Pushing the envelope

State-of-the-art glazing applications highlight office buildings
August 11, 2010

Transparent glazing is a shared feature of the curtain walls of the Halo Industries building in Niles, Ill., and the 23-story LVMH Building in New York City.

Promotional products firm Halo, seeking a strong corporate identity for its seven-story office/showroom building, commissioned Chicago-based architect Murphy/Jahn (M/J) to develop a design concept. Light is the essence of the design of the Halo headquarters, which is luminous, not illuminated. Its façade acts as a fabric that moderates the natural and the artificial light, becoming a screen.

Halo "takes ideas we've learned in our European work and introduces them [in the United States]," says Gordon Beckman, the building's principal architect. M/J President Helmut Jahn characterizes Halo's design as "40 percent as innovative as what's being done in Europe."

The building is arranged like a simple and clear diagram, with its components placed in a logical, rational and constructed way. Interest is in engineering and performance, rather than design and style. The result is a building of maximum transparency.

Functions within the building are placed around a seven-story open court. The lower floors contain loft-type offices, and the top two floors house showrooms and executive offices.

Motorized interior sunshades, which are controlled by roof-mounted sensors, modulate the entry of natural light from all four facades.

The building was developed and is owned by Centerpointe Realty Trust of Oak Brook, Ill., which awarded a design/build contract for the project to Chicago-based Harbour Contractors. M/J developed preliminary pricing documents. To keep the project within budget, Harbour retained Marina del Rey, Calif.-based Advanced Structures Inc. (ASI) to develop systems that would provide the amount of glazed area proposed in M/J's design. The result is 4,000 square feet of glass fin wall, a 12,000-sq.-ft. custom skylight and 17,000 square feet of interior glass, according to Will Shepphird, project engineer with ASI.

The ASI-designed wall and skylight comprise about one-fourth of the building's exterior glazed area. The remainder consists of a silicone-glazed, non-exposed system installed by Architectural Wall Solutions, Naperville, Ill.

The system developed by ASI to support the glass utilizes localized aluminum components to support the insulated glass lites through the glazing joints. Aluminum pinch plates are pinned to either a stainless-steel boot (for the fin wall) or a custom aluminum spyder (for the skylight). M/J had previously developed a cast aluminum system for a European project. Because of time and budgetary sensitivities, the cast system was replaced with CNC machined components finished with a clear satin anodizing.

The vault skylight is constructed of primary trusses at 15-ft. centers spanning in the 60-ft. dimension. Each truss uses a rolled steel pipe top chord, vertical pipe web members and a stainless-steel underslung cable.

Spanning between trusses are alternating glass fin purlins and steel pipe purlins at 5-ft. centers. The low-iron glass fin purlins are restrained against torsional buckling by small cables that connect to the adjacent pipe purlins.

Translucent, green glass blended

An intriguing combination of translucent and green glass is a key feature of the 23-story North American headquarters of Louis Vuitton-LVMH, the Paris-based provider of luxury items ranging from champagne to leather goods.

The design architect, Paris-based Christian de Portzamparc, was challenged to create a building with a unique identity on one of New York's premiere retail streets. De Portzamparc collaborated with Princeton, N.J.-based The Hillier Group, the architect of record.

The exterior of the building is highlighted by the contrast between transparent, low-iron glass and green-tinted glass. The ultraclear glass has a white sandblast coating on the No. 2 surface, while the green glazing obtains its color from an outer lite of green-tinted glass.

Separating the two glass types is a 300-ft.-long angled recess that begins at the second floor and continues to the top of the building. A shorter recess extends upward to the 10th floor. Both recesses are lined with reflective white metal panels that at night pick up light produced by fluorescent tubing encased in the notches.

Standard glass in the lower left portion of the structure is the third type of glazing that makes up 40,000 square feet of insulating glass units.

Although the LVMH headquarters uses only three basic types of glazing units, a detailed categorization reveals some 30 permutations caused by variations of patterns, coatings, shapes and other individual features, according to the project's New York City-based curtain wall and glazing consultant, Robert Heintges of R.A. Heintges Architects Consultants.

The spandrel and vision panels of the green glass have an applied ceramic frit dot screen pattern on the No. 2 surface. Its basic purpose is to provide a material surface for receiving nighttime lighting from neon tubing concealed within exterior folds of the curtain wall.

Sandblasting provides uniqueness

The low-iron, transparent glass and the standard glass window units were sandblasted on the No.2 surface to produce horizontal patterns. These fine lines appear to have been drawn by an old-fashioned ruling pen. In fact, the original artwork used to create the glass silk screens was actually hand-drawn. The lines vary in width, beginning densely and feathering out.

The sandblasting process is somewhat similar to the application of ceramic frit, although in reverse. But, unlike ceramic frit, the microscopic points that sandblasting exposes produce a unique luminance when struck by light, Heintges notes.

De Portzamparc initially envisioned curved insulating glass units for the LVMH curtain wall. This would necessitate the simultaneous bending of both inner and outer lites with the same mold, so that any imperfections in one piece would be transferred to the other. Pricing feedback from glass suppliers for this curved glass was incorporated into the initial budget for the wall, but actual bids were about twice as high as anticipated.

De Portzamparc then completely altered his plan. His revised scheme utilizes flat glazing and achieves a faceted appearance by faceting entire sections of curtain wall, varying from an area of 2,000 square feet to 3,000 square feet. Heintges likened these "superfacets" to the skin of a Stealth bomber, which contrasts with the continuously curved fuselage of a conventional aircraft. Had de Portzamparc attempted to achieve his original design objective by modifying the position of each 5-ft.-wide glazing unit, the result would have been much less dynamic, Heintges believes. The prohibitive economics of the initial concept thus provided an impetus for developing the final faceted wall design.

The most challenging aspect of the curtain wall design, according to Heintges, was to make the all-glass exterior satisfy requirements of the New York State energy code. A computer model evaluated each piece of glass by zone and area. Various combinations were studied as the design evolved. The effect of tints, coatings and the application of sandblasting and ceramic frits were also studied.

Had de Portzamparc simply applied New York City's zoning setback regulations, the building would express the traditional "wedding cake" form. His early design concepts did take this approach, notes James Greenberg, project principal with The Hillier Group. However, the French architect creatively addressed zoning requirements by unifying the building setbacks with a prismatic design.

The low-iron glass was produced by French-based Saint Gobain. Carleton, Mich.-based Guardian Industries fabricated the insulating units, performed the sandblasting and applied ceramic frits and low-emissivity coatings. Miami-based Glassalume International was the curtain wall fabricator.

         
 

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