Passive cooling refers to any technologies or design features adopted to reduce the indoor temperature of buildings without the need for conventional energy. Passive downdraft cooling (PDEC) system is an emerging system of passive technique and has proved to be successful in reducing the cooling load in buildings especially in hot and dry climates. The aim of this study is to explore the efficiency of PDEC systems in moderate and composite climatic regions of India, as well. The study is intended to understand the concept, spatial requirement, suitable climatic conditions and the mechanism of PDEC systems. The issues involved in design of PDEC towers have been addressed. The results suggest that effective design of PDEC towers could significantly reduce the energy bills and carbon footprints as well. This technique may therefore be widely relevant to non-residential buildings in hot climatic regions of India where more energy is required for mechanical cooling systems during the hot seasons; hence architects and engineers must initiate the importance of PDEC systems in their building design. © EM International.