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Colored Glass Clearly Has its Benefits
Structural engineer Michael Ludvik primarily creates bold, creative structures out of glass. But he also spends a fair bit of time playing educator— teaching building designers, architects and regulators about the strength and diversity of using glass as a structural element.
“Michael helps us architects realize dreams that we don’t even have,” said Audrey Wu, a senior associate and project architect at Gensler, a leading global design and architecture firm based in San Francisco. “Your natural instinct,” Wu said in a Nov. 21 telephone interview, “is that you handle glass with kid gloves, but Michael helps educate us, as well as building officials, about the strength that glass does have.”
For his part, Ludvik— who operates his own firm M.Ludvik & Co. in Brooklyn, N.Y.— notes that glass is indeed brittle, but it’s also strong like metal. The key to building big glass structures, he says, is “to engineer around the brittleness.” New and existing technologies help to do that.
Laminated glass, a composite type of safety glass that holds together when shattered, has been around for decades. Typically, two or more layers of laminated glass contain an interlayer, usually of polyvinyl butyral (PVB) or aliphatic thermoplastic polyurethane (TPU), which keeps the layers of glass bonded even when broken and prevents the glass from shattering into large, sharp pieces.
One also can chemically strengthen glass in a post-production process involving a salt bath. This type of glass is being used in the aerospace industry and is becoming more common, explained Ludvik, an Australian who has spent most of the past 15 years living in New York City. The process is expensive, but allows one to use complex geometries, and yields glass that is every bit as strong as structural steel— though it still needs to be laminated to serve as safety glass.
This was the process used to produce the glass used in one of Ludvik’s most spectacular applications— the SkySlide on the new U.S. Bank Tower in downtown Los Angeles. The 45-foot-long slide is 4 feet wide, 3½ feet tall, made of 1¼-inch-thick, triple-laminated hurricane glass, and is mounted on the outside of the skyscraper, some 1,000 feet above the ground. Hardy souls can buy a ticket to slide down the clear glass tunnel, from the 70th to the 69th floor. The slide is part of the building’s Gensler-designed, open-air Skyspace Observation Deck, which became California’s tallest when it opened this past summer.
Ludvik collaborated with Gensler on parts of that observation deck and on the U.S. Bank building’s main lobby, with its 34-foot-tall structural glass. Ludvik engineered that wall with curved glass and super tall glass fins.
He also has been involved in some other high-profile projects, including designing the distinctive, triangular glass TKTS booth in New York’s Times Square where theater-goers buy tickets.
Glass also plays a central role in the Gensler-designed, $200 million, 500,000-square-foot Hyundai Motor America headquarters and Tech Center building in Fountain Valley, Calif., on which Wu was the project architect. That effort won a 2015 Merit Award from the American Institute of Architects Los Angeles (AIALA).
“We used 15 different types of glass on the project to tell the architectural story and meet energy, acoustical and visual and thermal comfort requirements,” Wu said. “Given that the car company wanted freeway presence, we sited the building just over 100 feet from the 405 freeway. This necessitated the use of acoustical glass (3/8” outboard lite, plus 1" argon-filled interspace, plus ¼" laminated to ¼") on three sides of the unitized curtainwall and a 9-foot tall, cantilevered, laminated sound wall for the roof garden.“
Meanwhile, firms such as Eastman Chemical Co. have been helping to advance both the performance and aesthetic properties of glass for years. Eastman significantly boosted its holdings in this sector in 2012 when it acquired Solutia Inc., the world’s leading producer of interlayer films for laminated glass, including the market-leading Saflex® brand. In the same deal, valued at about $4.7 billion, Eastman also acquired Solutia’s Vanceva brand of PVB-based, colored interlayer films.
Julia Schimmelpenningh, Eastman’s global architectural applications manager, is a 29-year industry veteran who a decade ago also served a year as president of the Glass Association of North America. In a recent phone interview, she explained how the technology surrounding colored glass has evolved over more than half a century.
In the 1950s, earth tones such as blues and browns dominated among the limited colors of choice for glass interlayers. The early 1990s brought advances in color-blending technology, with firms looking at how paint was mixed and applying that approach to color creation for interlayer films. The Vanceva portfolio back then was based on nine foundational colors that could be combined to create some 3,000 unique colors by layering interlayers to create the desired hues. This was done instead of directly extruding the color as a single sheet, giving laminators and designers tremendous color flexibility from the nine base tints.
