The Potential of Static and Thermochromic Window Films for Energy Efficient Building Renovations





Glazing, Solar heat rejection, Window films, Thermochromic, Energy savings


The type of glazing implemented in a building plays an important role in the heat management of a building. Solar heat entering through glazing causes overheating of interior spaces and increases building’s cooling load. In this work, the energy saving potential of window films based on Cholesteric Liquid Crystals (CLC) is explored. This emerging technology allows for the fabrication of static and thermochromic solar heat rejecting window films and can provide a simple renovation solution towards energy efficient buildings. Simulations on a model office showed that static CLC-based window films can save up to 29% on a building’s annual energy use in warm climates. In climates with distinct summer and winter seasons, static solar heat rejecting windows films cause an additional heating demand during winters, which reduces the annual energy savings. In these climates, the benefit of thermochromic CLC-based window films becomes evident and an annual energy saving up to 22% can be achieved.

How to Cite

Kragt, S., van den Ham, E. R., Sentjens, H., Schenning, A. P. H. J., & Klein, T. (2022). The Potential of Static and Thermochromic Window Films for Energy Efficient Building Renovations. Journal of Facade Design and Engineering, 10(2), 87–104.




Al-Obaidi, K. M., Ismail, M., & Rahman, A. M. A. (2014). A review of skylight glazing materials in architectural designs for a better indoor environment. Modern Applied Science, 8(1), 68–82. Retrieved from

Al Dakheel, J., & Aoul, K. T. (2017). Building applications, opportunities and challenges of active shading systems: A state-of-the-art review. Energies, 10(10), 1672–1704. Retrieved from

Arbab, S., Matusiak, B., Martinsen, F., & Hauback, B. (2017). The impact of advanced glazing on colour perception. Journal of the International Colour Association, 17, 50–68.

Baetens, R., Jelle, B. P., & Gustavsen, A. (2010). Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review. Solar Energy Materials and Solar Cells, 94(2), 87–105. Retrieved from

Bahadori-Jahromi, A., Rotimi, A., Mylona, A., Godfrey, P., & Cook, D. (2017). Impact of window films on the overall energy consumption of existing UK hotel buildings. Sustainability (Switzerland), 9(5), 1–23. Retrieved from

Balamurugan, R., & Liu, J. H. (2016). A review of the fabrication of photonic band gap materials based on cholesteric liquid crystals. Reactive and Functional Polymers, 105, 9–34. Retrieved from

Broer, D. J., Mol, G. N., Haaren, J. A. M. M. Van, & Lub, J. (1999). Photo-Induced Diffusion in Polymerizing Chiral-Nematic Media. Advanced Materials (Deerfield Beach, Fla.), 11(7), 573–578. Retrieved from<573::AID-ADMA573>3.0.CO;2-E

Brzezicki, M. (2021). A systematic review of the most recent concepts in smart windows technologies with a focus on electrochromics. Sustainability, 13(17), 9604–9628. Retrieved from

Calvi, L., Leufkens, L., Yeung, C. P. K., Habets, R., Mann, D., Elen, K., … Buskens, P. (2021). A comparative study on the switching kinetics of W/VO2 powders and VO2 coatings and their implications for thermochromic glazing. Solar Energy Materials and Solar Cells, 224(February), 110977–110986. Retrieved from

Casini, M. (2014). Smart windows for energy efficiency of buildings. Proceesings of the Second International Conference on Advances in Civil, Structural and Environmental Engineering, 2(1), 273–281. Retrieved from

Casini, M. (2018). Active dynamic windows for buildings: A review. Renewable Energy, 119, 923–934. Retrieved from

Chen, X., Zhang, X., & Du, J. (2019). Exploring the effects of daylight and glazing types on self-reported satisfactions and performances: a pilot investigation in an office. Architectural Science Review, 62(4), 338–353. Retrieved from

Clear, R. D., Inkarojrit, V., & Lee, E. S. (2006). Subject responses to electrochromic windows. Energy and Buildings, 38(7), 758–779. Retrieved from

