The elegant form of this two-story Annex to Concourse D at Seattle-Tacoma International Airport evokes the joy of flight and natural splendor of the Pacific Northwest.
Built to relieve passenger congestion, the Annex acts as a conduit between the airport’s main passenger terminal and a hardstand on the tarmac. It includes six passenger gates, concession stands and a children’s play area.
The Annex is prominently featured along Departures Drive adjacent to the main terminal, and is connected to the existing Concourse D via a skybridge at the mezzanine level.The building’s simple shape conveys the dynamic nature of air travel.
The design creates an expressed structure and calming, sleek, daylit pavilion for travelers and airport staff. The two-story, column-free interior space brings a sense of openness and ease through its light color palette, sustainable finishes and clear circulation. The open plan contributes to clear paths of travel, intuitive wayfinding and free-flow circulation.
The use of local, sustainable materials inside and out creates a timeless, contemporary building. A unique glue-laminated (glulam) timber-and-steel truss system is constructed from locally sourced Douglas fir trees. The exposed trusses enhance the Pacific Northwest aesthetic and reduce the structure’s embodied carbon. The rotating pitch form of the roof reflects the passenger movement along the interior sloped walkway surface.
The building’s skin is a balance of glass and metal that maximizes interior natural light while minimizing glare, heat gain and energy loss. The Annex is the first airport terminal building in the U.S. to achieve Silver certification through the USGBC’s LEED v4 for Building Design and Construction.
An integrated design-build team including the Port of Seattle, HOK and The Walsh Group developed the Annex within a tight budget and in just 18 months.