Saint-Gobain, the company that made the mirrors for the Palace of Versailles way back in the 17th century, is investing millions to marry windows to computers.

The company has invested $80 million in Sage Electrochromics. Electrochromic windows are networked sheets of glass containing specialized chemicals that change the tint of the window to block or let in light from the sun upon command. The windows, ideally, will allow building managers to reduce both air conditioning and lighting bills.

The EU and some other agencies have begun to impose regulations that will require buildings to put exterior shades on their buildings to reflect heat. While these window coverings work well, they also block the view. Electrochromic windows preserve the view.

Under the alliance, Saint-Gobain will transfer its intellectual property to Sage and the two companies will share manufacturing and R&D duties. Sage will produce the windows at a $135 million factory now under construction in Faribault, Minn. and the two companies will share the factory output.

For electrochromic windows, it's a big deal.  Sage has been working on electrochromic windows since 1989 and the products are just now coming to market. Cost, complexity and performance concerns have been some of the chief challenges. Saint-Gobain, with its extensive manufacturing and logistics experience, can begin to push these types of windows into the mainstream. It's similar to how multinationals like Honeywell are buying and/or partnering with startups to accelerate the acceptance of new types of building management systems. It's all part of the rise of the green giants.

Darkening a window (which is accomplished by electrically stimulating molecules in a film inside the window) takes only 0.28 watts per square foot of glass; maintaining the tint takes about a tenth of a watt, Sage CEO John Van Dine told us last year. Controlling 1,500 square feet of glass takes about the same amount of energy as it takes to flip on a 60-watt bulb. You could run much of a building's window system onsolarcells.

In July, Sage rival Soladigm landed a loan and stimulus package to open a factory in Mississippi.