Salt Lake City has nation’s first net zero public safety building
Salt Lake City recently opened its Public Safety Building (PSB), the nation’s first net zero energy public safety building. The building houses the city’s police and fire departments, along with emergency dispatchers, and is designed to function in both everyday and out-of-the-ordinary circumstances. It can withstand a magnitude-7.5 earthquake and remain in operation, and is one of the first public safety buildings to achieve LEED Platinum certification.
Completed in 2013, PBS was designed by GSBS Architects, Salt Lake City, and MWL Architects, Phoenix, and provides office space for 400 employees. The 335,000-square-foot, $125 million project includes a 172,000-square-foot four-story building and 143,000 square feet of secure parking below grade.
Kevin Miller, AIA, principal at GSBS Architects, says there were multiple community members that had very specific design goals for the project. The mayor wanted a building that was iconic in its design, since it sits in the city’s municipal zone. Planning wanted a building that contributed to the urban fabric, with open space and a public plaza. And the police and fire, he says, wanted a state-of-the-art facility that would convey open policing, the community-based policing directive of the chief of police, through an open and inviting building. Plus, there was the net zero goal for the building, all while keeping the project within budget.
“The design goals were trying to figure out how to do all those things at once and find a way to balance them, and not do any of them in a way that compromised, ultimately, what the function of the building is, which is the headquarters for police and fire in Salt Lake City,” Miller explains.
Design Details
The design of the building is in its shape, form and expression, which, Miller says, are fundamentally driven by achieving the design goals. “The way the building organizes itself-the ground floor is bigger than the second floor is bigger than the third floor is bigger than the fourth floor-creates that lean and the step that is in the design,” he says. “But those are purely driven by functional requirements of police and fire; the spaces that require public interface were greater than the spaces that were needed for administration. So when we blocked and stacked the building it simply came out that way, and we used that function as an expression in the architecture.”
Miller goes on to say that despite the dictate to create an open and inviting building, it was essential to provide the appropriate level of protection for the employees of the police and fire departments. By limiting public access to the first floor, the design team tried to create a greater integration for the rest of the building, while also driving collaboration between the investigators, special task forces and other departments.
“The lobby, which extends up all four levels, is an open atrium space that was designed to encourage the occupants back out into that space, to draw them out,” Miller says. “And, by virtue of doing so, increase the opportunity for interaction between the various groups within the building.”
Overall, Miller says the building gives the appearance of being very public and open, while it is a very secure facility at the same time.
Curved Curtainwall
A central element to the design is the glass façade on the northwest-facing public face of the building. The serpentine glass curtainwall from Wausau Window and Wall Systems, Wausau, Wis., slopes from one wing to the other and angles in multiple directions. The curtainwall, which also meets the building’s seismic and ballistic requirements, allows in ample daylight, reducing the need for electrical lighting indoors in addition to the facility’s need for back-up generators in the event of a power outage.
The general contractor, Okland Construction, Salt Lake City, and LCG Facades, Salt Lake City, the glazing contractor, involved Wausau early on to figure out the project’s complex design and engineering needs. Ted Derby, business development manager at LCG Façades, says the company was brought in to answer GSBS Architects’ number one question: Can a curtainwall system segment and cant backward at 15 degrees and then change angle, while maintaining the cant through a reverse S curve? “We thought with Wausau’s help, we could make it happen,” he explains. “As soon as we received a wire frame 3-D model, we sent it to Wausau, and they came back with a conditional, but affirmative statement that they could make the design a reality.”
Each of the glass panels in the curtainwall is a unique size and shape, requiring customized design engineering, machining, fabrication, glazing and shipping. Gene Pagel, Wausau’s vice president of engineering, says the care and precision needed to make the project’s complex design a reality was incredible. “Every piece, dimension and angle of the 135 unique curtainwall units located at the center of this building is different,” he notes. “That meant each component of each trapezoidal unit required design engineering and 3-D layout, along with precise and unique machining, fabrication, glazing and even shipping provisions.”
“As the curtainwall cants back at 14.9 degrees, it also makes a transitional slope from back to front,” Derby explains. “The only solution was to divide the unitized sections into unique elements.”
Functional Goals
The curved wall, which Miller says follows the functional design of the building, harvests a great deal of daylight, helping to achieve the project’s net zero goals. Additionally, he notes that the curtainwall opens up to the city, giving the public a very transparent and clear message as they approach the building.
For the lobby and main floor, LCG installed more than 32,000 square feet of Wausau’s INvision Thermal Unitized Curtainwall including 19,150 square feet of its 7250i-UW Series and more than 13,000 square feet of its 6250i-HRX Series. LCG also installed nearly two dozen of Wausua’s 4250-Z Zero Sightline casement windows on the upper floors to support the goals for natural ventilation and providing a connection to the outdoors for occupants. Wausau also engineered and installed Clear Story interior light shelves and sunshades to allow light to penetrate deeper into interior spaces.
