Energy Efficiency Drives Commercial Window Design

Katy Devlin
November 22, 2013

In the commercial window business, energy efficiency reigns supreme. While manufacturers report demand for reduced sightlines, historic retrofit products, and more paint and finish options, thermal performance remains the top priority for fenestration.

The Admiral at the Lake in Chicago features Traco thermal windows and terrace doors that are capable of withstanding the city’s harsh weather conditions. Photo by FotoGraphix

“The demand for lower U-values and better thermal performance is growing every day. In just a short time, energy has become one of the most important job specifications,” says Coby Jones, sales manager for Peerless Products Inc.

To meet customer demand and tightening code requirements, manufacturers are investing heavily in the development of window products that offer high thermal performance, with options such as polyamide thermal breaks or struts.

“Window manufacturing is changing,” says Gary Flemming, windows business manager, YKK AP America. “There are larger struts, more chambers to contain air convection [and] larger gaskets to restrict air flow in the glazing and hardware cavity of the window. Cold exterior air will not be allowed access to the interior window surface, whether the window is aluminium or [made of ] alternate materials.”

The industry is seeing “development of windows that are truly thermally broken versus thermally improved,” says Lisa Jackson, product manager, windows, Kawneer Co. “Newer thermally broken windows work to isolate the interior components from the exterior at all possible meeting points...We expect to see this emphasis increase.”

Peerless Products supplied high-performance windows for the FIOR building in Texas.

Bryan Smith, sales manager, business development, Universal Window and Door, agrees. “We continually explore new ways to improve the energy performance of our windows,” he says. “Integral thermal break systems are changing design parameters daily. Their continual development with an eye toward combining materials for structural strength and distance to heat flow will move the industry forward.”

“Previously, we only offered a standard [pour-and-debridge] thermal break. Today, the demand for high-performance, energy efficient window products is strong,” says Jay Hatton, president of Sun Metals Systems Inc. “We developed and introduced new product lines to meet those needs. We achieved the desired performance with the use of a polyimide thermal break (Isobar technology) and high performance glass.”

Triple Glazing

Demand for increased thermal performance in commercial windows has brought triple-glazed insulating glass units into the market as well. And although manufacturers report varying levels of current demand for triples, they are positioning themselves for future growth in the product segment.

Sun Metals Systems supplied its Sun 400T and Sun Series 300 thermally broken windows for the 7th St. Flats Progression Place Residential
complex in Washington, D.C.

According to Universal’s Smith, “Triple-glazed IG demand is increasing exponentially. As architects and owners look for cost-effective ways to reduce building operation costs, the triple glaze with gas-fill option offers the single biggest net increase in energy savings in a window budget,” he says.

Other manufacturers report seeing only small gains in the triple glazing market. “Peerless has just seen a few triple-glaze projects,” Jones says. “However, we understand that with the growing demand for lower and lower Uvalues, we will begin to see an increase of triple-glazed units.” Nearly all of Peerless’ frame designs can accommodate the thicker triple IG units, Jones adds.

“We have in-house capability for triple glazing, which makes us more competitive,” says Kawneer’s Jackson. “Our designs are flexible to allow for dual insulating units as a standard option, but can easily accommodate triple insulating units. This enables architects to evaluate based on performance and budget requirements.”

At Universal, “Our newest product allows full triple glaze, with a variety of external, internal and interior muntin designs,” Smith says. “Our ability to manufacture units gives us the control for quality and satisfies the demands of the market.”

 Universal Windows and Doors specializes in historic fenestration. One recent project for the company was 110 Canal St. in Lowell, Mass., which features Series 700 Steel Replica - Fixed and Projected windows, and Awning ‘floating’ vents.

Designing for triple-glazed units is nothing new at Wausau Window and Wall Systems, says Steve Fronek, vice president of technical services. “More than 25 years of triple-glazed product development gives our northern Wisconsin-based company a unique ‘no problem’ perspective on energy-saving technology,” he says. “Whether the design calls for hermetically sealed, triple insulating glass, or triple glazing with between-the-glass blinds for privacy and control of solar heat gain, Wausau’s systems accommodate the most durable infill assemblies, orientation-tuned for maximum efficiency.”

Sun Metal Systems’ Hatton adds, “We believe the continued emphasis on energy efficient windows will be a constant change for window manufacturers. With the continued rise in energy costs, demand for energy efficient products will become more of a standard than a luxury. While consumers will spend more for energy efficient windows, they will realize long-term cost savings.”

Proving Performance

Going forward, thermal performance modeling will become increasingly important, as manufacturers look to prove their products’ performance. “Thermal performance reports are now being requested for almost every job we do,” Jones says. “Peerless has adapted and grown to meet this increasing demand. We offer certified thermal reports, we research the best thermal breaks, and we spend a lot of time and effort on developing the best possible frame designs.”

Wausau’s Fronek points out that “finite element thermal modeling software such as WINDOW and THERM from the Lawrence Berkeley National Laboratory’s Window and Daylighting Group is invaluable in the optimization process, whether designing standard products or developing project-specific applications.”

