Effect of global climate change on the sub-ambient radiative cooling performance of ideal coolers in different environments

Sub-ambient radiative cooling technology is capable of achieving sub-ambient cooling without the need for external work, and has been extensively researched due to its environmentally friendly and sustainable characteristics. In this study, we first propose an ideal theoretical vacuum model to investigate the theoretical lowest achievable temperature (TLAT) and cooling power of radiative coolers, and present a prediction method of the coolers' optical properties according to the designed temperature requirements. By analyzing optical properties and environmental conditions, we explore the impact of global warming on cooling performance. Our simulations show that compared with the significant positive contribution of water vapor, CO2 is not, as generally expected, the most critical greenhouse gas causing the reduction in radiative cooling performance. This suggests that in humid areas, it's better to use selective emitters to combat radiative cooling performance decline. But infrared broadband emitters can easily replace selective emitters with the decreasing total water vapor column. Our research reveals how the global warming affects the radiative cooling performance by theoretical simulation and is important for the further application development of radiative coolers to adapt to global climate change.