Until recently, Sage Electrochromics made electrically tintable windows on a relatively small scale. All that’s about to change. On Friday, the DOE announced that it would provide Sage with a $72 million loan guarantee to build a 250,000 sq. ft. plant in Faribault, Minn.

The company’s SageGlass windows can turn from clear to opaque and back with a click of the switch. (Okay, not literally that quick, but more like in 3-5 minutes after a small amount of voltage is supplied or cut off.) Sage says its product is the only commercially available, electronically tintable window glass in the world.

The loan nicely complements a $31 million Advanced Energy Manufacturing Tax Credit the company snagged from the DOE earlier this year.

Sage says its panes are coated with five layers of ceramic materials and use a low voltage:

“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 company uses a vacuum-deposition sputtering process coating conventional float glass. A second piece of glass is added to complete the sandwich, which is surrounded by an aluminum frame. The units can transmit less than 4% of the visible light in their tinted state.

The Lawrence Berkeley National Laboratory, according to the DOE, says SageGlass could cut a building’s heating and air conditioning equipment size by up to 25% and reduce overall cooling loads for commercial buildings up to 20% (by lowering peak power demand) besides shrinking lighting cost. Use of SageGlass may provide LEED credits.

While the glass panels currently operate only in either clear or opaque modes, the company says it will sell an intermediate-level tint system later this year. Sage also says PV-powered units are under development – a good match because of the low-voltage requirements.

The units can be connected to either a simple wall switch or as units integrated into a building management control systems. They also come in four colors (interior appearance – the exterior of appearance of the four are the same): black, green, blue and gray. The largest size currently available is 40″ x 60″ (in either dimension, W x L, or L x W).

The company offers an interesting portfolio on its website of SageGlass installations.

Faribault is located about 25 miles south of St. Paul. The company says the new factory will create about 160 new jobs.