Thermal comfort in indoor environments has a significant effect on user's health and wellbeing. Its effect becomes crucial especially in classrooms since it affects students' performance with respect to attention, comprehension and learning levels. This study assesses thermal comfort conditions via field measurements and subjective surveys. A university building, which is located in the Mediterranean climatic region of Turkey, was selected as a test site and the study was performed for ten days in the heating season. Indoor air temperature, mean radiant temperature, relative humidity and air velocity were monitored to obtain the Predicted Mean Vote (PMV) whereas a total of 235 subjective surveys were conducted to obtain the Actual Mean Vote (AMV). The comparison of PMV and AMV as well as the robustness of the relationship between PMV and AMV were analyzed via the t-test and Pearson correlation coefficient, respectively. In addition, the effect of users' relative humidity and air velocity perceptions on the thermal sensation and thermal acceptability were evaluated via cross tabulation and chi-square independence tests. The results show that the difference between the PMV and AMV values is statistically significant and the relationship between PMV and AMV has a very strong positive correlation. The results of the chi-square tests indicated that the thermal sensation and thermal acceptability are depended on users' relative humidity and air velocity perceptions. (C) 2017 The Authors. Published by Elsevier Ltd.