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Designing with Metal Louvers

Control sunlight entering buildings with well-designed metal louvers

Signeffectz Sept18 8
Photo courtesy of Sign Effectz Inc./AFX DIVISION

Buildings have to endure substantial amounts of heat from the sun. Metal sunshade louvers block undesired sun and heat gain while allowing natural light into buildings. By reducing negative solar impacts, sunshades can create significant energy savings for the life of a building, especially in hot climates. In particular, when windows are shielded from direct sun, they can provide desirable views and daylighting while avoiding negative glare, fading and excessive heat gain.

Sunshade louvers are also an attractive design element with a distinctive look that can elevate a building’s architectural aesthetic. Numerous blade shapes, blade spacings and trim profiles allow designers to meet project requirements.

LOCATION AND ORIENTATION

Building orientation, geographic location and the location of the opening to be shaded will determine the shading strategy needed to block direct solar radiation. Proper sunshade design should strive to minimize solar heat gain in the cooling months, and utilize the sun’s energy during the heating season. Mike Wallace, president, Quality Metal Crafts LLC, Rogers, Minn., insists for metal louvers to do this they should be installed only on the sides of a building where they will impact the sun penetration positively.

The best position to maximize sunshading is different for every building and even varies among different parts of any given building. “In the Northern Hemisphere, a building’s northern elevation is not subjected to direct solar radiation,” says Anthony Jackson, regional sales manager, The Airolite Co., Schofield, Wis. “The southern elevation is usually the easiest to defend against the sun’s energy throughout the year as the path of the sun and the opening are parallel to one another, which allows the designer to take full advantage of the most commonly used horizontal shading devices. The east and western elevations are very difficult to shade as both encounter very low sun angles during the morning and late afternoon/evening. These low sun angles present a challenge for designers who want to provide unobstructed views while minimizing solar heat gain. Vertical shading is commonly used to address the shading needs for the eastern and western elevations, but tradeoffs between unobstructed views and shading are common.”

Photo courtesy of The Airolite Co.

Photo courtesy of The Airolite Co.

By using a table of the sun’s position in relation to the project, architects can maximize a sunshade’s effectiveness on different elevations. Tables tell what level and type of sunshading will be most beneficial for a specific project at the critical time of shading, typically between 10 a.m. and 4 p.m. Joe Ray, president, Architectural Louvers, Cincinnati, suggests starting with the project location with these key pieces of information:

• Solar altitude at hourly intervals during peak heating season.
• Solar altitude at hourly intervals when the heating and cooling seasons swap.
• The orientation of your building relative to due south (if you are located in the Northern Hemisphere).
• Generate solar azimuth angles throughout the day at the times in steps 1 and 2.

ATTACHMENT

Metal louver sunshades are typically attached to either masonry, curtainwall or through metal wall panels back to the structure. Adam Brown, president, Sign Effectz Inc./AFX division, Milwaukee, contends the attachment technique and providing appropriate structure design are critical, but normally an afterthought. “Aesthetics are easier to incorporate later on. Think about attachment methods early in the process. They have higher loads applied to them than most might think. They also drive much of the budget and are often high-ticket change orders later if not planned out with the manufacturer early. Call in a sunshade manufacturer at the preliminary design stages to address these surprises before they hit you.”

For critical attachment, “In the case of masonry, sunshades are attached using wedge anchors, masonry screws or adhesive anchors,” Jackson says. “Sun control devices may be attached to curtainwall frames using custom curtainwall T-brackets or angle brackets with fasteners. When attaching back through to structural steel, the sunshade will use either a back plate of the T-brackets or angle brackets with fasteners to secure the connection. No matter which attachment method is used, it is recommended that the user determine loading requirements based on the local building code and should specify said code along with loading requirements. It must be specified if structural calculations are required to be submitted, or approved and stamped by a professional engineer. It is very important to recognize that sunshades have to endure wind loads, snow loads and thermal expansion, so care should be taken in their design in order to avoid catastrophic failure.”

Photo courtesy of Quality Metal Crafts

Photo courtesy of Quality Metal Crafts

Wallace admits that while the biggest challenge is fastening metal louver sunshades back to the curtainwall or structure, this can be worked through in most cases. “Incorporating sunshades into building designs can be seamless,” he adds.

