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A window into the future

Marc Gunther's picture
FORTUNE magazine

Marc Gunther is a writer and speaker who focuses on business and the environment. He worked for 12 years as a senior writer at FORTUNE magazine, where he is now a contributing editor. His most...

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  • Nov 12, 2010

Here’s a futuristic notion: Windows that darken on hot sunny days to block heat and glare, clear  up on cool or cloudy days to allow in sunlight and warmth, save lots of energy, eliminate the need for blinds or shades and, most important, allow people indoors to be connected all the time to the natural world.

This may sound like magic, but electrochromic windows are here today. You can see them, above, at the student center at Chabot College in Hayward, CA. They’re made by a small Minnesota-based company called SAGE Electrochromics, which is about to get bigger: This week,  SAGE announced that it sold 50% of itself for $80 million to  Saint-Gobain, a global building materials firm based in  France.

The partnership is a marriage of new and old–SAGE is a privately-held high-tech company founded in 1989,  while giant Saint-Gobain (EU37.8 billion in sales last year, 190,00 employees) traces its beginnings to the 17th century when it manufactured mirrors for  the Chateau de Versailles. Until they worked out their deal,  SAGE and Saint-Gobain had been competing to develop windows that would electronically control the sun’s energy that flows through them. 

John Van Dine

I spoke today to John Van Dine, SAGE’s founder and CEO, who was thrilled by the deal, which will finance a new plant to increase the firm’s manufacturing capacity. A New Jersey native, John was working at a solar photovoltaic firm in the 1980s when he got to thinking that “an electronically tintable glass had as much or more potential to save energy per unit of space as a solar cell had to produce it.” He began researching the idea at the Princeton University library and a Newark patent office (“This was before the age of the Internet”)  and quit his job in 1990 to work full-time at SAGE. Years of research and development (some of its financed by the goverment) followed. In 1998, he moved SAGE to Minnesota because it is, in his words, “the Silicon Valley of the windows industry.” Many of the world’s big window and glass makers (Andersen, Marvin, Pella) are located nearby.

How do SAGE’s windows work? The company’s website explains:

The SageGlass coating on the glass is made up of five layers. When voltage [less than 5V DC] is applied to these layers in their “clear” state, they darken as lithium ions and associated electrons transfer from the counter electrode to the electrochromic electrode layer. Reversing the voltage polarity causes the ions and associated electrons to return to their original layer, the counter electrode, and the glass untints. This solid state electrochromic reaction is controlled through a low voltage DC power supply. When the SageGlass coating darkens, the sun’s light and heat are absorbed and subsequently reradiated from the glass surface – much the way low-emissivity glass also keeps out unwanted heat.

I didn’t say I understood it. I just said the company website explains it.

In any event, John tells me the windows have no moving parts and they can be controlled through ordinary light switches or wirelessly. They can also be programmed to darken automatically when there’s lot of light or heat streaming through, and then return to their natural clear state when more light is needed inside. “Here at SAGE’s offices,” he says. “I can control the windows with my iPhone. It’s cool.”

SAGE HQ in Faribault, MN

Today, SAGE employs about 100 people. Earlier this year, the company secured about $100 million in government subsidies–a $72 million loan guarantee fromb the U.S. Department of Energy and a $31 million Advanced Energy Manufacturing Tax Credit–for a new plant. The loan and tax credit, along with this week’s investing, will enable SAGE to build a facility with enough capacity to make about 4 million sq. ft. of windows a year, compared to 100,000 sq. ft. at the current pilot plant.  The new plant is scheduled to open in the second half of 2012, at which time the company expects to employ about 300 people, according to Van Dine. Economies of scale should help drive the costs of the windows down, so they move from being a niche product into the mass market.

Energy Secretary Chu, by the way, is a fan of SAGE’s technology. DOE researchers found that SAGE’s glass could reduce cooling loads for commercial buildings by up to 20 percent and lighting costs by up to 60 percent. “This technology can help transform windows and skylights from energy liabilities to energy savers,” he said.

Even better, electrochromic windows mean you never need to close blinds or pull down shades to block a view. (As I write this, I’m at my desk in my home office, looking out at a sunny day and gorgeous fall foliage.) As John puts it: “Why do we put windows in buildings. They’re quite energy inefficient. They require cleaning. And they can break. We do it because we have such a strong desire to be connected to the outdoors, to have a view and harvest natural daylight. Sage glass is as much about people as it is saving energy or the environment.” Now that’s cool–a green product that makes life better in every way.


SAGE glass at Ball State (Ind.) University


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