Study on adaptive thermal comfort in Japanese offices under various operation modes

- Japan is yet to have adaptive comfort standards.
- We propose new analytical methods of the adaptive model suitable for Japanese climate.
- The lower and upper limit of the optimum comfort temperature is 23.5 °C and 26.6 °C.
- The optimum comfort temperature tends to increase and decrease at very low and high outdoor air temperatures respectively.
- Clothing and window-opening lead to variation in the comfort temperature.

This research focuses on determining thermal comfort and analysing adaptive opportunities in Japanese office buildings under various operation modes including free running (FR) mode. There are very limited studies on office buildings linking occupant's adaptive actions and various modes of operation, compared to studies on houses and air-conditioned buildings in Japan. Large data on Japanese lifestyle, socio-cultural setup and climate are required in order to construct the adaptive model that can be used for the design of indoor thermal environments of Japanese offices.We conducted questionnaire based field surveys to record thermal comfort responses of occupants and measured environmental variables simultaneously, in all the seasons in Tokyo and Kanagawa, Japan. The comfort temperature is evaluated with SET∗ (Standard effective temperature) in order to incorporate the effect of humidity and air velocity on thermal comfort. Nonlinear regression analysis is used to analyse the lower and upper limit of the optimum comfort temperature. Authors also examine adaptive models that can be used to design indoor thermal environment of Japanese office buildings under different operation modes. The limit of the optimum comfort temperature is shown at very low and high outdoor air temperature. The lower and upper limits of the optimum comfort temperature is approximately 23.5 °C and 26.6 °C in mixed-mode. In addition, it is seen that the optimum comfort temperature tends to increase and decrease at very low and high outdoor air temperatures respectively. We find behavioural adaptation related to clothing and window-opening leading to variation in the comfort temperature across different seasons.