INTEGRAL DESIGN

Alan Su, associate, designer, LEO A DALY, Washington, D.C., believes that louver design is integral to the overall massing and specifically, the building envelope. “The design consideration and implementation should not be an afterthought. The conversation needs to take place early in the design process with the design team and stakeholders. A well-designed element always seeks to find balance between function and aesthetics. It isn’t a debate about function being subservient to aesthetics or vice versa. But rather, if the sunshade is carefully designed and crafted with the rest of the building, it is going to contribute to shaping the building design and fulfill its intended function.”

When designing metal sunshade louvers, Brown suggests prioritizing the driving principles of your design: shade, weather protection, aesthetics, etc. “The open area of the sunshade can affect all of the above as well as the detail section of the louver. For example, airfoils produce less horizontal lines and blend better with the background.” He compares louver design to pinstripes on a hot rod. “They are there to accent the design of the building. Use different shapes, colors and sizes to accentuate the lines of the structure. It’s the manufacturer’s responsibility to engineer and produce the product.”

When Wallace visits with an architectural firm to discuss sunshade products, he emphasizes that there is the “cookie cutter” version of standardblade or louver-extruded shapes that most manufacturers carry. “With that said, we always emphasize that with the low cost of building a custom extrusion, we are able to manufacture a specific look or desire without jeopardizing their budget,” he explains. “There are so many different versions of sunshades to include perforated panels or even expanded metals. We encourage the architect to give us their thoughts on what their heart desires and work through any challenges, but ultimately give them the appearance they are looking for. Custom is not a dirty word, it does not mean expensive. The architect can freely come up with any design that they have dreamed up and it is our job as manufacturers to fulfill their dreams. We encourage early on communications so that we can steer them in the right direction using best practices and meeting budget constraints.”

Photo courtesy of Architectural Louvers

Wallace is seeing an increase in the use of vertical sunshades manufactured out of aluminum plate panels that can be solid or perforated. “They offer a sleek look to any building and can be done in several different types of applications,” he says. Jackson agrees that vertical sunshades are “all the rage,” especially when it comes to using custom extrusions for the fins. “While some architects and owners chose to blend sunshades into the building, many see sun control devices as an architectural feature, highlighting their presence on the building,” he adds.

Su advises that designers should keep in mind the building envelope maintenance strategy while designing the louvers. “Consult with facility managers early on to discuss window cleaning procedures,” he says.

FINISHED TO MATCH

Sunshades can be finished to match and complement just about any building aesthetic with a variety of finish types, such as anodizing, powder coating or liquid coating. Ray says finishes enhance product appearance to blend with other items in a building exterior. “These same finishes provide extended weathering resistance,” he adds. Ray lists the following as possible metal sunscreen louver finishes:

Kynar 500 or Hylar 5000: 70 percent PVDF paint finishes provide maximum resistance against color fade and chalking.

Baked Enamel: High-performance finish, long color life and resistance to chalking and chemicals.

Prime Coat: Preparation for field painting. Finish may be top coated with epoxy, vinyl, urethane and other heavy-duty coatings within six months of application.

Pearlescent: High-performance pearlescent finish. Pearlescent is a Kynar or Hylar-based finish that utilizes pearlescent mica pigments to simulate the metallic appearance of anodized and metallic paint finishes.

Color Anodize: Electrolytically deposited coating on aluminum. The color anodize process specified in Aluminum Association Code AA-C22A44 electrolytically deposits inorganic color pigment finish to a 0.7 mil (18μm) minimum surface depth on sulfuric acid anodized aluminum.

Photo courtesy of Page

Clear Anodize: Clear oxide coating for aluminum.Clear anodize preoxidizes the aluminum surface for uniform clear finish not easily affected by natural oxidizing influences. Improved metallic luster appearance is similar to mill finish.

Dan Arvelo, regional sales manager at Airolite, says the most popular by far is a liquid or powder coat Kynar paint finish. “Kynar coatings are the most durable finishes available and are offered in a wide variety of standard, custom, and even metallic colors,” he says. “Anodized finishes can also provide a beautiful metal sunshade, but are not as durable as Kynar coatings. Baked enamel paints are the most cost-effective finishes used for sunshades, but do not perform as well as Kynar finishes. Wood grain finishes are a specialty product for those projects where the natural wood look is desired.”

Modular designed metal louver systems allow for more diverse finishes due to the many size constraints in the finishing processes. For example, the size of most anodizing tanks is 13 feet long or less. “Powder coating rooms are typically limited as well and logistics of moving larger sun control panels in shop or over the road increases costs,” Brown says. “Anodized is my favorite and the best finish available for aluminum and is best with modular designs.”

Photo courtesy of LEO A DALY