Transparent Polymer Coatings for Energy-Efficient Daytime Window Cooling

• Published in: Cell reports physical science Vol. 1; no. 11; p. 100231
• Main Authors: Zhou, Zhengui, Wang, Xin, Ma, Yaoguang, Hu, Bin, Zhou, Jun
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 18.11.2020
• Subjects: cooling energy savings; infrared; radiative cooling; thermal management; window; radiative cooling; cooling energy savings; infrared; window; thermal management
• ISSN: 2666-3864; 2666-3864
• DOI: 10.1016/j.xcrp.2020.100231

Solar and thermal management of transparent windows is important for the energy efficiency of human-made structures. Functional layers that partially block solar radiation would also be heated by sunlight, thus accelerating the interior heat exchange and increasing daytime cooling energy consumption. Here, we propose a strategy to improve energy efficiency through window cooling using a transparent double-layer coating, which comprises a near-infrared reflective underlayer and a high mid-infrared emissive top layer. The addition of a top emitter can decrease the temperature of the near-infrared reflective window up to ∼7°C in outdoor tests, and can provide extra cooling energy savings ranging from 20 to 49 MJ ⋅ m−2 ⋅ year−1 for a typical building located in 11 cities worldwide. This accounts for ∼3%–∼8% of their total annual cooling energy consumption and indicates the significant impact of window cooling on interior energy efficiency. [Display omitted] Window cooling strategy is demonstrated based on passive daytime radiative coolingFunctional group matching is used to select emitters for windows coolingWindow cooling can save 20–49 MJ ⋅ m−2 ⋅ year−1 for a typical building Solar and thermal management of windows is closely related to energy efficiency. Zhou et al. report a radiative cooling strategy targeted toward cooling windows using a transparent polymer emitter and show the significant impact on interior cooling and thus the potential for energy savings around the world.