Volume 48, Issue 11- November 2013
Does Metal Matter?
Can Metal Screens Meet the Specs of High-Performance
By Megan Headley
With few exceptions, glass is rarely the only material in a façade. That’s why today many glazing contractors are working to help architects better understand how all of a building’s cladding materials work in combination to improve a building’s overall efficiency.
Tom Schlotfeldt, president of the glazing contractor Architectural Wall Systems Co. in West Des Moines, Iowa, explains that designing a wall to a certain R-factor is among the company’s biggest goals in the design-assist area right now.
“That is something that we are working very hard with a lot of designers to achieve: a whole wall R-factor instead of [focusing only] at a certain point,” Schlotfeldt says. “That seems to be a bigger issue right now, and a bigger goal than shading devices from our perspective.”
Yet shading devices can play a valuable role in helping glass extend across a façade. Although glass professionals tout their product’s positives, such as the big benefits of natural daylighting and connecting building occupants to an exterior view, glass is often better known by many designers for negative points such as allowing in too much heat and glare. Shading devices, including metal screens, louvers and sunshades, can work hand-in-hand with glass to allow a diffused light into a building, and create a classy design on the outside.
However, as more designers learn about their options in high-performance glass, metal products are being dropped from specs.
Buildings make use of metal as sunshades, light shelves and metal screens, among other devices, adding to not only the aesthetic but also the performance benefits of mostly glass-clad buildings.
“Providing shading, while allowing a little bit of deflected light in through a window, is going to cut down on warming things up,” says Mitchell Zelazny, architectural sales manager for Chicago-based metal product supplier Accurate Perforating.
“Primarily the energy-saving value is from reducing the solar impact on the glazing,” adds Jason Richter, sales manager for architectural products for Ohio Gratings Inc. in Canton, Ohio. “[Metal screens] reduce the solar heat gain of the interior of the building and allow the cooling units to not work as hard. It also can allow for indirect ambient interior lighting.” He adds, “Through different designs you can cut down on your energy costs from turning on lights during the middle of the day when it’s bright and sunny outside.”
Viviane Chan, director of sales for Unicel Architectural in Longueuil, Quebec, agrees. “If we add screens and louvers on the outside of the building we’re definitely giving the building the best energy performance in terms of heat buildup,” she says.
Richter explains that sunshades can be treated in a couple of different ways to provide these screening benefits. “The traditional [look] is to have them projecting off the face of the building. You also can have them running vertically depending on the building orientation; that might work better than the projected horizontal shades. There are a couple different ways to treat it to achieve a different focus on the orientation of the glass.”
These metal experts generally choose to work with the architect, rather than the glazing contractor, early in the project to make recommendations on how to achieve the best shading for a specific project.
“We make design recommendations on the spacing and angle of the blades to optimize the solar engineering for them. So long as we’re given the design criteria, we can maximize that and provide them with a system that is as light as possible that meets their shading goals,” Richter says.
Chan says most architects come to the metal supplier with their solar design questions firmly in hand.
“I get questions [from architects] that are more technical, such as how to anchor [the products] into the curtainwall on the building, how much span they can extend, or how much of an outrigger is allowed and things like that,” she says. “They’re pretty much set on the design they have to determine the angle of the louvers that’s optimal for the sun’s angle and the project location and so forth.”
Zelazny would say that architects generally want a glass and metal package that works “in combination” to keep a building interior cool. Yet Tom Bialk, LEED green associate and solar engineer with GKD Metal Fabrics in Cambridge, Md., points out that metal sunshades have begun to be value-engineered out of projects in favor of a clean looking, high-performing—and comparatively more cost-effective—glass option.
“A lot of times what happens is the architect takes it off totally, even the aluminum sunshades, and just puts in a high-performing glass. That’s probably our main competitor—the glass,” Bialk says.
“It’s definitely ‘glass versus metal,’” Richter agrees. He adds that this “is unfortunate because sometimes you can really get the best effects by blending the two, and some designers recognize that. But the technology advancements that the glazing industry has made with the low-E glasses and everything else have definitely rendered sunshades to a lesser extent irrelevant.”
