Smart Colored Window Technology

Improving Users' Comfort with an Interdisciplinary Approach



Traditional architecture can be a valuable source of inspiration for designers. Sustainable design concepts in traditional architecture have been explored by architects based on the regional environment for many years. Colored glass has been the main element of Orosi structures in traditional Persian architecture utilized in building facades. The colored glass used in Orosi structures controls the sunlight penetration and creates dramatic light patterns in the interior space of the building.

Smart windows, a promising category of advanced building technologies, have the ability to change their properties by responding to the variations in environmental conditions and thereby offer considerable energy savings. Colored glass windows, on the other hand, can improve occupants’ visual comforts by controlling solar discomfort effects such as glare and overloading light. The contemporary smart window technologies such as electrochromic or thermochromic glazing and photovoltaic technologies operate by selectively blocking and transmitting visual and near-infrared (NIR) solar radiation. The studies on these technologies are mainly centered on energy saving and are only designed in a limited color range, undermining the aesthetic aspects and users’ comfort. To the best of our knowledge, smart colored windows that combine energy-saving capabilities with enhanced users’ visual comfort are not sufficiently explored.

This study aims to develop a series of smart, clear coatings for window glass panes that could turn to different colors/shades by responding to the intensity of the exposed solar radiation. Thus, the proposed advanced smart window technology not only can reduce energy consumption by controlling the amount of transmitted daylight but can improve the visual comfort metrics through changing colors.

The smart coatings developed under this study will be applied on glass substrates and will be extensively studied for their optical properties (UV-Vis spectroscopy), simulation of a building envelope utilized for proposed technology using Rhino software, and evaluation of performance by measuring visual and thermal comfort metrics using ClimateStudio plug-in. The novel smart window technology is a promising alternative to the current products in the market.


Photo of Negar Heidari Matin

Negar Heidari Matin

University of Oklahoma

Photo of Seyed Mojtaba Mirabedini

Seyed Mojtaba Mirabedini

Visiting Professor at Eastern Michigan University

Eastern Michigan University

Photo of Zhina Rashidzadeh

Zhina Rashidzadeh

Ph.D. student at Gibbs College of Architecture

University of Oklahoma


1. Introduction

Traditional architecture can be a valuable source of inspiration for designers (Matin & Eydgahi, 2019). Sustainable design concepts in traditional architecture have been explored by architects based on the regional environment for many years. Intense sunlight in the Middle East has created the tradition of controlling daylight by shading screens in this region (Sherif, El-zafarany, & Arafa, 2012). Orosi structures constructed from wooden latticed with colored glasses are considered the main shading screen in ancient Persian architecture as shown in Figure 1 (Haghshenas, Bemanian & Ghiabaklou, 2016). Colored glasses used in Orosi create dramatic light patterns in the interior spaces of the building, which can affect the physical and psychological health of occupants (Hosseini, Mohammadi, Rosemann, & Schroder, 2018)

Figure 1. Orosi Structure used in Nasir-ol-Molk Mosque, Shiraz, Iran [Taken by Hesam Montazeri retrieved from]
Figure 1. Orosi Structure used in Nasir-ol-Molk Mosque, Shiraz, Iran [Taken by Hesam Montazeri retrieved from]

Regarding the psychological effects, the transmitted sunlight in various colors can relieve claustrophobia, depression, agitation, fatigue, and seasonal affective disorder; in addition, it can trigger human circadian systems more effectively than standard float glasses (Jalili & Nazari, 2016; Feridonzadeh & Sabri, 2014; Makani, Khorram, & Ahmadipur, 2012). Concerning the physical effects, the colored glasses in Orosi decrease the transmission of visible light and reduce the transmission of ultraviolet (UV) and Infrared (IR) wavelengths. UV and IR are considered harmful to human skin and furniture materials, and paint up to 60% compared to the standard float glasses (Haghshenas, Bemanian, & Ghiabaklou, (2017); Haghshenas, Bemanian & Ghiabaklou, 2016; Hosseini, Hosseini, & Heiranipour, 2020). It should be noted that the visual and thermal performance of different colored glasses, such as red, green, yellow, and blue glasses, in reducing the transmittance of visible light, UV, IR are not identical (Javani, Javani & Moshkforoush, 2010; Nabavi, Ahmad & Tee Goh, 2013).

Due to advanced chemical activities, smart windows enable the facade systems to continuously change their transparency in response to environmental stimuli, occupants' preferences and needs to improve facade visual performance (Heidari Matin & Eydgahi, 2020). Among all the smart, responsive options such as electrochromic (Geoff, Angus, Matthew, & Michael, 2016; Granqvist, 2016; Gugliermetti & Bisegna, 2005), thermochromic (Seyfouri & Binions, 2017), gasochromic (Feng, Zou, Gao, Wu, Shen, & Li, 2017), liquid crystal (Khaligh, Liew, Han, Abukhdeir, & Goldthorpe, 2015) and so forth, photochromic windows are a promising option in the development of smart windows (Meng, Wang, Jiang, Wang, & Xie, 2013; Wu, Zhao, Huang, & Lim, 2017).

