Load-responsive control of electrochromic windows for commercial buildings: Global cooling benefits and climate-dependent energy trade-offs

Pin-Yu Chen

Xinyi Tian

Yi Long

*Correspondence to: Yi Long, Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong SAR 999077, China. E-mail: yilong@ee.cuhk.edu.hk

Smart Mater Devices. 2027;3:202657. 10.70401/smd.2026.0053

Received: August 14, 2026Accepted: September 28, 2026Published: October 08, 2026

This article belongs to the Special lssue Smart Windows with Stimuli-Responsive Properties

This manuscript is made available in its unedited form to allow early access to the reported findings. Further editing will be completed before final publication. As such, the content may include errors, and standard legal disclaimers are applicable.

Abstract

Electrochromic (EC) glazing can regulate solar heat gain, but the control signal affects the balance between cooling and heating energy use. This study compares the Load strategy, which uses predicted sensible load, with the fixed temperature-based T24 strategy, which uses a 24 °C upper switching threshold. Both strategies were implemented through the EnergyPlus Energy Management System (EMS) under identical building, heating, ventilation, and air-conditioning (HVAC), thermostat, weather, and EC glazing conditions across 384 worldwide EnergyPlus Weather (EPW) records. EC (Load) reduced cooling electricity across most climates but increased heating gas use, with larger penalties in colder regions. The resulting annual energy-use intensity (EUI) was 146.54 kWh m^-2 year^-1 for EC (Load) and 145.23 kWh m^-2 year^-1 for EC (T24), while the carbon-equivalent response varied geographically because of the competing electricity and heating effects. These results indicate that the Load strategy primarily redistributes energy use between cooling and heating rather than providing a universal annual-energy advantage, thereby demonstrating the climate-dependent energy trade-offs associated with this strategy.

Keywords

Electrochromic glazing, smart windows, energyplus, load-responsive control, temperature-based control, climate-dependent energy performance

References

1. Zhao F, Wang B, Huang B, Zhang W, Chen J, Liu L, et al. Inorganic electrochromic smart windows for advancing building energy efficiency. Nat Rev Clean Technol. 2025;1(6):396-412.

[DOI]
2. Baetens R, Jelle BP, Gustavsen A. Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review. Sol Energy Mater Sol Cells. 2010;94(2):87-105.

[DOI]
3. Shao Z, Huang A, Cao C, Ji X, Hu W, Luo H, et al. Tri-band electrochromic smart window for energy savings in buildings. Nat Sustain. 2024;7(6):796-803.

[DOI]
4. Li H, Zhang J, Liu Y, Bai Z, Liang H, Hou C, et al. Scalable all-in-one electrochromic glazing for full-spectrum solar radiation management. Nat Sustain. 2026;9(6):910-920.

[DOI]
5. Wu X, Bao B, Bai Z, Fan Q, Hou C, Zhang Q, et al. Heteroaromatic π-stacking engineered near-infrared absorption for highly stable near-zero transmittance electrochromic window. Nat Commun. 2025;16(1):9964.

[DOI] [PubMed] [PMC]
6. Bao B, Hao Y, Wu X, Xiao R, Hou C, Li Y, et al. Redox-bipolar mesoporous two-dimensional covalent organic framework for multi-color electrochromism. Sci Adv. 2025;11(42):eaea1304.

[DOI] [PubMed] [PMC]
7. Li R, Ma X, Li J, Cao J, Gao H, Li T, et al. Flexible and high-performance electrochromic devices enabled by self-assembled 2D TiO₂/MXene heterostructures. Nat Commun. 2021;12:1587.

[DOI]
8. Cannavale A, Carlucci F, Pugliese M, Maiorano V, Ayr U, Fiorito F. Low-cost gel-polymer electrolytes for smart windows: Effects on yearly energy consumption and visual comfort. Energy Build. 2023;301:113705.

[DOI]
9. Li Y, Shah KW, Li W, Xiong T. Experimental investigation on indoor thermal environment improvement and energy-saving of electrochromic window under Singapore’s tropical climate. J Build Eng. 2023;73:106779.

