In recent years, the adoption of energy-saving measures has been widely promoted in workplaces. Such measures include turning off the lights automatically while workers are absent and introducing office automation equipment with sleep mode. Thus, the absence or presence of workers tends to cause a large variation in the thermal load within an office. In this paper, a workplace is modeled using several combinations of patterns based on the assumption of internal thermal load generation in accordance with workers' absence or presence in order to understand such variations quantitatively. Furthermore, a case study involving the simulation of a general-type single-duct VAV system is conducted to quantitatively understand the influence of internal thermal load variation which is mainly dependent on variations in the presence rate and its effects on the air-conditioning energy consumption and indoor thermal environment.

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We proposed a multi-source multi-use heat pump (MMHP) system that attains a higher coefficient of performance (COP) than conventional air-source heat pumps. Thus far, we have demonstrated the technological development of instantaneous hot water dispenser heat pumps, air-conditioning heat pumps, and solar- and air-source heat pumps suitable for the proposed system. These heat pumps showed high COP when evaluated individually. The energy-saving effects of MMHP as a total system have not been clarified thus far, these effects depend on the design and operation of the system. Therefore, we built a simulation tool and evaluated the annual operating performance of this system by introducing it in a detached house. We found that this system required a borehole length of 200 m and a nominal output of 5 kW with a solar- and air-source heat pump for suitable operation. Under these conditions, for prolonged stabilization of the heat source temperature, the ratio of artificially recovered heat by the solar- and air-source heat pump to naturally recovered heat by the ground source was 44 to 56. This system has been shown to reduce energy consumption by around 15% as compared with conventional systems.

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In recent years, the green movement has been sweeping across our society. Some studies provide evidence on the economic value of the certifying "green buildings". It is difficult to evaluate the economic value of energy-savings investment without risk quantification. An effective method for risk quantification is the Monte Carlo method. This method obtains the distribution of an unknown probabilistic entity with repeated random sampling. In this study, a stochastic weather process model was developed with the intention of applying the Monte Carlo method. The time series of weather factors (dry-bulb temperature, humidity ratio and atmospheric transmissivity) were decomposed into four components (trend component, annual cycle component, circadian cycle component and irregular component). The cloud amount was expressed using a simple Markov chain model. In addition, the model parameters for six major cities in Japan (Tokyo, Osaka, Sapporo, Sendai, Fukuoka and Naha) were estimated using the stochastic weather process model.

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In a convenience store, the odor generated by cooking fryers in a kitchen may leak into the sales area. In summer and winter, the thermal environment in the kitchen is not comfortable because outdoor air is directly introduced for ventilation. In this paper, a method for improving the kitchen environment is proposed and the effectiveness of the proposed method is studied on the basis of CFD simulation and experiments. In the proposed method, the disturbance due to airflow from air conditioners and supply openings of outdoor air is reduced in order to ensure high capture efficiency of the exhaust hood, and the ventilation rate is decreased to reduce energy consumption. The CFD simulation and experimental results show that the capture efficiency of the exhaust hood is improved; therefore, the proposed method provides a better thermal environment and odor concentration than the present HVAC system.

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This study was carried out to experimentally evaluate a heat-pipe built-in outdoor air-conditioning unit that can reheat and dehumidify without using extra energy. The outdoor air was precooled from 30.6 ℃ to 25.8 ℃ by the precooling heat pipe and reheated from 17.8℃ to 22.8℃ by the reheating heat pipe for a given air volume in the air-handling unit. In addition, the heat load of the cooling coil was reduced from around 32% to 22% as compared with the existing air-handling unit. Thus, during summer, the unit was introduced in an actual building, and we performed an evaluation based on the BEMS data. It was confirmed that the heat pipe provided a higher heat recovery ratio than the standard specification and the condition of the reheat and dehumidification cycle was normal.

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