OK, maybe I'm getting ornery because it's late, but this is one that really frosts me... This company's booth (Viracon) is entitled Architectural Glass: Sustainable Design, as you can clearly see. I thought "this is great!" Sustainable glass! So I asked about the details. It turns out that much of their stuff is rated near R-4, and the best they can possibly do is R-8. That's very good for glass, but let's compare: The cheapest insulated stud wall you can build has R-11 insulation, plus whatever the insulation value of the sheathing and sheetrock are. You're probably sitting somewhere around R-13 or so when you're done. That means that the cheapest possible stud wall performs three times as well as their mainline "Sustainable Glass!" So what it really means is "slightly less wasteful glass," or more pointedly, "a slightly less wasteful brand of the stupidest material you can possibly sheathe an entire building in, if you're interested in sustainability." Is this Viracon's fault? Clearly, they should tell it like it is, but then they wouldn't sell much glass. But the real problem is the architects, because they're the ones insisting on continuing to do glass-clad buildings long after it's clear how poorly they perform. And don't even start talking about how building occupants need more light... most curtain wall glass is deeply shaded to cut out most of the light, otherwise the glare would be so bad nobody could work. No, it's purely about style... and it's time for that to change.