Wausau-based Linetec finished Wausau’s aluminum curtainwall and window frames, light shelves and sunshades in Minneapolis-based
The Valspar Corp.‘s Fluropon Classic II coating in MC Platinum using a two-coat, 70 percent fluropolymer mica flake paint. Valspar’s coating adds a pearlescent finish to the project, providing long-lasting brilliance. Viracon Inc., Owatonna, Minn., fabricated the high efficiency, triple insulating glass that was used in the curtainwall along with the low-E, insulated glass installed in the casement windows. In some curtainwall units, three different thicknesses of glass were required to provide the needed security.
Solar and Beyond
Conroe, Texas-based CST Covers designed and fabricated the building’s entry canopy, which features photovoltaic (PV) glass from SCHOTT North America Inc., Elmsford, N.Y. Miller notes that the PV inlaid in the glass of the canopy demonstrates the net zero aspirations of the project. “We wanted people to be aware,” he says. “We wanted to communicate the building had more going on in it then what you might think about normally, and one of the ways we did that was integrating the PV into the canopy.”
Derby says the biggest challenge with the canopy was the large 8-foot overhang from the structural steel support, which required 12-inch-deep aluminum tubes. “The wiring for the photovoltaic glass was run through an aluminum chase on the underside of the canopy,” he adds.
Miller says the solar canopy is very important to the mission of the building, as it informs people of the importance of low energy use and the message that Salt Lake City was trying to send in the building decisions they were making. “From a message point of view and from what we were trying to communicate with the design, it really is pretty powerful,” he says.
LCG Facades assembled and glazed the solar canopy, in addition to fabricating and installing the building’s fascia and soffit system with nearly 23,000 square feet of Chesapeake, Va.-based Mitsubishi Plastics Composites America Inc.‘s 4-mm ALPOLIC aluminum composite material (ACM) panels with an FR core finished with Valspar’s two-coat Valflon FEVE in Mica Platinum. The ACM panels were installed in a pressure-equalized rainscreen system.
According to Miller, the metal panels fit the architecture of the building, while aiding in the building’s seismic requirements. “They’re lightweight, and bring us back to the overall building footprint, while creating the overhang,” he says. “The overhang is important, not just because the top floor happens to be smaller, but it protects the glass from direct sunlight and provides a terrific building envelope.”
The PBS’ roof is covered by more than 1,000 solar panels from Intermountain Rain & Solar, Woods Cross, Utah, with a capacity of 350-kilowatts, which complement the 30-kilowatt solar canopy. In the case of a blackout, 30 percent of the rooftop solar panels have been wired to provide emergency electricity directly to the building. The city also has an off-site PV farm that helps power the PBS.
The PBS has achieved an Energy Star performance rating of 100, the highest possible score, and the Utah Pollution Prevention Association and Clean Utah honored it with the 2013 Outstanding Award in Pollution Prevention. The project also received a Merit award in the category of projects greater than $75 million for the 2014 Innovative Design in Engineering and Architecture with Structural Steel awards program (IDEAS2) from the American Institute of Steel and Construction.
Salt Lake City Public Safety Building, Salt Lake City
Owner: City of Salt Lake
Owner’s representative:
MOCA Systems, Salt Lake City
Architects: GSBS Architects, Salt Lake City, and MWL Architects, Phoenix
General contractor: Okland Construction, Salt Lake City
Glazing systems-finisher: Linetec, Wausau, Wis.
Structural engineers: Dunn Associates, Salt Lake City, and Holmes Culley, San Francisco
Steel fabricator/erector:
SME Steel Contractors Inc., West Jordan, Utah
Steel detailer: SNC Engineering Inc., Compton, Calif.
Glazing contractor/fascia and soffit system fabricator/installer: LCG Façades, Salt Lake City, www.lcgfacades.com
Canopy: CST Covers, Conroe, Texas, www.cstindustries.com
Coatings: The Valspar Corp., Minneapolis, www.valsparcoilextrusion.com
Curtainwall/glazing systems: Wausau Window and Wall Systems, Wausau, Wis., www.wausauwindow.com
Glass assemblies: Viracon Inc., Owatonna, Minn., www.viracon.com
Metal wall panels: ALPOLIC-Mitsubishi Plastics Composites America Inc., Chesapeake, Va., www.alpolic-americas.com
Photovoltaic glass: SCHOTT North America Inc., Elmsford, N.Y., www.us.schott.com
Rooftop photovoltaics: Intermountain Rain & Solar, Woods Cross, Utah, www.intermtnwindandsolar.com