Use of Thermally-Broken Curtainwall Expands: Industry Equips and Adapts
The curtainwall industry has increasingly found itself in the business of thermal breaks during the past few years. Machinery companies have responded accordingly.
“[M]anufacturers across the board are having to adapt to evolving energy codes, which can be a moving target,” says C.R. Laurence vice president of marketing Andrew Haring.
He says with the uptick in the demand for energy efficient buildings, u-factors and ratings reports “have become hot topics and critical criteria for our industry.” Another driver has been an increased aim within the architectural and design community for LEED certification.
The purpose of a thermal barrier is simple—keep out the heat in warm climates, and keep out the cold in cool climates. The concept isn’t new, and thermal barriers in aluminum window and storefront systems have been around for nearly four decades, according to Jerry Schwaubauer, vice president of sales and marketing at Azon.
“While the curtainwall industry traditionally developed products that were largely non-thermal or used thermal isolators, Schwaubauer says manufacturers in that sector gradually have adopted thermal barrier systems to answer the call for higher energy efficiency.
“This requires slightly different designs and receptors [of the curtainwall system] to accommodate the thermal barrier used,” says Azon CEO Dave Mills. “Once extruded and finished, the lineal is required to be processed through equipment that adds the thermal barrier. Although it is an additional process, through added equipment, the energy efficiency of the overall system is improved greatly.”
Companies such as Azon are developing machinery to meet the demand, something Schwaubauer says has led to exciting innovations in thermal barrier processing equipment.
“Extrusion processing equipment for pour-and-debridge systems has become more fully automated and has expanded to process larger aluminum extrusions,” he says. “Additionally, dual cavity systems are growing in popularity, and processing equipment has been designed to process multiple cavity extrusions in a single pass at high rates of speed.”
Pour-and-Debridge vs. Polyamide Thermal Barrier Strips
Pour-and-Debridge is a polyurethane-based system. The mixture is poured into a barrier channel in the aluminum extrusion. After pouring and curing, the barrier channel is debridged. The debridging process creates the separation between the inner and outer surfaces. A mechanical locking system on the extrusion is recommended to eliminate possible problems with dry shrinkage.
Polyamide thermal barrier strips are pre-extruded profiles that lock in place in pockets extruded into two separate (inner and outer) aluminum extrusions. This process enables finished assemblies with different finishes and colors on each surface. Aluminum extrusion pockets need to be knurled prior to insertion of the polyamide profiles, and strips are “rolled” to create a structurally secure finished assembly.
SOURCE: American Architectural Manufacturers Association
Pour-and-debridge systems using polyurethane are one option, while polyamide thermal barrier strips are another. “Within each of these systems, the thermal barrier equipment will have nuances to meet the particular design of the system that is being produced,” says Mills.
Proline Automation focuses on the latter with its thermal break insertion system called Zipper, which combines three processes—knurling, inserting the strip and crimping—into one.
Todd Tolson, director of sales at Proline, says a typical system of the kind would have three stations. The high demand for a more automated process that required less labor and a smaller footprint has led Proline to develop a system designed for glass and aluminum fabricators.
The company initially developed Zipper four years ago and has since re-adapted it twice, working with customers to find the right balance between automation and operational control.
For example, software included with the machine allows it to constantly adjust the rolling force based on feedback from the part. “When you’re rolling a 20-foot-long part, there’s going to be a certain amount of twist and bow in the extrusion,” says Tolson, adding that variation of thickness can be another factor. “We’re able to adjust those tolerances on the fly.”
Because of code stringency, Tolson says aluminum fabricators and contract glaziers in Canada have been quicker to invest in this kind of machinery and adopt the practice of rolling their own thermal barriers. He says glaziers in the U.S., however, have been more apt to use stick-built curtainwall systems and are doing less custom profile designs than their Canadian neighbors.
He says a contract glazier that can roll its own profiles has the flexibility to mix-and-match surface treatments for the interior and exterior.
—Nick St. Denis
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