Designing a building to meet the requirements of the Living Building Challenge (LBC) means taking the concept of green building to the next level. Living Buildings must meet performance standards in seven “petals”—Site, Water, Energy, Health, Materials, Equity, and Beauty—and each petal is subdivided into a number of imperatives. The designers of Seattle’s Bullitt Center also are taking the LBC to a new level in terms of scale: They are now constructing what is expected to be the first multistory urban development in the world to attempt Living Building certification.
Upon completion in fall 2012, the six-story Bullitt Center (formerly the Cascadia Center for Sustainable Design and Construction) should be the greenest office building in the world, according to the architect, Seattle-based Miller Hull Partnership. It is designed to be a 250-year building that generates all of its power on site thanks to a 230,000-kilowatt-hour rooftop solar array. The indoor temperature will be regulated by ventilation through large, computer-automated windows, as well as a hybrid heating and cooling system that combines 36 geothermal wells with an ultra-efficient heat exchanger. An extremely tight building envelope designed to eliminate air infiltration and thermal bridging; a high-performance, triple-glazed curtainwall; a 500-square-foot green roof; enough daylighting to reduce lighting loads in office spaces to less than half of what’s allowed by Seattle codes; and dramatically reduced plug loads are planned to cut the 52,000-square-foot building’s Energy Use Index to 16 from Seattle’s more typical 92.
“The intention is to set a new prototype of sustainable urban development to show it can be done,” says Brian Court, AIA, an associate at Miller Hull and the project architect on the Bullitt Center. “Part of the project is identifying the barriers.”
From addressing occupant behavior to getting financing for a project with no market comparisons, plenty of barriers exist on the Bullitt Center’s path to Living Building certification, which requires a minimum of 12 months of post-occupancy performance data.
Located in an area well-served by transit, the center is being built with parking only for bikes. The LBC requires a net-zero-water building, with all of the occupants’ water use coming from captured precipitation or closed-loop water systems, so all of the center’s graywater will be treated on the green roof, waste from composting toilets will be processed on site, and rainwater will be collected in a 50,000-gallon underground cistern for reuse on site.
Meeting the energy requirements of the LBC raised another challenge. While all buildings of a similar size in the Department of Energy’s High Performance Building database purchase energy every year, the LBC requires that all of a project’s energy needs be supplied by on-site renewable energy on a net annual basis. This forced the nonprofit Bullitt Foundation, the building’s owner and developer, to act as a second lender, since no bank would finance the entire project.
Generating all of its power on site meant first reducing the building’s energy consumption as much as possible, otherwise the solar array would be four times the size it is now, according to Court. After designing an energy-efficient building, the project team turned its attention to plug loads and occupant behavior. Each tenant will be separately metered and even individual plugs can be tracked, if a tenant desires. Bullitt Center leases will include a maximum allocation of annual electricity use.
To further address occupant behavior, the designers are using visibility as a tool. Energy dashboards, a view of on-site waste-treatment systems, and smart outlets at every workstation will all play a role. The team also placed windows along the external wall in a stairway that had the best views in the building, with the hope of enticing occupants and visitors away from the elevators. If successful, this unorthodox measure could reduce energy use by 3,000 kilowatt-hours per year.
Still, finding a way to make the solar array large enough to power a Class A office building and be aesthetically pleasing was tricky. The array will be located entirely above the building, but will extend past the property line almost to the curb face, Court says. It was a choice necessary to account for the larger square footage of a multistory building located in Seattle versus the current Living Buildings: one-story structures located on less-developed campuses.
Court says that the design choice—which has been called awkward looking—is an expression of place. “In Seattle … that large sheltering roof, there is a sense of comfort to it,” he says. “So we feel that the expression is about its place. It is about Seattle trying to power a six-story building in an urban environment.”
Future net-zero buildings might not have to make that kind of choice if the vision of Denis Hayes, president and CEO of the Bullitt Foundation, comes to pass. His theory is that urban developments will have to work with existing buildings to create eco-districts or living cities that are largely self-sustaining. The City of Seattle recently passed a Living Building Program ordinance that provides leeway in some development standards such as accommodation for solar rooftops and graywater removal.
“The Bullitt Center is a step in the right direction, but we don’t think it’s the ultimate solution in that you have a bunch of buildings that are totally self-contained and autonomous,” Court says. “We want to see neighborhoods working together, sharing resources.”
Charles Redell writes about sustainability from Seattle.