This paper analytically investigates and compares the performance of a proposed 'all-natural' NH 3 /CO 2 cascaded booster system to a conventional R404A direct expansion system as well as to an 'all-CO 2 ' system with multi-ejector unit and flooded evaporator. Performance comparison is made based on the annual combined COP and Life Cycle Climate Performance (LCCP) for operation in selected cities of Middle East and India. Our results show that in extreme warm climate, the energy efficiency of the proposed configuration exceeds that of all-CO 2 configuration by a maximum of about 12.23% and the total emissions are lower by up to 11.20%. However, the all-CO 2 multi ejector system performs better in cold and mild warm climate. In the NH 3 /CO 2 cascade, the high temperature NH 3 system can be designed to be isolated from the accessible locations of the supermarket. The work presented is expected to help adoption of natural refrigerants such as CO 2 and NH 3 for commercial application in extreme warm climate conditions prevailing in many cities of Middle East and India.

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