Eco-nomics: Photo and Temperature Sensitive Window Tinting

This is cool.  [Yes, the pun is intended] The New York Time's Green blog reports on a new innovation in window tinting film - film that is both photo and temperature sensitive.  So when it is hot and bright the windows darken keeping the interior cool, but when it is cold and bright that windows stay clear, letting all the warmth in. And they key is it does it without an electrical current.

How does it work? They are not saying save to say that it is "an organic, nontoxic polymer which changes its molecular structure in response to temperature.”

Just having this film on windows has been found to lower building energy consumption 30 to 40 percent. Like I say: cool.

I would imagine that this film has to be on double paned windows given the response to ambient temperature, so putting the film on old windows in old houses might not work so well, and I imagine that this 30 to 40 percent figure is for glass cladded buildings.  Which is all to say, it does not seem like it is a really effective residential solution which is where the big aggregate savings are to be had.  But it is another good step in reducing energy usage.