Thermal comfort and energy-saving potential in university classrooms during the heating season

•PMV overestimated the thermal sensation of students.•Students preferred cooler thermal environment.•A higher percentage of students felt local thermal discomfort.•The lower limit for 80% acceptability determined by TAV could be 19 ℃.•If indoor design temperature is 19 ℃, 3.46% of annual heating load can be saved. A classroom thermal environment directly not only influences students’ thermal comfort but also energy-saving. Numerous studies indicate that students’ actual thermal comfort is different from the PMV and adaptive model predictions, and the current thermal comfort standards could not be applicable for the classroom thermal environment design and evaluation. This paper aims to study the university students’ general and local thermal comfort by a field survey conducted in a classroom during the heating season in Taiyuan, China. The results indicated that PMV overestimated the thermal sensation of students. Thermal acceptance vote (TAV) defined the widest acceptable temperature range, and the lower limit for 80% acceptability could be 19 ℃ in Taiyuan. Students preferred a cooler than a neutral environment. The indoor design temperature determined by the heating load duration curve (LDC) was about 21.85 ℃. If the indoor design temperature could decrease from 21.85 ℃ to 19 ℃, 3.46% of the annual heating load could be saved. Moreover, although a majority of students found the environment general thermal acceptable, a higher percentage of students felt local thermal discomfort. Local thermal comfort should be a critical issue for the classrooms’ thermal environment improvement.