Synchronous Radiative Cooling and Thermal Insulation in SiO<sub>2</sub>/Poly(vinyl alcohol) Composite Aerogel for Energy Savings in Building Thermal Management
Chao‐Qun Ma, Chao‐Hua Xue, Wei Fan, Xiao-Jing Guo, Jun Cheng, Meng-Chen Huang, Huidi Wang, Yong-Gang Wu, Bing‐Ying Liu, Shi-Qiang Lv
Abstract
Daytime passive radiative cooling is an effective way to reduce energy consumption for building cooling. However, overcooling might occur in radiative cooling at low-temperature which presents limitations in thermal management. Herein, a new SiO 2 /poly(vinyl alcohol) composite aerogel with nanomicro–multistage porous structure for thermal insulation and radiative cooling was fabricated by a non-solvent-assisted freeze-drying strategy. In the fabrication process, the nonsolvent (acetone) for poly(vinyl alcohol) was utilized to control the proportion and size of the macro-porous structure inside the SiO 2 /poly(vinyl alcohol) composite aerogel, making the thermal conductivity of the aerogel decreased to 0.0390 W/mK while spontaneously increasing its solar reflectance and infrared (8–13 μm) emissivity to 93.70% and 98.19%, respectively. The composite aerogel achieved sub-ambient cooling of up to 14.1 °C during the day and above-ambient warming of 3.8 °C at night, avoiding nighttime overcooling. The SiO 2 /poly(vinyl alcohol) composite aerogel demonstrates adaptive thermal management compared to commercial insulation materials, making it suitable for intelligent thermal management of energy-saving buildings.