Cui, Y., Ke, Y., Liu, C., Chen, Z., Wang, N., Zhang, L., … Long, Y. (2018). Thermochromic VO2 for Energy-Efficient Smart Windows. Joule, 2(9), 1707–1746. Retrieved from

Curcija, C., Goudey, H., & Mitchell, R. (2017). Low-e Applied Film Window Retrofit for Insulation and Solar Control. Retrieved from

Day, J. K., Futrell, B., Cox, R., & Ruiz, S. N. (2019). Blinded by the light: Occupant perceptions and visual comfort assessments of three dynamic daylight control systems and shading strategies. Building and Environment, 154(February), 107–121. Retrieved from

DeForest, N., Shehabi, A., Selkowitz, S., & Milliron, D. J. (2017). A Comparative Energy Analysis of Three Electrochromic Glazing Technologies in Commercial and Residential Buildings. Applied Energy, 192, 95–109. Retrieved from

Dennis, A. (2018). Global trends in thermal comfort in air conditioned and naturally ventilated offices in six climates. UC Berkeley. UC Berkeley. Retrieved from

Dierking, I. (2014). Chiral Liquid Crystals: Structures, Phases, Effects. Symmetry, 6, 444–472. Retrieved from

Ding, G., & Clavero, C. (2017). Silver-Based Low-Emissivity Coating Technology for Energy-Saving Window Applications. In N. Nikitenkov (Ed.), Modern Technologies for Creating the Thin-film Systems and Coatings (pp. 409–431). IntechOpen. Retrieved from

Duan, M., Cao, H., Wu, Y., Li, E., Wang, H., Wang, D., … Yang, H. (2017). Broadband reflection in polymer stabilized cholesteric liquid crystal films with stepwise photo-polymerization. Physical Chemistry Chemical Physics : PCCP, 19, 2353–2358. Retrieved from

Dussault, J. M., Gosselin, L., & Galstian, T. (2012). Integration of smart windows into building design for reduction of yearly overall energy consumption and peak loads. Solar Energy, 86(11), 3405–3416. Retrieved from

European Comission. (2020). A Renovation Wave for Europe - greening our buildings, creating jobs, improving lives. European Commission. Retrieved from

Fan, B., Vartak, S., Eakin, J. N., Faris, S. M., Fan, B., Vartak, S., … Faris, S. M. (2008). Broadband polarizing films by photopolymerization-induced phase separation and in situ Swelling Broadband polarizing films by photopolymerization-induced phase separation and in situ Swelling. Applied Physics Letters, 92, 061101–061105. Retrieved from

General Services Administration. (2014). Electrochromic and Thermochromic Windows. Public Building Services (Vol. GPG-010). Retrieved from

Glass for Europe. (2019). Glazing Potential - Energy Savings & CO2 emission reduction. Retrieved from

Gonzaga, E. R. (2009). Role of UV light in photodamage, skin aging, and skin cancer: Importance of photoprotection. American Journal of Clinical Dermatology, 10(SUPPL. 1), 19–24. Retrieved from

Guo, R., Li, K., Cao, H., Wu, X., Wang, G., Cheng, Z., … Yang, H. (2010). Chiral polymer networks with a broad reflection band achieved with varying temperature. Polymer, 51(25), 5990–5996. Retrieved from

Hui, S. C. M., & Kwok, M. K. (2006). Study of thin films to enhance window performance in buildings. In Proceedings of the Sichuan-Hong Kong Joint Symposium 2006 (pp. 158–167).

