Ultraviolet durable and recyclable radiative cooling covering for efficient building energy saving.

Abstract

Passive radiative cooling (PRC) is a zero-energy thermal management technology used for efficient building energy saving. Polymer-based porous films are promising PRC materials, but their low ultraviolet (UV) durability and lack of recyclability limit their long-term and widespread application. Herein, a recyclable polymer-based porous radiative cooling film with excellent ultraviolet durability was developed as the covering of a building. Owing to the Mie scattering effect of the porous structure and strong infrared emittance of ethyl cellulose, the film demonstrated a radiative cooling capability of 10.6 °C at a solar irradiance of 510 W m^-2. The calculated energy consumption results indicated that the average cooling consumption reached 429.4 kW h, and 31% of the cooling energy could be saved. Notably, owing to the conjugated benzene ring structure of styrene-ethylene-butylene-styrene (SEBS), the film blocked most of the incident UV radiation and diffused the absorptive energy through the delocalization effect of electron clouds. Thus, the film retained high solar reflectivity after continuous UV exposure for 240 h. Notably, the film could be cyclically utilized using a simple nonsolvent-induced phase separation (NIPS) approach. This research offers new insights into the design of UV-durable and recyclable PRC materials, providing a promising prospect for minimizing global building energy consumption and facilitating the development of sustainable buildings.