Hybrid Air-Cooled and Water-Cooled Chiller Strategy for Energy and Water Optimization in a Hot, Water-Stressed Climate

Abstract

This case study presents the technical and economic evaluation of upgrading an existing water-cooled chiller plant to a hybrid configuration integrating inverter-driven air-cooled chillers with a retained water-cooled unit. The project is located in Hyderabad, India, where high ambient temperatures and increasing water scarcity create operational and financial challenges for conventional cooling tower–dependent HVAC systems. The study compares existing and proposed systems in terms of energy consumption, water usage, installation cost, maintenance expenditure, and five-year lifecycle cost. Results indicate substantial reductions in water consumption, operating cost, and maintenance complexity, with an estimated return on investment (ROI) of approximately 260% and a simple payback period of about two years. The findings demonstrate that hybrid chiller plants offer a practical balance between energy efficiency and water conservation in hot climates.