Indoor temperature in Japan and high-risk residents
HEAT, COLD, STRETCHES
Japan stretches across several climate zones from north to south. The climate is mostly temperate, but becomes subarctic mainly in Hokkaido. According to data from the Ministry of Land, Infrastructure, Transport and Tourism, 30% of the ~50 million houses in Japan are without insulation, and in 2018, only 11% were sufficiently insulated to meet the country’s highest thermal insulation standards [We reported the actual status of houses throughout Japan before insulation retrofitting [Average living room temperature at home in each prefecture from ref. [We also examined characteristics common to residents of cold houses. Lower household income was a risk factor for living in cold houses, likely because it may force residents to use heating sparingly or to live in houses with poor insulation. Single-person household was also a risk factor. Furthermore, lower room temperature was associated with the use of a kotatsu (traditional Japanese heating device which does not heat an entire room) and wearing of multiple layers of clothes. These results will aid in identifying “high-risk” residents in greater need of active housing intervention.Separately to our study, Saeki et al. reported that mean living room/bedroom temperature was 16.1/12.6 °C in the cold season (October–April) in the Kansai region [