A previously-announced plan from Woods Bagot and The Miller Hull Partnership is moving forward in Washington State after officials with the Port of Seattle Commission finally approved the $399 million C Concourse Expansion for the Seattle-Tacoma International Airport.

The expansion will add 145,530 square feet in total, including a 20,000-square-foot Alaska Airlines passenger lounge, multifaith prayer room, meditation center, nursery room, amphitheater, and a retail/dining area called The Grand Stairs, to an existing structure from 1966. The firms say their proposal “rethinks the airport experience where design creates an intuitive journey, a sense of calm, and climate consciousness.” Turner has been contracted to lead the construction.

SEA planning officials are optimistic its realization will add to its claims of being the most energy-efficient port in the country as the first major construction to be undertaken in accordance with their new Sustainable Project Framework. Noteworthy considerations include a rooftop solar PV array, electrochromic glazing of the glass curtain wall panels, biophilic elements, and low-carbon materials such as timber, which will feature prominently in the ceiling and columns of the terminal’s interior. A LEED v4 Silver certification is the project’s stated goal overall.

“This is an exceptional project in terms of elevating the customer experience,” Port of Seattle Commission President Sam Cho said after the approval. “However, customer experience is not the only reason why we take on these major projects. The expanded concourse will expand opportunities for local businesses and support the financial stewardship of the airport by increasing revenue opportunities. The whole time we build with intention by focusing on sustainability and ensuring that our construction expands opportunities through the entire community.”

The project was first enacted in 2021. Officials are hoping for construction to begin as early as next year, with a 'substantial completion' to follow later in 2026.

Miller Hull was also recently honored with a Prix Versailles World Selections designation for their collaboration with SOM on the design for the airport's newInternational Arrivals Facility. Woods Bagot's LAX Midfield Satellite Concourse South expansion also broke ground this year. That project is likewise seekingLEEDSilver certification ahead of its own completion by the end of 2025.