Sustainability drives concourse expansion at Seattle airport. July 13, 2026 By The Construction Specifier The new concourse expansion at Seattle-Tacoma International Airport (SEA) is focused on delivering more sustainable service. Developed as part of the Port of Seattle's "Upgrade SEA" program, the C Concourse Expansion marks several achievements for the airport. These include its first all-electric terminal project, a photovoltaic installation, a public airside outdoor space, and its first project designed to achieve LEED Platinum certification. Designed by The Miller Hull Partnership and Woods Bagot, the expansion opened in June 2026. The project increases the concourse from 7,525 m[2] (81,000 sf) to 21,274 m[2] (229,500 sf). It also adds four new floors above the existing building. The larger facility improves passenger circulation, accessibility, and comfort while supporting future growth. The project eliminates fossil fuels for heating and domestic hot water by using all-electric building systems. A 500-kW photovoltaic array is expected to generate about 12 percent of the building's annual energy demand. Electrochromic glazing automatically adjusts to changing daylight conditions, reducing glare and solar heat gain while maximizing natural light. Low-flow plumbing fixtures reduce water use, while waste reduction and food donation programs support environmental goals. "The concourse responds to the changing light and weather of the Pacific Northwest," said Rich Whealan, principal at The Miller Hull Partnership. Inside, a two-story marketplace anchors the expansion, with dining, retail, and tiered public seating, all connected by a central grand stair. Residency program. The project also introduces the Lookout at C, the airport's first public outdoor airside space enclosed in glass, with views of the airfield and Olympic Mountains. Other passenger amenities include a sensory room, a nursing room, an interfaith prayer and meditation room, and a pet relief area. The expansion also features a new artist-in-residence program developed by the Port of Seattle in partnership with Pilchuck Glass School and Tacoma's Museum of Glass. Regional artists created permanent installations throughout the concourse, reinforcing the project's connection to the Pacific Northwest. Turner Construction Company served as construction manager and general contractor. Magnusson Klemencic Associates provided structural and civil engineering, while PAE Engineers led mechanical, plumbing, and sustainability engineering.

Seattle Airport expands with four-storey C Concourse by Miller Hull and Woods Bagot. Seattle Airport has officially opened its long-awaited C Concourse Expansion, a major addition designed by The Miller Hull Partnership in collaboration with Woods Bagot. Developed for the Port of Seattle, the approximately 229,500-square-foot (21,300 sq m) expansion transforms one of the airport's busiest concourses into a light-filled, passenger-focused environment inspired by the landscapes of the Pacific Northwest. The project welcomed its first passengers in June 2026, marking a significant milestone in SEA Airport's ongoing modernization program. Video Muted A vertical expansion above an operating Concourse. The Seattle-Tacoma International Airport (SEA) project was constructed above the existing Concourse C, adding four new levels while allowing airport operations to continue below throughout construction. The intervention expands the original 81,000-square-foot facility to approximately 229,500 square feet, creating substantially more room for passengers without increasing the airport's overall footprint. The expansion forms part of the Port of Seattle's broader strategy to accommodate increasing passenger numbers while improving circulation, comfort, and operational efficiency. Architecture rooted in the Pacific Northwest. The design takes inspiration from the forests, mountains, and open landscapes of Washington State. The architects sought to blur the relationship between interior and exterior through abundant daylight, panoramic glazing, and natural materials. One of the defining architectural features is the "Tree at C," a sculptural timber column positioned at the heart of the expansion. Supporting a sweeping wood ceiling, the structure serves as both a visual landmark and a central gathering space for passengers. Throughout the interiors, timber finishes, stone textures, regional artwork, and expansive airfield views reinforce the character of the Pacific Northwest. The building also introduces the Lookout at C, a publicly accessible glass-enclosed viewing space overlooking the airfield and the Olympic Mountains, providing travelers with panoramic views rarely found in airport terminals. New passenger amenities. Designed to improve the airport experience, the expansion introduces a range of passenger amenities distributed across multiple levels. These include: * More than 41,000 square feet of new Alaska Airlines