Published Papers

Volume 32 - Issue 3 (Theme Issue)

The role of shading and window-to-wall ratio on the energy-saving potential and daylighting associated with thermochromic smart windows

Yin Hoi Chan, Thilhara Tennakoon, Yi Zhang, Sau Chung Fu, Ka Chung Chan, Chili Wu and Christopher Yu Hang Chao
Pages: 1-13Published: 23 Apr 2026
DOI: 10.33430/V32N3THIE-2024-0060
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CHAN YH, TENNAKOON T, ZHANG Y, FU SC, CHAN KC, WU C, CHAO YH, The role of shading and window-to-wall ratio on the energy-saving potential and daylighting associated with thermochromic smart windows, HKIE Transactions, Vol. 32, No. 3 (Theme Issue), 2026, 10.33430/V32N3THIE-2024-0060

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Abstract:

Thermochromic smart windows (TSWs), which regulate their properties by switching reversibly between clear and tinted states based on the temperature variation, can passively alleviate energy wastage caused by energy-inefficient fenestration. This study on the energy-saving potential of TSWs not only provides new insights into the practical application but also their integration into modern building designs. Unlike previous studies that compare TSW performance using their optical indices, this work comprehensively evaluated the energy-saving and daylight performance of three advanced TSW materials‑hydrogel, perovskite, and vanadium dioxide—using self-created EnergyPlus simulation models. The impacts of orientation, window-to-wall ratio (WWR), and roller shade (RS) on TSW performance were assessed under Hong Kong’s cooling-dominated climate. The perovskite-TSW demonstrated superior energy-saving potential, achieving power savings of 11‑35% while ensuring maximum working hours (75-89%) with desirable daylighting (UDI500-2000). The study identified a range of WWR between 0.34 and 0.67 where balanced illumination between the centre and rear of the office were achieved with different windows across orientations. The findings suggest that high-performance glazing like TSWs can potentially negate the need for RS, and demonstrate the feasibility of adopting a multi-TSW configuration for different orientations, offering more efficient and optimistic solutions for building energy management.

Keywords:

Building energy simulation; Thermochromic smart window; Perovskite; Hydrogel; Vanadium dioxide

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