IEA. (2018). The Future of Cooling Opportunities for energy- efficient air conditioning. Retrieved from

IEA. (2019). 2019 Global Status Report for Buildings and Construction. UN Enviroment programme (Vol. 224). Retrieved from

Jelle, B. P., Hynd, A., Gustavsen, A., Arasteh, D., Goudey, H., & Hart, R. (2012). Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities. Solar Energy Materials and Solar Cells, 96(0), 1–28. Retrieved from

Jelle, B. P., Kalnæs, S. E., & Gao, T. (2015). Low-emissivity materials for building applications: A state-of-the-art review and future research perspectives. Energy and Buildings, 96(7491), 329–356. Retrieved from

Ke, Y., Chen, J., Lin, G., Wang, S., Zhou, Y., Yin, J., … Long, Y. (2019). Smart Windows: Electro-, Thermo-, Mechano-, Photochromics, and Beyond. Advanced Energy Materials, 9(39), 1–38. Retrieved from

Ke, Y., Zhou, C., Zhou, Y., Wang, S., Chan, S. H., & Long, Y. (2018). Emerging Thermal-Responsive Materials and Integrated Techniques Targeting the Energy-Efficient Smart Window Application. Advanced Functional Materials, 28(22), 1800113–1800130. Retrieved from

Khandelwal, H., Loonen, R. C. G. M., Hensen, J. L. M., Debije, M. G., & Schenning, A. P. H. J. (2015). Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings. Scientific Reports, 5, 11773–11782. Retrieved from

Khandelwal, H., Loonen, R. C. G. M., Hensen, J. L. M., Schenning, A. P. H. J., & Debije, M. G. (2014). Application of broadband infrared reflector based on cholesteric liquid crystal polymer bilayer film to windows and its impact on reducing the energy consumption in buildings. Journal of Materials Chemistry A, 2(35), 14622. Retrieved from

Khandelwal, H., Schenning, A. P. H. J., & Debije, M. G. (2017). Infrared Regulating Smart Window Based on Organic Materials. Advanced Energy Materials, 7(14), 1–18. Retrieved from

Khandelwal, H., Timmermans, G., Debije, M. G., & Schenning, A. P. H. J. (2016). Dual electrically and thermally responsive broadband reflectors based on polymer network stabilized chiral nematic liquid crystals: the role of crosslink density. Chemical Communications, 52(66), 10109–10112. Retrieved from

Khandelwal, H., Van Heeswijk, E. P. A., Schenning, A. P. H. J., & Debije, M. G. (2019). Paintable temperature-responsive cholesteric liquid crystal reflectors encapsulated on a single flexible polymer substrate. Journal of Materials Chemistry C, 7(24), 7395–7398. Retrieved from

Kim, D.-Y., Lee, K. M., White, T. J., & Jeong, K.-U. (2018). Cholesteric liquid crystal paints: in situ photopolymerization of helicoidally stacked multilayer nanostructures for flexible broadband mirrors. NPG Asia Materials, 10, 1061–1068. Retrieved from

Kim, G., & Kim, J. T. (2010). UV-ray filtering capability of transparent glazing materials for built environments. Indoor and Built Environment, 19(1), 94–101. Retrieved from

Kim, J., Baek, S., Park, J. Y., Kim, K. H., & Lee, J. (2021). Photonic Multilayer Structure Induced High Near-Infrared (NIR) Blockage as Energy‐Saving Window. Small, 17, 2100654–2100662. Retrieved from

Knoop, M., Stefani, O., Bueno, B., Matusiak, B., Hobday, R., Wirz-Justice, A., … Norton, B. (2020). Daylight: What makes the difference? Lighting Research and Technology, 52(3), 423–442. Retrieved from

Komanduri, R. K., Lawler, K. F., & Escuti, M. J. (2013). Multi-twist retarders: broadband retardation control using self-aligning reactive liquid crystal layers. Optics Express, 21(1), 404–420. Retrieved from

Kraemer, M., & Baur, T. (2019). Achromatic devices in polarization optics. Optical Engineering, 58(8), 082406-1–15.

