By Jay Fox

Winners of the 2025 American Institute of Architects (AIA) Committee on the Environment (COTE) Top Ten Award were announced last week. The Top Ten Awards program is the profession’s best-known recognition program for sustainable design excellence, and for the first time in the program’s 28-year history a Passive House certified project, The Bush School New Upper School in Seattle, was among the award recipients.

Designed by Mithun—an integrated design firm with offices in Seattle, San Francisco, and Los Angeles—the project is the largest Passive House certified school building in the Western United States, and first Salmon Safe certified school in the country with stormwater systems that enhance the watershed and protect salmon habitats. The new school building expands the capacity of the Bush School, an independent K-12 school founded in 1924, and features healthy materials, natural light, and flexible spaces that serve as a learning laboratory for students in grades 9-12.

“Over my years at Mithun, I have been fortunate and am deeply grateful to have had various roles now on a handful of projects honored with an AIA COTE Top Ten award,” said Mithun Associate Principal Mike Fowler. “Each one of them is special, but this latest one for the Bush School stands out and holds a unique place in my heart. On a project with a list of firsts, becoming the first certified Passive House project to receive this prestigious award recognition marks a groundbreaking moment—not just for the project but for the entire Passive House community.”

“This is a watershed moment for the school, and we are proud to achieve this national recognition. The architects and builders listened to the school’s team and created a beautiful edifice that is the physical manifestation of our mission and values,” said Percy Abram, head of school at The Bush School.

The Phius and Zero Energy certified academic building features a post-and-beam glulam structure and mass plywood panel decking to reduce embodied carbon and optimize construction. The optimized design was simulated and tested for passive survivability using the 2021 Pacific Northwest heat dome conditions with three days above 100 degrees and for the building having no power. Even at 108 degrees peak outside temperature on the third day, the interior heat index remained below 90 degrees.

“It’s rare to work with such a committed client that couples high aspirations for sustainable design with the strong intention to have their facilities be a visible example of change in the broader community,” said Mithun partner Brendan Connolly FAIA. “From the outset, The Bush School wanted this project to matter to more than just its students, to also broadcast powerful new ideas like Mass Timber and achieving Passive House certification to the broader city and region. It’s exciting to see the positive impact happening beyond its property lines!”

The 2025 award is the ninth AIA COTE Top Ten Award for Mithun, continuing the firm’s leadership among national practices with multiple COTE honors.