"Selecting window, storefront and curtain wall systems is a far cry from just reviewing standard products in catalogues and selecting the desired profile," Altenhofen says in a recent article in The Construction Specifier.

"A lot of architects-most architects-are very good at what they do. However, most of them can't keep up with the nuances of curtain walls," says Jerry Johnson, senior design consultant for Dallas-based Curtain Wall Design and Consulting Inc. "There is so much going on, and the complexity of these systems has increased dramatically."

Contemporary architectural aluminum framing systems are carefully isolated from the building frame so that they support only their weight and the force of wind. They are insulated and "thermally broken" to obtain higher energy efficiency and reduce moisture condensation; utilize glazing and spandrel materials that offer precise control of thermal performance and emissivity and are carefully drained and gasketed to prevent water leaks.

Part of the confusion about specifying framing systems may stem from what now have become industry-wide definitions, themselves.

There exists what Walter Scarborough, vice president and director of specifications for Dallas-based HKS Inc., calls "a terminology issue" within the curtain wall industry.

"Our documents, for instance, now refer to ‘glazed aluminum wall systems'," says Scarborough. "The terms that the industry has come to use have different meanings to different people. The term ‘storefront,' for example has come to represent, what, by comparison, is a low-performance system. The contractor will, too often, acquire a low-performance system, regardless of your needs, and it is an uphill battle from there.

"Until they have tried to understand window systems for what they are, a lot of people don't understand the complexities of those systems or see the importance of one system over another system," he says. "If you have a building 20 stories tall on the coast of Florida and you install what is commonly referred to as a ‘storefront' system, your building will perpetually suffer leakage, and owners don't want to spend millions of dollars for a (cladding) system and have it leak all the time."

Essentially, says Fred Grunewald, research and development manager for a Texas-based manufacturer, "architects specifying (cladding) systems need to know the local code requirements regarding items such as wind loads, seismic considerations, and life safety issues to allow them to determine the specific performance requirements for a project."