Hisashi Miura

Estimation of Cooling Energy Reduction by Utilizing Cross-Ventilation in Detached Houses, within the Japanese newly introduced Energy Regulation - Evaluating Energy Consumption for Different Uses

Abstract The reduction of carbon dioxide emission due to energy consumption in the household sector is an urgent task, worldwide. As a measure to respond to the task, a new regulation has just been enforced since April 2009, in Japan. This regulation evaluates the energy performance of detached houses by estimating the primary energy consumption for different uses, namely, heating, cooling, ventilation, domestic hot water and lighting. Especially in mild or hot climates, it has been frequently claimed by practitioners that the regulation, which is heavily focused on insulation performance, is not enough and broader aspects should be equally evaluated. The effectiveness of cross ventilation in reducing cooling energy is one of these aspects. However, there have been difficulties to overcome in predicting the effectiveness of cross ventilation on cooling energy reduction. Among such difficulties are the decrease of the discharge coefficient of openings with inclined airflow, variation of the wind pressure coefficient depending on surrounding conditions, etc., occupants’ window opening behaviour and actual energy efficiency of air conditioners depending on their output and outdoor conditions. By referring to the results from experiments and observations on cross ventilation and air conditioners, the authors have proposed a solution for the Japanese new energy regulation on how to predict cooling energy consumption, taking the above factors into consideration. Even though there are still problems to be solved, the solution by the authors, shown in this paper, can be a guidepost to a more reasonable evaluation of the energy performance for cooling in buildings, as well as to a more reasonable design practice for windows and openings on the partition walls.

PERFORMANCE EVALUATION AND METHOD OF PERFORMANCE EVALUATION TO ESTIMATE PRIMARY ENERGY CONSUMPTION ON DOMESTIC OIL-FIRED HEATING BOILER

In order to consider performance and method of performance evaluation to estimate primary energy consumption on domestic oil-fired heating boiler,an experiment on 3 types of combustion(vapourizing,rotary spraying,and pressure spraying combustion),was performed. The following result were obtained:1)The performance evaluation of boiler was found no relationship with using antifreeze,setting water temperature,ambient temperature of boiler,and combustion air temperature. 2)The boiler efficiency for load factor was in the range of 60 to 85%. 3)As a result of experiment,the equation to estimate boiler efficiency for load factor was made out.

DEVELOPMENT OF CALCULATION METHOD FOR ENERGY CONSUMPTIONBASED ON REFRIGERANT TEMPERATURES

An energy calculation model for hot water based heat pump was developed. In this model, the theoretical heat pump cycle efficiency can be calculated based on the condensation refrigerant temperature and the evaporation refrigerant temperature, which can be presumed from the operating condition and the thermal output, and then the actual efficiency of the heat pump under various operating conditions can be calculated by modifying the theoretical heat pump cycle efficiency, considering heat loss form the refrigerant pipes, the degradation of the compressor efficiency, and the auxiliary power consumption. We showed the possibility that the actual efficiency and the power could be calculated when three coefficients in the developed model could be identified appropriately.

Verification of the Effect of Cross-Ventilation on Energy Conservation by Simulating Occupant Behaviour

Abstract Recently, natural ventilation, which is a traditional cooling method in Japan, has become considered as the key method for cooling energy conservation. The results of experiments are presented to measure the indoor thermal environment and cooling power consumption in an experimental dwelling by simulating occupants’ life-style including thermal control with natural ventilation and air conditioning. Based on the experimental results the cooling power consumption from July to September has been estimated. The results show that natural ventilation is an effective technique for saving cooling energy consumption. They also suggest that temperature parameters (the upper limit of room temperature, without using an air conditioner, and the preset temperature of an air conditioner) are very important to estimate the cooling energy saving effect with or without using natural ventilation.