Bedroom thermal environment in Nagoya, Japan

OBJECTIVES: The objective of this study was to estimate the indoor thermal environment and the air-conditioning pattern in bedrooms during sleeping time, and to evaluate the relationship between the indoor thermal environment and the dwelling characteristics in Nagoya, Japan. METHODS: Temperature, relative humidity and information on dwelling characteristics were obtained from 84 dwellings in summer and 100 dwellings in winter from 1995 to 2001. RESULTS: The mean percentage of bedrooms air-conditioned during sleeping time was 23% when cooled in summer and 7% when heated in winter. The mean temperature and relative humidity in bedrooms during sleeping time was 27.7 degrees C and 62% in summer, and 13.1 degrees C and 61% in winter, respectively. The temperatures in bedrooms during sleeping time were found to comply with the recommended values for an indoor thermal environment (24-28 degrees C in summer and 15-21 degrees C in winter) in 39% of the dwellings in summer and 24% of them in winter. The mean temperature in bedrooms during sleeping time was significantly higher in apartments than in separate houses (p < 0.01) in winter, although there was no significant difference of mean temperature between apartments and houses in summer. There was no significant difference in mean relative humidity between apartments and houses in both summer and winter. CONCLUSION: Although the mean temperature in bedrooms during sleeping time varied widely depending on the type of dwelling, there also appeared to be differences between apartments and houses with respect to the temperature in bedrooms during sleeping time in winter.