The Tempe Transportation Center, a mixed-use mass-transit hub in Tempe, Ariz., was designed to be green in nearly every aspect. It will be submitted for Washington, D.C.-based U.S. Green Building Council LEED Platinum certification. It incorporates a bike station, which offers secure, indoor valet parking for bicycles, as well as showers, lockers and a repair center for bike riders; a commercial greywater system; a vegetated roof using native plants; and is designed without a car parking lot to encourage alternative modes of transportation.
The $27.4 million project had a lot riding on it. Washington-based Federal Transit Administration monies were used, in part, to build the structure; they intended to meet Silver LEED certification requirements, but surpassed that and likely will receive Gold or Platinum level LEED certification.
Bigger Plans, Smaller Footprint
“The project started out as just a 5,000-square-foot (465-m2) building to house a ticket office and restrooms for bus drivers,” says Bonnie Richardson, AIA, LEED AP, the principal planner and an architect with Tempe’s transportation division. “But in talking about it, we decided an urban plaza was needed to integrate everything within the downtown and we realized with the upcoming light rail system we had a broader opportunity.”
Completed in December 2008, the Tempe Transportation Center was unveiled as a 40,000-square-foot (3716-m2), 3-story masonry and steel-framed structure that includes a large plaza with 15 bus bays and shelters that serve the new Metro light rail station, as well as local and regional bus systems. The building houses transportation offices for the city, a 1,200-square-foot (111-m2) community/conference room, the transit operations center, and about 3,614 square feet (336-m2) of for-lease office and retail space. The center also offers bike storage, food shops and ticket sales. Showers and lockers are available for regular commuters. The narrow 3-story office/retail building anchors the west side of the transit plaza, which unites light rail with buses, bicycle storage, the city of Tempe government plaza and the campus of Arizona State University.
“There is no parking on site, other than a couple handicap-accessible spots, which is pretty unique,” says John Kane, FAIA, LEED AP, design principal with Tempe-based Architekton, who co-designed the project with Portland, Ore.-based Otak Inc. “It’s a truly multimodal building, with everything but the car.” Parking is available across the street, but the center was built to encourage the use of public transportation.
“We demanded a lot from our materials,” says Kane. “They had to be sustainable, recycled, have dimensional stability, low maintenance, long life, fit the budget and had to be a material that can be a wall or a roof or a [certain aesthetic look]. That’s a pretty small group of materials that fits those requirements, so it was obvious from pretty early on that we would be using metal.”
The jewel of the setting, according to Richardson, is the center’s community room, which juts out above the bus terminal plaza below, giving the impression of a floating urban terrace. From the plaza, people can look up at part of the floor of the community room. The 1,200-square-foot (111-m2) community room’s resemblance to a shiny, multifaceted gem was enhanced by the use of metal wall panels. It required fabrication of 420 panels, with 150 variations of angled sizes created through 3-D shop drawings.
“We wanted a material that would play in the sun, so we were really excited when we found material that appears to change color in the light,” says Kane. “On five sides of the Community Center, we used iridescent material. On the sixth side, which acts as a roof over the public plaza below, we used a more standard platinum color. We also used the platinum color on the fascia and soffits of the main building.” The main building used 570 panels and 160 panels were used for the soffits.
A Secure Transparency
Stainless steel wire mesh fabric was used to create 14 framed panels using a standard commodity extrusion frame. The panels were prefabricated and installed at the site as security mesh on the external stairs, guardrail panels and the south wall of the building, creating an “Arizona room” for the south balconies of the building. An Arizona room is a variation of a screened porch. The mesh encloses the porch but allows fresh air in; when the weather is nice, doors can be opened to create an indoor/outdoor room. When the weather is too hot or rainy, the doors are closed. “During fall and spring we have beautiful weather,” says Kane. “We designed the offices so that they can open completely to the outdoors. The mesh creates an abstraction of a bug screen, acting as a guardrail and cutting down some of the direct sun while providing natural ventilation and enclosing the space with a sheer material.”
“We liked the transparency of the mesh and used it in several locations,” says Kane. “There are staircases, for example, used and seen by the public during daylight hours, but those needed to be secured at night. The mesh gave us a light, open feeling, but it is also lockable and not climbable.
The Green Challenge
In addition to the metal mesh shading devices, the Tempe Transportation Center includes a vegetated roof with thickly planted Sonoran desert natives, greywater treatment, a 14,000-gallon (52990-L) rainwater recovery system, low-flow water fixtures, solar-heated hot water, double-pane/low-E glass, fluted self-shading masonry block to reduce solar-heat gain, underfloor air supply and recycled acoustical ceiling tiles. There also is a photovoltaic solar-collection conduit for future implementation when the budget allows.
Recycled content was required in building materials for LEED certification, and construction waste was reduced by 94 percent by sorting waste on site for recycling, recycling all steel and metal, and grinding the asphalt and concrete on the site and using it in the alleyways and to stabilize the soil. Natural light in the offices cuts down on the use of artificial light. The building was designed to be 52 percent more energy-efficient than traditional buildings of its kind, but according to Richardson, current building operations have found that tenants do not turn on overhead lighting fixtures during the day, so energy optimization rates may be even greater.
“One of the biggest challenges was simply that we were proposing to do things differently from how they were typically done,” says Richardson. “That requires a lot of education. There were lots of details to track—when we started this project, green building was in its infancy. There weren’t as many green materials available and there was a lot of concern that it would be wildly expensive just because it was green. We had to help people understand life-cycle cost analysis and that was a big job,” explains Richardson. “When you are doing something so new, it just takes awhile. I think that future green projects will be considerably faster.”
Although the project turned out to be considerably larger than first envisioned and faced numerous challenges from the site and the project’s green goals, Kane says the construction went remarkably smoothly. “I’m sure that was a testament to the team,” he says. “The client, the contractor, the metal fabricators, our partner architects at Otak—everyone was just incredible. I feel like we were really lucky that way.”
Lisa Anderson Mann writes about architecture and metal construction from Petaluma, Calif.