“Smart Glass” Reduces Glare, Improves Comfort

Fall 2016
The west and south facades of Saint-Gobain’s U.S. headquarters in Malvern, Pennsylvania, feature 17,000 square feet of SageGlass, marking one of the largest installations of electrochromic glass to date. Photos ©Jeffrey Totaro, 2015

Dynamic glass panes can decrease energy demand, glare and heat, resulting in a more comfortable indoor environment, while still letting the sunshine in.

WALK INTO THE MODERN, glass-clad Saint-Gobain headquarters in Malvern, Pennsylvania, on a summer afternoon and it should be overly bright, warm and stuffy. Yet the new two-story atrium lobby, which links two newly renovated headquarters buildings, is none of those. The LEED-Platinum certified building is a comfortable 71 degrees, even facing due west, without glare or discomfort. 

The building “is a living lab,” says Jill Betters, manager of commercial and architectural programs for CertainTeed, a division of Saint-Gobain. “When the company decided to build our new headquarters here, it made sense to showcase our products, and this atrium really is a great example of our SageGlass.”

Betters is referring to the company’s dynamic glass product. Think Transitions lenses (the eyeglasses that darken in bright sunlight) on a massive scale. The tintable electrochromic glass — also known as photochromic or dynamic glass — is designed to help make indoor spaces more comfortable. The panes, the company claims, reduce energy demand, glare, heat and discomfort while increasing employee well-being and productivity.

It works like this: SageGlass panes are coated with five layers of ceramic materials at a total thickness of less than 1/50th that of a human hair. When voltage is applied across the coatings, ions travel from one layer to another, prompting a reversible solid-state change that causes the coating to tint and absorb light. In other words, the glass gets darker. Reversing the polarity of the applied voltage causes the ions to migrate back to their original layer, untinting the glass. 

Controlled by a physical switch, automated settings or an app, each pane has three tint choices. In full tint mode — often the preferred setting for presentations in conference rooms — the process removes 99 percent of visible light, providing complete protection from the sun’s harshest rays while still remaining clear enough to see through. Other settings remove 60 and 20 percent of visual light. There is also a “clear” setting. The transition takes a gradual seven to 10 minutes, and every 2,000 square feet of the glass consumes the power of a very cost-effective 60-watt lightbulb as it transitions.

For developer Eli Kahn of E. Kahn Development, the Saint-Gobain headquarters was his first exposure to tintable electrochromic glass. 

“I have never seen a building with window shades in architectural renderings,” says Kahn. “And then the building goes up, and all you need to do is stand outside on a sunny afternoon to see shades across buildings in an infinite number of positions. You understand in that moment how people struggle with heat and glare.”

photchromic glass conference room

Photochromic glass dynamically controls sunlight, maximizing daylight while minimizing glare and solar heat. Here, the glass is at full tint in the top zone, partial tint in the second- and third-from-top zones, and clear in the bottom zone.

Kahn sees the return on investment of dynamic glass in three ways: “First, there’s the energy payback. Our models show this is about a seven- to 10-year window. Then there is the contribution it makes to LEED certification. And most importantly, there’s the comfort and productivity of employees. Isn’t that why we started putting air conditioning in buildings in the 1960s? People just work better when they are comfortable.” 

SageGlass, one of the first and largest companies to produce dynamic glass, was formed in 1989 based on a simple principle: Companies could save energy by tinting windows to prevent heat from entering or leaving buildings, rather than by using HVAC systems to mitigate it. In 2010, the company began partnering with Saint-Gobain, the world’s largest building products company. In 2012, Saint-Gobain bought SageGlass. Other companies that produce dynamic glass include Glass Apps, Suntuitive and InvisiShade

SageGlass CEO Alan McLenaghan, who holds a Ph.D. in polymer physics, has been at the helm of SageGlass since the acquisition, and his passion for the product is palpable.

“It’s obvious: Humans need to feel connected to the outdoors! With this product we can help architects open up spaces; we can bring the outside in.”

McLenaghan commutes to his office in Minnesota from his home in Indiana, spending a fair amount of time at Minneapolis-St. Paul International Airport Terminal One. SageGlass recently installed 2,800 square feet of dynamic glass near the terminal’s Transportation Security Administration (TSA) checkpoint, where heat and glare had long been a problem. In line for a flight, he found himself simultaneously speaking to a fellow traveler about his job and realizing that the other people in line had no idea the glass was changing as they stood there.

“It’s such a subtle process,” says McLenaghan. “You are standing next to it and it’s doing its job and you don’t even know it.” He anticipates that the long-term value of dynamic glass at commercial office buildings, airports and especially health care facilities — where blinds and fabric shades can harbor bacteria and viruses — can’t be understated. The glass offers energy savings of 6 to 40 percent over regular glass. Those savings are influenced by factors such as the size, shape and orientation of the building.