2020 Green Home of the Year Award Winner: Multifamily Masterpiece

It’s elegant, it’s efficient, and it’s a sign of things to come, according to these Seattle developers.

Sitka surpasses expectations about the possibilities afforded by sustainable design. The seven-story, 384-unit building in Seattle uses innovative technology and design techniques to achieve a level of energy efficiency previously not seen at this scale, making it one of the most-sustainable multifamily buildings in the region.

The building’s design evokes the ethos of Northwest modernism and the landscapes of the surrounding area. Three cabin-like buildings are slightly angled to create a concave backdrop to the adjacent park, while the south wing’s sloped green roof reflects regional forms and allows light into the courtyard.

The design team—which included architect Brian Runberg, founder of Runberg Architecture Group, builder Sean Stimac of Exxel Pacific, and landscape architect Jason Henry of Berger Partnership PS—wanted to create a property with a strong sense of place. “We wanted to infuse Sitka with regional identity,” Runberg says. “We didn’t want it to look identical to all the other midrise multifamily buildings that are springing up across the city.”

Powering Up

From the Judges: “Ultimately economic success and great design will make this project a strong example for others

 

Project Stats
Name: Sitka, Seattle, Wash.
Architect/Designer: Brian Runberg,
Runberg Architecture Group
Builder: Sean Stimac, Exxel Pacific
Developer: Alicia Stedman, Vulcan Real Estate
Landscape Architect: Jason Henry,
Berger Partnership PS
Interior Designer: Christiane Pein,
Lair Design, LLC
Photographer: ©Christophe Servieres;
©Michael Walmsley

Sitka’s energy design began by analyzing the energy needs in multifamily buildings and then applying a series of efficiency measures.

As the largest source of energy use in new multifamily buildings, hot water was the design team’s No. 1 focus. The Wastewater Heat Recovery System, the first in the U.S. for this application, captures heat from outgoing wastewater and reuses it for domestic hot water heating. This process effectively recycles heat in the hot water system by using water-to-water heat pumps to capture and move heat from outgoing wastewater to the next day’s hot water supply, according to Runberg. Also, the project also utilizes a greywater harvesting system that diverts water from showers and laundry for on-site irrigation.

Heating and cooling are relatively low demands for compact apartments in Seattle that are built to the new energy code. But the design team looked for ways to improve energy performance and reduce energy consumption even further.

Sitka’s system offsets any energy needs during the winter and summer. 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 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.

For 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.

More Key Components

Additional energy-efficient elements include LED lighting throughout, ENERGY STAR® appliances and a high-efficiency 14-foot-diameter fan in the fitness center. Sustainable features include a green roof with drought-tolerant plants; bioretention planters to capture roof runoff, and provide detention and some filtration prior to discharge to the city storm sewer; use of recycled and locally sourced materials; and low-flow toilets and fixtures.

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 runoff 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, the company notes.

These energy-efficient elements combined helped Sitka achieve LEED for Homes Platinum certification. Sitka is also on track to achieve ambitious local 2030 targets for reductions in water and energy use, as well as receive an Energy Star energy use intensity (EUI) score of 16—way below the multifamily housing average of 59. The property uses nearly 28 percent less energy than a typical baseline design. “These savings aren’t just beneficial for the environment,” Runberg Architecture Group notes. “They represent a considerable reduction in the property owner’s overhead costs and in residents’ monthly utility expenses.”

Overall, Sitka’s development was a success, according to Runberg. “People are drawn to Seattle not just for jobs, but for the lifestyle, the landscape and the chance to immerse themselves in nature,” he notes. “Washington is a beautiful state, and we wanted to bring some of that Pacific