- 日本建築学会環境系論文集 (ISSN:13480685)
- vol.83, no.745, pp.225-233, 2018 (Released:2018-03-30)
The Japanese population is ageing, and currently has the world's highest proportion of elderly people. As one consequence, the number of residents in nursing homes is increasing. The Ministry of Health, Labour and Welfare of Japan has identified preventing a need for care as an important aim. The ministry defines “care prevention” in two parts: preventing a care-requiring condition from arising and, when a care-requiring condition already exists, aiming to improve while preventing deterioration. However, mean care level in nursing homes is still increasing, and existing care-prevention strategies are not enough to prevent future increase. A field survey was conducted to clarify the effect of indoor thermal environment on the care-requiring condition of residents in nursing homes. Twenty private residential-nursing homes, located in the Osaka, Kyoto, Nara and Hyogo prefectures of Japan, were included in this study. Room temperature and relative humidity were measured over approximately 4 weeks in private rooms, the dining room and other rooms of each facility at 20-min intervals in winter 2015. Additionally, questionnaire surveys were conducted twice, in winter 2015 and winter 2016. In the questionnaire, care level and date of certification of care needs was investigated for all care certifications in effect after occupancy until the time of the survey. Most facilities had a relatively warm but dry indoor environment. Fifteen facilities were classified into two groups (warm and cold) based on measured room temperature and two groups (moist and dry) based on measured relative humidity. The Kaplan-Meier method was used to analyse the speed of deterioration (i.e., intensification) of required care level. Residents in the dry facility deteriorated with respect to care level more quickly than residents in the moist facility. In contrast, there was no significant difference according to room temperature. Many factors influence care requirements, including not only the indoor thermal environment but also individual attributes, injury and diseases. To assess these influences, multivariate analysis was carried out. Cox proportional hazards regression analysis was used for multivariate analysis to assess the effect of indoor thermal environment on the care-requiring condition of residents in nursing homes. Two questions were evaluated: “Did the care level deteriorate?” and “If so, how long did it take for care level to deteriorate?” The analysis result showed the cold group and the dry group having a higher risk of deterioration of care level. Furthermore, residents in facilities that were both warm and moist had the lowest risk. This result suggests that both temperature and humidity are important for care prevention. The study results are expected to contribute to improvement in indoor thermal environments and to care-prevention among residents of nursing homes.