The world of architecture figuratively doffed its cap to Earth Day on Monday with the opening of the Bullitt Center in Seattle. The Bullitt Center aims to meet the rigorous Living Building Design Challenge, which looks beyond design criteria and scrutinizes a building's green credentials, including energy self-sufficiency, over the course of a year in use. But more significantly, its developers claim that the Bullitt Center is the greenest commercial building in the world.

The headline tech is the Bullitt Center's rooftop solar array. Lying almost flat, the array creates eaves extending well beyond the building's footprint. It's claimed that the 5º pitch compromises only 10 percent of their performance while allowing more panels to be packed into the same area.

The New York Times reports that, on paper, the 244-kW solar array should be good for 230,000 kWh of electrical energy per year, which it's hoped should prove enough thanks to the building being much more efficient than similar office buildings. The Bullitt Foundation points out that Seattle receives more solar radiation than the average in Germany, a country where solar installations are booming.

A view of the Seattle skyline from the roof of the Bullitt Center as a workman lays cable for the rooftop solar array, August 2012 (Photo: John Stamets)

One efficiency measure used is the maximizing of daylight. Remarkably, the Bullitt Foundation claims that the building can operate for 90 percent of the time without need of any electric lighting at all (being an office, it is primary used during daylight hours, which obviously helps). When it is needed, presence detection, daylight sensors and dimming ensure that no more lighting is used than is necessary.

The building must demonstrate water self-sufficiency, too. To that end the building is fitted with dry composting toilets and rainwater collection on the roof, which directs water to underground storage for purifying.

To accord with other items on the Living Building Challenge checklist, no prohibited materials, such as PVC, cadmium, lead or mercury (so no fluorescent lighting), have been used in construction. The building is reportedly the first mid-rise in Seattle since the 1920s to make structural use of heavy timber (certified by the Forest Stewardship Council), which is used alongside steel frame. The building is therefore ahead of the curve in what appears to be an emerging interest in timber as a high-performance building material.

Bullitt Center makes extensive use of structural timber (Photo: John Stamets)

Though the building's windows are motorized and automated to regulate internal temperature, some can be opened and shut by tenants, providing building users a degree of control over their surroundings that can contribute to workplace satisfaction. The Bullitt Center also does without on-site parking, promoting pedestrianism, cycling, and public transport instead. A cycle park the size of three garages is located on site.

"We've gotten to the point where incrementalism is no longer doing the trick," said Bullitt Foundation President, Denis Hayes in a PR video release. "We've got to make giant strides – giant leaps – into a new way of doing things."

This radical "new way" extends to the building's longevity. Unlike other contemporary commercial buildings which now often have a design life of mere decades, Bullitt Center is designed to last 250 years. The building became a working test case for Seattle authorities to review its planning regulations to encourage sustainable design.

A composter is lowered into the basement, March 2012

Better still, the Bullitt Foundation hopes that the building will form a blueprint for similar construction in America's northwest, and is sharing lessons learned in construction with construction professionals and, seemingly, anyone interested in the design. Visitors to the building can scan QR codes to learn about aspects of the design, including the electrical and mechanical services routes which, unusually, are visible rather than hidden from view.

Talking to the New York Times, Hayes explained that if, in a decade's time, the Bullitt Center is still one of the best-performing buildings, it will not have lived up to its purpose. An admirable sentiment. We look forward to seeing how the year pans out, and if other developers pick up the gauntlet.

You can see the Bullitt Center promo reel below.

Sources: Bullitt Center, New York Times