Sustainable in Seattle

Rate this item
(0 votes)
Submitted by on Wed, 20.02.2013 - 17:11

March-April 2013
Vol 105. Number 682

By Steven Nicholas

Read full article

Sustainable in Seattle

Creating a new LEED Gold headquarters for USACE Seattle District meant honoring local history and design elements while meeting federal energy and sustainability mandates.
By Steven Nicholas

Using prefabricated bridge elements helped the Massachusetts Department of Transportation replace 14 bridges in one construction season and minimize the impact to drivers.
Airmen from the 647th CES, Joint Base Pearl Harbor-Hickam, Hawaii, join with Airmen from the 355th Aviation Engineering Wing, Basa, Philippines, to help renovate Cacutud Elementary School in Malabacat, Philippines during Pacific Unity 12-6. U.S. AIR FORCE PHOTO COURTESY OF 647TH CES

In March 2009, the U.S. General Services Administration (GSA) received authorization under the American Recovery and Reinvestment Act of 2009 to transform a 1940s warehouse on the outskirts of Seattle into a new district headquarters for the U.S. Army Corps of Engineers (USACE). The agency envisioned an integrated highperformance building that would achieve LEED Gold certification by reusing a significant part of the existing warehouse structure and introducing modern building systems and innovative technologies.

Designed to be one of the most sustainable office buildings of its time, Federal Center South opened in October 2012. By using energy savers like geothermal for heating and cooling, a phase change storage tank and daylighting along with new products such as chilled beam sails, the facility is expected to be among the top 1 percent of U.S. buildings for energy performance, as well as the region’s most energy-efficient office complex.

DESIGN-BUILD—WITH AN EMPHASIS ON DESIGN

Before issuing its request-for-proposal, GSA commissioned Heery International to compose detailed owner’s program requirements (OPR) that would serve as a foundation for the entire design-build program. By conceiving OPR as a performance-based document rather than a prescriptive one, a clear “destination” was provided, but while leaving it up to the design-build team to determine the best way of getting there. It was this approach to the delivery process that spurred the many creative solutions that made the project successful.

OPR included both detailed performance requirements and warranty criteria, specifying minimum finish levels for each program space as well as minimum performance requirements. The document identified emergency power requirements and Department of Defense blast requirements; data cabling and port requirements for each user space; and soils analysis and hazardous material surveys. OPR also established the owner’s expectation of the structure’s square footage requirements, performance and warranty criteria, sustainability and LEED rating. It did not, however, specify manufacturers or provide sizing or installation criteria, as is common with design-bid-build, multi-prime, or Construction Management At-Risk. For example: Although energy performance was specified to be a minimum of 30 percent below the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Standard 90.1, OPR did not dictate which equipment or strategies be used to achieve that requirement. In the end, the building’s energy performance may exceed ASHRAE Standard 90.1 by as much as 40 percent.

A RIVER RUNS THROUGH IT

The new USACE Seattle District headquarters faces the Duwamish River. Using this connection between people and place as a point of departure, ZGF Architects, with general contractor Sellen Construction, referenced one of the river’s original oxbow shapes by designing the new building in the shape of a horseshoe.

The relationship between people and place is carried through the entire design, from the silver shingles of its façade (reminiscent of fish scales) to the features that pay homage to the Duwamish’s history and its tributaries. Distinct stone markers that reference the water harvesting and circulation system serve as a directional system throughout the building and are named after the four tributaries of the Duwamish—the Cedar, Green, Black and White Rivers.


Using prefabricated bridge elements helped the Massachusetts Department of Transportation replace 14 bridges in one construction season and minimize the impact to drivers.
Nearly 200,000-ft of salvageable structural timber from a decommissioned warehouse formerly on the site was milled and reused as framing and decking within the central commons.
LEADING TO LEED

The U-shaped form of Federal Center South maximizes daylight access on both sides of the floor plate, providing 90 percent of the facility with natural light. Its orientation and massing further optimize the use of daylight and reduce solar heat gain. The result is a building in balance with its natural environment. Exterior orientation-specific sun-shading elements, clerestory glazing and internal adjustable window coverings control heat gain and glare while further enhancing the building’s energy efficiency.

The building’s diagonal grid (diagrid) structure requires less structural steel than conventional steel frame supports. The diagrid also eliminates the need for large corner columns, improving load distribution and maximizing usable floor space. Together with the U-shaped floorplate, the diagrid allowed the design-build team to meet the owner’s requirement for a facility that will accommodate the turnover of occupants over a 50-year period. A flexible floor plan allows the program to grow and shrink around the commons—a central hub that creates a sense of workplace community, encouraging collaboration and interaction.

Sustainable initiatives are prevalent throughout: orientation-specific solar shades; under-floor fresh air distribution; rainwater harvesting; natural convection workspace tempering systems; and restoration of large paved areas into green space. Nearly 200,000-ft of salvageable structural timber from the decommissioned warehouse was milled and reused as framing and decking within the central commons. Reclaimed wood decking also was used to clad interior walls and as formwork for concrete site walls.

Each year, 430,000-gal of water will be harvested and stored in a 25,000-gal cistern for use in toilets, rooftop cooling tower and to water the building’s indoor greenscape. This will reduce sewage conveyance by 78 percent and curb irrigation demands by 14 percent. A reduction of 58 percent in potable water use is predicted through efficient fixtures, landscaping that requires little watering and rainwater reuse.

THERMAL INNOVATION

The building’s HVAC needs are satisfied by a field of geothermal wells working in a closed circuit to support heat recovery chillers, a cooling tower, a phase change material (PCM) thermal storage tank as well as a natural gas boiler. These features improve the building’s energy use intensity and reduce the on-site burning of fossil fuels. When required, cooling or condensing water is pumped through the geothermal loops of underground plastic pipes. These extend to an average depth of 150-ft, allowing the building to inject waste heat into the ground in summer and extract heat from the ground in winter. The silent, closed system does not consume additional water and requires little maintenance.

Federal Center South also features the first significant use of PCM thermal storage in the United States. In this application, the PCM (salt hydrates suspended in a synthetic gel) is designed to “freeze” at 52°-F and liquefy at 59°-F. This means the building’s PCM tank can be charged (frozen) at night using cooled water from the cooling tower in “free cooling mode” or a single chiller when electrical rates are low. During the daytime, cooling water is circulated through the tank and the chilled sails to cool the office.

By targeting a 58-°F supply water temperature to the chilled sails, the system can meet the cooling demands for at least four hours when there is a low to moderate need for cooling. This helps the mechanical systems achieve greater efficiency by reducing chiller operation during the day, especially in the shoulder seasons and through operating the central plant at night when energy costs are lower.

FINISHED PRODUCT

Now that nearly 700 USACE employees have moved into their new district headquarters, Federal Center South will be put to the test. As part of the LEED Gold rating that is expected to be granted in early 2013, $300,000 in federal funding is being kept in escrow, as an incentive, until the building proves that it can, in fact, operate in the energy-efficient manner in which it was designed. The measurement and verification will occur over a 12-month period.

Federal Center South sets a new standard for government facilities. The innovative design-build approach enabled GSA to achieve significant cost savings. And USACE Seattle District now has a new headquarters that is an exemplary showcase of what a 21st century, highperformance office facility can be.


Steven Nicholas is Senior Associate/Senior Project Manager, Heery International; 206-587- 0473, or This email address is being protected from spambots. You need JavaScript enabled to view it. .

Read 38518 times Last modified on Friday, 12 April 2013 19:21

Leave a comment

Make sure you enter the (*) required information where indicated. HTML code is not allowed.