At the Spirit Lake Casino & Resort in northeastern North Dakota, the fine-dining restaurant is called the View because its third-floor panorama looks out on Devil’s Lake and its marina. But diners could not always avail themselves of that view: evening sunlight could be so direct and intense that the restaurant had to close its curtains and blinds to block the glare. But during the restaurant’s renovation in 2014, glass that automatically changes tint was installed across nearly 80 feet (24 m) of windows, replacing the curtains and blinds. Now at sunset, outdoor sensors activate the window-tinting process to block glare but still allow diners to enjoy the vista.
“Basically, we had lost our view because of the sun, but now we have a beautiful 180-degree view of the lake all the time,” says Mark Matheny, the casino’s project manager.
Smart-glass tinting technology is not necessarily new. It has been used for decades in products ranging from airplanes to sunglasses, but with mixed results, which gave self-tinting glass a less-than-stellar reputation. That is changing now, though, with the emergence of new generations of technologies and the ability to manufacture larger panes of smart glass. This has led architects, spurred by building codes and building owners that demand greener designs, to increasingly incorporate smart windows in the sun-facing facades of commercial buildings. This trend has the potential to transform traditional window treatment designs, basically eliminating the need for outdoor louvers and angled baffles, as well as indoor blinds and shades.
“Smart windows are on the cusp of larger-scale adoption,” says Amy Jiron, a technology deployment manager in the U.S. Department of Energy (DOE) Building Technologies Office. “New-construction building owners are very interested in that technology.”
The new generation of smart-glass windows is based on advanced technologies. Traditional energy-saving windows, such as triple-paned glass and low-e (low emissivity) glass, are considered static: they do not change with fluctuating weather conditions. Smart windows are active: their shading levels can be controlled depending on the sunlight or season.
One driving force in the evolution of smart windows in real estate is the emergence of a host of startup smart-glass manufacturers and providers. DOE has helped support several companies, including Sage Electrochromic, View Inc., and Grand Rapids, Michigan–based Pleotint. In addition, equity funding has boosted the fledgling industry; for example, financial services company Wells Fargo provided incubator funding for Chicago-based Smarter Shade and its controllable window-tinting product.
Sage, based in Faribault, Minnesota, outside Minneapolis, is owned by French building materials company Saint-Gobain and has established what it calls the world’s largest dynamic glass manufacturing plant, at 324,000 square feet (30,000 sq m). View, based in Milpitas, California, a suburb of San Jose, and backed by a reported $500 million in equity capital funding, did not start selling its smart windows until 2013 and already has more than 150 installations.
So far, adoption of smart-glass windows has been most prevalent in office buildings, hospitals, and universities. Some of the facilities that are installing or have installed automatically tinting smart-glass windows in just the past couple of years include Overstock.com’s new headquarters in Salt Lake City; a new Humber River Hospital building in Toronto; the Donna–Rio Bravo Land Port of Entry on the U.S. side of the Texas-Mexico border; a new dining hall on the campus of Southern Methodist University in Dallas; and the Mall of America in suburban Minneapolis, which has added a smart-glass atrium skylight as part of its expansion.
“We’re fundamentally changing the whole thinking about glass buildings,” says View chief executive officer Rao Mulpuri. “People just don’t expect that they can sit under the sun in their office and feel comfortable. People don’t believe that today’s buildings can do that, but it’s where the world is going.”
The market for smart windows is poised to take off. Globally, the U.K.-based firm BCC Research forecasts that the value of smart-glass products will jump from $1.9 billion in 2014 to $3.3 billion in 2020. Research firm MarketsandMarkets estimates the global market for smart glass will more than triple from $1.6 billion in 2013 to $5.8 billion in 2020. For the United States, a Grand View Research report predicts that the smart-glass market will double from $600 million in 2015 to $1.2 billion in 2021. This same report also identifies architectural uses as the second-largest industrial market for smart glass, after transportation.
