Smart glass: the next big thing for windows?

A customer who was looking for replacement windows for his single-glazed casements, asked me about windows that darken on command and diminish the sun's impact inside the home. What he was talking about is electrochromic glass, or "smart glass," as it's sometimes called. A metallic coating and a small electrical charge that runs through the glass keeps it clear while the charge is on. When the charge is turned off, the glass becomes milky white. The result is instant privacy.

Smart glass is used mainly in commercial buildings where security is required. It blocks images but allows some ambient light through. Because of the wiring required to turn the electrical charge on and off, electrochromic glass is difficult to use in residences, where most windows open and close. I don't know of any window manufacturers who make residential windows with smart glass, except where privacy is desired and window coverings are not.

Smart glass technology: ahead of its time?

Electrochromic glass windows run about $100 per square foot, which would make them quite costly for the average home owner. However, Soladigm, a company in California, has developed a method for making smart glass more affordable for homes and office buildings by reducing the cost to around $20 per square foot. Soladigm achieves their lower cost using two layers of oxide film sandwiched between two sheets of glass. Similar to the more expensive technology, when the current changes the glass clears or darkens. By contrast, most pre-manufactured residential windows cost about $8-$10 per square foot.

The appeal of smart glass is obvious: reduced heating and cooling costs, and instant privacy without the cost of traditional window coverings. It may still be a bit premature, but just as low-e glass was still rare in the early 1980s and is pretty much the standard now, smart glass could someday be the norm.