Photochromic materials are a type of smart material that could change color upon exposure to light. These materials can be used to design colored glass to create smart windows that directly impact saving energy and increase users' visual comfort in buildings. Photochromism is simply defined as a light-induced reversible change of color (Dürr & Bouas-Laurent, 2003). From a chemical perspective, Photochromism is the reversible transformation of a chemical species between two forms by absorbing electromagnetic radiation, where the two forms have different absorption spectra (Dürr & Bouas-Laurent, 2003).

Thus, utilizing smart materials in the design of colored glass can provide an innovative opportunity to express the ancient concept of colored Orosi or similar structures in modern architecture. This study aims to develop a series of smart clear coatings for window glass panes that turn to different colors/shades through the intensity of the exposed solar radiation. The smart coatings colors include red, medium blue, and yellow and their dual and triple combinations of three main colors. Then, colorimeter tests such as (UV-VIS) spectroscopy test, L*, a*, b* color coordinate, and RGB determination tests were conducted to characterize the optical characteristics of developed photochromic glasses.

Next, RGB data obtained from RGB determination tests have been utilized for simulating photochromic glasses through the Honeybee-plug in for the Grasshopper in the Rhino software. The visual performance of developed photochromic glasses used in three window design scenarios was evaluated using Daylight Glare Probability (DGP) and Useful Daylight Illuminance (UDI) metrics on 25th May and 16th September at 12:00 PM and 6:00 PM in Ann Arbor, MI. An office room with a smart facade was simulated parametrically to test the proposed photochromic glasses for different design scenarios. The visual performance evaluation was repeated for four main facade directions: South, East, North, and West.

The presented results reveal the influence of multi-color photochromic windowpanes on controlling discomfort glare and improving useful indoor illuminance. In addition, the findings of this study show how inspiring from ancient architecture and expressing with advanced technology can improve occupant's comfort.

2. Materials and Paint Samples Preparation

Photochromic dyes, including red (PDF200R), medium blue (PDF200MB), and yellow (PDF200Y), were obtained from QCR Solutions Corp. First, specific amounts of each dyestuff were dissolved in Tetrahydrofuran (THF) solvent for

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3. Colorimeters

To specify the behavior of photochromic glass samples in various sun irradiation conditions, different methods were utilized including ultraviolet-visible (UV-VIS) spectroscopy (Heidari Matin, Eydgahi, Zareanshahraki, 2021), color-coordinate measurements (Mamedbeili, I.

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4. Visual Comfort and Photochromic Glasses

To determine photochromic-coated glasses' visual performance, Grasshopper plug-in for Rhinoceros software was utilized to simulate one pane and two-panes windows made of photochromic-coated glasses applied to a simple office room

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5. Results and Fundings

Figures 11 and 12 present how the different colors coating glasses affect the percentage of daylight glare probability (DGP) in three windowpane scenarios during office hours on 25th May and

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6. Conclusion

This study focused on the visual performance of a series of smart photochromic coated glasses, including red, medium blue, and yellow, and their dual and triple combinations of three main

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I would like to express my sincere gratitude to the Gibbs College of Architecture at the University of Oklahoma. This study was sponsored by the Gibbs College of Architecture’s Program for Research Enhancement (PRE). I would also like to thank Dr. Mirabedini and Dr. ZareanShahraki form the Coating Institute at Eastern Michigan University who provided us photochromic samples. And at the end, I would like to thank OU PhD Student Zhina Rashidizade who assist us in data collection.

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Dürr, H. & Bouas-Laurent, H. (2003). Photochromism: Molecules and Systems. Elsevier.

Feng, W. Zou, L., Gao, G, Wu, G., Shen, J. and. Li, W. (2016). Gasochromic smart window: optical and thermal properties, energy simulation and feasibility analysis, Sol. Energy Mater. Sol. Cells. 144, 316–323, doi: 10.1016/j.solmat.2015.09.029.

Feridonzadeh, H., & Cyrus Sabri, R., (2014). Window Design in Ardabil Traditional Houses for Conservation of Energy. Armanshahr Architecture & Urban Development. 7, 1-11.

Geoff, S., Angus, G., Matthew A., & Michael, C. (2016). Nanophotonics-enabled smart windows, buildings and wearables,” Nanophotonics. 5(1), pp. 55–73.

Granqvist, C. G. (2016). Electrochromics and Thermochromics: Towards a New Paradigm for Energy Efficient Buildings,” Mater. Today Proc.3, S2–S11, doi: 10.1016/j.matpr.2016.01.002.

Gugliermetti F. & Bisegna, F. (2005). A model study of light control systems operating with Electrochromic Windows,” Light. Res. Technol.37, (1), 3–19, doi: 10.1191/1365782805li123oa.

