An apartment building with several of its individual units in different orientations, heights and multiple ownerships can be considered to be a dynamic system. The overall performance of the building may not provide useful insight into the performance of a specific apartment. This paper investigates the thermal performance of such individual apartments in multi-storeyed residential buildings in hot humid environment. Environmental Parameters such as indoor temperature, humidity, air velocity, globe temperature, radiation and heat flux flow through wall were measured on a 24hour cycle at 15 minutes interval in summer and winter. Outdoor measurements for the ambient temperature and relative humidity were obtained from the Meteorological Authority in the same period. The selected apartment building is simulated using Designbuilder software. Performance is evaluated through parametric analysis on the extent to which the orientation of the apartment within a floor and the height at which the apartment is located has an influence on thermal comfort indoors. Simulated data is validated using measured data. Results showed that mean indoor temperature is increasing with height except for first floor which showed slightly high temperature due to ground reflections and the top most floor showed peak temperature due to exposed roof. North west corner of the building is found to be the hottest room in summer. Pre-design guidelines have been developed to improve indoor thermal comfort with respect to orientation and height.