"We are going through a new cycle," says Grunewald. "The glass box became popular in the 1960s, then the energy crunch did away with the glass box. But with advancements in technology, daylighting and high-visibility buildings are undergoing a revival. The goal is to allow as much light as possible to enter a structure and still maintain energy efficiency. As technology improves, it is becoming easier to do that.

Ohio, Grunewald says, has begun a statewide school construction program, with an eye toward efficiency, in which all windows will be triple-glazed and include venetian blinds, an extremely expensive option, but a highly efficient one. "In 15 years we have gone from single pane windows to triple-glazed systems," he says.

"These are reliable, soundly performing systems that work around standard assemblies but can be manipulated to achieve a variety of aesthetics," says Blanchfield. "Many of these manufacturers have a lot of engineering horsepower in-house, and they have a lot of production capacity. That makes them attractive for jobs with tight schedules and not too many peculiarities.

"What I see consistently, however, among architects who have not done a lot of curtain walls is an insufficient knowledge of tolerances---in the manufacture, the construction, and in the ability of builders to hold dimensions true," he says. "There is a false expectation that contractors can build as straight and as true as the architect can draw, and that is not always the case. These kinds of things aren't discovered until the actual work is underway and they can then become a source of problems. Sometimes contractors are errant in their work, but often problems stem from a lack of judgment and experience on the part of architects. If they anticipate real circumstances, they can avoid many of the hardships."

"Curtain wall systems are a commodity item," says Blanchfield, "and like most commodities, the price of curtain wall systems is market-driven. Although both materials and energy costs have risen, the price of most curtain wall systems has gone down. It is a buyer's market right now."

"We now live in a world of specialization," says Sprague. "Whether it's a wall system or a power system, we owe it to ourselves to seek the best information we can find. Our clients don't want excuses."