Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings: A nationwide comparative assessment of radiative sky cooling and green roofs

Jianheng Chen; Jinqin Zhong; Zhongzheng Chen; Jufeng Shu; Yelin Zhang; Ze Li; Wenqi Wang; Wenchao Shi

doi:10.1016/j.apenergy.2026.128695

Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings: A nationwide comparative assessment of radiative sky cooling and green roofs

Jianheng Chen^*
, Jinqin Zhong
, Zhongzheng Chen
, Jufeng Shu
, Yelin Zhang
, Ze Li
, Wenqi Wang
, Wenchao Shi^*

^*Corresponding author for this work

School of Energy and Environment

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

Abstract

The building sector faces mounting pressure to decarbonize as urban heat intensifies. Roofs offer a critical intervention point, yet the comparative performance of advanced passive cooling strategies, radiative sky cooling roofs versus green roofs, remains poorly understood across diverse climate zones, particularly regarding their coupled techno-economic and environmental trade-offs. This study addresses this gap by developing an integrated optical-thermal modeling framework to systematically evaluate five roof configurations (baseline, typical white roof, super-cool roof, and three green roof types) across eight representative U.S. cities spanning very hot humid to cold humid and mixed marine climates. Energy savings, heating penalties, net cost savings, and CO₂ avoidance are quantified for each strategy. The results reveal strong climate-dependent performance. Super-cool roofs achieve the highest annual cooling electricity savings (up to 4.83 kWh/m² in Honolulu) and carbon reductions (2.69 kg CO₂/m² on average) but incur significant heating penalties in cold climates (reaching 29.47 MJ/m² in Denver), yielding negative net savings in mixed marine cities. Conversely, green roofs provide positive net cost savings across all climates, with superior performance in cold-dominant regions due to heating energy conservation. Optimal roof design is therefore climate-specific: super-cool roofs are optimal for hot and warm regions, while green roofs are optimal for cold and mixed climates. Holistic envelope analysis indicates that combining optimal roof strategies with spectrally selective cooling walls and thermally insulated windows amplifies savings by an average of 37.8% relative to roof-only optimization. However, plant viability constraints, specifically frost tolerance, drought resistance, and winter survival, can influence green roof recommendations. This study provides the national-scale evidence base for climate-responsive roof retrofitting, enabling cost-effective and low-carbon building decarbonization pathways. © 2026 Elsevier Ltd

Original language	English
Article number	128695
Number of pages	19
Journal	Applied Energy
Volume	426
Issue number	Part B
Online published	14 Aug 2026
DOIs	https://doi.org/10.1016/j.apenergy.2026.128695
Publication status	Online published - 14 Aug 2026

Funding

The research work was supported by the National Natural Science Foundation of China (Grant Nos. 52408140 and 52504069 ), the Natural Science Foundation of Shandong Province (Grant Nos. ZR2024QE291 , 2025HWYQ-039 and 2025HWYQ-038 ), the Qingdao Postdoctoral Fund Project (Grant Nos. QDBSH20240202125 and QDBSH20250201001 ), the China Post-doctoral Science Foundation (Grant Nos. 2025M770581 and GZB20250679 ), Shandong Provincial Postdoctoral Innovation Project (Grant Nos. SDCX-ZG-202501025 ), the Fundamental Research Funds for the Central Universities (Grant Nos. 24CX06007A ) and Research Start-up Funding Project ( KYQD20250002 ).

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy
SDG 9 Industry, Innovation, and Infrastructure
SDG 11 Sustainable Cities and Communities
SDG 12 Responsible Consumption and Production
SDG 13 Climate Action
SDG 14 Life Below Water

Research Keywords

Carbon reduction
Climate-responsive design
Green roof
Low-energy buildings
Radiative sky cooling
Super-cool roof

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@article{de6a3075a84e4ada9b2d07e646daa963,

title = "Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings: A nationwide comparative assessment of radiative sky cooling and green roofs",

abstract = "The building sector faces mounting pressure to decarbonize as urban heat intensifies. Roofs offer a critical intervention point, yet the comparative performance of advanced passive cooling strategies, radiative sky cooling roofs versus green roofs, remains poorly understood across diverse climate zones, particularly regarding their coupled techno-economic and environmental trade-offs. This study addresses this gap by developing an integrated optical-thermal modeling framework to systematically evaluate five roof configurations (baseline, typical white roof, super-cool roof, and three green roof types) across eight representative U.S. cities spanning very hot humid to cold humid and mixed marine climates. Energy savings, heating penalties, net cost savings, and CO2 avoidance are quantified for each strategy. The results reveal strong climate-dependent performance. Super-cool roofs achieve the highest annual cooling electricity savings (up to 4.83 kWh/m2 in Honolulu) and carbon reductions (2.69 kg CO2/m2 on average) but incur significant heating penalties in cold climates (reaching 29.47 MJ/m2 in Denver), yielding negative net savings in mixed marine cities. Conversely, green roofs provide positive net cost savings across all climates, with superior performance in cold-dominant regions due to heating energy conservation. Optimal roof design is therefore climate-specific: super-cool roofs are optimal for hot and warm regions, while green roofs are optimal for cold and mixed climates. Holistic envelope analysis indicates that combining optimal roof strategies with spectrally selective cooling walls and thermally insulated windows amplifies savings by an average of 37.8\% relative to roof-only optimization. However, plant viability constraints, specifically frost tolerance, drought resistance, and winter survival, can influence green roof recommendations. This study provides the national-scale evidence base for climate-responsive roof retrofitting, enabling cost-effective and low-carbon building decarbonization pathways. {\textcopyright} 2026 Elsevier Ltd",

