September 18, 2025
The C Concourse’s expanded facility at Seattle-Tacoma International Airport (SEA) will be the airport's greenest building yet, not only creating a better travel experience but also setting a new standard for climate-conscious design and construction. SEA is working with design partners Miller Hull and Woods Bagot, to renovate this concourse to integrate everything from all-electric systems and water conservation methods to biophilic design — a testament to our commitment to a greener future. You've probably seen the crane and construction activity, but we're excited to show you that behind the barricades, a truly sustainable building is taking shape.
Fossil fuel-free operations
A key feature of the C Concourse Expansion is its strong commitment to reducing reliance on fossil fuels. The building's heating, hot water, and even tenant cooking equipment are powered by all-electric systems. This is made possible by air source heat pumps that handle all heating and most of the cooling needs, along with the use of electrochromic glazing on the main window wall, eliminating the use of natural gas and reducing the airport's operational carbon emissions. The heat pumps have been installed, and their piping systems are up next.
Harnessing solar power
The expansion's roof features a photovoltaic (PV) array, a visible and powerful symbol of the project's dedication to renewable energy. These solar panels are expected to generate up to 12% of the building's annual energy needs, helping the facility meet overall energy efficiency and sustainability goals. The PV array panels are onsite and ready to be installed.
Connecting with nature
The expansion's design is a tribute to the Pacific Northwest, with biophilic design creating a calming and natural environment. This approach is evident in the addition of an outdoor public lookout with airfield and Olympic Mountain views, and the use of locally-sourced materials, Forest Stewardship Council ( FSC)-certified wood, and local stone for the terrazzo floors. The glass is now installed in the public lookouts. In the coming weeks, crews will pour the terrazzo floors with a special pea gravel mix using local stone, and install the wood ceiling and tree centerpiece, bringing a natural feel inspired by our region’s unique beauty.
Reusing and reimagining
The C Concourse Expansion is not just a new build; it is a building renovation. The project team made conscious design decisions to augment the existing structure; adding height and new slabs while also reusing 62% of the existing structure — therefore minimizing the embodied carbon investment of new construction.
Water and waste reduction
The project incorporates several features designed to conserve our natural resources. Low-flow water fixtures will increase water efficiency and help conserve potable water. To reduce solid waste from single-use plastics, the dining facilities will include dishwashing capabilities for vendors and dedicated storage sites for community food donations. The focus on waste diversion has been a key effort, with the project team targeting a 75% construction waste diversion rate by carefully sorting and recycling building materials like wood, metal, and carpet fragments.
Pursuing LEED Gold certification
Initially targeting Leadership in Energy and Environmental Design ( LEED) v4 Silver certification, the project is now on track to achieve LEED Gold certification. This is a significant milestone for SEA, as it is the first project to apply the Port's Sustainable Evaluation Framework, an internal process for applying sustainable design to capital projects. The project team, including the project’s main contractor, Turner Construction, has exceeded initial sustainability goals, including incorporating more local materials on the project, reducing the embodied carbon of certain concrete mixes, and utilizing a sustainability checklist for each product data submittal and every subcontractor to ensure all project partners are aligned with the Port's vision for a greener airport.
The completion of the C Concourse Expansion project in mid-2026 is a significant milestone, but it's just one piece of the Port of Seattle’s broader vision. As the Port works toward its ambitious goal of becoming the greenest Port in North America, the C Concourse Expansion sets a new standard for sustainable infrastructure.
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