Performance Evidence and Regulatory Gaps in Evaporative Cooling Across Institutional Publications

Rising global demand for space cooling is driving peak electricity loads, greenhouse gas emissions, and refrigerant pollution from vapor compression air conditioning. Evaporative cooling is a proven, low-electricity alternative using no synthetic refrigerants, but its evidence base is fragmented and its regulation underdeveloped. This review synthesizes sixteen publicly available institutional publications from 2009 to 2024, analyzing performance, barriers, and deployment conditions. Multistage indirect evaporative cooling achieved reported or simulated energy reductions of 57–95% against study-specific vapor compression baselines in hot–dry climates, with Energy Efficiency Ratio values of 63–76 versus a rooftop unit baseline of 12. These figures rest almost entirely on monitoring in one ASHRAE climate zone, with several compared against modeled rather than measured baselines. Two independent reviews published twelve years apart each identify Iran as the only country with mandatory energy performance requirements for evaporative coolers; water use labeling remained similarly underdeveloped. The evidence base is asymmetric: the United States provides the most rigorous monitoring, while India’s larger deployment, exceeding 800 buildings, lacks equivalent verification. Five research gaps are identified, most urgently the absence of integrated water–energy life-cycle accounting. A four-part policy response is proposed: climate suitability mapping, mandatory performance and water use standards, open monitoring for publicly funded pilots, and prioritization of data centers for market development. The regulatory gap identified here also holds in the European Union, where the Ecodesign framework addresses vapor compression air conditioners but does not constitute standalone evaporative air coolers as a regulated product group.