Hierarchical-Morphology Metal/Polymer Heterostructure for Scalable Multimodal Thermal Management

Abstract

The cooling and heating energy consumption of buildings poses a serious threat to the energy supply and increases greenhouse gas emissions, thus adversely impacting global warming and the long-term climate change trends. Here, inspired by the structure of the louver, this work demonstrates a multimodal device that integrates radiative cooling, natural lighting, and solar heating to deal with the grand challenge of building energy consumption. The blades integrate a selective radiative cooling material with a solar heating material. The selective radiative cooling material (solar reflectance ∼97%, selective emittance ∼0.82 in the 8−13 μm waveband) combines a solar reflective melt-blown polypropylene film and a solar transparent mid-infrared emitter polyethylene/ silicon dioxide film. In addition, the heating material (solar absorptance ∼91%, thermal emittance ∼0.04) is zinc (Zn) film deposited with copper (Cu) nanoparticles, based on the Cu−Zn galvanic-displacement reaction. Hence, by rotating the blades, the conversion of radiative cooling, solar heating, and natural lighting functions can be realized. In the daytime, the multimodal device displays a subambient temperature of 4 °C, a superambient temperature of 2 °C, and a superambient temperature of 5 °C for the cooling mode, transmitting mode, and solar heating mode, respectively. On the basis of the energy-savings simulation, integrating these modes and dynamic converting these modes in the corresponding climate could save ∼746 GJ in the contiguous United States for one year (38% of the baseline energy consumption), which is equivalent to ∼147 tons of carbon dioxide emission reduction. Because of its excellent multimodal thermal management performance, this multimodal device will push forward the transformative change of building thermal management toward decarbonization and sustainability and being more green.

Mechanically Switchable Multifunctional Device for Regulating Passive Radiative Cooling and Solar Heating

“…The multifunctional device integrating RC and SH is very advantageous to energy saving for buildings . After being combined with PC membrane, the multifunctional device can control the temperature at a more steady state.…”

“…The multifunctional device integrating RC and SH is very advantageous to energy saving for buildings. 7 After being combined with PC membrane, the multifunctional device can control the temperature at a more steady state. The optical properties of the multifunctional device in the direction of the RC model and SH model are shown in Figure S6.…”

“…Li et al 37 proposed a dual-mode device for energy saving in buildings. Yang et al 7 proposed a metal/polymer heterostructure for multimodal thermal regulation, which was inspired by the structure of louvers. Due to the advantages of simple structure and easy fabrication, the dual-modal materials are more likely to be mass produced.…”

“…Passive radiative cooling (RC) and solar heating (SH) could, respectively, drop and raise the temperature automatically without any energy input. Combining RC with SH is an alternative way for attaining thermal regulation in buildings . Both RC and SH can be realized by the appropriate optical properties of materials.…”

“…Combining RC with SH is an alternative way for attaining thermal regulation in buildings. 7 Both RC and SH can be realized by the appropriate optical properties of materials. The outer space can be considered as a heat sink with a temperature of ∼3 K, 8 and only long-wave infrared (LWIR) light within 8−13 μm [called atmospheric window (ATW)] can reach the outer space through the ATW.…”