In the heart of downtown Phoenix stands a modern high-rise office building that is distinctly different from the ones around it. By using innovative technology instead of opaque materials, the 26-story Freeport-McMoRan Center mitigates the intense heat gain and glare of the desert environment.
Formerly known as One Central Park East, the building currently is named after the Freeport-McMoRan mining company headquartered in the tower. Surrounded by the new development of Arizona State University’s downtown campus and Civic Park, along with the central bus transit hub and a light rail station across the street, this is one of the newest large-scale, transit-oriented development projects in Phoenix.
A New Concept
The concept was to create a new type of office building that would attract a major national or international prime tenant, says Mark Roddy, AIA, design principal at SmithGroup, Phoenix. Part of a recent rebirth within the downtown area, the building incorporates office and environmental strategies. “The design is an alternative to the existing context that has attempted to respond to the intense heat gain and glare of the desert environment by simply incorporating opaque materials,” Roddy explains. “This project takes the opposite approach by using transparency and incorporating current glass technology and a high-performance curtainwall system, along with innovative shading to provide sun control.”
Completed in November 2009, the building includes approximately 485,000 square feet of office space on 28,000-square-foot floor plates with 8,000 square feet of ground-level retail. The building is unique to the Phoenix market as it incorporates a large office plate that is typically found in suburban office buildings, and places it on top of a stacked parking structure. The office market demanded on-site parking but providing it below-grade was cost prohibitive, resulting in this unique solution of stacking 16 floors of office space above nine levels of parking.
The office program is characterized by large efficient floor plates with 9-foot floor-to-ceiling glass, which provide dramatic panoramic views of the surrounding city and mountain ranges. Additionally, eliminating the corner columns and cantilevering the plate 15 feet each way expresses the building corners, resulting in a visual significance to the corners of the building, offering unobstructed views from the interior.
The building’s integrated parking structure is naturally ventilated, accommodating views, airflow and natural light by using a perforated standing seam metal roof panel. During the day, cars are completely screened, and at night the parking structure becomes transparent.
“The goal was to design a high-performance modern high-rise office building using a sophisticated curtainwall system while maintaining an appropriate response to the Arizona desert environment,” explains Greg Buchanan, AIA, project architect. “Shading is critical. The use of aluminum allowed for a cohesive design connection between all the facade components. It also was easy to use the different components within the unitized curtainwall system.”
Using varying shading strategies on each façade makes it possible to provide floor-to-ceiling transparency on all sides. Insulated glass units that are a combination of low-E coated clear and spandrel glass are used on the north and south facades. The same units are also used on the east and west façade, but include an additional 15 percent graduated ceramic frit patter that reduces the solar heat gain coefficient, thereby reducing the building’s overall cooling load.
Additionally, each façade responds fittingly to its orientation, Roddy says. “Each individual façade works simultaneously with the others, facilitating a didactic expression of the building’s relationship with its environment.”
According to Roddy, the project has three primary façade strategies. First is the cladding of the above-grade parking structure that features perforated panels to allow for airflow and natural ventilation, while still visually screening the cars.
Next is the horizontal shading on the south façade by two custom 17-inch airfoil blade shade fins per floor that block direct heat gain and bounce indirect light into the building.
Lastly is vertical shading for low angle sun on the east and west facades. Continuous custom 17-inch airfoil blades at 5 feet on center provide shading while maintaining views. The custom graduated ceramic frit pattern on the glass adds an additional 15 percent shading. Only the north façade does not require the use of shading devices.
“We used modeling for shading analysis to determine shading performance that in turn dictated frequency of shade fins, depth and orientation,” Buchanan says. The curtainwall contractor, Walters and Wolf, mocked-up the facade at its fabrication facility in Gilbert, Ariz., to determine its aesthetic appeal, ensure tenant views and maintain quality craftsmanship and constructability. The façade also was tested at the Construction Consulting Laboratory West testing facility in Ontario, Calif., for water and air filtration.
The building features “sky gardens,” or patios, on the 25th floor and an array of dichroic glass fins that indicate the entry on the south façade. The dichroic glass feature is made up of SCHOTT NARIMA dichroic glass from SCHOTT North America Inc., Elmsford, N.Y., sandwiched between 1/4-inch low iron tempered glass, each separated by 0.060 PVB layers. The glass is point-supported at the ends of each 5-foot unitized section. The perceived color change of the dichroic glass depends on several factors, such as the angle of the sun, the angle at which the glass is viewed and the background it is against, explains Buchanan.
“In essence, the biggest challenge was designing an all-glass building in the desert,” Roddy says. “The client very much wanted an all-glass building so that drove decisions about the performance of the curtainwall system. This resulted in the different shading strategies for the east, west and south facades. Preserving the all-glass strategy with shading elements gave the client what they wanted from a leasing perspective while having the building maintain its environmental responsiveness to heat gain.”
“The design of the façade is very rigorous,” he continues. “The team had to work diligently in order to get everything to line up between the different exterior building systems. With the various connections to structure, floor-to-floor heights and fly-bys, it was imperative that the final product came across as a cohesive building even though each façade orientation is treated to respond to the environment differently.”
Metal Products Used
Primary system: 6-inch aluminum unitized curtainwall fabricated by MK Architectural Metal Inc., North Canton, Ohio.
Addition components include:
- 48,000 square feet of perforated aluminum ribbed metal wall panels from Kalzip Inc., Michigan City, Ind.
- 25,275 square feet of Chesapeake, Va.-based Mitsubishi Plastics Composites America Inc.’s ALPOLIC aluminum composite material panels
- 25,630 linear feet of sunshades from C/S Group, Cranford, N.J.
- Insulating glass units from Viracon, Owatonna, Minn.
- Dichroic glass from SCHOTT North America Inc., Elmsford, N.Y.
Freeport-McMoRan Center, Phoenix
Development manager: Mesirow Financial, Chicago
Design architect/MEP engineer: SmithGroup, Phoenix
General contractor: Holder Construction Co., Phoenix
Structural engineer: PK Associates LLC Consulting Structural Engineers, Scottsdale, Ariz.
Consulting engineer: Evans Kuhn & Associates Inc., Phoenix
Landscape architects: Laskin & Associates Inc., Phoenix
Curtainwall fabricator: MK Architectural Metal Inc., North Canton, Ohio
Curtainwall subcontractor: Walters & Wolf, Gilbert, Ariz.
Façade testing: Construction Consulting Laboratory West, Ontario, Calif.
Metal wall panels: Kalzip Inc., Michigan City, Ind.
Aluminum composite material: Mitsubishi Plastics Composites America Inc., Chesapeake, Va.
ACM panel fabricator: Armetco Systems Inc., Justin, Texas
Sunshades: C/S Group, Cranford, N.J.
Insulating glass units: Viracon, Owatonna, Minn.
Dichroic glass: SCHOTT North America Inc., Elmsford, N.Y.