The Carbon Footprint of Clothing Considering the Relationship Between Clothing Layering and Heating Usage

Approximately 20% of CO2 emissions from Japanese households are attributed to heating usage. Consequently, as part of its climate change policy, the Ministry of the Environment has promoted the “WARM BIZ” campaign, which encourages setting room temperatures to about 20 °C during heating, through practices such as layering clothing. However, according to the Life Cycle Assessment (LCA) of clothing, the environmental impacts of clothing production, washing, and drying are significant. Therefore, it is essential to evaluate heating usage within the clothing lifecycle to assess the greenhouse gas (GHG) emission reduction effect of practicing WARM BIZ. In this study, we calculated the household heating energy consumption in four regions of Japan, and, by incorporating these data, estimated the GHG emissions over the clothing’s lifecycle, from production and use to disposal. The results showed that those practicing WARM BIZ had approximately 9 to 26% lower GHG emissions over the entire lifecycle than those who were not. Furthermore, by using the Predicted Mean Vote (PMV) index, it was shown that by adding a light long-sleeved shirt (0.18 clo), light long pants (0.18 clo), and a cardigan (0.37 clo) to the standard clothing scenario, the room temperature could be set 3.1 °C lower than the current setting, potentially reducing GHG emissions over the entire lifecycle by approximately 18%.