Cooling demand in apartment buildings is an important problem due to the global warming today. Implementing passive design techniques to reduce cooling requirements cannot be possible in dense cities. Therefore, energy performance of apartment buildings usually depends on uncertainties caused by local climate and design parameters such as window size, zone height, features of materials and so on. The main aims of dissertation are to determine design parameters that have the most impact on the annual cooling energy loads for low-rise apartment blocks in hothumid climatic region of Turkey, and to evaluate uncertainty in annual cooling loads caused by design parameters and global warming. Global sensitivity and uncertainty analysis methods are performed by using morphology of an existing low-rise apartment block in Izmir, Turkey. The minor aim of thesis is to develop a practical guide to help architects while designing low-rise apartment blocks which have low cooling load located in Izmir. This practical guide was developed by using the results of sensitivity and uncertainty analyses and interviews with architects who have worked on commercial architectural projects in Izmir and are considered to be experts on energy efficiency in buildings. The results show that the sensitivity of evaluated design parameters and annual cooling energy loads in low-rise apartment blocks varies based on the effect of global warming and floors in the apartment block. In addition, total window area, natural ventilation and solar heat gain coefficient of the glazing based on the orientation have the most influence on annual cooling load of low-rise apartment blocks in hot-humid climates. Furthermore, the developed practical guide is feasible and could be used in design process of low-rise apartment blocks targeted low cooling demand in hot-humid climates.