An Analysis of Energy-Saving Potential of Household Refrigerators Based on a Number Balance Model

Abstract

A mathematical model was developed for estimating the energy-saving potential of household refrigerators in Japan. In the model, refrigerators were categorized into 44 classes by power consumption and volume. Number distribution of the refrigerators in each class used in a given year was estimated by the number balance of refrigerators disposed and produced in the year. The total power consumption was calculated from the distribution. The model well described the past trend of statistical data on the power consumption. Based on the model, the energy-saving potential in the future (up to 2010) was simulated by assuming several types of number distribution of the refrigerators shipped in the future, and the average period of use before disposal. It was found that the power consumption in 2010 could be as small as 73.7% of that in 1997 when the power-consumption efficiency of all the refrigerators produced after 2004 equals to that of the highest model produced in 1999. This assumption corresponds to a situation satisfying the New Energy-Saving Law of Japan (1999). The smaller volume and the shorter period of use before disposal also decreased the total power consumption, but those effects were not so large.