It’s the world’s greenest office building.

The Bullitt Center, finished in the summer of 2013 and located on the edge of Seattle’s downtown, is designed to mimic the Douglas fir forests that once stood on the site.

Powered by sun and fed by rainwater, the building doesn't produce any waste. Its automated window shades open and close like an organism’s pupil, regulating the amount of light that enters. The 600-panel solar array, which is expected to generate all the energy the building needs in a year, is arranged on the roof so that rays of sunlight can pass through and create a dappled pattern on the sidewalk below — similar to the way light passes through a forest canopy. And all the wood used in the structure came from local forests that harvest trees sustainably.

Designed to be as self sufficient as any arboreal ecosystem, the center also has a 56,000-gallon cistern, which will provide tenants with all their water needs. All waste generated will be treated on site thanks to the world's first six-story composting toilet system, and a rain garden will filter the wastewater from sinks, showers, and floor drains.

“Nature has had a long time to figure out how to live successfully on this planet,” says Jason F. McLennan, founder and creator of the Living Building Challenge,most rigorous certification process for green building. “There is a lot we can learn from it.”