In modern society, because people spend more than 90% of their time indoors, the indoor air quality (IAQ) of the building greatly influences the quality of life. In recent years, photocatalytic oxidation (PCO) processes have attracted attention. The PCO processes are effective for purification of indoor air polluted with volatile organic compounds (VOCs), especially at their low concentration levels. In the previous reported papers (Part 1 and Part 2), kinetic studies were carried out on the photocatalytic oxidation of toluene in the gas phase over photocatalyst-bound building material with a small 20L test chamber, and computational fluid dynamics (CFD) simulations were also carried out on the same boundary conditions that were used in the experiments. In this study of the series, building materials in the form of ceramic tiles with bound TiO₂ as photocatalysts were prepared with the thermal spraying technique without using any binder and used as photocatalytic building materials. The kinetic equation for toluene photooxidation over TiO₂-coated building material can be expressed by the Langmuir-Hinshelwood-type kinetics. The kinetic parameters for the surface reaction were first determined by using experimental results and then optimized by using the corresponding CFD simulations for considering nonuniform distributions of toluene on photocatalyst-bound building materials. These kinetic parameters were identified as a function of the illumination intensity. In this paper (Part 3), a CFD-based numerical simulation method integrated with a Langmuir-Hinshelwood-type model was applied to the analysis of toluene concentration distributions in a real-scale room model. The toluene concentration reduction performance of the PCO process was parametrically analyzed as a function of the layout of the TiO₂-coated building material. Further, a large-scale test chamber experiment was also carried out to examine the toluene concentration reduction performance. On the basis of a comparison between the experimental and numerical simulation results, essential parameters to improve the prediction accuracy of CFD-based toluene concentration distribution analysis were discussed.

Recently it has become important to study net-zero energy buildings and load leveling of buildings to limit the power demand. In this study, it is intended to clarify efficient equipment operation methods such as PV and storage batteries for energy saving and load leveling. First, we constructed an energy network system utilizing PV and storage batteries in the building. The measured results showed that 44% of the electric power for a HVAC system is supplied by the PV and storage batteries. Second, the results using simulation demonstrate that load leveling and energy savings have been achieved by the new control for batteries which is combined with the commercial power supply minimization mode and peak shaving mode. In addition, this battery control is very effective for low-rise commercial buildings aiming at becoming zero energy buildings.

This paper constitutes Part 1 in a series of studies on preheating hot water supply systems using a palisaded heat exchanger combined with plastic pipes and hot spring water. The palisaded heat exchanger was newly developed, and the initial plan was for it to utilize hot springs as a sustainable source of energy and solve the corrosion or clogging problem in metal plate heat exchangers. The exchanger consists of two units that sandwich each other alternately. The units consist of eight or nine panels connected by horizontal pipes. The panels are formed by thermal fusion bonding between 40 narrow longitudinal pipes and upper and lower horizontal header pipes with bored holes. Heat exchange is initiated by soaking the exchanger in a tank with hot spring water or waste hot water. The width, height, and depth of the prototype exchanger are 893, 1023, and 560 mm, respectively. The overall heat transmission coefficient of the exchanger is 65-73 W/(m²·K). Though this value is less than that of the metal plate or tube-type heat exchanger, the exchanger appears to work well when heat recovery from the following types of springs is carried out: springs that corrode metal because of the low pH value and springs with plenty of suspended solids, such as waste hot water from the spa facilities.

Many studies on peak cut of the electricity demand or energy saving in buildings have been conducted up to now. However, in tenant buildings, where was different from the owned building, the action of peak cut or the energy saving achieved by collaboration between the owner and tenant was not sufficient. In this study, we performed the verification examination of the peak cut for many tenant buildings in the summer and the winter season. In summer, we performed the peak cut with an appeal to the tenants and examined the demand control and the schedule control. In addition, we controlled the heating start time in winter and examined the results of "preheating", in which air conditioners were operated early. As a result, it became clear from the examination in the summer what could control demand by direct control surely, that room for examination stayed, on the other hand, to start a demand suppressant effect only by indirect control. In addition, from the winter examination, we learned that we could control demand by preheating, but it became clear to judge the adoption or rejection of a reduction effect of the demand restraint and the in total pre-heat because electric energy increased.

This study describes a ventilator used for an IH cooking heater installed in the kitchen of a house. The ventilator was developed by utilizing the characteristic of the IH cooking heater. Because the IH cooking heater is not treated as a fire equipment, the standoff distance to the circumference is not limited. Therefore, it is possible to install the ventilator near the heat source equipment vicinity. In this report, the location change effect and the reduction effect of the ventilating volume of the ventilator were examined. In addition, the effect of providing air supply and exhaust through the same ventilator was also examined. The summary of the findings is as follows: (1) The Ventilator exhibited similar exhaust ability when the location was moved from the upper area to the back. (2) The Back ventilator has the same ventilation performance as the upper ventilator in reducing the ventilatory volume from the upper ventilator. (3) The ventilatory volume reduction rate of the back ventilator becomes 56% of the upper ventilator. (4) Air supply from the ventilator main body does not affect the ventilation performance of the back ventilator. (5) When air supply and exhaust are carried out, the ventilatory volume reduction rate of the back ventilator becomes 84% of upper ventilator. (6) The Back ventilator reduced the air volume flowing opening in comparison with the upper ventilator from 16% to 86%, when air was supplied from the main body of the back ventilator.