Kragt, A. J. J., van Gessel, I. P. M., Schenning, A. P. H. J., & Broer, D. J. (2019). Temperature-Responsive Polymer Wave Plates as Tunable Polarization Converters. Advanced Optical Materials, 7(21), 1901103–1901109. Retrieved from

Kragt, A. J. J., Zuurbier, N. C. M., Broer, D. J., & Schenning, A. P. H. J. (2019). Temperature-Responsive, Multicolor-Changing Photonic Polymers. ACS Applied Materials & Interfaces, 11(31), 28172–28179. research-article. Retrieved from

Li, C., Tan, J., Chow, T. T., & Qiu, Z. (2015). Experimental and theoretical study on the effect of window films on building energy consumption. Energy and Buildings, 102, 129–138. Retrieved from

Liang, Y. (2015). Liquid Crystals. Retrieved from

Liu, C., Fuh, A. Y., Chen, Y., Chen, J., Chen, L., Chen, J., & Chen, L. (2016). Research progress of cholesteric liquid crystals with broadband reflection characteristics in application of intelligent optical modulation materials ∗. Chinese Physical B, 25(9), 096101–096111. Retrieved from

Long, L., & Ye, H. (2014). How to be smart and energy efficient: A general discussion on thermochromic windows. Scientific Reports, 4, 6427–6436. Retrieved from

Mann, D., Yeung, C., Habets, R., Vroon, Z., & Buskens, P. (2021). Building energy simulations for different building types equipped with a high performance thermochromic smart window. IOP Conference Series: Earth and Environmental Science, 855(1), 12001-12005. Retrieved from

Mann, D., Yeung, C., Habets, R., Vroon, Z., & Buskens, P. (2020). Comparative Building Energy Simulation Study of Static and Thermochromically Adaptive Energy-Efficient Glazing in Various Climate Regions. Energies, 13, 2842–2859.

Marchwinski, J. (2014). Architectural evaluation of switchable glazing technologies as sun protection measure. Energy Procedia, 57, 1677–1686. Retrieved from

Mardaljevic, J., Kelly Waskett, R., & Painter, B. (2016). Neutral daylight illumination with variable transmission glass: Theory and validation. Lighting Research and Technology, 48(3), 267–285. Retrieved from

Mcconney, M. E., Tondiglia, V. P., Hurtubise, J. M., Natarajan, L. V, White, T. J., & Bunning, T. J. (2011). Thermally Induced , Multicolored Hyper-Reflective Cholesteric Liquid Crystals. Advanced Materials, 23, 1453–1457. Retrieved from

Mitov, M., Nouvet, E., & Dessaud, N. (2004). Polymer-stabilized cholesteric liquid crystals as switchable photonic broad bandgaps. The European Physical Journal E, 15(4), 413–419. Retrieved from

Mitov, M. (2012). Cholesteric Liquid Crystals with a Broad Light Reflection Band. Advanced Materials, 24(47), 6260–6276. Retrieved from

Mohelníková, J., & Altan, H. (2009). Evaluation of optical and thermal properties of window glazing. WSEAS Transactions on Environment and Development, 5(1), 86–93.

Ortiz-Gutiérrez, M., Olivares-Pérez, A., & Sánchez-Villicaña, V. (2001). Cellophane film as half wave retarder of wide spectrum. Optical Materials, 17(3), 395–400. Retrieved from

Painter, B., Irvine, K. N., Waskett, R. K., & Mardaljevic, J. (2016). Evaluation of a mixed method approach for studying user interaction with novel building control technology. Energies, 9(3), 1–23. Retrieved from

Pérez-Lombard, L., Ortiz, J., & Pout, C. (2008). A review on buildings energy consumption information. Energy and Buildings, 40(3), 394–398. Retrieved from

Piccolo, A., & Simone, F. (2009). Effect of switchable glazing on discomfort glare from windows. Building and Environment, 44(6), 1171–1180. Retrieved from

Prieto, A., Knaack, U., Klein, T., & Auer, T. (2017). 25 Years of cooling research in office buildings: Review for the integration of cooling strategies into the building façade (1990–2014). Renewable and Sustainable Energy Reviews, 71(May 2015), 89–102. Retrieved from