[DOI]
10. Teixeira H, Rodrigues AM, Aelenei D, Gomes MG. Simulation-based evaluation of the impact of an electrochromic glazing on the energy use and indoor comfort of an office room. Energies. 2024;17(9):2110.

[DOI]
11. Jain S, Wienold J, Lagier M, Schueler A, Andersen M. Perceived glare from the Sun behind tinted glazing: Comparing blue vs. Color-neutral tints. Build Environ. 2023;234:110146.

[DOI]
12. Tzempelikos A, Athienitis AK. The impact of shading design and control on building cooling and lighting demand. Sol Energy. 2007;81(3):369-382.

[DOI]
13. DeForest N, Shehabi A, Selkowitz S, Milliron DJ. A comparative energy analysis of three electrochromic glazing technologies in commercial and residential buildings. Appl Energy. 2017;192:95-109.

[DOI]
14. Assimakopoulos MN, Tsangrassoulis A, Santamouris M, Guarracino G. Comparing the energy performance of an electrochromic window under various control strategies. Build Environ. 2007;42(8):2829-2834.

[DOI]
15. Lee ES, Tavil A. Energy and visual comfort performance of electrochromic windows with overhangs. Build Environ. 2007;42(6):2439-2449.

[DOI]
16. Sun Y, Hao Y, Wang D, Wang W, Deng S, Qi H, et al. A predictive control strategy for electrochromic glazing to balance the visual and thermal environmental requirements: Approach and energy-saving potential assessment. Renew Energy. 2022;194:334-348.

[DOI]
17. Isaia F, Fiorentini M, Serra V, Capozzoli A. Enhancing energy efficiency and comfort in buildings through model predictive control for dynamic façades with electrochromic glazing. J Build Eng. 2021;43:102535.

[DOI]
18. Ganji Kheybari A, Steiner T, Liu S, Hoffmann S. Controlling switchable electrochromic glazing for energy savings, visual comfort and thermal comfort: A model predictive control. CivilEng. 2021;2(4):1019-1051.

[DOI]
19. Sun Y, Li Y, Xu W, Wang W, Wei W, Zhang C. A glare predictive control strategy for split-pane electrochromic windows: Visual comfort and energy-saving assessment. Renew Energy. 2023;218:119259.

[DOI]
20. Alkhatib H, Lemarchand P, Norton B, O’Sullivan DTJ. Comparative simulations of an electrochromic glazing and a roller blind as controlled by seven different algorithms. Results Eng. 2023;20:101467.

[DOI]
21. Riganti M, Li Castri G, Serra V, Manca M, Favoino F. Energy saving potential of advanced dual-band electrochromic smart windows for office integration. Energy Build. 2025;327:115084.

[DOI]
22. Deru M, Field K, Studer D, Benne K, Griffith B, Torcellini P, et al. U.S. Department of Energy commercial reference building models of the national building stock. Golden, CO: National Renewable Energy Laboratory; 2011 Feb. Report No.: NREL/TP-5500-46861. Available from: https://oasis.library.unlv.edu/renew_pubs/44/
23. Wang S, Jiang T, Meng Y, Yang R, Tan G, Long Y. Scalable thermochromic smart windows with passive radiative cooling regulation. Science. 2021;374(6574):1501-1504.

[DOI] [PubMed]
24. Lee D, Choi JS, Kim YJ, Chae YT. Dynamic glazing for a sustainable building future: An in-situ performance evaluation of electrochromic windows in cooling operation. J Build Eng. 2026;120:115574.

[DOI]

Copyright

© The Author(s) 2027. This is an Open Access article licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing, adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Publisher’s Note

Science Exploration remains a neutral stance on jurisdictional claims in published maps and institutional affiliations. The views expressed in this article are solely those of the author(s) and do not reflect the opinions of the Editors or the publisher.

Share And Cite

Science Exploration Style

Chen PY, Tian X, Long Y. Load-responsive control of electrochromic windows for commercial buildings: Global cooling benefits and climate-dependent energy trade-offs. Smart Mater Devices. 2027;3:202657. https://doi.org/10.70401/smd.2026.0053