“Warm in Winter and Cool in Summer”: Scalable Biochameleon Inspired Temperature-Adaptive Coating with Easy Preparation and Construction

Abstract

The highly reflective solar radiation of passive daytime radiative cooling (PDRC) increases heating energy consumption in the cold winter. Inspired by the temperature-adaptive skin color of chameleon, we efficiently combine temperature-adaptive solar absorption and PDRC technology to achieve “warm in winter and cool in summer”. The temperature-adaptive radiative cooling coating (TARCC) with color variability is designed and fabricated, achieving 41% visible light regulation capability. Comprehensive seasonal outdoor tests confirm the reliability of the TARCC: in summer, the TARCC exhibits high solar reflectance (∼93%) and atmospheric transmission window emittance (∼94%), resulting in a 6.5 K subambient temperature. In the winter, the TARCC’s dark color strongly absorbs solar radiation, resulting in a 4.3 K temperature rise. Compared with PDRC coatings, the TARCC can save up to 20% of annual energy in midlatitude regions and increase suitable human hours by 55%. With its low cost, easy preparation, and simple construction, the TARCC shows promise for achieving sustainable and comfortable indoor environments.

Highly Optically Selective and Thermally Insulating Porous Calcium Silicate Composite SiO2 Aerogel Coating for Daytime Radiative Cooling

“…The annual average radiative cooling power in the southern coastal areas of China is less than 70 W/m 2 , while the annual average radiative cooling power in the north and northwest can reach 95 W/m 2 due to the hot climate conditions and high-altitude geographical conditions. Therefore, SiO 2 –CS coating can have better radiative cooling performance in the western and northern regions of China. , …”

“…Therefore, SiO 2 −CS coating can have better radiative cooling performance in the western and northern regions of China. 72,73 In order to test how much energy can be saved by the SiO 2 − CS coating compared with the white coating, we chose to conduct a real house test in the northwest region (Yangquan), which is rich in radiative cooling resources. The wall area of two test houses is 103.5 m 2 , the actual brushing area is 100 m 2 , and the coating thickness is 1 mm; the building area is 45 m 2 ; the construction of the two test houses is identical, one house is coated with SiO 2 −CS coating and the other is coated with white coating.…”

Self-sustained and Insulated Radiative/Evaporative Cooler for Daytime Subambient Passive Cooling

“…Recently, greater attention has been directed toward radiative/evaporative coolers (REC) that incorporate atmospheric water harvesting. 27 EC based on atmospheric water harvesting (AWH-EC) has emerged in the past 2 years as a self-replenishment method. This cooling technology uses solid adsorbent materials such as metallic organic frameworks 28 and organic polymer adsorbent materials such as hydrogel 29−32 to capture atmospheric water for EC.…”

“…Recently, greater attention has been directed toward radiative/evaporative coolers (REC) that incorporate atmospheric water harvesting . EC based on atmospheric water harvesting (AWH-EC) has emerged in the past 2 years as a self-replenishment method.…”

A Facile and Effective Design for Dynamic Thermal Management Based on Synchronous Solar and Thermal Radiation Regulation

“…Efficient thermal management technology can be based on different external physical fields − (such as electrical, mechanical force, − solar-thermal, − and dielectric environment , ). Currently, a popular approach to achieve dynamic spectral regulation is through a moisture transfer technique, − which has been of benefit in water harvesting. − However, the current thermal modulation is mainly concentrated in a single solar band or mid-infrared band, ,− and dynamic thermal management only occurs under sunlight. An ideal dynamic modulation system would be to achieve temperature regulation throughout the entire spectra from solar to thermal radiation (>0.3 μm).…”