Lounge space * New dining and retail destinations * Additional passenger seating overlooking the airfield * An Interfaith Prayer and Meditation Room * A Nursing Room * Flexible office space for airport partners, airlines, and the TSA * Expanded circulation areas that reduce congestion during peak travel periods. The new spaces are intended to create quieter waiting areas while improving wayfinding and accommodating future passenger growth. Sustainability at the core. The C Concourse Expansion is the first capital project to implement the Port of Seattle's Sustainable Project Framework, establishing environmental benchmarks for future airport developments. Its sustainability strategy includes: * Rooftop photovoltaic solar panels * Fossil fuel-free systems for heating and hot water * Electrochromic smart glazing that reduces heat gain and glare * Low-flow plumbing fixtures for water conservation * Embodied carbon reduction strategies * Commercial dishwashing facilities that minimise disposable food-service products * Biophilic design principles integrate daylight, vegetation, and natural materials. These measures support the Port's ambition of creating one of North America's most sustainable airport facilities. Supporting future growth at SEA Airport. The expansion arrives as Seattle-Tacoma International Airport continues to experience sustained passenger growth. The project is one of several major investments intended to increase terminal capacity while improving passenger experience across the airport. The C Concourse Expansion prioritizes public gathering spaces, regional identity, and environmental performance, reflecting a broader shift toward airport terminals that function as civic destinations as well as transportation infrastructure. Seattle Airport project facts. Project: C Concourse Expansion Location: Seattle-Tacoma International Airport (SEA), Seattle, Washington, USA Client: Port of Seattle Architects: The Miller Hull Partnership + Woods Bagot Area: Approximately 229,500 sq ft (21,300 sq m) Original Building Size: 81,000 sq ft Construction Cost: Approximately US$399 million Opened: June 2026

Port of Seattle awards $850K for community-led environmental improvements in region. The Port of Seattle announced this week that it will award $850,000 to 18 community-led organizations with projects that improve the environment in communities around Sea-Tac Airport (SEA), including in South King County. The funding, awarded to the largest number of organizations to date, is provided through the South King and Port Communities Fund Environmental Improvements Program, which supports projects that expand access to green space, restore natural habitats, and promote environmental education in historically underserved communities. "These investments put resources directly in the hands of community organizations that are leading solutions on the ground in communities near the airport," said Port of Seattle Commissioner Toshiko Hasegawa. "This fund is a reflection of our commitment to addressing the environmental needs of our neighboring communities." The Environmental Improvements Program (EIP) - formerly the Environmental Grants Program - invites community-led groups to apply for funding for activities such as: * Habitat and park restoration and tree planting * Environmental education programs * Park or playground enhancements * Public art installations with an environmental focus Through funding and partnerships with community-based organizations, the Environmental Improvements Program (EIP) supports projects in communities that have been historically overlooked due to inequitable land use practices and displacement. The EIP allows the Port to invest in cities around the airport, extending to Kent Valley, Duwamish Valley, Rainier Valley, and Beacon Hill and fund projects led by those most familiar with their community's needs. The Port offers multi-year awards to applicants for projects spanning one, two, or three years, up to $20,000 per year and up to $60,000 for multi-year funding. Multi-year funding increases the impact of the Port's community investments and helps to support sustainable project planning and implementation. "Your Money Matters is honored to partner with the Port of Seattle and Auburn Parks and Recreation through the South King and Port Communities Fund's Environmental Improvements Program to empower young people to lead meaningful environmental change in their own community," said Your Money Matters Executive Director Clinton Taylor. "This project is about more than restoring a neglected public space, it is about investing in BIPOC youth as environmental stewards, leaders, and future professionals in the green economy. Through hands-on restoration, native planting, and ongoing site care, our youth will help transform this area into a vibrant and sustainable community asset that reflects pride, resilience, and opportunity for Auburn residents for years to come." Expanding community