When the U.S. General Services Administration (GSA) required approximately 180,000 square feet of office space to meet current U.S. Army Corps of Engineers (USACE) workforce projects, ZGF Architects LLP, Seattle, redeveloped and modernized a portion of an existing 1940s-era warehouse, known as Building 1202, located at Federal Center South in Seattle.
The $72 million project was funded through the American Recovery and Reinvestment Act (ARRA). Part of the GSA’s Design Excellence Program, the project features aggressive mandates for reuse and energy performance. The design-build project with Sellen Construction, Seattle, transforms a 4.6-acre brownfield industrial warehouse site into a highly flexible and sustainable, 209,000-square-foot, three-story headquarters for the USACE Northwest District. Planned and designed in under 18 weeks, construction began in July 2010, and was completed in October 2012.
“Every major aspect of the building is designed and programmed to create a high-performance environment that supports a new modern, sustainable workplace standard,” says Todd Stine, principal and project architect, ZGF Architects. “The project demonstrates the role of the built environment in conserving energy and responding to climate change.”
An Ideal Workplace Environment
Federal Center South expresses the USACE’s distinct identity and keeps with its mission of “Building Strong.” The building’s oxbow shape respects the site’s historic context, including the natural oxbows that characterize the Duwamish Waterway and adjacent historic Albert Kahn-designed warehouse. The building’s siting, orientation, form and massing, along with material selection and construction, are all structured to provide the USACE with the most ideal workplace environment, while breathing new life into the historic campus.
“The building design celebrates the importance of connecting to nature and views both inside and outside while promoting the positive effect of biophilia-the intrinsic bond between human beings and living systems,” says Stine.
The oxbow design provides the USACE a collaborative workplace environment, and the greatest flexibility to expand and contract around the needs of each user group. “The indoor campus environment enhances the concept of creating a collective community and identity by centralizing all common services within the
‘commons,’ or social heart of the building,” Stine explains. The focal point of the commons is timber reclaimed from the existing non-historic 1202 warehouse originally on-site. Bridges and stairs that are clad in reclaimed timber span across the atrium to connect people across the building. Additionally, they are strategically located adjacent to informal seating and touchdown work surfaces that encourage impromptu collaboration.
A Structural Theme
The building’s exposed “diagrid” structure and mechanical systems exemplify the engineering rigor, strength and stability of the USACE’s focus as an agency, Stine says. The perimeter diagrid design integrates sloped columns and spandrel girders into a single structural system to provide lateral resistance and a redundant support system for floor framing.
The diagonal forms on the west-facing building ends promote the “Building Strong” structural theme in a dynamic formal statement along the river’s edge. “The diagrid naturally ends with the southwest and northwest corners of the building opening toward the Duwamish Waterway,” Stine notes.
Federal Center South Building 1202 features 60,000 square feet of Guardian SunGuard Super-Neutral 62 glass from Guardian Industries, Auburn Hills, Mich., for the advanced, energy-efficient curtainwall system. The 6-mm laminated glass brings enough natural light into the building to allow the indoor lighting to be turned off 61 percent of the time during daylight hours.
Similar to the roof form of the adjacent 1201 building, the roof form is distinguished by a sloped atrium skylight and clerestory from DeaMor Associates Inc., Seattle. By optimizing the floor depth and façade design, designers were able to use extensive daylighting that will allow 90 percent of the building being naturally lit. “The narrow 60-foot floor plate of the oxbow optimizes daylight penetration, reducing the need for artificial lighting and associated energy costs,” Stine explains.
Custom Metal Shingles
The design team identified stainless steel shingles as being the best option to meet the project’s aesthetic, performance and budget requirements. Working closely with Millennium Tiles, Elkhorn, Wis., the design team investigated options for a vertically oriented semi-custom shingle that would reinforce the building’s proportions and would install smoothly around the curving façade.
Millennium Tiles created a tile twice as tall and half as long as its original tile system. Due to the project’s location on the inlet of Puget Sound, the tile had to be fabricated in a marine alloy of stainless steel. The project utilizes approximately 23,000 8-inch-wide by 16-inch-high stainless steel shingles in Type 444 alloy, to cover approximately 20,000 square feet of wall space.
The tile’s Pewter finish varies the reflection from tile to tile, giving the building the impression of being covered by fish scales, which references the maritime history of the project’s location, and evokes the naturally occurring variation in the color of the masonry cladding on the existing buildings.
Performance Expectations
Earning an Energy Star rating of 100, the building is expected to perform in the top 1 percent of energy-efficient office buildings in the nation. The project also complies with the goals of the 2030 Challenge, and is currently targeting LEED New Construction Gold certification.
Current energy models predict Building 1202 will operate at an Energy Use Index (EUI) of 20.3 kBtu/SF/year, performing 40 percent better than ASHRAE 2007. The building will use energy management and verification devises to monitor energy use.
“Anticipated to be the region’s most energy-efficient air conditioned building-using one-fifth of the estimated energy of a standard office building in the Northwest-it also serves as one of the first projects in the region to use structural piles for geothermal heating and cooling,” Stine notes. “A Phase Change Material storage tank on the rooftop stores and releases cold energy to reduce the building’s cooling needs.”
Exterior orientation-specific sunshading elements, clerestory glazing and internal adjustable window coverings help control heat gain and glare while providing uninterrupted views to the outdoors, and time of day and weather condition awareness. “The ribbon system is designed with vertical blades across the entire perimeter,” explains Stine. “The system is augmented with horizontal sunshades tuned to the orientation starting with zero on the north and transitioning to one, two and three as the façade transitions around the oxbow from east to west.” The project’s peak cooling loads are targeted for a 30 percent reduction in the perimeter zone, which results in a 10 percent reduction in the central plant cooling capacity.
Raising the Bar
As with any team, Stine notes that getting the right team members is critical. “GSA sets a high bar from the very beginning of the project, and fostered a delivery process that enabled the team to meet and exceed those high expectations,” Stine says.
“For those of us who have had the opportunity to be a part of it, Federal Center South Building 1202 often feels like a once-in-a-lifetime type of project,” he adds. “However, we know that this is really a stepping stone to the next generation of high-performance buildings.”
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PHOTOS: Benjamin Benschneider
