Seattle’s Bullitt Center is being heralded as the greenest, most energy-efficient commercial office building in the world. It’s not that the six-story, 50,000-square-foot building is utilizing never-before-seen technology. But it’s combining a lot of different existing technologies and methods to create a structure that’s a showpiece for green design–and a model for others to follow.

A project of the Bullitt Foundation, a Seattle-based sustainability advocacy group, the Bullitt Center has an incredibly ambitious goal. From the website:

The goal of the Bullitt Center is to change the way buildings are designed, built and operated to improve long-term environmental performance and promote broader implementation of energy efficiency, renewable energy and other green building technologies in the Northwest.

Credit: Miller Hull Partnership

“The most unique feature of the Bullitt Center is that it’s trying to do everything simultaneously,” says Bullitt Foundation President Denis Hayes. “Everything” includes 100% onsite energy use from solar panels, all water provided by harvested rainwater, natural lighting, indoor composting toilets, a system of geothermal wells for heating, and a wood-framed structure (made out of FSC-certified wood). These are all positive things for the Bullitt Center and its future inhabitants–they may even meet the goals of the ultra-tough Living Building Challenge–but they could also change the way buildings are designed elsewhere.

Think about the Bullitt Center’s location. When I spoke to Hayes, he told me that it was 42 degrees in Seattle–cloudy, of course–and it had been raining hard for the last four days. He notes that most people would laugh at the notion of a building in the city getting all of its energy from solar power. “If you were to choose the single location in the United States where solar makes the least sense, it’s arguably Seattle,” he admits. “Because though you have less sun in Alaska, you have really expensive electricity. In Seattle we have a combination of very little sunlight and really cheap electricity.”

That won’t necessarily be the case for long; Seattle’s cheap and clean power comes from its dams built in the 1930s, but dirtier sources will likely start coming online as electricity needs grow. And if the environmental impacts of coal and other dirty energy sources make them politically unattractive (still waiting on that one to happen), building designers might opt for solar. Says Hayes: “If you can do it for a six-story building in Seattle, that sends a powerful message to Santa Fe and Los Angeles.”

Credit: Miller Hull Partnership

Solar installations don’t usually face big legislative hurdles. But rainwater harvesting is a little more difficult. Hayes believes that the Bullitt Center, which was designed by the Miller Hull Partnership, is first conventional office building in the U.S. to get all of its water from rain–specifically, from a cistern in the basement that can hold 56,000 gallons of water. Tenants are expected to use about 500 gallons of water per day, so the cistern should theoretically be able to keep the building hydrated during a 100-day drought (not that that’s likely to happen in Seattle anytime soon).

Rainwater harvesting was actually illegal in Washington state–as it is in many places in the Western U.S.–up until a couple years ago. “You didn’t have the right to build a dam much less a cistern to save [water],” explains Hayes. “There was this weird moment in time where it was against the law to use rainwater on your roof but the government of Seattle would give you rain barrels for free to capture water.”