Evaluation of domestic washing in Japan using life cycle assessment (LCA)

Abstract

AbstractChanging lifestyles and family structures have changed consumer domestic washing behaviour in our country, with growing use of washer‐dryers and changing detergent preferences, including use of concentrated detergents. In particular, there has also been an increase in the number of combined washer‐dryers, which both save space and reduce the housework burden. However, power consumption for drying is extremely high compared to that for washing. This study reveals the drying performance of sweat‐absorbent, quick‐drying clothing in domestic washing, and uses the life cycle assessment method to evaluate washing and drying with heat‐pump washer‐dryers compared with the conventional washer‐dryer. In this study, it was assumed that drying was used on 99 days per year, based on the mean number of 99 days per year with rainfall in Tokyo. Both types of washer‐dryer showed high CO2eq emission levels for usage, with the highest levels for power consumption during drying. Compared with the conventional washer‐dryer, the heat‐pump washer‐dryer was able to reduce CO2eq emissions significantly through power savings and used less water as well, although it did require the use of larger amounts of detergent. However, the largest portion of CO2eq emissions was attributable to the drying process, and the use of sweat‐absorbent, quick‐drying clothing enabled these emissions to be reduced by approximately 10%. The residual moisture content of clothing after washing and spin‐drying, which significantly affects the amount of CO2eq emissions generated at the drying stage, depended on spin‐drying times and the proportion of polyester fibres in the clothing.