Vanceva films are 15-gauge, or just 0.38 mm or 15,000ths of an inch thick, vs. the more traditional 30-gauge interlayer films in the U.S. that are twice as thick. Schimmelpenningh noted, though, that the Vanceva system is designed to layer the colors to achieve "custom” colors. That means that although the Vanceva films are made as 15-gauge interlayer, the use of the product ranges from 15 to 60 gauge, depending on what colors the users choose for their projects.
The Vanceva color system is now based on 16 basic colors. While more layers are possible, Eastman recommends limiting the number of layers in any given laminated glass construction to four. The resulting combinations produce individual colored glass, and can yield a broad spectrum of colors that are unachievable using stock selections of glass.
Today, Schimmelpenningh said, “Vanceva color interlayers can be combined to produce more than 17,000 transparent, translucent, or solid color options to help you create the perfect tone and intensity.”
Laminated glass made with these interlayers delivers effective protection from UV radiation, blocking up to 99% of damaging UV light. And the Vanceva interlayers themselves are made with heat- and light-stable colorants that resist fading and ensure long-term color stability. This unleashes a world of possibilities for architects and designers who wish to inject a splash of color into their projects.
To underscore this point, in 2000 Solutia launched a design awards program to recognize the creative architectural use of laminated colored glass. Known now as the Vanceva World of Color Awards, this contest recognizes its winners at the international Glasstec trade fair in Düsseldorf, Germany.
Eastman crowned the latest winners at Glasstec this past September, with top honors going to a stunning shopping mall in Malmö, Sweden. Called Emporia, the mall features two main entrances with each made of colored curved glass – one using amber Vanceva color interlayers and the other one in blue. It’s like the sun and the sea at opposing ends of this massive structure, notes Eastman. In between, three stories of blue, red and green-themed retail space are arranged in a figure-eight layout. The architect’s goal was to confer these colors while maintaining high transparency and low hazing.
Spanish glass fabricator Cricursa manufactured 567 molds to slump a total of 815 curved glass panels. It implemented a new way to control curved glass tolerances in 3D geometries. The largest panel in the project measured 3,571 x 2,718 mm, or just under 12 x 9 feet.
Ludvik also noted other Eastman products that are playing a key role in architectural glass construction these days. Its XIR® solar control film for laminated glass is a very thin (2 mil) PET film with a low-E coating that helps to improve a building’s energy-use performance. XIR has a low-reflectance appearance that allows more than 70% visible light transmittance while reflecting about 50% of the invisible heat. Gensler used Eastman’s XIR film on the 30-foot-tall structural glass walls in the U.S. Bank building’s main lobby in Los Angeles.
Ludvik also likes the Eastman’s Saflex® DG structural interlayer film. Made from plasticized PVB, the latest version – Saflex DG41 – offers an extra-clear version of this existing range, Ludvik said. The DG series provides superior structural capacity and is designed for use in applications where increased interlayer rigidity and high glass adhesion are required relative to standard glazing interlayers. It’s also compatible with the Vanceva color system.
Schimmelpenningh sees this new structural interlayer as a definite growth area, enabling greater use of glass in floors, stairs and walls.
She also sees a big trend toward acoustic dampening for glazing, to help minimize or isolate noise transmission from the outside and between spaces on the inside. A soft, rubbery interlayer can enhance sound dampening. Ludvik notes that “breaking up the geometry” of a building’s hard surfaces also can play a large role in enhancing acoustics.
Regarding colored laminated glass, Schimmelpenningh noted some geographical and cultural differences. In the United States, not surprisingly, the first city to adopt the product in a big way was Las Vegas, and particularly on The Strip, with its neon lights and blazing colors. Generally speaking, Asian countries have been early adopters, and Latin America, where there’s a love of rich, vibrant colors, became the first region to use the Vanceva Color system widely in interiors. The Middle East favors more subdued colors, and tends to use vibrant colors only as an accent.
Eastman supplies its interlayer film material in rolls, and Schimmelpenningh suggests that one of the biggest challenges involves getting customers to understand the nomenclature used to designate the thousands of different color combinations. The firm hosts “lunch and learn” sessions, consults with customers of specific projects, and offers a lot of supporting information on its Vanceva website. Once Eastman spells out how the system works, and all the possibilities, Schimmelpenningh says, “You can see the lightbulb go on, and the wheels go in motion.”
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