Weather‐Adaptive Janus Aerogel Integrated with Phase Change Materials Enables Dual‐Mode Thermal Regulation via Radiative Cooling and Solar Heating

Abstract Passive radiative cooling offers an electricity‐free strategy to reduce energy consumption. However, most radiative cooling systems focus solely on maximizing cooling performance while neglecting diurnal temperature fluctuations and weather variations under intermittent solar irradiation. To address this limitation, a dual‐mode, weather‐adaptive thermal regulation system is developed using a bilayer‐structured Janus aerogel/phase change material (PCM) composite. This innovative design integrates a radiative cooling layer with a solar heating layer, coupled with a PCM, to dynamically respond to changing environmental and seasonal conditions. In cooling mode, the Janus aerogel/PCM composite achieves a maximum sub‐ambient temperature drop of 14.2 °C under peak solar irradiance (1057 W m −2 ). In heating mode, the composite demonstrates a maximum sub‐ambient temperature rise of 14.9 °C under a peak sunlight intensity of 772.8 W m −2 . The PCM plays a critical role in “peak‐shaving and valley‐filling” by storing excess solar energy during high‐temperature periods and releasing it during low‐temperature phases. This mechanism enhances both radiative cooling and solar heating efficiency, ensuring stable thermal regulation. The Janus aerogel/PCM composite developed by this work represents a significant advancement in sustainable thermal management, offering adaptable solutions for passive radiative cooling and solar heating applications in variable climates.