LEED v3 EBOM (Existing Buildings) Gold
Using a Design-Build delivery model to get ARRA funds committed as quickly as possible, the Sellen Construction and ZGF Architects LLP team developed an integrated design and construction solution that fuses programmatic, functional and aesthetic objectives with a new standard for high-performance, cost-effective and sustainable workplace environments. The project was planned and designed in under 18 weeks in order to guarantee the performance-based contract that met GSA’s construction budget, energy performance goals and an aggressive design and construction schedule starting with a design competition at the beginning of 2010 and resulting in a completed building before the end of 2012.
The “oxbow” design solution provides an ideal workplace environment for the USACE emblematic of their mission of “Building Strong.” The building’s form—reflecting the natural oxbows past and present in the course of the adjacent Duwamish Waterway—is functional and flexible to accommodate the USACE’s nearly constantly changing team-based work. The diagrid structure extending around the building meets GSA’s security requirements for progressive collapse, ensuring the building will remain standing should one of the column elements be compromised. The exterior stainless steel shingle cladding emphasizes “Building Strong” and complements the nearby historic 1930s Albert Kahn-designed 1201 building. The dramatic, daylit wood-clad atrium—the “commons”—features timber reclaimed from the former warehouse that stood on the site and serves as the social heart of the building.
Ventilation + Heat recovery
Innovative cooling system
High efficient façade
No light pollution
Outdoor view maximised
Setting a new standard for high-performance office buildings, Federal Center South Building 1202 has met its energy goal in the first year of operation. The building is operating in the top 1% of similar-sized office buildings across the nation with an ENERGY STAR® score of 98. The project has established energy performance nearly 40% better than ASHRAE 90.1, with an EUI of 25.7 kBTU/SF/year and earned LEED-Platinum certification in the fall of 2014.
Conventional building systems have been replaced with efficient hydronic heating and cooling, and a healthier, more energy-efficient 100% outside air underfloor air distribution system. To enable these systems to perform at an optimal capacity within the project budget, an ultra-efficient building envelope - offering a high level of insulation, while transmitting ample daylight - reduces the magnitude of heating and cooling demand and optimizes the use of daylight within.
Energy and water introduced into the building are leveraged to their highest possible use. Conditioned air is delivered to the workspace via air handling units and exhausted passively through the atrium to high-efficiency heat recovery systems. Available daylight, controlled for glare and unwanted heat gain with a varying degree of frit across the atrium skylight to respond to sun exposure, is directed to the office floor plates from two sides, to offset the maximum possible amount of electric lighting.
High-efficiency boilers, cooling towers and heat pumps generate the required heating and cooling. The equipment efficiencies are high per current best practices, with the difference being that design integration has resulted in systems substantially smaller than would conventionally be required. Electric lighting design is a simple, repetitive task/ambient design that achieves a building-wide lighting power density of approximately 0.72 W/SF or lower.
PHASE CHANGE MATERIAL AND THERMAL STORAGE
Daily and seasonal patterns of sun, wind and light create a highly variable range of exterior conditions that the building attenuates to maintain internal comfort. The design capitalizes on these cyclic patterns to create thermal energy when available and store it for use when required. A thermal storage tank containing Phase Change Material (PCM) – a solution with a high heat of fusion that melts and solidifies at 55⁰F, a temperature that is often achieved in Seattle’s mild climate, absorbing or releasing heat as it does so. Together, these two systems – one seasonal in nature and the other diurnal – reduce the amplitude of cyclical climate variation, and enable the building and its occupants to work with the natural world instead of against it.
With the most efficient energy being energy that is not required, the integrated design is developed to avoid the need for on-site renewable generation to meet the required energy goals. Life-cycle cost analysis of a solar domestic hot water system and supplemental photovoltaic system were both outside the range of acceptable return.
Orientation and massing optimize daylight while reducing solar heat gain. The U-shaped form of the office bar creates daylight access on both sides of the floor plate, providing natural light to over 90% of the building to enhance energy performance and human comfort.
Exterior orientation-specific sun-shading elements, clerestory glazing, and internal adjustable window coverings control heat gain and glare while providing uninterrupted view to the outdoors, as well as time of day and weather condition awareness. The ribbon system is design with vertical blades across the entire perimeter. 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 south. Peak cooling loads are targeted for a 30% reduction in the perimeter zone, resulting in a 10% reduction in the central plant cooling capacity.
On-site drainage run-off is treated within stormwater surface ponds, rain gardens and wet ponds. The runoff is collected around the perimeter of the site and directed to the western-most pond, mimicking natural site drainage patterns, and leveraging low-impact development techniques. The rainwater reuse system captures water from the roof and stores it in a 25,000-gallon cistern to be used for toilets, irrigation, a rooftop cooling tower and water features in the “commons.” These systems provide required water quality treatment. A series of exterior rain gardens were designed to drain and treat a 95th percentile rain event entirely on-site eliminating the need for a connection to the City’s stormwater system.
An estimated 430,000 gallons of rainwater will be harvested annually – providing a 79% reduction in potable water use for toilet flushing and a reduction of irrigation demand by an additional 14%. Potable domestic water use is reduced by 58% through efficient fixtures, low-water landscape and rainwater reuse.
In response to the ARRA funding requirement to reuse portions of the existing warehouse that previously stood on the site in the design of the new 1202 building, approximately 200,000 board feet of salvageable structural timber and 100,000 board feet of decking (92%)was reclaimed to form the building’s foundation, structural system, and the interior cladding of the “commons.”
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U.S. General Services Administration (Tenant: U.S. Army Corps of Engineers)
ZGF Architects LLP
The Greenbusch Group
Building services engineer:
WSP Flack + Kurtz/University Mechanical , Lane Coburn & Associates, LLC/Sequoyah Electric, LLC
SiteWorksop LLC , Lane Coburn & Associates, LLC , Studio SC , Lerch Bates , Rolf Jensen & Associates , Tuazon Engineering , Hart Crowser & Associates, Inc , WSP Flack+ Kurtz
KPFF Consulting Engineers