Dewpoint indirect evaporative cooling (DIEC) offers an energy-efficient, eco-friendly alternative to conventional air conditioning by using water and air to lower temperatures. With the rising demand for sustainable cooling solutions—especially in regions facing water scarcity and high energy costs—optimizing these systems for real-world conditions is more important than ever. One major challenge is ensuring that DIEC systems perform well when water is supplied intermittently rather than continuously. In this review, we examine how intermittent water supply affects the cooling performance and overall efficiency of DIEC systems. We discuss recent studies that highlight the importance of key factors such as the properties of heat exchanger materials, design modifications, and control strategies. Our analysis reveals that while innovative materials like hydrophilic membranes and adaptive design features can improve performance, their widespread use is often limited by cost and scalability. We also point out critical research gaps, particularly in applying intermittent water spraying to non-porous heat exchangers. Overall, our findings underscore the need for integrated water management strategies in DIEC design. We advocate a cross-disciplinary approach—bridging fluid dynamics, material science, and environmental engineering—to develop more resilient and sustainable cooling technologies.

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.