As s tudents spend one-third of their time at school, their health, comfort, and productivity are mos tly influenced by thermal condition and indoor air quality of classrooms. Regarding that manual window-opening is a common way for providing fresh air in classes and s tudents aren't allowed to change their uniform, position or control the windows during the lesson hours, providing thermal comfort in winters may cause a lack of fresh air and therefore, dissatisfaction. This article is trying to evaluate the indoor air quality, and thermal condition of the classrooms, in two typical classrooms for 15-16-year-old girls in Arak, Iran. The overall s tudy objective is to compare indoor microclimate measured parameters, with (1) s tudents' subjective judgment, collected through a ques tionnaire, and (2) s tandards and to inves tigate the effects of microclimate on the indoor environmental condition of classrooms. According to the results, the thermal sensation of the students depends on their clothing rate and their understanding of the thermal state. In contrast, their thermal satisfaction is affected by the amount of fresh air provided. In winter, because of closed windows, students are mostly dissatisfied with the air quality and, therefore, thermal comfort, while in spring that the indoor environmental conditions meet the standards; the students feel satisfied with the conditions. The results of this research show that the indoor environment of the classrooms is mainly influenced by internal loads; consequently, its thermal condition is not a defining parameter.
