One of the early customers of Sage Electrochromics' new window factory will be ... the factory itself.

The new plant in Faribault, Minn., with its 286,000 square feet of production space, is lit largely by natural light streaming through big windows.

And Sage didn't manufacture them.

CEO John Van Dine said that's because until the plant starts running, Sage can't produce electronically tintable glass panels that are big enough for the openings.

That will change when production starts in 2013, and the plant's brand-new, conventional windows are gradually replaced with SageGlass, he said.