Research on the thermal comfort of houses in Japan has developed mainly in some parts of the field of architectural environmental engineering. It is believed to have its roots in the hygienic sciences that sought to improve the poor living conditions of urban residents during the Industrial Revolution in the United Kingdom. In 1964, a part of the architectural planning theory field was renamed to architectural environmental engineering, but the majority of the research conducted was related to environmental physics. In the early days, research on the sensation of temperature and comfort was mainly based on diagrammatic stimulus-response (S-R) research. Later, the research framework was expanded to include the development from human sensation and perception to cognition, multisensory research, occupant behavior, and social psychological aspects.

Historically, Japanese housing has been characterized by low thermal insulation and airtightness, which has led to a warmth-preservation lifestyle for the occupants. The persistence of the idea that “even in the house, it is cold in winter ” has persisted even in recent years. Massabuau, J. P. observed that in regard to Japanese housing, the function of heat and cold protection has been neglected and extreme priority has been given to simplicity and aesthetics. In Japan, there is definitely a tendency to regard a warm environment in winter as a luxury, and this may be a disincentive to promote the insulation and airtightness of houses.

Furthermore, we included discussions on the importance of cultural perspectives in future research in this field.

Installation of air conditioner in school gymnasium is proceeding gradually for avoiding heatstroke and preparing evacuation sites. The measurements of temperature, humidity and CO₂ concentration were conducted in two school gymnasiums with air conditioners in operation for determining condition of air conditioner use. The air conditioners were installed in these two gymnasiums just before starting the measurements in summer of 2019. The measurements continued for two years. One gymnasium was well insulated, and another less insulated. Temperature drop by air conditioner use and degree hours while air conditioner in operation were calculated based on the measured data.

As a result, the following points were obtained.

1) There were some differences in insulation characteristics, air conditioner operation frequency, air conditioner operation time per one operation between two gymnasiums, and those had an influence on the measured room temperature.

2) The thermal performance of the gymnasiums during the air conditioner in operation was estimated by using degree hours during air conditioner in operation (DHAC). It was found that the DHAC per one operation for F school gymnasium which was well insulated, was lower than that of O school.

3) Heatstroke cases that occurred at secondary and high schools located in seven Japanese cities, i.e., Sendai, Tokyo, Nagoya, Osaka, Hiroshima, Fukuoka, and Kumamoto, were linked to the meteorological data point acquired from the nearest meteorological station where the accident of heatstroke occurred. And the relationship between the outdoor temperature and heatstroke occurrence was determined. As a result, heatstroke occurrence estimated by the mean degrees during air conditioner in operation (MD) for F school gymnasium, which was well insulated, was 44 % of that of O school.

The influence of air conditioner installment to gymnasiums on the whole power consumption of the measured schools was not dominant.

We conducted a summertime field survey of the bedroom thermal environments and nocturnal sleep of elderly people living in urban and rural areas of Nara Prefecture in Japan. This study aimed to evaluate bedroom thermal environments and examine the effects on sleep quality. The field survey was conducted for one week from July 2017 to September 2019. A total of 86 elderly people were surveyed (51 in the target urban area and 35 in the target rural area; mean age 74.8 ± 10.3 years). The air temperature and relative humidity in participants’ bedrooms were measured to monitor the thermal environment during participants’ nocturnal sleep. Participants’ body movement during sleep was measured using an activity meter worn around their waists, and sleep parameters such as time in bed and sleep efficiency were calculated. Participants rated their sleep quality using a subjective sleep evaluation (OSA sleep inventory MA version), thermal sensation, and thermal comfort after waking up. In addition, participants answered questionnaires on their housing and the use of cooling devices in their bedrooms. Over 60% of participants in the urban area often used air conditioners; in the rural area, they used electric fans and opened windows for ventilation rather than air conditioners to keep cool. Outdoor and bedroom temperatures during the night were higher in the urban than in the rural area. The rate of air conditioner use increased as the outside nighttime temperature increased, suggesting that differences in outdoor temperature influence regional differences in air conditioner use. Most air conditioner users applied timers or turned the system on and off at night, with less than 10% keeping the air conditioner on throughout the night. The mean bedroom temperature during sleep was 28.0°C ± 1.2°C in the urban area and 25.6°C ± 1.4°C in the rural area. We compared the recorded bedroom temperatures to the recommended standard summer bedroom temperature for elderly people (temperature: 23-27°C, relative humidity: 60-80%) and found that 19% of the urban and 68% of the rural area were within standard ranges. Most participants in both urban and rural areas rated their bedroom thermal environments as neutral to cool and comfortable. As bedroom temperatures increased, the wake after sleep onset tended to increase. In addition, the time in bed increased as the wake after sleep onset increased, suggesting that the increase in time in bed prevented the decrease in sleep efficiency. These show that a high-temperature environment affects sleep quality in elderly people. Therefore, it is essential to use air conditioners and adjust bedroom thermal environments appropriately to maintain sleep quality during summer.