Liquid crystal windows offer an innovative solution to the lack of energy efficiency and protection of traditional glass.

Liquid crystal windows offer an innovative solution to the lack of energy efficiency and protection of traditional glass.Transparency and light are the core topics of modern architecture. The big challenge lies in combining the aesthetic possibilities of glass with vital sun protection and energy efficiency. Liquid crystal windows offer an innovative solution. With this new technology, the amount of daylight streaming in can be controlled at the touch of a button. The innovative pane allows people to still see through the glass, even when it is darkened.

Switchable glass technology has not been able to catch on before now. Merck KGaA, Darmstadt, Germany, has spent many years researching and developing appropriate materials, marketed under the licrivisionTM brand. The result is liquid crystal windows, which open up completely new possibilities for designs with glass, especially large glass façades. For over 110 years, the company has worked with liquid crystals, and due to its extensive experience in this field, it is the world’s leading supplier for manufacturers of all types of displays. While the use of liquid crystals has been concentrated in applications such as flat-screen televisions and smartphones until now, the company has been doing research on windows with liquid crystals for several years.

Now, Merck KGaA, Darmstadt, Germany, is seeking further innovative partners from the glass, window and façade industry who are committed and prepared to invest into a mass production of liquid crystal windows. Together with these partners, the company will develop the technology into a cutting-edge product. Higher requirements for long-term stability, the solubility of the dyes in the liquid crystal mixtures, and use in exterior applications are only a fraction of the challenges that the researchers and developers had to face.

Pure Design Freedom

People love buildings with a lot of glass because the rooms are bright and provide ample views, but as soon as the sun creates glare, the blinds are closed. How is it possible to create the perfect balance between the need for light and a glare-free environment?

Liquid crystal windows regulate incidence of light as needed and create a comfortable atmosphere at the touch of a button. This provides extraordinary freedom in designing interactive façades and planning the shape, size and color of windows. Liquid crystal windows can switch from light to dark and/or transparent to opaque and back extremely quickly and blend in seamlessly; thus, they combine functional efficiency with aesthetic flexibility. At the same time, centralized home automation is possible using indoor and outdoor sensors. Currently, liquid crystal windows are being tested in a number of pilot projects, research activities and studies. Well-known architectural firms have conducted simulations to examine the various possibilities for use in buildings. Design and planning processes as well as the long-term effects related to temperature and appearance are being analyzed. Initial renderings show the possibilities for window and façade designs and dynamic design elements, such as segmented switching, dynamic colors, home automation functions and display technologies. Liquid crystal windows can be used in conjunction with any conventional glass and adapt to several shapes and different colors.

Technology of the Future

Liquid crystal windows are switchable glass panes with a layer of liquid crystals that change light transmittance and thus regulate the transit of Liquid crystal windows offer an innovative solution to the lack of energy efficiency and protection of traditional glass.light and heat. It creates privacy by switching from transparent to opaque. When low voltage is applied, the liquid crystal material switches in a fraction of a second. This switching process influences not only light transmission, but also the overall energy transmittance of the glazing.

Energy Efficiency and Peak Performance

In modern and in older residential buildings with large glass surfaces, energy loss, solar heat gains and the associated high costs for cooling are daily affairs. Liquid crystal windows enable window applications with improved energy efficiency and greater sustainability because the energy loss is lower and the solar heat gain can be better regulated. This creates simple, elegant and flexible solutions with great energy-saving potential. The cleaning and maintenance costs are no higher than for normal glass installation and windows.

Studies have revealed that, depending on the installation location and orientation of a façade fitted with liquid crystal windows, energy savings of up to 16 percent can be achieved for heating in winter, 13 percent through cooling in summer, 28 percent through light and 7 percent through ventilation. Overall, it is possible to reduce energy consumption by approximately 30 percent. If a neutral gray color is selected for the façade glazing, the result can be very pleasant. The color rendering index is 94 to 97 percent.

As one of the first large pilot projects, Merck KGaA’s modular Innovation Center in Darmstadt, Germany, was recently equipped with this new window technology. The liquid crystal window technology used there allows light transmission of 53 percent in the bright state and 11 percent in the dark state with an overall energy transmittance of between 0.4 and 0.25. The technology also helped achieve the European standard of heat protection.

Creative Future

The liquid crystal material used in the modular Innovation Center is not only an example of a variety of possibilities to meet physical building requirements for façades. It is possible to adapt to greater light transmission (bright 70 percent to dark 20 percent) or less (bright 40 percent to dark 4 percent) in combination with scattering mode to create privacy atmosphere – while simultaneously changing the degree of overall energy transmittance. If triple-pane insulating glazing is selected, the thermal insulation of the liquid crystal windows can be increased. The color of the liquid crystal windows can also be varied: A range including green, blue, red-violet and yellow is available.

The development of liquid crystal window technology for architecture has only just begun. The boost in energy efficiency, further development of the color spectrum and the increase in the contrast ratio are only a few topics on the research agenda.

MARTIN ZITTO is business development manager for liquid crystal window technology that belongs to Merck KGaA´s display materials business unit. He joined Merck KGaA, Darmstadt, Germany, from Schott, a leading technology group in the areas of specialty glass and glass ceramics. Before joining Schott, Zitto held various technical and management positions in the high-end façade industry in Germany and Austria. From 1997 to 2000, he studied glass technology and business administration. For more information, visit www.emd-pm.com.

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