Nature-inspired temperature-adaptive module: Achieving all-season passive thermal regulation for buildings

Abstract

With the increasing focus on sustainable energy practices, thermal management within the building sector has been recognized as an important strategic approach to reducing energy consumption and improving overall energy efficiency. Passive radiative cooling (PRC) offers cooling without external power, but most PRC systems lack the ability to modulate cooling power automatically in response to climate variations, leading to increased heating energy penalties during cold periods. Integrating passive cooling modules with a tunable solar heating function could provide a more efficient solution than one-way control, optimizing energy efficiency in buildings. Inspired by the self-folding leaves of the Mimosa pudica, we introduce a new dual-mode temperature-adaptive module (TAM) for architectural applications. The TAM is composed of a three-layer structure, consisting of a bottom bilayer with Janus thermal expansion properties and a top waterproofing layer. This configuration enables the TAM to autonomously switch between open and closed states in response to changes in ambient temperature, while exhibiting excellent outdoor durability. Field tests confirmed the effective radiative thermal regulation capability of the TAM under varying external conditions. In terms of its diurnal performance, it provides a thermal insulation effect, resulting in an above-ambient temperature increase of 1.98 °C during cold nighttime and a sub-ambient temperature decrease of 8.79 °C during hot daytime. When considering its seasonal/regional performance, it offers up to 16.77 °C of above-ambient heating in cold months/regions while providing cooling in hot conditions. The module also comes in various colors to fulfill aesthetic and design prerequisites. This scalable and economically viable innovation represents a notable leap forward in radiative thermal management, delivering tangible benefits for buildings in climates with considerable diurnal and seasonal temperature fluctuations.