A Colored Temperature-Adaptive Cloak for Year-Round Building Energy Saving

Abstract

Achieving year-round energy savings in buildings holds great significance toward reaching carbon neutrality and sustainability. Switchable thermal-management materials offer an energy-free solution to dynamically regulating internal building temperatures, by passively emitting heat into cold outer space in summer, and absorbing heat from hot sunlight in winter. In addition to dynamic thermal regulation, color display is another pursuit for addressing aesthetic considerations; however, most current dynamically switchable materials lack color options, due to an optical conflict between adaptive solar reflection and selective visible absorption, limiting their wide adoption in aesthetic scenarios such as commercial exterior walls. Herein, a colored temperature-adaptive cloak (CTAC) that achieves dynamically switchable thermal management in an energy-neutral way without sacrificing year-round vibrant color display is reported. This is realized by decoupling solar reflectivity modulation and color display through the choice of two individual constituent components, including thermochromic microcapsules, and fluorescent dyes. Moreover, compared to single-mode samples with similar colors, the CTAC with dual modes stays 5.6–3.4 °C warmer during cold winter and 14.9–7.9 °C cooler during hot summer (peak solar irradiance: ≈735 and 1030 W m⁻², respectively), exhibiting a remarkable potential to achieve year-round building energy savings.