title: Product lifetime, energy efficiency and climate change: A case study of air conditioners in Japan.
abstract: This study proposed a modelling technique for estimating life-cycle CO2 emissions of durable goods by considering changes in product lifetime and energy efficiency. The stock and flow of durable goods was modelled by Weibull lifetime distributions and the trend in annual energy efficiency (i.e., annual electricity consumption) of an "average" durable good was formulated as a reverse logistic curve including a technologically critical value (i.e., limit energy efficiency) with respect to time. I found that when the average product lifetime is reduced, there is a trade-off between the reduction in emissions during product use (use phase), due to the additional purchases of new, more energy-efficient air conditioners, and the increase in emissions arising from the additional production of new air conditioners stimulated by the reduction of the average product lifetime. A scenario analysis focused on residential air conditioners in Japan during 1972-2013 showed that for a reduction of average lifetime of 1 year, if the air conditioner energy efficiency limit can be improved by 1.4% from the estimated current efficiency level, then CO2 emissions can be reduced by approximately the same amount as for an extension of average product lifetime of 1 year.
authors.affiliation: Faculty of Economics, Kyushu University, 6-19-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. Electronic address: nishijindaiko@gmail.com.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nishijima
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control*; D002245:Carbon Dioxide / Q000032:analysis*; D057231:Climate Change; D003247:Conservation of Natural Resources; D004526:Efficiency; D006794:Household Articles; D006801:Humans; D008962:Models, Theoretical
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide
keywords: Life-cycle CO(2); Limit energy efficiency; Product lifetime; Reverse logistic curve; Weibull distribution