Soladigm will open a factory in Mississippi to see if a decades-old green building technology can finally take flight.

The company specializes in electrochromic windows which change tint when an electric current is applied. The idea is that building owners can turn down air conditioners and save energy on hot days by tinting the windows and blocking solar heat. Alternatively, office lights can be dimmed in the morning by keeping the windows clear.

"You can think of it as building with sunglasses," said CEO Rao Mulpuri.

Electrochromic windows also won't block or disturb views, like window shades or permanently tinted windows, he points out. The EU and some other jurisdictions have already passed regulations requiring window shading for efficiency, opening the market for these kinds of windows.

Cue harsh reality. Companies like Sage Electrochromics have been working on electrochromic windows since 1989 and the products are just now coming to market. The culprits? Cost, complexity and performance concerns.

Mulpuri (and execs at Sage) say that many of these problems have been conquered. Soladigm's active ingredient is coated onto the inside surface of the outer pane of glass in its double-paned windows. The company exploits techniques developed in the semiconductor market to apply the chemical. Wiring the windows is fairly easy with prefab construction techniques and the windows will function property for 30 years to 50 years. Unlike those photo grey glasses in the '70s, the windows won't devolve into a permanent shade of gray. 

Soladigm's windows cost more, but the difference will more than be made up through energy savings. Air conditioning accounts for an inordinate amount of power consumption in the U.S. Along with window makers like Soladigm, a number of start-ups -- Ice Energy, Optimum Energy, Chromasun, BuildingIQ, Smart Cool Systems -- have emerged to tackle the problem.

The state of Mississippi gave Soladigm a $40 million loan and $4 million grant. The new factory in Olive Branch will employ 300 people. It's the second greentech victory for governor Haley Barbour this year. In April crazy-secretive solar power company Twin Creeks Technologies -- which has raised over $65 million -- announced a plant in Senatobia.

Soladigm has been in semi-stealth mode for quite some time. It was founded by Paul Nguyen and was previously called Echromics. It started in Santa Rosa but moved to Milpitas, and has raised around $24 million in a few rounds last year.

Tags: air conditioning, barbour, energy efficiency, green building, mississippi, sage chromatics, sage electrochromatics, soladigm