Haghshenas, M., Bemanian M. & Ghiabaklou, Z. (2016). Analysis the Criteria of Solar Trasmittance from Stained Glasses Used in Some of the Orosis from Safavid Dynasty. Journal of Color Science and Technology 10 (2016) 55–64.

Haghshenas, M., Bemanian, M., & Ghiabaklou, Z. (2017). Investigating the Effect of Changing the Transmitted Light’s Color on Thermal and Visual Comfort. Naqshejahan. 6-4, 013–025.

Heidari Matin, Eydgahi, Zareanshahraki, 2021. Interdisciplinary Educational Modules: Using Smart Colored Windows in Responsive Façade Systems. Technology Interface International Journal, 21(2),11-20.

Heidari Matin, N., and A. Eydgahi. 2019. “Factors Affecting the Design and Development of Responsive Facades: A Historical Evolution.” Intelligent Buildings International 11: 1–14. doi:10.1080/17508975.2018.1562414.

Heidari Matin, N., and A. Eydgahi. 2020. “Technologies Used in Responsive Facade Systems: A Comparative Study.” Intelligent Buildings International 12 (4): 1–20. doi:10.1080/17508975.2019.1577213.

Hosseini, S. M., Mohammadi, M., Rosemann, A., and Schroder, T. (2018). Quantitative Investigation through climate-based daylight metrics of visual comfort due to colorful glass and orsi windows in Iranian architecture. Journal of daylighting, 5, 21–33.

Hosseini, S.N., Hosseini, S.M., HeiraniPour, M. (2020). The Role of Orosi’s Islamic Geometric Patterns in the Building Façade Design for Improving Occupants’ Daylight Performance. Journal of Daylighting. 7, 201-22.

Hosseinzadeh Khaligh, H., Liew, K., Han, Y., Abukhdeir, N. M., & Goldthorpe, I. A., (2014). Silver nanowire transparent electrodes for liquid crystal-based smart windows. Sol. Energy Mater. Sol. Cells, 132, 337–341, doi: 10.1016/j.solmat.2014.09.006.

Jalili, T. & Nazari Poorgol Sefidi L. (2016). The survey of the color and light psychological effects in Iranian traditional architecture (case study: tabataba’ees house). IIOABJ,7,469–483.

Javani, A., Javani, Z., & Moshkforoush, M.R. (2010). Studying Relationship between Application of Light and Iranian Pattern of Thought (the Iranians ideology). The proceeding of color and light in architecture, 2010, pp. 39–46, Knemesi, Verona, Italy.

Makani, V., Khorram, A., & Ahmadipur, Z., (2012). Secrets of Light in Traditional Houses of Iran, International Journal of Architecture and Urban Development. 2, 45–50.

Mamedbeili, I., Cakiroglu, F., Bektas, G., Riza, D., Hacizade, F. (2013). Reflection, Transmission and Color Measurement System for the Online Quality Control of Float Glass Coating Process. Proceedings of SPIE - The International Society for Optical Engineering, Munich, Germany. DOI: 10.1117/12.2020763

Mardaljevic, J. & Nabil, A. (2005). Useful daylight illuminance: A new paradigm for assessing daylight in buildings. Lighting research and technology. 37(1), 41–59.

Matin, N. H., & Eydgahi, A. (2019). Learning Modules for Geometric Pattern Identification and Mathematical Modeling of Facade Systems. In 2019 ASEE Annual Conference & Exposition.

Meng, Q., G. Wang, H. Jiang, Y. Wang, and S. Xie, (2013). Preparation of a fast photochromic ormosil matrix coating for smart windows,” J. Mater. Sci.. 48 (17) 5862–5870, Sep. 2013, doi: 10.1007/s10853-013-7382-x.

Nabavi, F., Ahmad, Y. & Tee Goh, A. (2013). Daylight design strategies: A lesson from Iranian traditional houses, Mediterranean Journal of Social Sciences. 4, 97-103.

Nabil, A., & Mardaljevic, J. (2006). Useful daylight illuminances: A replacement for daylight factors. Energy and Buildings, 38, 905–913.

Reinhart, C.F. & Weisman, L. (2012). The daylit area: Correlating architectural student assessments with current and emerging daylight availability metric. Building and Environment, 50, 155–164.

Seyfouri M. M. & Binions, R. (2016). Sol-gel approaches to thermochromic vanadium dioxide coating for smart glazing application,” Sol. Energy Mater. Sol. Cells, 159, 52–65, doi: 10.1016/j.solmat.2016.08.035.

Sherif, A., El-Zafarany, A., and Arafa, R. (2012). External perforated window solar screens: The effect of screen depth and perforation ratio on energy performance in extreme desert environments. Energy and Buildings, 52, 1–10.

Wu, L. Y. L., Zhao, Q., Huang, H. & Lim, R. J. (2017). Sol-gel based photochromic coating for solar responsive smart window. Surf. Coat. Technol. 320, 601–607, doi: 10.1016/j.surfcoat.2016.10.074.