TY - JOUR
T1 - Zwitterionic hydrogel smart windows
T2 - Radiative cooling, privacy protection and energy savings
AU - Chen, Jiwei
AU - Li, Gang
AU - Jiang, Tengyao
AU - Wang, Shancheng
AU - Hu, Hebing
AU - Bai, Zhiyuan
AU - Shi, Dongjian
AU - Chen, Mingqing
AU - Guan, Jianguo
AU - Tan, Gang
AU - Long, Yi
N1 - Y. Long is thankful for the funding support from Global STEM Professorship Scheme sponsored by the Government of the Hong Kong Special Administrative Region, and Start-up funding from The Chinese University of Hong Kong. J. Chen acknowledges the scholarship support from China Scholarship Council (CSC, No. 202106790089), the characteristic application discipline of material science engineering in Hunan Province (grant number [2022]351), and Scientific research start-up project of Hunan Institute of Technology (grant number HQ23037).
Publisher Copyright:
© 2024 Elsevier Ltd. All rights reserved.
PY - 2024/5
Y1 - 2024/5
N2 - Current thermochromic smart windows based on lower critical solution temperature (LCST) behavior can achieve solar regulation and energy saving by modulating solar transmission at the cost of visibility at higher temperature. To tackle this issue, a new concept of smart window based on the upper critical solution temperature (UCST) characteristic of zwitterionic hydrogel has been developed, giving daytime luminous transparency, all day radiative cooling and nighttime privacy protection. This design rule is suitable for energy saving smart windows for regions where cooling demand is dominant. The UCST smart window panel provides moderate luminous transmission (Tlum) of 37.1 % and low near-infrared transmission (TNIR) of 20.3 % during the daytime, all day near unity long-wave infrared emissivity (ƐLWIR) of 0.96 facing outdoor to promote radiative cooling with outer space, low ƐLWIR 0.19 facing indoor to suppress heat transfer, and low visible transmission (Tvis) of 1.4 % at night mode for privacy protection. Energy-saving simulations demonstrate that compared to commercial low-emissivity (low-E) windows in three climate zones (zone 0, 1, 2), the UCST smart window achieves an impressive annual energy-saving up to 30.7 %. This work introduces a novel conceptual design specifically tailored for climate zones where cooling demands prevail, offering a combination of moderate luminous transparency, suppressed NIR transmission, excellent radiative cooling with outdoor environment and reduced heat transfer with indoor combining with an added privacy protection feature.
AB - Current thermochromic smart windows based on lower critical solution temperature (LCST) behavior can achieve solar regulation and energy saving by modulating solar transmission at the cost of visibility at higher temperature. To tackle this issue, a new concept of smart window based on the upper critical solution temperature (UCST) characteristic of zwitterionic hydrogel has been developed, giving daytime luminous transparency, all day radiative cooling and nighttime privacy protection. This design rule is suitable for energy saving smart windows for regions where cooling demand is dominant. The UCST smart window panel provides moderate luminous transmission (Tlum) of 37.1 % and low near-infrared transmission (TNIR) of 20.3 % during the daytime, all day near unity long-wave infrared emissivity (ƐLWIR) of 0.96 facing outdoor to promote radiative cooling with outer space, low ƐLWIR 0.19 facing indoor to suppress heat transfer, and low visible transmission (Tvis) of 1.4 % at night mode for privacy protection. Energy-saving simulations demonstrate that compared to commercial low-emissivity (low-E) windows in three climate zones (zone 0, 1, 2), the UCST smart window achieves an impressive annual energy-saving up to 30.7 %. This work introduces a novel conceptual design specifically tailored for climate zones where cooling demands prevail, offering a combination of moderate luminous transparency, suppressed NIR transmission, excellent radiative cooling with outdoor environment and reduced heat transfer with indoor combining with an added privacy protection feature.
KW - Multifunctionality
KW - Privacy protection
KW - Radiative cooling
KW - Smart window
KW - Zwitterionic hydrogel
UR - http://www.scopus.com/inward/record.url?scp=85185396020&partnerID=8YFLogxK
U2 - 10.1016/j.nanoen.2024.109386
DO - 10.1016/j.nanoen.2024.109386
M3 - Journal article
AN - SCOPUS:85185396020
SN - 2211-2855
VL - 123
JO - Nano Energy
JF - Nano Energy
M1 - 109386
ER -
