Thermal Homeostasis Enabled by Dynamically Regulating the Passive Radiative Cooling and Solar Heating Based on a Thermochromic Hydrogel

Thermal homeostasis can maintain body temperature of warm-blooded organisms in a narrow range to avoid hypothermia, ensuring the normal operation of life activities. Thermal homeostasis can make the internal temperature of target relatively insensitive to temperature changes of surrounding environment, which is of great significance to the efficient operation of equipment and the service life of material. The current systems that maintain thermal homeostasis need to consume electricity, which is very detrimental to energy consumption and global warming. Here, we propose a novel thermal homeostasis program by means of tunable sunlight-scattering behaviors of thermochromic hydrogel, without external energy input such as electrical energy and mechanical energy. A sandwich structure thermal homeostasiser (SSTH) generated by the thermal homeostasis program consists of three parts: the radiative cooling part at the top, the thermochromic part in the middle and the solar heating part at the bottom. The feasibility of thermal homeostasis based on SSTH has been verified theoretically and experimentally. With the ambient air temperature difference of more than 6 °C, SSTH can maintain its own temperature difference within 1.2 °C. The SSTH is a simple-feasible paradigm for achieving thermal homeostasis. This new thermal homeostasis method we proposed can fill the vacancy of the current thermal homeostasis control means and show great potential as a complementary mean of the existing building environment control system to go a step further toward zero-energy building.