National Public Radio: You may have noticed that clear-glass buildings are springing up in cities across the United States. The reason dates back to some 1970s-era research designed to make windows more energy-efficient. In fact, this line of research turns out to be one of the biggest success stories to come out of the last energy crisis — and there are lessons to be learned, as America once again ramps up its energy research. Glass Towers The technology is called low-emissivity window …