Chameleon-Inspired Temperature-Adaptive Cooling/Heating structural cementitious composite

• Integration of thermochromic and radiative cooling polymers enabled TARCHC with adaptive thermal regulation properties. • TARCHC composites demonstrated dynamic solar reflectance ranging from 75.8% to 93.4% across varying temperature conditions. • TARCHC composites achieved an average sub-ambient cooling of ∼ 3.8 °C at high ambient temperatures. • Conversely, it exhibited a more modest heating performance of ∼ 1.7 °C at low ambient temperatures. • The lightweight honeycomb architecture provided sufficient mechanical strength, enabling its application in construction. Building indoor cooling and heating contributes significantly to global energy demand and carbon emissions. Passive radiant thermal regulation materials, particularly those that combine both passive daytime radiative cooling (PDRC) and solar heating (SH), offer a sustainable solution by responding dynamically to environmental conditions. However, while the potential of dual-mode PDRC/SH has been demonstrated in coatings and glazings, its integration into the most widely used building material, cement-based materials, remains largely unexplored. Here, we present a temperature-adaptive radiative cooling/heating cement (TARCHC) composite, developed by strategically integrating a cement-based honeycomb architecture with microstructured PDRC/SH polymers to achieve a cement-based composite that exhibits not only thermal regulation functions but also adequate mechanical strength. Bio-inspired by the chameleon, the developed TARCHC composite exhibits adaptive solar reflectance (ranging from 75.8% to 93.4%) while maintaining excellent longwave-infrared emissivity (∼95.0%) across varying thermal conditions. Under daytime outdoor testing, the optimal TARCHC composite achieves effective average subambient cooling of up to ∼ 3.8 °C and heat gain of ∼ 1.7 °C, while being lightweight (∼899 kg/m 3 ) and presenting adequate mechanical strength (0.0062 MPa·m 3 /kg) and water-repellent properties. These findings address the need for adaptable thermal regulation systems and pave the way for the development of energy-efficient, climate-responsive green roof technologies.