Owing to the rising environmental concerns, today, many organizations are adopting smart technologies to reduce energy consumption and improve the comfort of their occupants. Building owners are making everything in their building smart and connected and soon the windows and walls or partitions could be also hit with the smart tag too. Smart glass windows are a type of windows which can change the light to dark and back again either manually or in response to external temperature and lighting conditions. It is useful in controlling a room’s ambiance and temperature while also reducing a building’s energy needs.

Technologies

Smart glass also referred to as switchable or dynamic glass, are special high-tech glass that has the ability to switch from clear to dark in seconds. It automatically dims and brightens to suite the outdoor lighting condition. Smart glass switches their states either automatically or manually and can be used for managing glare, the amount of heat or light transmitted and so on.

The technology behind the smart glass relies on chromism, the term for any process that causes the material to change colour. There are mainly three types: Electrochromic, Thermochromic and photochromic. Electricity triggers are used in Electrochromic glass. That is, when exposed to an electric voltage, ions move into another layer of glass and the tint and reflectiveness change. Thermochromic glass is triggered by heat from sunlight. Based on outside temperature, it automatically switches from transparent to opaque and back again. Photochromic glasses operate similarly, on the basis of light exposure.

Then there are liquid crystal glasses, a type of electrochromic glass, which uses electric voltage to change its states. In this, a thin layer of liquid crystals is positioned in between two transparent electrical conductors on plastic films, which in turn is sandwiched between two layers of glass. The technology is collectively known as Polymer Dispersed Liquid Crystal (PDLC). It uses electrical voltage to control transparency. It required a constant power supply for complete transparency, else the glass turns translucent. The level of translucency depends on the amount of voltage applied, and the technology is largely used to enhance indoor privacy.

Another type of electrochromic glass is Suspended Particle Device (SPD) that contains molecular particles suspended in a solution between plates of glass. In its natural state, the particles move randomly and collide, blocking the direct passage of light. When it triggered by an electric voltage, the particles align rapidly and the glazing becomes transparent.

Major Players

Minnesota, US-based SageGlass, which was acquired by the French multinational corporation Saint-Gobain in 2012, was the first company to enter the electrochromic smart glass market. SageGlass launched its first product in 2003 and completed more than 700 projects to date.

About seven years ago, another US-based company View Inc., launched its electrochromic product and has raised a huge $1.8 billion in funding across a number of big rounds, including $1.1 billion back in November 2018. View’s Dynamic Glass adopts a model-based control system that uses algorithms to automatically adjust tint levels based on the building’s location, design, layout, orientation, time of day, and the outside weather conditions. It uses information from light sensors and real-time weather feeds to adjust the tint level.

The electrochromic glass windows and partitions manufactured by View and Sage are coated with a layer of metal oxide inside dual panes of glass. When a small amount of electric voltage applied, the oxide causes electrically charged lithium ions to move between the layers in the glass and hit the electrochromic material, turning the glass darker. The windows and partitions can be programmed to tint automatically in response to outdoor weather conditions, or the glass can be manually controlled through via smartphone, computer, or other internet-connected devices.

Another established player in the smart glass market is Kinestral Technologies that recently received a $100 million investment from SK Holdings, a large conglomerate in South Korea. The San Francisco-based company’s smart-tinting glass, Halio, tints automatically or on-demand to dark shades to stop the unwanted intrusion of both glare and solar heat while giving users complete privacy. The integration with Amazon’s Alexa voice-activated technology also enables Halio users to control their windows through voice commands.

Apart from commercial and residential building the smart glass technology can also be used in automotive and aerospace industries. The companies such as Gentex offers smart aircraft window that allows passengers to enjoy expansive views from their seats, without annoying glare. It enables users to automatically control the amount of visible light entering into the cabin. Gentex also uses electrochromic technology to develop automatic tinting glasses for aircraft windows. It sandwiches an electronic gel medium between two thin glass panels and allows an electric current to pass through it to cause an electrochemical reaction to occur in the gel. When applying a small DC voltage across the gel causes it to darken, while removing the voltage allows the gel to return to its natural, transparent state.

To conclude…

This is an interesting new area and with the addition of IoT based techniques like smart building or home management, it has the potential to become one of the most adopted technologies in high rises. But, currently the cost is a major impediment. It is expected that with the rise of large scale manufacturing, the costs would come down eventually. This could be expedited further with the rise of Chinese players.

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