Easy Way to Achieve Self-Adaptive Cooling of Passive Radiative Materials

Abstract

Passive radiative cooling includes using the atmospheric window to emit heat energy to the cold outer space and hence reduce the temperature of objects on Earth. In most cases, radiative cooling is required in summer and suppressed in winter for thermal comfort. Recent radiative cooling materials cannot self-adjust cooling capacity according to season and environment, thus limiting their applications. In this study, we have designed a temperature-controlled phase change structure (TCPCS). The TCPCS benefits radiative coolers to adjust their cooling ability according to the ambient temperature. In the outdoor test, the TCPCS can help the cooler to turn off at low temperatures and turn on at high temperatures automatically; the coolers with and without TCPCS have maximal temperature differences of 9.7 and 19.6 °C, respectively, in a whole day. Furthermore, we have further improved and designed a V-shaped TCPCS that can simultaneously achieve the dual functions of cooling in summer and heating in winter. The TCPCS assembled here is a simple, feasible, and scalable structure for self-adaptive cooling.