An in-situ study on occupants' behaviors for adaptive thermal comfort in a Japanese HEMS condominium

We conducted a series of survey on occupants' behaviors for adaptive thermal comfort together with indoor air temperature measurement in a condominium equipped with Home Energy Management System (HEMS), from November 2015 to October 2016, in which 17,026 votes were collected. The data was categorized into Free Running (FR), Cooling (CL) and Heating (HT) mode and were analyzed thoroughly. The results showed that the indoor air temperature was highly correlated with outdoor air temperature in FR mode. In CL mode, the mean indoor air temperature was 27.3 °C, which was close to the recommended air temperature for summer in Japan equal to 28 °C. In HT mode it was found that indoor air temperature was maintained around 20 °C. Similar indoor air temperature was also observed in FR mode during winter. The occupants' thermal sensation votes were most likely to be neutral. The mean clothing insulation was 0.43 clo in summer and 0.89 clo in winter. The occupants' behaviors in this condominium for clothing insulation adjustment were found to be quite similar to those in detached houses found in previous studies. The occupants seemed adapting to the indoor thermal environment by window-opening behaviors to adjust thermal comfort during summer. The use of fan was found to increase as the indoor air temperature increased. The occupants were found to take these passive means along with the use of air conditioning unit for cooling. Mechanical heating was used only for a limited period for the condition of outdoor air temperature being low.