Runberg Architecture Group Raises the Bar for Urban Housing
Sitka, a new multifamily project located in Seattle’s South Lake Union neighborhood, is upending expectations about the possibilities afforded by sustainable design. Designed by Runberg Architecture Group for Vulcan Real Estate , the seven-story, 384-unit building uses cutting-edge technology and innovative design techniques to achieve a level of energy efficiency previously not seen at this scale. The result is a visually arresting property that not only met each one of Vulcan’s pro forma targets, it’s also one of the most sustainable multifamily properties in the nation.
A Distinctive—and Distinctly PNW—Design Sensibility
Runberg’s design team knew from the start that they wanted to create a property with a strong sense of place. Sitka’s design evokes the ethos of Northwest Modernism and the landscapes of the nearby San Juan Islands. Three cabin-like buildings are slightly angled to create a concave backdrop to the adjacent historic Cascade Park, while the south wing’s sloped green roof reflects regional forms and allows light into the courtyard. “We wanted to infuse Sitka with regional identity,” said Brian Runberg, Principal and Founder of Runberg Architecture Group. “We didn’t want it to look identical to all the other midrise multifamily buildings that are springing up across the city.” The full block project has entrances at every street frontage, each representing an environmental characteristic of the Northwest—mountains, meadows, forests, and waterways—which act as passageways into the tree-filled courtyard for both residents and the public.
Human-Centered Design Meets Urban Oasis
“Our mission is to design places where people want to be,” said Brian Runberg. “When creating Sitka, we asked ourselves what was missing from most of South Lake Union—what would make people feel good about spending time here—and it was green space. We wanted to create an oasis for residents and neighbors in the midst of the hard cityscape.”
The elimination of the typical mid-rise podium allows Sitka’s structures to sit at street level, while the mid-block pedestrian walkway invites foot traffic onto the property and eases access to neighboring buildings and to Cascade Park. The project’s sloping green roof, rooftop community garden, and indoor/outdoor entertainment zones were designed to connect residents to the environment. But the concept of nature in the city is most clearly expressed in the property’s interior courtyard, which features a running stream, tree-covered hilltops nestled between rock walls, and an imaginative take on a treehouse designed by Seattle’s Lead Pencil Studio . The treehouse, which is accessible from the second story of the building, features a working fireplace and charming views of the courtyard and surrounding neighborhood. At ground level, fiber optic lights at the bottom of the pond suggest the reflection of a starry sky, while a fog feature is reminiscent of mist rolling in off the coastal waters.
“People are drawn to Seattle not just for jobs, but for the lifestyle, the landscape and the chance to immerse themselves in nature,” continued Runberg. “Washington is a beautiful state, and we wanted to bring some of that Pacific Northwest magic to our design.”
Raising the Bar for Sustainable Urban Housing
Ecotope , a local energy consultant, was instrumental in the energy design for the building. The teams focused on the primary consumers of energy in new multifamily buildings: hot water, heating and cooling. Sitka is the first project in the United States to utilize a Wastewater Heat Recovery system in a multifamily application. The system captures heat from outgoing wastewater, harvests the heat on site and then reuses it for the next day’s domestic hot water needs.
While heating and cooling demands are relatively low for apartments built to Seattle’s new energy code, the design team looked for opportunities to improve energy performance and reduce energy consumption even further. All of the building’s west- and south-facing units (and roughly one third of the project’s remaining units) feature ductless heating pumps, which provide cooling in the summer and reduce heating needs in the winter by a factor of three. The reduction in heating energy use more than makes up for the increase in cooling energy use in the summer. Ductless heat pumps and heat recovery ventilation systems are also present in Sitka’s amenity spaces.
By breaking up the building massing at both the west and south points, direct sunlight is able to filter into the courtyard at midday and afternoon. The sloped green roof on the south building allows more sunlight into the courtyard-facing units, reducing the need for artificial lighting during the day. On the interior, the corridors were designed with large windows at each end to allow natural light and ventilation into the hallways. The project’s exterior elevator reduces the amount of energy lost via air leakage from the repeated opening and closing of the doors. Additionally, the lobby staircase was designed to be visible from the main elevator to encourage residents to travel by foot instead.
The building’s other energy efficient attributes include LED lighting, EnergyStar appliances, recycled and locally sourced materials, low-flow toilets and fixtures, and a high efficiency 14’ diameter fan in the fitness center. The building’s green roof features drought tolerant plants capable of surviving Seattle’s dry summers. A greywater harvesting system diverts water from showers and laundry for on-site irrigation, and bioretention planters at ground level capture runoff from the roof during the rest of the year. Vulcan Real Estate also provided street front access to the City of Seattle for its “Swale on Yale,” a large, man-made wetland designed to treat the majority of street run-off from the Capitol Hill neighborhood before it is discharged into Lake Union. The swale will significantly improve the water quality in the lake while providing an attractive amenity for pedestrians.
Environmentally Friendly Design That’s Both Profitable and Repeatable
Sitka is certified LEED for Homes Platinum and is on target to achieve Seattle’s 2030 Challenge for Planning goals for reductions in water and energy use. The property uses roughly 28% less energy than a typical baseline design, saving approximately 10 kBTU/ft 2 per year, or roughly 5,073,220 kBTU annually. These savings aren’t just beneficial for the environment, they represent a considerable reduction in the property owner’s overhead costs and in residents’ monthly utility expenses.
Perhaps the most impressive fact is that the project team did not have to secure special funding, conduct R&D, or produce custom-designed materials to make this development possible: Sitka was built using conventional funding and off-the-shelf components. Sitka is a compelling example of how to successfully marry sustainability with good design at a large scale in an evolving city like Seattle. The project team hopes Sikta will serve as a beacon for progress and that the innovative technologies it employs will become more widely adopted by the housing industry.