Ranjkesh, A., & Yoon, T. H. (2019). Fabrication of a Single-Substrate Flexible Thermoresponsive Cholesteric Liquid-Crystal Film with Wavelength Tunability. ACS Applied Materials and Interfaces, 11(29), 26314–26322. research-article. Retrieved from

Ranjkesh, A., & Yoon, T. H. (2021). Ultrathin, transparent, thermally-insulated, and energy-efficient flexible window using coatable chiral-nematic liquid crystal polymer. Journal of Molecular Liquids, 339, 116804. Retrieved from

Rezaei, S. D., Shannigrahi, S., & Ramakrishna, S. (2017). A review of conventional, advanced, and smart glazing technologies and materials for improving indoor environment. Solar Energy Materials and Solar Cells, 159, 26–51. Retrieved from

Sedaghat, A., Abbas Oloomi, S. A., Malayer, M. A., Alkhatib, F., Sabri, F., Sabati, M., … Chowdhury, S. (2021). Effects of Window Films in Thermo-Solar Properties of Office Buildings in Hot-Arid Climates. Frontiers in Energy Research, 9, 1–22. Retrieved from

Seeboth, A., Ruhmann, R., Mühling, O., Seeboth, A., Ruhmann, R., & Mühling, O. (2010). Thermotropic and Thermochromic Polymer Based Materials for Adaptive Solar Control. Materials, 3(12), 5143–5168. Retrieved from

Selkowitz, S. E. (1999). High Performance Glazing Systems : Architectural Opportunities for the 21 st Century High Performance Glazing Systems : Architectural Opportunities for the 21 st Century. In Glass Processing Days Conference (pp. 1–11).

Serpe, M. J. (2019). Gel sandwich smartens up windows. Nature News & Views, 565, 438–439.

Tzeng, S. T., Chen, C., & Tzeng, Y. (2010). Thermal tuning band gap in cholesteric liquid crystals. Liquid Crystals, 37(9), 1221–1224. Retrieved from

United Nations. (2018). The World’s Cities in 2018. Retrieved 10 January 2020 from

United Nations. (2019). World Population Prospects 2019. Department of Economic and Social Affairs. World Population Prospects 2019. Retrieved from

Van Heeswijk, E. P. A., Kloos, J. J. H., Grossiord, N., & Schenning, A. P. H. J. (2019). Humidity-gated, temperature-responsive photonic infrared reflective broadband coatings. Journal of Materials Chemistry A, 7(11), 6113–6119. Retrieved from

van Heeswijk, E. P. A., Meerman, T., de Heer, J., Grossiord, N., & Schenning, A. P. H. J. (2019). Paintable Encapsulated Body-Temperature-Responsive Photonic Reflectors with Arbitrary Shapes. ACS Applied Polymer Materials, 1(12), 3407–3412. Retrieved from

van Heeswijk, E. P. A., Yang, L., Grossiord, N., & Schenning, A. P. H. J. (2020). Tunable Photonic Materials via Monitoring Step-Growth Polymerization Kinetics by Structural Colors. Advanced Functional Materials, 30, 1906833–1906840. Retrieved from

Wang, Y., Runnerstrom, E. L., & Milliron, D. J. (2016). Switchable Materials for Smart Windows. Annual Review of Chemical and Biomolecular Engineering, 7(1), 283–304. Retrieved from

White, T. J., McConney, M. E., & Bunning, T. J. (2010). Dynamic color in stimuli-responsive cholesteric liquid crystals. Journal of Materials Chemistry, 20(44), 9832–9847. Retrieved from

Wu, X., Yu, L., Cao, H., Guo, R., Li, K., Cheng, Z., … Yang, H. (2011). Wide-band re fl ective fi lms produced by side-chain cholesteric liquid-crystalline elastomers derived from a binaphthalene crosslinking agent. Polymer, 52(25), 5836–5845. Retrieved from

