Computer classrooms present challenges for cooling because internal heat gains higher than typical classrooms. Focused on thermal comfort, this paper presents the results of a field and computational study of a computer seminar room in west England. A mechanical ventilation system with phase change materials thermal storage has been installed in the room to provide thermal comfort and indoor air quality. Monitored data of internal air temperature, CO2 and humidity were analysed and compared with current requirements for indoor air quality and comfort. The analysis indicates that good internal environmental conditions are provided by the system. To better understand the ventilative cooling performance of the system a week in early September was chosen and analysed in detail. In addition the hottest hour of the week was chosen for further analysis using CFD using air temperature monitored data for calibration. Results show that even for the most extreme external conditions of the monitored period, the seminar room has a uniform temperature distribution within thermal comfort requirements and air velocity ranging between 0.11 to 0.17 m/s close to the students and will not cause uncomfortable draughts.