Daytime passive radiative cooler using zeolite

As a passive, efficient, and renewable powerless cooling method, radiation cooling has received widespread attention in the field of energy conservation. Radiators with high reflectivity in the solar radiation band can achieve daytime radiation cooling, which can better meet people’s needs. In this work, zeolites were used as a functional material for radiative cooling due to its high solar reflectivity, high mid-infrared emissivity, and low heat conductivity. The influence of zeolite spectral properties and thermal insulation performance on their cooling effect were systematically studied. The cooling test showed that the ZSM-5-470 zeolite-based coating achieved a coating temperature (T) decrease of ~ 21 °C compared to a pure aluminum plate and a decrease of ~ 4 °C compared to a TiO2 coating under direct sunlight. However, the inside temperature (T in ) of ZSM-5-470 coating reached at most ~ 3.2 °C lower than TiO 2 coating. This may suggest that the spectral properties of zeolites have more obvious effect on the daytime radiative cooling than their thermal conductivities. Zeolites are convenient to manufacture for mass production, which makes them the potential daytime cooling materials to achieve economic and environmental friendly cooling.