Ventilation and comfort assessment of buildings is not a new practice in post occupancy evaluation (POE) of buildings. Most evaluations have been based on perceived assessments by the occupants collated through questionnaires asking for a Yes/No response or qualitative scale rating. While this study does not deal with a POE survey, it was initiated by the lack of comfort and overheating complaints of the occupants of the subject university building. It is for this reason that an investigation was conducted on the design expectations and actual ventilation performance associated with the thermal comfort of this building. The floor plan of this university building is typical to office buildings, comprising of a central interior hallway, with rooms to either side fronting an external operable window. It is intended that this building is treated to comply with natural ventilation principles. Door grilles are provided to allow for an expected air flow exchange between rooms and hallways, as well as a total crossflow ventilation through the building. No HVAC (mechanical) system is used for heating or cooling in this building. Heating is through a hydronic perimeter radiator system. This study involved an investigation into ventilation and associated thermal comfort through continuous measurement in a specified room of the building. Its aims are to: 1. To establish thermal comfort conditions for a typical office in the building. 2. To establish the existing ventilation performance under various external conditions. 3. To analyse the possible reasons for the passive thermal control problems, and to provide alternative measures for improvement.