The American Council of Engineering Companies of Colorado (ACEC Colorado) recently honored engineering firms from across the state at the organization’s annual Engineering Excellence Awards program. The highest honor, the Grand Conceptor Award, was presented to ME Engineers of Highlands Ranch, Colorado, for the Climate Pledge Arena in Seattle, Washington.

Formerly known as KeyArena, the venue was originally constructed for the 1962 Seattle World’s Fair and underwent significant renovations in the 1990s. However, KeyArena was still primarily only designed for basketball and concerts, so the City of Seattle made the decision to transform KeyArena into Climate Pledge Arena, nearly doubling the size of the former arena and opening the venue up for a variety of new events.

ME Engineers performed mechanical, electrical, plumbing, technology, lighting, sports lighting, and ice sheet design work, as well as energy modeling and commissioning services on the $1.15 billion project. When the 800,000-square-foot Climate Pledge Arena was completed in October 2021, it became the first all-electric sports arena and the first certified zero carbon arena in the world.

“When the decision was made that Climate Pledge Arena was to become the world’s first net-zero certified arena, we all realized that we would have to lean heavily into sustainable building systems,” said George Reiher, P.E., Senior Principal at ME Engineers. “We had originally planned for a highly efficient gas-fired boiler plant, but midway through construction we pivoted to renewable electric energy.”

Because Seattle’s clean electric grid utilizes mostly hydro power, ME Engineers was able to convert all of the arena’s systems to be 100 percent electric. The arena is powered solely on renewable energy sources, which includes on-site solar energy on the parking garage and atrium roof. The LEED Gold-certified project also implemented zero single use plastic and zero waste measures.

Preservation of the arena’s historic roof and exterior glass curtain wall created some complex challenges during construction, since the structure below the roof needed a near-total demolition. The construction team temporarily suspended the 44-million-pound roof while 680,000 cubic yards of earth were excavated underneath, expanding the underground space and doubling the arena’s previous square footage.

“This arena has been an important part of the Seattle community for 60 years,” Reiher said. “The original roof, which was preserved, is a designated landmark. We were able to deliver a world-class venue for the community while preserving an important part of its history and setting a new standard of sustainable arena design.”

In order for natural air to circulate through the underground portion of the arena, ME Engineers designed a network of “snorkels” (tubes as wide as 40 feet and as long as 60 feet) to pipe fresh air in from the outside. To combat the humidity brought into the arena by the snorkels, ME Engineers also designed the first all-electric dehumidifying system.

In addition, ME Engineers created a system that harvests rainwater from the roof and converts it into ice for the hockey games held at the new arena. Climate Pledge Arena is the only NHL arena using reclaimed water for ice sheet production and has so far saved an estimated 120,000 gallons of domestic water. “The ice is made using rainwater collected from the ‘rain-to-rink’ system with zero greenhouse gas emissions,” Reiher said. “Even the Zambonis are electric.”

“Climate Pledge Arena was an extremely complex project that would not have been possible without a visionary ownership group and innovative project team,” Reiher said. “Throughout the project, our team developed new protocols and technologies that rejected fossil fuels and embraced renewable energy.”