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Let the Sun Shine In

Marcy Marro, Editor, Posted 06/01/2017

Perforated metal gives designers plenty of options for sunshades

perforated metal sunshades, june 2017, metal architecture 

Perforated metal offers architects many options and benefits as a sunshade. The hole size and pattern can change how much light is let through, and how much can be seen through the design element. With the option of being used in both horizontal and vertical formats, or as a screenwall, perforated metal sunshades provide a unique look for buildings and parking garages.

"Perforated metal offers great flexibility in design, color and performance with low-maintenance, cost-effective solutions," says Steve Kotecki, marketing at Hendrick Manufacturing, Elgin, Ill.

Shawn Bowman, CSI, national director of sales and marketing at DAMS Inc.-D. Architectural Metal Solutions Inc., Alsip, Ill., says the beauty of any of perforated metal is in its versatility. "Perforated metals come in hundreds of patterns or can have custom patterns," he explains. "In addition, perforated sunshades and panel systems can be formed, rolled and machined, allowing the design not only to be perforated, but to be three-dimensional as well."

"The flexibility to custom design a shading  system based on solar orientation, desire for varied levels of transparency or opacity, and any desired aesthetic in terms of pattern or relief, shade and shadow, is easily accomplished with perforated metal," says Mark Kranz, FAIA, vice president, design director at SmithGroupJJR, Phoenix. "We constantly experiment with new and untested approaches, materials, profiles and this allows us to keep learning. Most of the time, the end product offers some element of surprise that you can take with you to the next project."

 

perforated metal sunshades, june 2017, metal architectureHole Size and Pattern

In perforated metal, the size of the holes and the pattern create an open area, which is commonly expressed as a percentage. "The greater the open area, the more light will get through," explains Kotecki. "The adverse happens with a lower open area."

The ability to manipulate transparency and opacity by varying hole size, pattern and density gives architects the opportunity to calibrate the level of light penetration and shading performance in a very predictable way. Mike Griffith, marketing manager at Kovach Building Enclosures, Chandler, Ariz., says they've done perforated patterns as small as 1/8- inch holes, which doesn't let a lot of light through. If the holes are kept closer together, Griffith says the further you are from a building, the more it gives the appearance of a solid louver.

"I'm always surprised by how transparent a seemingly opaque perforated wall, screen or scrim becomes when viewing from the inside of a building out," Kranz adds.

Additionally, Griffith notes that as a shade on parking garages, perforated metal also acts as a natural exhaust system. "What perforated metal achieves is enough sunlight to make it comfortable inside, but it also provides ventilation," he explains. "There are code requirements in parking garages if they're not vented internally with a duct system, so you have to have enough natural air movement to clear out the exhaust."

 

perforated metal sunshades, june 2017, metal architecturePanel Material and Thickness

To support the desired sunshade design, the correct panel thickness is required. "The hole pattern chosen combined with the material of the panel will usually dictate the thickness of the material needed," Bowman says. "Bent or formed shapes can affect the thickness required to meet a design intent as well."

Griffith says aluminum is the go-to material in their experience because of its strength-to-weight ratio, while Kotecki says the majority are manufactured in various grades of aluminum or stainless steel. "The aluminum products finishes can be supplied in all ranges of RAL colors for 70 percent PVDF powders and liquids along with Class I anodizing," Kotecki says. "The stainless steel products can be supplied with mechanical brushed finishes."

Choosing the right material gauge is critical in designing perforated metal sunshades. "Even a thick steel plate that is perforated can show up on the job site with too much waviness and or imperfections," Kranz says. "We've found that when working with sheet material, that providing structural stability through breaking and bending creates relief and shadow while also eliminating oil canning and deflection that is perceivable." 

The type of material and its thickness also directly relate to its structural performance, corrosion resistance and warranty. Bowman says thinner gauge material can be framed to give it structure, while thicker materials can be frameless. "When the choice is made to utilize perforated material in a design the choices can sometimes be overwhelming," Bowman says. "We see architects and designers incorporate any of hundreds of standard perforated patterns or choose to create their own design completely."

[SIDEBAR]

Expanded Metals and Sunshades

In addition to perforated metal, expanded metal is also a good option for sunshades. According to the National Association of Architectural Metal Manufacturers (NAAMM), its Expanded Metal Manufacturers Association (EMMA) has completed testing for the effectiveness of expanded metal used as a sunshade for windows and other openings.

The testing showed that expanded metal is effective as a sunshade. The Solar Heat Gain Coefficient (SHGC) varies from 0 to 1, with the lower coefficient value indicating a more effective shade. The EMMA tests show that at a maximum sun angle of 60 degrees, the SHGC varied from 0.09 to 0.14. Three different expanded metal materials were tested with minor variations between the materials. The SHGC varied from 0.1 to 0.5 through the full range of sun angles for all tests. Testing was done in the 48-inch Solar Calorimeter ICN #62060 by Intertek/Architectural Testing at its Fresno, Calif., facility.

To obtain the complete test reports, go to naamm.org/division/4.

And, the size of the panel is typically determined by structural performance rather than its ability to be manufactured. Ranges are often figured on given wind loads, snow loads and spans, Kotecki adds.

"The larger the panel, the fewer the connections and perhaps reduced labor cost in fabrication," Kranz explains. "But the larger the material, the higher the risk of deflection, visual waviness and oil canning becomes. We've found that a collaborative 'design-assist' approach with the best industry subcontractors is the most strategic approach to reducing risk, coming up with something innovative, constructible, installable and warrantee-able. It's always great when you can grow your technical knowledge with someone who lives in that world every day. It expands your perspective and opens up the potential to consider new design ideas."

 

Collaboration

When it comes to designing perforated metal sunshades, Griffith recommends bringing in the specialty contractor as early as possible. "When we get the chance to really sit with the architect and understand their design intent, perforated metal just gives us a lot of options," he says. "There is a lot you can do with perforated metal that is economical and attractive, and still gives you the shade that you're looking for."

Working with a specialty contractor may also help you get the most out of your perforated metal sunshades, as they are a very energy-efficient building product and can help a project achieve LEED credits. These credits can include EA Credit 1: Optimize Energy Performance (up to 19 points); MR Credit 4: Recycled Content (1-2 points); MR Credit 5: Regional Materials (1 to 2 LEED points); and IEQ Credit 8.1: Daylight and Views Daylight (1 point).

*Photos courtesy of (from top): Hendrick Manufacturing; DAMS Inc.-D. Architectural Metal Solutions Inc.; Kovach Building Enclosures

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