Sequential optical modulation in smart glazing: A hierarchical thermochromic strategy for climate-adaptive building envelopes

Shuangdui Wu; Bingqian Ren; Yucan Peng; Borong Lin

doi:10.59717/j.xinn-energy.2026.100189

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Sequential optical modulation in smart glazing: A hierarchical thermochromic strategy for climate-adaptive building envelopes

1.
Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
2.
Key Laboratory of Eco Planning & Green Building, Ministry of Education, Tsinghua University
3.
College of Architecture and Environment, Sichuan University, Chengdu 610065, China

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Corresponding authors: yucan.peng@pku.edu.cn (Y. Peng); linbr@mail.tsinghua.edu.cn (B. Lin)
Received Date: May 10, 2026

Accepted Date: August 31, 2026

Published Online: October 15, 2026

The Innovation Energy https://doi.org/10.59717/j.xinn-energy.2026.100189 | Cite this article

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1. A hierarchical thermochromic window sequentially regulates near-infrared (NIR) and visible light.
  
  Across 3,600+ global administrative units, 96% and 79% exceeded 30% cooling and total energy savings.
  
  Sequential switching balances cooling, heating, and lighting while keeping over-illumination below 10%.
  
  A vanadium dioxide (VO₂)-hydrogel prototype verified staged optical switching over 50 thermal cycles.

ABSTRACT

ABSTRACT

Thermochromic glazing can passively regulate solar gains, but single-response systems often trade solar-heat rejection against daylight preservation. Here we propose a hierarchical response composite window that sequentially activates near-infrared (NIR) and visible-light modulation: a 28 °C VO₂ layer first limits NIR heat transmission, whereas a 40 °C hydrogel introduces stronger broadband attenuation only under intense solar thermal stress. Within a simulation-first, prototype-verified reverse-design framework, literature-derived optical spectra were implemented in EnergyPlus, validated against full-scale measurements (indoor-temperature RMSE = 0.45 °C), and assessed across more than 3600 global administrative units, 370 Chinese municipal-level units, and representative hot, mixed, and cold climates. Globally, 96% and 79% of valid units achieved cooling and total energy saving rates above 30%, respectively. In China, the composite window delivered mean cooling and total energy saving rates of 32.18% and 11.45%, with 84.1% of units exceeding 20% cooling savings. Matched-parameter controls further showed that sequencing improves the annual balance among cooling, heating, and lighting rather than maximizing cooling savings alone. It also suppressed over illumination to below 10% and improved useful daylight availability. Prototype spectra verified a VO₂-dominated NIR-first state followed by hydrogel-dominated broadband attenuation, while more than 50 thermal cycles confirmed short-term reversible operation. These results establish sequential thermochromic regulation as a climate-aware design principle for reconciling energy and daylighting demands in adaptive glazed façades.
- Thermochromic smart window /
- Visible–near-infrared decoupling /
- Climate-adaptive building envelope /
- Hierarchical optical modulation /
- Building energy simulation

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Wu S., Ren B., Peng Y., et al. (2026). Sequential optical modulation in smart glazing: A hierarchical thermochromic strategy for climate-adaptive building envelopes. The Innovation Energy 3:100189. https://doi.org/10.59717/j.xinn-energy.2026.100189

Wu S., Ren B., Peng Y., et al. (2026). Sequential optical modulation in smart glazing: A hierarchical thermochromic strategy for climate-adaptive building envelopes. The Innovation Energy 3:100189. https://doi.org/10.59717/j.xinn-energy.2026.100189

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Sequential optical modulation in smart glazing: A hierarchical thermochromic strategy for climate-adaptive building envelopes

GRAPHICAL ABSTRACT

PUBLIC SUMMARY

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