Introduction: In recent times, instances of heat disorders in elderly people in residential buildings have been increasing in Japan. Heat disorders are serious illnesses that are potentially fatal, and thus, their prevention is urgent and important. Consequently, we have investigated the thermal environment in the residences of elderly people during summer. Instances of heat disorders have been found to occur in bedrooms, living rooms, and kitchens (Shibata et al., 2010). However, details of the thermal environment in these spaces remain unknown. To prevent heat disorders, residents need to be aware of their exact indoor thermal environment.

The purpose of this study is to make residents aware of their actual indoor thermal environment during summer in order for them to adjust their environment appropriately. This study is motivated by the urgent need to prevent heat disorders, particularly among the elderly.

Method: We measured the temperature and relative humidity in five rooms in each of 53 residential buildings. Temperature/humidity loggers were installed in the living rooms, bedrooms, kitchens, toilets, and dressing rooms. We simultaneously surveyed 75 residents of Kyoto about the methods they use to control their thermal environment in summer. We also surveyed the residents to determine whether they were aware of the exact indoor temperature. In order to determine the imagined temperature, we asked the following question: ‘Please imagine the temperature of the living room during day, and of the bedroom during night, during the midsummer.

Result and Discussions: The survey periods were from August 1 to August 14, 2011 and from August 2 to August 15, 2012. Our results show that the average temperature during the survey periods was high and uncomfortable, producing a risk of heat disorders. Both, during the day and during the evening, indoor temperatures reached dangerous levels. The residents might have heat disorders.Therefore, for many respondents, the average temperature became high and uncomfortable, producing heat disorder risk.Room spaces were reported to be unbearably hot in midsummer.n the survey, the ratio of respondents who answered ‘the bedrooms are too hot and unbearable’, ‘the kitchens are too hot and unbearable’, ‘the toilets are too hot and unbearable’, and ‘the living rooms are too hot and unbearable’ were 48.0%, 36.0%, 28.0%, and 25.3%, respectively. The imagined temperatures for living rooms and bedrooms were not accurate. The correlation coefficient of the imagined temperature and the actual measurement value in the living room and the bedroom were R2 = 0.0139 and R2 = 0.0711, respectively. It is important for a resident to imagine the ambient air temperature accurately. On a daily basis, 64% of the respondents reduced their use of air conditioners to save energy, while 74.7% continued to use electric fans. The response rate of respondents who used both air-conditioners and electric fans was 48.0%. In order to improve the thermal environment, residents need to be aware of their exact indoor thermal environment. Moreover residents must have reliable knowledge about the temperature which they can take to protect themselves. This study may be useful in preventing heat disorders.