Optically modulated passive broadband daytime radiative cooling materials can cool cities in summer and heat cities in winter

Date

2022

Authors

Khan, Ansar
Feng, Jie
Khorat, Samiran
Khatun, Rupali
Doan, Quang-Van
Santamouris, Mattheos

Director

Publisher

MDPI
Acceso abierto / Sarbide irekia
Artículo / Artikulua
Versión publicada / Argitaratu den bertsioa

Project identifier

Impacto
No disponible en Scopus

Abstract

Broadband passive daytime radiative cooling (PDRC) materials exhibit sub-ambient surface temperatures and contribute highly to mitigating extreme urban heat during the warm period. However, their application may cause undesired overcooling problems in winter. This study aims to assess, on a city scale, different solutions to overcome the winter overcooling penalty derived from using PDRC materials. Furthermore, a mesoscale urban modeling system assesses the potential of the optical modulation of reflectance (ρ) and emissivity (ε) to reduce, minimize, or reverse the overcooling penalty. The alteration of heat flux components, air temperature modification, ground and roof surface temperature, and the urban canopy temperature are assessed. The maximum decrease of the winter ambient temperature using standard PDRC materials is 1.1 ◦C and 0.8 ◦C for daytime and nighttime, respectively, while the ρ+ε-modulation can increase the ambient temperature up to 0.4 ◦C and 1.4 ◦C, respectively, compared to the use of conventional materials. Compared with the control case, the maximum decrease of net radiation inflow occurred at the peak hour, reducing by 192.7 Wm−2 for the PDRC materials, 5.4 Wm−2 for ρ-modulated PDRC materials, and 173.7 Wm−2 for ε-PDRC materials; nevertheless, the ρ+ε-modulated PDRC materials increased the maximum net radiation inflow by 51.5 Wm−2 , leading to heating of the cities during the winter.

Description

Keywords

Urban heat mitigation, Broadband radiative cooling emitters, Overcooling, Optical modulation, WRF-SLUCM, Kolkata

Department

Ingeniería / Ingeniaritza

Faculty/School

Degree

Doctorate program

item.page.cita

Khan, A., Carlosena, L., Feng, J., Khorat, S., Khatun, R., Doan, Q.-V., & Santamouris, M. (2022). Optically modulated passive broadband daytime radiative cooling materials can cool cities in summer and heat cities in winter. Sustainability, 14(3), 1110. https://doi.org/10.3390/su14031110

item.page.rights

© 2022 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.

Licencia

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