Seattle’s South Lake Union (SLU) neighborhood is a quickly developing core with a flurry of new projects catering to biotechnology, life sciences and technology companies. A push for more pedestrian-friendly connections has resulted in projects like the developing Lake2Bay corridor, which will establish a new green pedestrian connection between Lake Union and Elliott Bay, as well as the SR-99 tunnel, which will create ground plane connections for pedestrians to pass through Seattle Center and SLU.
In an effort to further connect these neighborhoods and fit into the pedestrian-friendly urban context of the city, West Coast-based architecture and planning firm Miller Hull Partnership has developed 333 Dexter, a mixed-use office building located at the core of SLU, to act as a hub that links previously disjointed neighborhoods and promotes pedestrian activity in and around the site.
“[Our client] Kilroy [Realty Corporation] approached us with the desire to create a differentiated product offering in the rapidly developing South Lake Union core,” said Scott Wolf, partner at Miller Hull, in an email to The Registry. “We were intrigued by this approach and were also excited about the opportunity to reimagine such a large central block in the SLU core given the location of the project, the new SR-99 tunnel and the reimagining of 7th Avenue as a pedestrian-oriented urban street, rather than the vehicular entry/exit to the previous Battery Street Tunnel.”
According to the design team, project goals focused on the distinct yet similar aspects of the relationship between 333 Dexter’s two towers. Each tower needed to respond to the context of the surrounding site, including the Lake2Bay trail which runs along the south of the site and the redirected SR-99 vehicular traffic to the north, while also complementing one another with relation to the bulk and scale of the project. The team also wanted to ensure the site allowed for pedestrian access, while also maximizing visitor views to the surrounding neighborhood, nearby Space Needle and distant water and mountain scapes.
333 Dexter is 632,000 square feet and differentiated into two multilevel, separate towers set on a large block above podium level, which adheres to land use code. Wolf explained the team’s interest in expressing the two towers in different yet harmonious ways so as to reduce the building’s apparent scale. The team refers to the north tower as the “quiet tower” because the design is a more traditional rectilinear form, and refers to the south tower as the “active tower” because of its dynamic, angled facades that create pedestrian-friendly open spaces along Thomas Street to the north.
The fifth and eighth levels of the south tower feature roof decks, and the project’s ground plane feature setbacks, furniture and open plazas which all contribute to the open-access environment of 333 Dexter.
“Angled ‘walking columns’ unified the two towers at the ground plane and helped to create one of the most distinctive features of the project,” Wolf said. “A covered through-block under the podium between the two towers provided protected outdoor space and fed the entries to the two separate towers.”
Much of the project’s ground plane was designed with pedestrian experience in mind, even down to fire department connection panels which are custom-designed, fabricated and coated to blend in with the surrounding architecture.
“Attention to detail at the ground plane sets itself apart from other cookie-cutter projects in SLU,” said Tetsuo Takemoto, designer at Miller Hull. “Everything from the leather-wrapped door handles to the custom site pavement treatment elevates the experience for not only the users but also for the general public that can meander through the site.”
Wolf explained how each side of the site responds to neighborhood context, beginning with Thomas Street and continuing along to Dexter Avenue to the east. As a major cycling arterial that extends into the downtown core, the team ensured that retail spaces and the through-block main entry to the project connected appropriately to the right of way along Dexter. To the west, 7th Avenue acts as a more pedestrian-friendly connection than the previous Battery Street Tunnel, which was vehicular heavy and has since been replaced by the SR-99 tunnel. Harrison Street along the north is also a pedestrian-friendly connection that features an art mural display to protect the loading dock from public view.
The team explained the challenges they faced during the material selection process, as they wanted to ensure the texture and material palette not only fit the neighborhood context, but also was compatible with the curtain wall system being used. As such, the plan for materials changed during early design phases before the team made final decisions.
“For cost reasons, we landed on a unique off-the-shelf metal panel shape as the primary cladding material but found it challenging to fit them into the tight tolerances for a unitized system,” Takemoto said. “In collaboration with the glazing contractor, the curtain wall fabricator, the metal panel fabricator and the envelope consultant – including numerous visits to the fabrication plant to quality control the units before shipment to the site – the team settled on a custom formed metal panel that met the tolerance specifications in order to maintain the desired architectural form.”
The materials the team ultimately used helped to further connect the two towers together while creating distinct personalities for each. Both towers use the high performance curtain wall system and feature the profiled metal panel building skin Takemoto mentioned previously. The north tower takes cues from the brick warehouse architecture popular in SLU during the early 1900s, with punched windows and a palette of glass, steel, brick and profiled metal panels for a more modern approach. The south tower’s palette of corrugated metal panel and glass emphasize the importance of movement and activation along Aurora Avenue and the Lake2Bay pedestrian connection.
“The materials chosen for the project balanced a number of project parameters including aesthetics, cost and durability,” Wolf said. “The metal panels used on the towers were a fairly standard shape, although we introduced a slight butterfly bend mid-panel which served to animate the facade and break down the scale to the panels under different lighting conditions. A combination of brick and glass storefront was used at the ground plane to create a more open, welcoming experience for pedestrians. Wood benches and planters were incorporated in the open spaces and the through-block at ‘high-touch’ areas to introduce warmth and provide comfortable places for people to hang out.”
333 Dexter, which is LEED Gold certified, extends Miller Hull’s sustainability efforts through the firm’s EMission Zero initiative, a program announced in 2021 that commits to offset greenhouse gas emissions released up until the date of occupancy for all constructed projects. For this particular project, offsets will fund the Dempsey Ridge Wind Energy Farm Project. The design team aims to encourage partners to join their efforts and noted that because Kilroy is focused on energy performance, this project was a good fit for the initiative.
“Because of Kilroy’s focus on energy performance, the project is a good energy performer that is just shy of the target for the 2030 Commitment,” said Jim Hanford, principal at Miller Hull. “There wasn’t a focus on embodied carbon so it acts as a baseline for our firm for an urban office building that we can use to compare current design projects against. For the offset part of EMission Zero, it represented 2/3 of our total offset for the 2021 project completion year so it is hugely significant, and highlights why we need to focus on large projects for maximum impact.”
Miller Hull was awarded the project in 2015 and construction took place primarily between 2017 and 2019. The tenant initiated office fit-out in 2020 and is currently occupying 333 Dexter while they finish their amenity floors.