LAUSR

Abstract The aim of this study was to understand occupant thermal comfort and air-conditioning (AC) usage behavior in mixed-mode dwellings in China. Longitudinal field measurements were conducted in 43 homes in Tianjin during the warm half of the year, May through November 2016. Room air temperatures and AC on/off events were recorded continuously using autonomous data-logging devices (iButtons). Occupants’ “right-here-right-now” thermal responses were collected through an online questionnaire delivered intermittently to their smartphones throughout the survey period. A total of 4157 AC events and 1697 online questionnaires were collected and then matched against concurrent indoor and outdoor temperatures. Results indicate that thermal sensations of the Tianjin residents were less sensitive to variations of the room temperature, compared to findings from previous studies conducted in offices. The indoor temperature limits corresponding to 80% thermal acceptability for our Tianjin residential sample were estimated to be 21.0 °C (the lower limit) and 27.3 °C (the upper limit). Average “trigger temperature” for AC cooling in summer was 27.6 °C resulting in a cooling of the room by 4.1 °C on average, and the average trigger temperature for AC heating in winter was 18.6 °C heating the room by 6.6 °C. Our analysis also indicated that the householder's education level and household income were associated with their AC usage decisions.