Windows that change tint may not be that far away anymore.

Soladigm, which makes electrochromic windows, has raised $30 million in a third round of financing. Investors in the company include Khosla Ventures and General Electric. Thus far, private investors have put $57 million into the company. The state of Mississippi has also loaned the company $40 million and given it a $4 million grant.

The funding -- combined with the announcement of an $80 million investment in Sage Electrochromics by French glassmaker Saint-Gobain last month -- is strong evidence that the market for these windows may finally be emerging. With electrochromic windows, building owners can turn down heaters and/or air conditioners by tinting the windows to blocking (or permit) solar heat. Alternatively, office lights can be dimmed in the morning by keeping the windows clear.

"You can think of it as a building with sunglasses," said CEO Rao Mulpuri told us earlier this year.

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 have been trying to sell electrochromic windows since 1989. The obstacles? Cost, complexity and performance concerns. Passive coatings and thermal windows can also accomplish much of what these windows do wihout networking headaches.

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.

A few other things to note:

--France. Saint-Gobain made the mirrors for the Palace of Versailles. Today, French electrical equipment giant Schneider Electric bought two building management companies, Vizelia and D5X, that also happen to be French. Last week, smart meter maker Itron bought Asais, another French developer, to help it manage and analyze meter data. Earlier this year, Areva, the utility largely owned by the government of France, bought solar thermal specialist Ausra.

China isn't the only country passing us up.

--Mississippi. Republicans dominate state offices in the state. The governor, Haley Barbour, is a likely 2012 presidential candidate. Yet the state is issuing loans and stimuli to attract greentech manufacturers like crazy. Besides loaning money to Soladigm to build factories, Mississippi this year also loaned $75 million to biofuel maker Kior and issued $54 million in stimuli to solar maker Twin Creeks Technologies. Investors tell me that the state has made it incredibly easy to set up businesses there, particularly compared to the bureaucratic tangle that California can be.

But think of it for a second. That's $169 million in green incentives to three companies in a single year. Either Barbour is a closet socialist ("Power, and Holiday Pecan Nut Logs, to the People," declares Comrade Haley) or he's found a way to convince voters that green means jobs. We'll get to the bottom of it.

Tags: energy efficiency, general electric, green building, haley barbour, khosla ventures, mississippi, sage electrochromics, soladigm