In order to maintain a good quality of daylight and ventilation, school classrooms tend to have large area of windows. Thus, determining how to prevent excess solar heat from penetrating indoors has become the key focus of the regulations regarding the performance of building envelopes in Taiwan. This research conducted a year-long monitoring of the thermal conditions of classrooms with different values of standard energy-conserving measurements. The thermal comfort criterion: ASHRAE standard 55 is applied to perform a comfort analysis on these different classrooms, based on the long-term monitoring data. By examining the hours when the discomfort of overheating or overcooling occurs, this paper discusses the role of the standard energy conserving measures for school buildings in Taiwan to achieve thermal comfort on the part of students.