R Pandiyan, Praveen Kumar G
• Materials like aluminum (ϵ=0.95) and PDMS (ϵ=0.90) for high IR emissivity. • Metamaterials like VO 2 and TiO 2 /PMMA coatings offer tunable emissivity. • RadiCold subsystem saves 26-46% energy annually, costs $50.0-$78.9/m², 8-year payback. • SRC systems like super-cool roofs save 42.9-97.8 kWh/m²/year, cut 24.6-56.1 kg CO 2 /(m²⋅yr). • SiO₂ and double-layer LDPE films reduce internal temperatures of greenhouse by 4–5 °C. Sky radiative cooling (SRC) is a modern passive cooling technology that employs the sky as a heat sink has been shifted from a nighttime cooling to a full-day operation with the help of spectral engineering breakthroughs. This review consolidates fragmented SRC literature, offering a unified framework to classify materials, such as bulk, multilayer, porous and nanostructured systems, based on their radiative properties, structural configurations, and spectral selectivity. The study thoroughly examines the applications of radiative cooling in building cooling, photovoltaic performance enhancement, water harvesting, electronics, and transportation, giving considerable attention to the topics of its extent, economic viability, and technology compatibility with the Sustainable Development Goals (SDGs). The potential of several new materials like hierarchical metamaterials and adaptive or phase change composites for the features which include humidity resilience and angle independent emission as well as the regional climatic adaptability (arid vs. tropical) are discussed. Key barriers to large-scale deployment particularly trad-offs among cooling efficiency, cost and manufacturing scalability are identified. Future research directions are outlined, focusing on broadband versus spectrally selective emitters, atmospheric effects on cooling performance and hybrid system integration. Furthermore, the review provides coherent roadmap for advancing SRC technologies towards scalable, climate resilient, energy efficient cooling solutions aligned with sustainability goals.