Design and performance investigation of a novel self-adaptive radiative cooling module for thermal regulation in buildings

Daytime radiative cooling utilizes the process of reflecting sunlight and radiating heat through the atmospheric transparent window (8–13 μm) to achieve spontaneous cooling of an object. However, the existing challenge lies in the disparity between the cooling supply and demand, necessitating the development of self-regulating radiative cooling. This study introduces a novel design that combines paraffin wax with a radiative cooler, leading to the development of a self-adaptive radiative cooler (SRC) with two distinct modes based on dynamic optical properties. The spectral properties of the four SRCs were calculated by Fresnel equation, and it was found that the SRC possessed the ability to optimally absorb solar energy (Δα = 0.322) and automatically adjusted their thermal emittance (Δε = 0.552) in response to ambient temperature changes, facilitated by the liquid-solid transition, especially for Case 1. Therefore, the novel SRCs demonstrate a unique behaviour: they are warmer than static radiative coolers (ΔT = 3 K) in cold ambient conditions, while maintaining high cooling power in hot environments. Through extensive simulations for various cities and climates, this study demonstrates the superior energy-saving performance of the SRCs in building thermal regulation compared to that of static radiative coolers (Δδ1 = 9.6%).