The world’s greenest office building is set to open in Seattle on Earth Day

Tenants have already begun moving into the six-story Bullitt Center, in advance of its grand opening on Earth Day, April 22. With the final touches nearly complete on the 50,000-sq. ft office building, which bills itself as the world's greenest, its occupants are about to embark upon an unparalleled and very public experiment in sustainability.

Once settled in, they will be guinea pigs in a $30 million living laboratory distinguished by its composting toilets, strict energy and water budgets and a conspicuous lack of on-site parking.

To earn its environmental bragging rights, the Bullitt Center must complete a rigorous one-year certification process called the Living Building Challenge, which requires both water and energy self-sufficiency, among a list of 20 demands.

Provided that the building clears a few remaining regulatory hurdles, all its water will be supplied by rainwater collected in a 56,000-gallon cistern before being filtered and disinfected. A rooftop array of photovoltaic panels, extending beyond the building like the brim of a graduation mortarboard, will produce an estimated 230,000 kilowatt-hours a year, hopefully just enough to break even for a building that is 83 per cent more efficient than the city's typical commercial site.

The project's backers, led by the environmentally minded Bullitt Foundation, hope to demonstrate that a carbon-neutral office space can be commercially viable and aesthetically stunning without saddling its occupants with onerous demands. And they are determined to make their strategy and performance so transparent that it can be easily copied.

Instead of tucking the mechanical and electrical rooms out of sight, for example, large plate glass windows will showcase the engineering, while quick response codes tag points of interest so that tourists can use their smart phones to learn about individual elements. A kiosk will also allow visitors access to real-time measurements like the building's indoor air quality, energy consumption, photovoltaic power production and water levels.

If the building is still the highest-performing of its kind 10 years from now, said Denis Hayes, president and chief executive of the Bullitt Foundation, the experiment will have failed. The Living Building Challenge's imperatives go far beyond those of the better-known LEED (Leadership in Energy and Environmental Design) certification.

Its year-long vetting process is designed in part to avoid the embarrassment suffered by some LEED-certified buildings, where seemingly efficient buildings have proven to be much less so after the buildings have been completed and undergone energy audits. The Living Building Challenge process is so demanding that only three buildings in the US have been fully certified so far; the largest of those is one-eighth the size of the Bullitt Center.

With advertised lease rates of $28-$30 a square foot, the building is in line with comparable properties. It helps that a group of enthusiastic early adopters has already leased more than two-thirds of the available office space.