抄録
Longer usage of products does not always result in better environmental performance. In the case of products that use energy in their use phase, early replacement of old products with new energy efficient products may contribute to the reduction of CO2 emission. In order to find out optimal circulation period, our previous study formalized optimum circulation period of the products in terms of CO2 emission. It also calculated the optimal circulation periods of air conditioner, refrigerator, CRT TV, and gasoline vehicle, soled in 1991-2000 in Japan. In order to evaluate recent advances in energy-saving products, this paper calculates optimal circulation periods of air conditioner, refrigerator, LCD TV, gasoline vehicle, and hybrid electric vehicle, sold in 2004-2013 in Japan. The comparison clarified energy efficiency increases in all products; especially, in air conditioner and refrigerator, and the optimal circulation periods in air conditioner and refrigerator became longer as a result of saturation in the improvement of energy efficiency. The proposed method succeeded in evaluating the transition from CRT TV to LCD TV and gasoline vehicle to hybrid electric vehicle. Finally, this paper discusses advantages and limitations of the proposed method and potential of application.
