Self-Adaptive Thermal Regulator for Dynamic Heating and Cooling through Coupled Thermal Energy Storage and Solar Modulation

Abstract Indoor climate control accounts for nearly half of global building energy consumption and can impose substantial stress on power grids under extreme weather conditions. Developing energy-efficient thermoregulation technologies is therefore critical for reducing building energy demand and improving infrastructure resilience. While conventional insulation materials function as static thermal barriers, they are unable to adapt to changing environmental conditions and seasonal thermal demands. This work reports a heterostructured adaptable optical–thermal dual-mode thermoregulator (AOT-DTR) that integrates a thermo-responsive poly(N-isopropylacrylamide) (PNIPAM)-based top layer with a solar-absorptive phase change material (PCM)-based underlayer to achieve self-adaptive heating and cooling. The PNIPAM-based layer dynamically modulates solar energy utilization in response to ambient temperature, switching the AOT-DTR from a heating mode with a solar absorptivity of 86.4% (below the lower critical solution temperature [LCST]) to a cooling mode with a solar reflectivity of 75.1% (above the LCST). Meanwhile, the PCM-based underlayer provides thermal buffering through latent heat storage, exhibiting a melting enthalpy of up to 126.5 J/g with a melting temperature of 33 °C. This stored thermal energy can be released for passive nighttime heating, extending the thermal regulation capability beyond daytime operation. By coupling thermo-responsive solar modulation with latent heat storage, the heterostructured AOT-DTR achieves substantially enhanced thermal regulation performance compared with systems relying on either mechanism alone. More importantly, by strategically pairing the LCST of the PNIPAM layer for solar modulation with the solid–liquid phase change temperature (PCT) of PCM, our modeling for the subtropical climate of Dallas, Texas, reveals that the utilization efficiency of latent heat storage can be maximized to achieve all-season thermal regulation. This synergistic design establishes a self-adaptive thermal regulation strategy that integrates solar modulation and thermal energy storage within a single material platform, creating new opportunities for sustainable and energy-efficient building envelopes and next-generation passive thermal management technologies.