Radiative cooling (RC) is a compelling passive thermal strategy, dissipating heat via thermal radiation to outer space (≈3 K) without energy input, being useful across subambient to above‐ambient temperatures. Recent nanophotonics and metamaterials breakthroughs significantly enhance RC, enabling subambient cooling even under sunlight. This requires tailored spectral properties: high solar reflectivity (0.3–2.5 μm) to minimize heat gain, and high atmospheric window emissivity (8–13 μm) to maximize heat loss. However, widespread deployment faces hurdles in scalability, durability, cost, and adaptability. This review synthesizes recent progress in RC materials (polymers, photonic structures, paints), system designs, and applications like building thermal regulation, personal comfort textiles, and enhancing photovoltaic/electronic efficiency. It incorporates fundamental thermodynamics governing heat exchange, quantifying cooling power via relevant equations, and life‐cycle sustainability considerations. Drawing from current literature, the review critically evaluates commercialization barriers, including the lack of performance standardization, long‐term degradation, and manufacturability, and proposes research directions for robust, scalable, and viable RC technologies. Emphasis is placed on recent quantitative performance gains and the engineering challenges (atmospheric effects, parasitic heat gains, and material degradation) in translating lab‐scale results to real‐world deployments for a sustainable future.
Alberto Boretti (2025) studied this question.