model was also applied to reused wastewater. On-site maintenance is performed so that the residual chlorine concentration at the terminal hydrant is 0.1mg/L or higher. Maintenance is said to be carried out so that the concentration of chlorine in wastewater is approximately 15mg/L and that in rainwater is approximately 2mg/L. Therefore, this study examines whether the residual chlorine concentration after adding chlorine is appropriate and elaborates on how disinfection should be managed.

In Japan, the mass concentration of suspended particulate matter (SPM) in rooms must be maintained under 0.15mg/m³ according to the Building Sanitary Law. On the other hand, the average SPM mass concentration of buildings in Tokyo city is approximately 0.008~0.012mg/m³, which is considerably lower than the value accepted by this law. In general, temporal inspection is carried out for a duration of approximately 5 min., and if the average concentration is less than the regulated value, the room is judged as sufficiently clean. However, a period of 5 min is not enough to obtain a statistical sample, and a judgement based on this measurement has no statistical meaning. In this study, the distribution of the SPM mass concentration was investigated though an actual survey, and a statistical temporary distribution model was suggested. Based on the results of this survey, a model to judge the SPM concentration was suggested by using the sequential sampling method. Moreover, the proposed model was verified using Monte-Carlo simulations. The results are as follows; 1) Poisson distribution was developed with the trends in the temporal SPM concentration fluctuation, 2) An SPM concentration judgement model was developed by using the sequential sampling method, 3) The significance of this model was confirmed using Monte-Carlo simulations, 4) According to this model, the concentration of SPM in ordinary rooms can be judged to be acceptable or not according to the regulation in a few minutes.

The energy-saving performance of a highly insulated house was evaluated based on the difference in temperature settings for crawl space heating with a single air conditioner. This heating system does not use dedicated ducts or fans for transporting warm air indoors. Air conveyance from under the floor to indoors is realized using ventilation fans. The temperature of the air conditioner was set to 22°C and 25°C, and the comparison results showed a 0.3°C difference in the room temperature of the living room. Also, comparing the difference between the living room temperature and the outside temperature was 0.7°C. The air conditioner power consumption differed by approximately 30% under the two settings, despite the fact that the average temperature difference was almost negligible. The conditions for indoor heat generation and heat gain by solar radiation were not significantly different between the two, and the difference was mainly due to the state of heat loss from the foundation slab under the floor. The following findings were noted. When the temperature setting of the air conditioner is lowered, heating stops even though the air conditioner is running, and the system enters a low-power consumption mode. Despite not being heated, the room temperature drops very slowly. For example, from 1:20 p.m. on February 8 to 0:20a.m. on February 9, the underfloor northeast corner air temperature decreased by 3.2°C, while the room temperature in the living room decreased by 1.3°C and the room temperature in 2F Room B increased by 0.5°C. The thermal image at this time showed that the wall and floor surface temperatures were the same or higher than the room temperature. In addition, it was confirmed that under the floor, the temperature drop was suppressed by the effect of heat stored in the foundation slab. When the air conditioner was operated at a high temperature setting, the heating ran continuously due to insufficient capacity. In this case heat continued to flow out of the foundation slab, resulting in higher power consumption. This indicates that heat loss from the foundation slab should be considered in heating load design and that moderate intermittent heating is necessary to achieve the energy-saving effect of heat storage.

In recent years, extreme weather events and large-scale disasters have occurred frequently, and gymnasiums are being increasingly used as evacuation centers. In addition, the increasing risk of heat stroke due to rising summer temperatures has made it necessary to improve the thermal environment of gymnasiums. When introducing air conditioning to a gymnasium, it is necessary to consider both the comfort and the effects of air conditioning on sports competitions from the perspectives of an evacuation center and a sports facility. On the other hand, given that an independent radiant cooling system does not generate airflow, it provides a high level of comfort and its effects on sports competitions are negligible. Therefore, this system is considered suitable for gymnasium air conditioning, and the number of its installations is increasing. This study aimed to understand the basic performance of an independent radiant cooling system in large spaces. We conducted measurements in a real facility with a large space where this system was introduced to evaluate the indoor thermal environment and cooling capacity in actual operation. As a result, it was confirmed that independent radiant cooling quickly lowers the room temperature and MRT in the occupied area and dehumidifies only the bottom layer locally in a large space, suggesting that it is suitable for cooling large spaces. In this measurement, the average percentage of latent heat removal to total cooling capacity was 11.3% for Panel A and 16.3% for Panel B. Additionally, the cooling capacity in actual operation was approximately 16% lower on average than that in the laboratory, which suggests the need for appropriate consideration of capacity reduction in actual operation during design. Note that this measurement is just one example of the evaluation of cooling capacity in actual operation. In future research, the effects of latent heat removal and cooling capacity reduction in actual operation should be studied based on other examples.

In the first part of this paper, we summarize the issues involved in the practical application of a thermal controllable chair and describe the process of solving these issues. The performance requirements for the fixture were seating comfort, usability, safety, durability, manufacturability, and maintainability. We aimed to address each of these needs by matching the function of thermal control and the performance as a fixture with fixture manufacturers. Finally, a practical specification was developed. In the latter part of this paper, we present the implementation of a variable airflow function in thermal controllable chairs. The 1/f fluctuation was theoretically generated and implemented in a practical machine. The trial evaluation indicated a favorable evaluation. However we found some problems with sound were noted.