Interest in the innovation of automatically tinting windows is growing because buildings account for 40 percent of total U.S. energy consumption and more than 70 percent of electricity use, according to DOE. Windows are commonly regarded as one of the least energy-efficient building components, responsible for up to 40 percent of total energy consumption for heating and cooling, as well as lighting when natural light blocked by shades has to be replaced by artificial light, according to the California Energy Commission.
But smart-glass windows can block not only glare from the sun, but also solar heat gain indoors, giving them the potential to lower a building’s electricity use and energy costs. Using computer simulations to test certain types of automatically tinting windows, the DOE’s National Renewable Energy Laboratory in 2010 determined such windows could reduce air conditioning consumption in a typical U.S. building by up to 49 percent and lower peak electricity demand by up to 16 percent.
“Because the windows modulate the building’s interior climate, the rest of the heating, cooling, and illumination systems can be smaller, leading to lower construction costs and lower monthly energy bills,” the laboratory wrote.
Another federally supported lab, the Lawrence Berkeley National Laboratory in Berkeley, California, tested Sage’s SageGlass product and determined it could reduce lighting costs by up to 60 percent. View, performing its own modeling to compare energy use of buildings using low-e glass and the company’s smart-glass product, says simulations for a high-rise building showed smart glass reduced heating/cooling/lighting energy consumption by 20 percent. The company’s simulations for a low-rise office building produced smaller savings—a 14 percent reduction.
Meanwhile, with today’s building interiors increasingly incorporating open floor plans and natural lighting, smart-glass windows are touted as helping improve the productivity of building occupants, according to a host of studies and surveys. View, for example, cites a 2003 California Energy Commission study of indoor environments that found, among other things, that “an ample and pleasant view was consistently found to be associated with better office worker performance.” Likewise, a 2012 survey of nearly 500 architects found that almost 98 percent of respondents said building occupants perform better when they have a view of the outdoors.
“Everyone wants a view, but you can’t just integrate natural light into a building and expect it to be comfortable,” says Helen Sanders, Sage’s vice president of technical business development. “You have to properly manage that light.”
That is what the Saint Paul RiverCentre convention center in Minnesota wanted to do. Its second-floor boardroom overlooks part of the city’s skyline but faces the southeast, meaning its windows are flooded with sunlight in the morning. The boardroom was equipped with mechanical screens and blackout curtains, but the room still was hot on summer mornings. So as part of its long-term sustainability initiative, the convention center installed Sage’s automatically tinting windows in the boardroom in 2014.
“It immediately had an impact. The room has never been as hot as it used to be,” says Jim Ibister, the center’s general manager. The new controls took some getting used to—it takes ten to 15 minutes to change from clear to the darkest tint—but the skyline view is no longer completely closed off now. “From the inside when it’s fully tinted, it looks like you’re looking through dark sunglasses,” he says.
Smart glass is available in different types of technologies—thermochromic, liquid crystal displays, and electrochromic—but each has limitations. Thermochromic makes a window reflective, limiting the ability to see through it from outside or inside in some cases, which generally limits its use to skylights. Liquid crystal displays and suspended particle displays are limited by their requirement of a continuous high-voltage current when the glass is in a transparent or translucent state. The degree of transparency is controlled by the voltage applied; at no voltage, the liquid crystal glass is a translucent milky white. This means they do not provide energy savings, according to the California Energy Commission. Electrochromic glass takes time for the tinting to occur, but it is considered the most suitable choice for energy control in buildings because the tinting can be easily controlled.
The electrochromic windows manufactured by View and Sage are coated with a layer of metal oxide inside dual panes of glass. Application of a small electrical voltage to 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 can be programmed to tint automatically in response to outdoor conditions, or the glass can be manually controlled through via smartphone, computer, or other internet-connected device because each window has an internet protocol (IP) address.