In the field, Schlotfeldt says he’s seen no more and no less call for metal shades than in the past, and that’s largely because of the distinctive aesthetics these exterior-affixed devices offer a building.
“With the higher performing glass you certainly get better performance than we’ve seen in the past, but there still is a place for things such as sunshades to help the performance of the building,” Schlotfeldt says. “We have seen architects who want to have a very smooth look on their building that have been able to value-engineer out certain things like sunshades because of the high-performing glass. However, they certainly do provide a benefit.”
Aesthetics over Function
The benefit is pure looks. Of the demand for metal products, Zelazny would say “it’s heavily leaning toward the aesthetics …” There are few instances where the need for reduced solar heat gain can’t be achieved by the glass alone.
Richter would agree that the architect’s budget usually stretches to cover metal components when it compliments the overall look of the façade. “There’s a little bit of a budget trade-off,” he says of the glass versus metal question, adding, “sometimes they want the look more than anything else.” He adds, “It certainly is function-driven, but with architects and designers they’re always looking for something unique and different, and we’ve got so many different products that we can throw out there that there’s generally something that they haven’t done before.”
For Chan, aesthetics and function must go hand-in-hand when it comes to designing with metal. “It’s definitely a combination of the two,” she says. “I think, aesthetically speaking, [sunshades] certainly can be attractive, if done the proper way.”
Schlotfeldt agrees that performance and appearance should go hand in hand when it comes to glass-and-metal heavy projects. He adds, “Obviously the architect has to balance the performance of the building and their aesthetic goals. Sometimes their aesthetic goal does not include the use of gingerbread things such as sunshades, but it still is a balance between the aesthetic and the performance because [metal screens] do certainly aid in the performance to the wall.”
Chan agrees that the budget must allow for this certain look, since performance can be found from the glass package alone.
“One of the drawbacks is from seeing the costs that come with [sunshades]. That can usually be the deal killer. If it’s too expensive, then they’ll look for other options,” Chan says.
Although there are more options than ever for letting in light without the heat, metal products still provide a unique, trendy look that many architects want.
“I haven’t seen any increase or decrease [in metal products], to be honest,” Schlotfeldt says. “It seems like our business really is determined by the architect’s preference. There are ways to achieve the performance without them and, if that’s what the architect’s preference is, that’s the way we go about helping them with their design. But if that’s what they’re looking for there are certainly great opportunities in sunshades and screening to meet their goals.”
Balancing the Benefits of Daylight
The designers at Lewis & Malm Architecture in Bucksport, Maine, had a distinct vision to make the renovated Woolwich School in Woolwich, Maine, more energy-efficient and learning-friendly than its predecessor. The architect especially wanted to optimize daylight to help create a stimulating environment for students.
“Together with school officials, we shared a common vision to leverage sunlight for a more student-friendly learning environment that supports green initiatives,” says project architect, Richard Malm of Lewis & Malm Architecture. “The resulting facility puts students first, ramps up energy efficiencies and creates an aesthetically-pleasing architectural environment.”
The $16.2 million, 66,000-square-foot addition includes expansive use of glass, from a three-story curtainwall along the classroom forum to a wide-open curtainwall in the cafeteria. Although the windows and curtainwall all make use of insulating units comprised of low-E glass, the architects also used a number of sunshading solutions to help control both heat and glare.
Thirty-six exterior outrigger sunshades, extending 3 feet beyond the face of the building, spanned all three floors of the school’s new classroom addition. Each sunshade was composed of 4-inch louvers angled at 45 degrees. These sunshades allow filtered sunlight into the building while minimizing the impacts of solar heat gain and glare.
According to Unicel Architectural, which supplied a number of insulating glass units with its integrated cord-free louvers, as well as the exterior sunshading solution, the facility harnesses daylight to help reflect light into classrooms and create optimal daylit conditions for students.
To conserve energy, monitors will automatically turn off the electric lights when enough daylight enters the interior spaces. Additional daylight is brought to each classroom on all three floors through automatically controlled light tubes extending to the roof.