Though it is set against the high drama of the Rocky Mountains, the city of Denver is remarkably flat. But along Interstate 25, a stretch of highway that runs north to south through the Mile High City, a series of facilities in a public works complex cuts a jagged form of man-made peaks. This is the Denver Central Platte Campus (DCP), a seven-building, 18-acre facility that serves as command central for the city's civic services. The campus—which includes a vehicle garage, a fuel-and-wash facility, and a massive salt dome, among other structures—totals nearly 112,000 square feet. If this doesn't sound like the usual arena for design-minded sustainable construction, that's because it isn't: Of Denver's 20 LEED-certified buildings owned by public agencies, DCP's LEED Gold fleet maintenance building and Gary Price Operations Center are the only municipal facilities that made the list.
Location Denver, Colorado (South Platte River watershed)
Gross area 111,611 ft2 (10,360 m2)
Completed September 2010
Cost $29 million
Annual purchased energy use (based on utility bills; Operations Center only) 70 kBtu/ft2 (798 MJ/m2), 10% reduction from base case
Annual carbon footprint 11 lbs. CO2/ft2 (54 kg CO2/m2)
TEAM & SOURCES
Doors Tubelite medium stile aluminum doors; Horton Easy Flow revolving door
Low-slope roofing Firestone ECOWhite 90 mil EPDM, RubberGard Platinum 90 mil EPDM
Custom woodwork Roseburg SkyBlend
Doing something different with a generally lackluster building type was exactly what Tom Wuertz and Dick Shiffer, design principal and senior principal at RNL, respectively, had in mind. "We wanted the architecture to scream sustainability," Wuertz quipped during a recent tour. So, to make the best use of their prominent, highway-side site, RNL topped the 29,000-square-foot operations center with a sawtooth roof you'd be hard pressed to miss while driving down the interstate. Panes of translucent polycarbonate on the roof's north-facing sides provide ample interior daylight, while the south-facing slopes of each "tooth" accommodate photovoltaic (PV) panels. This innovative thinking helped the team win the commission in a competition hosted by Denver's city government.
The atypical roof form and RNL's commitment to aesthetics weren't without technical complications: RNL's design called for general contractor Pinkard Construction to reposition the corrugated metal panels on the operations center's facade so that the panels would be on a diagonal, rather than in the more traditional vertical orientation. "We did some pretty extensive constructability reviews," says Tony Burke, senior project manager at Pinkard. He cites waterproofing the roof as a particular challenge. "It ended up requiring some dismantling and reassembly to make sure things fit tightly." RNL took a similar tack with the 40,000-square-foot vehicle maintenance facility: It also features diagonally corrugated panels on its peaked rear facade, but PV panels have yet to be installed due to budget constraints.
Inside, the steel-frame operations center is high-ceilinged and light-filled, with offices, men's and women's locker rooms, and a trio of open storage spaces that house various equipment and materials: large street sweepers, piles of metal, and reams of foam, among other items. The building also holds a flexible multipurpose area called a muster room, in which workers frequently gather for debriefings and other, less formal meetings. RNL specified custom cut low-e glass to fit to fit the irregularly sloped window casings.
At the fleet maintenance building, RNL's primary concern was to provide easy-to-use work areas. Large winches and other machinery for vehicle maintenance occupy open bays, while RNL carved out separate areas for welding, tire repair, and various operations essential for the city's convoy of trucks and sweepers. Buildings like these usually hog energy, because "a lot of outside air needs to be brought in for ventilation and vehicle exhaust needs to be pushed out, all while balancing cooling and heating," explains Ken Urbanek, associate principal at MKK Consulting Engineers. To help mitigate these problems, MKK specified radiant flooring, as well as an HVAC system that "uses heat-recovery systems to reuse energy from the exhaust air stream" from vehicles, and avoided refrigerant in favor of evaporative cooling systems, which "work really well in our semiarid climate," Urbanek explains.
Environmental issues informed exterior spaces, too: Heavy-metal contaminants like arsenic and lead lurked in the layers of sediment beneath the campus, remnants of previous public works buildings on the site. To prevent these pollutants from seeping into the nearby South Platte River—which, along with a public bike path, runs parallel to the operations center—RNL capped the site with a 12-inch layer of clay and covered it with an aggregate of pebbles and crushed, recycled glass from Colorado beer factories. "When we first placed the glass, you could walk across it and still the smell the beer," says Shiffer, with a laugh.
Wuertz and Shiffer hope DCP will help retool thinking about how public works facilities are built and designed. Municipal projects can—and should—be held to the same standards as other building types when it comes to sensitivity to place, scale, and environmental impact, Wuertz argues. "We didn't separate DCP from the highway, the bike path, the river," he says. "We thought 'This has to be a good design. We need to be good neighbors.'"