Sustainable passive ventilation has been promoted as the way forward in ventilation systems in Sub-Saharan Africa. Whether this is real or factual will be determined by this investigation on how well installed ventilation systems meet the comfort needs of office building occupants. The study gave an indication of the priorities that were attached to climatic suitability of ventilation designs in high rise office buildings. The study investigates the use of both mechanical and natural ventilation systems in some high rise office buildings. It provides information on one hand, on the level of adoption of ventilation systems in office buildings located in the Central Business District (CBD) in Nairobi, Kenya, and on the other hand, the adequacy of the installed ventilation systems as perceived by the building occupants. 34 tenants of high rise buildings located in the CBD area were purposively sampled and were the units of the study analysis. Analysis of their responses was presented using simple descriptive and interpretative techniques. The study finds that installed ventilation systems were inadequate and rarely meet tenants' needs in high rise buildings. Occupants require greater flexibility in ventilation design and desire ventilation systems that could incorporate some measure of individual control of air circulation to enhance their general comfort.