I saw an article that said some windows were made from recycled glass. Have any of you used this type of window? If so, how does it compare to the standard energy efficient window?

Virtually all window (and automotive) glass used in North America is manufactured using the "float" process.

In the float process, silica sand and other materials are melted in order to form the glass. As part of the process, recycled glass is dumped into the mix - 30% (or more) of the mixture may be "cullet" or recycled glass.

So, virtually all "new" glass contains a certain amount of recycled glass.

However, if you mean recycling as in recovering glass from older windows and then reusing it in newer windows, I don't know of a single company that does that (other than a few restoration folks), but I would avoid that idea under any circumstance! Way too many possible problems!

i dunno, it looks like you're just asking out of curiosity, if so then I'll just let you know a reason they are using this float glass technology now is also because its more cost effective and has the high quality of plate glass, so it's great for homes. -Fishfool @ The Reef Tank