The revolution in glazings that began in the early 1980s has given designers of low-energy-use buildings a much wider set of options. By choosing the appropriate type of glass, we can determine a window's solar heat gain and transmission of visible light, as well as its ability to block heat loss. But to gain the greatest advantage at a practical cost, the designer must choose and apply the modern glazings thoughtfully. Here's an example from one of my recent jobs. Superglass to the Rescue Superglass, a trademark of Southwall Technologies (1029 Corporate Way, Palo Alto, CA 94303; 800/365-8794), has the highest insulating value of any readily available glazing: R-9 in a 1- inch-thick assembly using 1/8-inchthick glass, or a 11/8-inch-thick assembly