YKK AP developed its own modeling tool called My Thermal Assistant. “We provide a tool for our customers, architects, engineers, owners or contractors to use on our website,” Flemming says.

Aesthetic Trends

The National Renewable Energy Laboratory Research Support Facility expansion in Golden, Colo., features triple-glazed INvent windows from Wausau Window and Wall Systems. The project is designed to be a carbon-neutral, net-zero energy building. CREDIT: Photo by DOE/NREL, Dennis Schroeder.

Beyond energy efficiency, manufacturers also are closely eyeing aesthetic trends, with reduced sightlines topping the list. “We are seeing a demand for products that look sleek and streamlined in appearance,” Kawneer’s Jackson says.

Peerless Products has also seen this trend. “Customers want more glass and less frames for their projects,” Jones says. “In response to this demand, Peerless has designed and engineered custom frames to satisfy their needs.”

YKK AP recently introduced a “zero sightline” window that “provides the appearance of an entire glass wall but has high-performance ventilation included,” Flemming says.

Wausau is also seeing a call for narrow sightlines, along with “large daylight openings, flush surfaces, unlimited color choices and profile customization,” Fronek reports.

Vinyl window manufacturers address structural concerns in commercial segment

The push for thermal performance has led to greater interest in vinyl window products for commercial applications, manufacturers report. The traditionally residential window-frame material has “been readily accepted in light commercial projects such as hotels and multi-family housing for quite a few years,” says Eric Thompson, product sales specialist, Quanex Building Products. “More recently, larger high-rise, multi-use projects are utilizing the benefits of vinyl windows.”

“Because of enhanced and increased thermal requirements, driven by codes, we are seeing an increase of vinyl in these sorts of projects,” agrees Matthew Matlak, manager of commercial systems for Veka Inc.

Filip Geeraert, president and CEO of Deceuninck North America, says that from a code point of view, “vinyl will win over aluminium [in terms of thermal performance], even in … commercial applications.”

While vinyl windows are an increasingly common product option for multifamily residential, the windows are gaining more gradual traction in commercial buildings, according to officials from Quanex Building Products.

In order to perform in commercial applications, vinyl window manufacturers have developed systems offering increased structural performance. Through the use of metal or fiberglass reinforcements, or non-metallic internal stiffeners, vinyl windows can achieve the strength requirements for commercial projects, suppliers say.

Commercial vinyl window and door products, however, continue to fight the perception that they do not offer the structural support of more traditional metal-framed windows. “Years of conditioning and misinformation have affected a significant percentage of the architectural community,” Thompson says. “The challenge is to continue to educate, inform and demonstrate the current capabilities of today’s vinyl window products.”

Matlak agrees. “There is a stigma that vinyl—even though it is now reinforced—still presents some with question marks about structural performance,” he says. Vinyl window manufacturers are looking beyond the more traditional metal structural reinforcement solutions to maintain the thermal performance benefits of vinyl. “Most vinyl manufacturers are looking for new and better materials to enhance structural performance without compromising thermal capabilities,” Matlak reports.

“Specifically, non-metallic stiffeners are increasing in popularity, so there is a strong effort on our part to identify the best possible use of polymer-based solutions,” Thompson adds. “The next generation of energy efficient windows will likely incorporate many of the same materials now on the market, only utilizing the combinations in different ways. Modern software helps designers with proper placement of insulating materials and thermally efficient stiffeners for optimal performance.”

Deceuninck recently introduced a commercial version of the Revolution Tilt & Turn window system, pictured here in a new configuration that allows for the integration of air-conditioning units typically used in light commercial applications like hotels and

Another concern in the commercial community is long-term performance. “For some, there remains the outdated concern over long-term performance,” Matlak says. “Vinyl products have consistently improved from the ‘60s to the ‘70s to today. The long-term performance can meet that of any type of wood-clad or aluminium products.”

Quanex, Veka and Deceuninck have all worked to improve their product offerings for the commercial market.

“Quanex continuously evaluates and explores new materials and technologies for insulating glass, window systems and components,” Thompson says. “We have a number of new technologies on the horizon that will continue to answer the growing need for energy performance and sustainability.”

Veka is also looking to sell the other benefits of vinyl systems, Matlak says. In addition to its thermal performance, vinyl systems can offer customers cost benefits in addition to shorter lead times, he says. “Most commercially rated window systems have an 8-to-12-week lead time. Vinyl can be secured in a much quicker manner—typically about four to six weeks,” he says. “Because the manufacturing process for vinyl is more mechanized, it requires less hands-on work.”

Deceuninck North America recently launched several new products for the commercial segment, including the Icon Series of vinyl windows and doors for commercial applications, as well as a commercial version of its Revolution Tilt-and-Turn window system.

“We see our customers [fabricators] getting more and more into the light commercial space,” Geeraert says. “Although that space is still dominated by aluminium, it’s moving more towards vinyl. I think that will increase in 2014.”

Katy Devlin is editor for Glass Magazine. E-mail Katy at