investment. In 2024, the Port of Seattle Commission authorized $14 million, an increase from $10 million the previous five years, to continue South King and Port Communities Fund (SKPCF) community-led projects that advance equity, environmental improvements, and access to jobs in port-related industries. Since its launch in 2020, the program has revolutionized how the Port works with communities to improve access to funding opportunities. SKPCF investments have fostered new partnerships with BIPOC-led, community-based organizations and increased support of structurally excluded communities of color. The 2025-2029 funding cycles include: * Reducing the match requirement for recipient organizations from 3:1 to 2:1, according to Washington state law, lowering the barrier for community-led projects * Expanding the eligible geographic region to include areas of South King County, the Duwamish Valley, and Beacon Hill that the Port of Seattle's Equity Index identifies as having disparities * Continuing to prioritize the Port's commitment to the six near-airport cities and identifying how applications for projects in those cities will receive priority status Beyond the 18 organizations now receiving funds, eight organizations are continuing work on environmental projects in Burien, Des Moines, Federal Way, Normandy Park, Seatac, and Tukwila through the program's multiyear funding option. 2026 EIP recipients. Here's more about the organizations and programs selected to receive funding. * Bridging Cultural Gaps - $60,000 to connect immigrant and refugee youth to nature to restore and activate public green spaces in SeaTac, Burien, and Tukwila, facilitating belonging and cultural wellness * Dirt Corps - $60,000 in funding goes toward its Outdoor Innovators Program which will work with youth leaders to restore Hilltop Park in Burien * Duwamish River Community Coalition - $60,000 to fund Duwamish Valley art installations in public areas supporting traffic safety * Duwamish Valley Sustainability Association (DVSA) - $60,000 to install flood mitigation measures as a model of community resilience in the Duwamish Valley * Earthgen - $60,000 to support the restoration and maintenance of stormwater projects in partnership with Highline and Renton school districts; the projects take place in Burien, SeaTac, Renton, and Normandy Park * Environmental Science Center - $60,000 to the Beach Heroes Program, which facilitates beach cleanup and restoration at Seahurst Park through community events and education focused on children and young people in South King County * Food Forest Collective - $60,000 to support soil remediation and garden maintenance at Food Forest Community Garden in Beacon Hill * Highline Homeschool Program - $5,000 for the Sensory Garden and Native Plant Nature Trail Project in Des Moines * New Start Community Garden - $19,000 in funding for an art installation in the Shark Garden in Burien to improve safety and access * Partner In Employment - $60,000 supports its Youth Restoration Crew which organizes park cleanup efforts in SeaTac, Burien, and Federal Way * Rainier Beach Action Coalition - $60,000 supports cleanup and restoration work in public areas throughout the Rainier Valley/South Beacon Hill area * Renton Art Oasis - $5,000 funds a Cedar River salmon mural installation in Renton * River Access Paddle Program - $60,000 to support the Back to the River Program, facilitating community paddling, mental health, and water stewardship on the Duwamish River * Tilth Alliance - $60,000 in funding for the South King County Garden Project, which supports community garden stewardship in Tukwila and Burien * Troop 361 - $1,000 to create a bee pollinator program at Hylebos Blueberry Farm Park in Federal Way * Trust for Public Land - $60,000 to enhance public amenities at Legacy Park in Renton * Your Money Matters - $60,000 to support the Fresh Groundz program that engages youth to revitalize neglected public land in Auburn * Youth Experiential Training Institute (Y.E.T.I.) - $60,000 to support youth-led cleanup and restoration projects in the Highline and Tukwila school districts; projects will take place in Burien, SeaTac, Tukwila, and Des Moines About the South King and Port Communities Fund (SKPCF). The Port established the South King County Community Impact Fund (now South King and Port Communities Fund) in 2019 to develop equity-based partnerships and provide resources and support to historically underserved, ethnically and culturally diverse near-airport communities. From 2020 to 2024, the SKCCIF launched four cycles of the Economic Recovery (now Economic Opportunities for Communities) program and the Environmental Grants (now the Environmental Improvement) program, to fund community-led projects that create pathways to training and well-paying jobs, and to fund environmental improvements. Since the fund's inception, more than 50 organizations have received a total of $9.25 million, which has funded over 80 projects.