keywords = "Carbon reduction, Climate-responsive design, Green roof, Low-energy buildings, Radiative sky cooling, Super-cool roof",

author = "Jianheng Chen and Jinqin Zhong and Zhongzheng Chen and Jufeng Shu and Yelin Zhang and Ze Li and Wenqi Wang and Wenchao Shi",

year = "2026",

month = aug,

day = "14",

doi = "10.1016/j.apenergy.2026.128695",

language = "English",

volume = "426",

journal = "Applied Energy",

issn = "0306-2619",

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}

Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings: A nationwide comparative assessment of radiative sky cooling and green roofs. / Chen, Jianheng; Zhong, Jinqin; Chen, Zhongzheng et al.
In: Applied Energy, Vol. 426, No. Part B, 128695, 12.2026.

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

TY - JOUR

T1 - Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings

T2 - A nationwide comparative assessment of radiative sky cooling and green roofs

AU - Chen, Jianheng

AU - Zhong, Jinqin

AU - Chen, Zhongzheng

AU - Shu, Jufeng

AU - Zhang, Yelin

AU - Li, Ze

AU - Wang, Wenqi

AU - Shi, Wenchao

PY - 2026/8/14

Y1 - 2026/8/14

N2 - The building sector faces mounting pressure to decarbonize as urban heat intensifies. Roofs offer a critical intervention point, yet the comparative performance of advanced passive cooling strategies, radiative sky cooling roofs versus green roofs, remains poorly understood across diverse climate zones, particularly regarding their coupled techno-economic and environmental trade-offs. This study addresses this gap by developing an integrated optical-thermal modeling framework to systematically evaluate five roof configurations (baseline, typical white roof, super-cool roof, and three green roof types) across eight representative U.S. cities spanning very hot humid to cold humid and mixed marine climates. Energy savings, heating penalties, net cost savings, and CO2 avoidance are quantified for each strategy. The results reveal strong climate-dependent performance. Super-cool roofs achieve the highest annual cooling electricity savings (up to 4.83 kWh/m2 in Honolulu) and carbon reductions (2.69 kg CO2/m2 on average) but incur significant heating penalties in cold climates (reaching 29.47 MJ/m2 in Denver), yielding negative net savings in mixed marine cities. Conversely, green roofs provide positive net cost savings across all climates, with superior performance in cold-dominant regions due to heating energy conservation. Optimal roof design is therefore climate-specific: super-cool roofs are optimal for hot and warm regions, while green roofs are optimal for cold and mixed climates. Holistic envelope analysis indicates that combining optimal roof strategies with spectrally selective cooling walls and thermally insulated windows amplifies savings by an average of 37.8% relative to roof-only optimization. However, plant viability constraints, specifically frost tolerance, drought resistance, and winter survival, can influence green roof recommendations. This study provides the national-scale evidence base for climate-responsive roof retrofitting, enabling cost-effective and low-carbon building decarbonization pathways. © 2026 Elsevier Ltd

AB - The building sector faces mounting pressure to decarbonize as urban heat intensifies. Roofs offer a critical intervention point, yet the comparative performance of advanced passive cooling strategies, radiative sky cooling roofs versus green roofs, remains poorly understood across diverse climate zones, particularly regarding their coupled techno-economic and environmental trade-offs. This study addresses this gap by developing an integrated optical-thermal modeling framework to systematically evaluate five roof configurations (baseline, typical white roof, super-cool roof, and three green roof types) across eight representative U.S. cities spanning very hot humid to cold humid and mixed marine climates. Energy savings, heating penalties, net cost savings, and CO2 avoidance are quantified for each strategy. The results reveal strong climate-dependent performance. Super-cool roofs achieve the highest annual cooling electricity savings (up to 4.83 kWh/m2 in Honolulu) and carbon reductions (2.69 kg CO2/m2 on average) but incur significant heating penalties in cold climates (reaching 29.47 MJ/m2 in Denver), yielding negative net savings in mixed marine cities. Conversely, green roofs provide positive net cost savings across all climates, with superior performance in cold-dominant regions due to heating energy conservation. Optimal roof design is therefore climate-specific: super-cool roofs are optimal for hot and warm regions, while green roofs are optimal for cold and mixed climates. Holistic envelope analysis indicates that combining optimal roof strategies with spectrally selective cooling walls and thermally insulated windows amplifies savings by an average of 37.8% relative to roof-only optimization. However, plant viability constraints, specifically frost tolerance, drought resistance, and winter survival, can influence green roof recommendations. This study provides the national-scale evidence base for climate-responsive roof retrofitting, enabling cost-effective and low-carbon building decarbonization pathways. © 2026 Elsevier Ltd

KW - Carbon reduction

KW - Climate-responsive design

KW - Green roof

KW - Low-energy buildings

KW - Radiative sky cooling

KW - Super-cool roof

UR - https://www.scopus.com/pages/publications/105047161021

UR - https://www.scopus.com/pages/publications/105047161021#tab=impact

U2 - 10.1016/j.apenergy.2026.128695

DO - 10.1016/j.apenergy.2026.128695

M3 - RGC 21 - Publication in refereed journal

SN - 0306-2619

VL - 426

JO - Applied Energy

JF - Applied Energy

IS - Part B

M1 - 128695

ER -

Climate-responsive roof cooling strategies for low-energy carbon-neutral buildings: A nationwide comparative assessment of radiative sky cooling and green roofs

Abstract

Funding

UN SDGs

Research Keywords

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