Xiao, L., Cao, H., Sun, J., Wang, H., Wang, D., Yang, Z., & He, W. (2016). Double UV polymerisation with variable temperature-controllable selective reflection of polymer-stabilised liquid crystal ( PSLC ) composites. Liquid Crystals, 43(10), 1299–1306. Retrieved from

Xu, X., Zhang, W., Hu, Y., Wang, Y., Lu, L., & Wang, S. (2017). Preparation and overall energy performance assessment of wide waveband two-component transparent NIR shielding coatings. Solar Energy Materials and Solar Cells, 168, 119–129. Retrieved from

Yang, H., Mishima, K., Matsuyama, K., Hayashi, K.-I., Kikuchi, H., & Kajiyama, T. (2003). Thermally bandwidth-controllable reflective polarizers from (polymer network/liquid crystal/chiral dopant) composites. Applied Physics Letters, 82(15), 2407–2409. Retrieved from

Yang, T., Yuan, D., Liu, W., Zhang, Z., Wang, K., You, Y., … Zhou, G. (2022). Thermochromic Cholesteric Liquid Crystal Microcapsules with Cellulose Nanocrystals and a Melamine Resin Hybrid Shell. ACS Applied Materials & Interfaces, 14(3), 4588–4597. Retrieved from

Yeung, C. P. K., Habets, R., Leufkens, L., Colberts, F., Stout, K., Verheijen, M., … Buskens, P. (2021). Phase separation of VO 2 and SiO 2 on SiO 2 -Coated float glass yields robust thermochromic coating with unrivalled optical properties. Solar Energy Materials and Solar Cells, 230, 111238–111249. Retrieved from

Yuan, X., Zhang, L., & Yang, H. (2010). Study of selectively reflecting characteristics of polymer stabilised chiral nematic liquid crystal films with a temperature-dependent pitch length. Liquid Crystals, 37(4), 445–451. Retrieved from

Zhang, B., Lin, X., You, Y., Hu, X., de Haan, L., Zhao, W., … Yuan, D. (2019). Flexible thermal responsive infrared reflector based on cholesteric liquid crystals and polymer stabilized cholesteric liquid crystals. Optics Express, 27(9), 13516–13526. Retrieved from

Zhang, L., Wang, M., Wang, L., Yang, D., Yu, H., & Yang, H. (2016). Polymeric infrared reflective thin films with ultra- broad bandwidth. Liquid Crystals, 43(6), 750–757. Retrieved from

Zhang, P., Kragt, A. J. J., Schenning, A. P. H. J., Haan, L. T. De, & Zhou, G. (2018). An easily coatable temperature responsive cholesteric liquid crystal oligomer for making structural colour patterns. Journal of Materials Chemistry C, 6, 7184–7187. Retrieved from

Zhang, W., Kragt, S., Schenning, A. P. H. J., De Haan, L. T., & Zhou, G. (2017). Easily Processable Temperature-Responsive Infrared-Reflective Polymer Coatings. ACS Omega, 2(7), 3475–3482. Retrieved from

Zhang, W., Froyen, A. A. F., Schenning, A. P. H. J., Zhou, G., Debije, M. G., & de Haan, L. T. (2021). Temperature-Responsive Photonic Devices based on Cholesteric Liquid Crystals. Advanced Photonics Research, 2, 2100016–2100043. Retrieved from

Zhang, W., Schenning, A. P. H. J., Kragt, A. J. J., Zhou, G., & De Haan, L. T. (2021). Reversible thermochromic photonic coatings with a protective topcoat. ACS Applied Materials and Interfaces, 13(2), 3153–3160. Retrieved from

Zhao, Y., Zhang, L., He, Z., Chen, G., Wang, D., Zhang, H., & Yang, H. (2015). Photoinduced polymer-stabilised chiral nematic liquid crystal films reflecting both right- and left-circularly polarised light. Liquid Crystals, 42(8), 1120–1123. Retrieved from