The automatic tinting is triggered through outdoor sensors, which take into account the building’s orientation, the sun’s path, and cloud cover to adjust the window’s shading level. The tinting process can take upward of 15 minutes, depending on the glass size, but the voltage needed for tinting is minimal: it is estimated that 100 such windows use about as much energy as a single 75-watt lightbulb over the same period.
Smart-glass applications have come a long way during this decade. Just a few years ago, smart-window companies only had the manufacturing capability to produce enough glass for one long wall. Now they can accommodate tens of thousands of square feet—enough for an entire building facade. And only a few years ago, in 2013, a Navigant Research analyst told MIT Technology Review that “buying smart glass purely on the basis of its energy efficiency is not something that’s really happening today.” But it is happening now.
The lobby atrium of the Hilton Los Angeles/Universal City hotel faces to the southwest, which sometimes causes the lobby to become uncomfortably hot when the afternoon sun blazes through the 35-foot-tall (11 m) windows. “There was so much heat [coming] through the glass that the air conditioning couldn’t keep up,” says Steve Thompson, the hotel’s property operations director. When Hilton began a $7 million renovation, it looked for some way to reduce the warming of the lobby. It considered covering the windows in a high-performance film, but ultimately chose View’s automatically tinting glass. It was installed in 2014, and “we no longer get complaints about the heat,” Thompson says. And he estimates the hotel is saving about $1,000 per month on cooling costs.
However, Hilton’s smart-glass windows also cost more than any other option it considered.
View estimates that its windows cost 40 to 50 percent more than a standard glass curtain wall; Sage estimates that its SageGlass windows cost about twice as much as a package of low-end office windows with interior manual blinds. Recent installations of automatically tinting windows cost more than $1,000 for a five-by-seven-foot (1.5-by-2 m) pane. Matheny says Spirit Lake Casino paid $100 per square foot ($1,076 per sq m) for SageGlass, about five times its price estimate for low-e glass.
Cost, then, is a major challenge for adoption of smart glass. “We studied [smart windows] for other projects, but for various reasons, like cost, it was decided not to use it,” says Robert Karow, a senior associate with the Shalom Baranes Associates architecture firm in Washington, D.C., and a project manager on the renovation of the U.S. General Services Administration (GSA) headquarters building in Washington. That 2013 project incorporated Sage’s automatically tinting skylights.
Yet, Sage officials say their prices have dropped by half over the past four years as new manufacturing capabilities with economies of scale have ramped up. “The price coming down makes this technology very competitive,” says David Winstead, GSA commissioner of public buildings from 2005 to 2009 and now a real estate practice leader with Washington, D.C., law firm Ballard Spahr.
In addition, Sage and View officials maintain that the return on investment for their windows typically ranges from months to five years, depending on the size of the installation. Boston-based architecture firm Payette recommended View electrochromic glass for a 4,000-square-foot (372 sq m) atrium skylight at a health care laboratory and office building in Cambridge, Massachusetts, because the windows require no mechanized shading or louvers. “The upfront cost was higher [than alternatives], but when you looked at all the features, it was the best option on the table, especially when considering long-term maintenance and operating savings,” says Chris Bloomquist, a project architect at Payette.
Automatic window-tinting innovations are continuing, with another startup company, Berkeley, California–based Heliotrope Technologies, experimenting with nanotechnology that could be less expensive and improve the commercial prospects of smart windows. But even with current technologies, the more that building developers and designers are exposed to automatically tinting window products, the more they are intrigued with them.
“We like the idea, and I think we’ll find a way to use it,” says Rich Carr, a principal with CCY Architects near Aspen, Colorado, and assistant chairman of ULI’s Recreational Development Council (Gold Flight). “Glass that can react to the climate on its own has some long-term legs on where it can be taken.”
Jeffrey Spivak, a senior market analyst in suburban Kansas City, Missouri, is an award-winning writer specializing in real estate development, infrastructure, and demographic trends.