Force of Nature

Sept. 1, 2007

Earth's elements are cornerstone of EPA's new Denver digs

By Chelsea Houy

It may be the closest one might ever get to Mother Nature without ever actually stepping outdoors: clouds, cascading waters, dancing daylight, breathtaking views.

EPA Region 8 Headquarters is a nexus of nature, a living laboratory shaped by the same elements - wind, water, and sunlight - that have sculpted the surrounding Rocky Mountains.

Technology tempers, and, at times, takes advantage of these elements in testimony to the Environmental Protection Agency's (EPA's) mission - to protect human health and the environment.    

"We wanted the building to be a tangible representation of what our mission is," explains Joni Teter, new lease project coordinator, EPA Region 8, Denver. "We wanted to have a building that was a very visible example of what can be done with sustainable design."

Maximize, Manage
Located in hip and historic LoDo (Lower Downtown) Denver, the building's eclectic skin is formulated from an amalgamation of the area's architectural influences - 19th century industrial and 21st century modern - its brick, glass, and steel a graceful duality disguising a design as dynamic as Denver's climate.

The structure is defined by two inverted, L-shaped wings resting on a former post office foundation. The primary entrance to the building forms a joint, uniting the east ends of each L. The west ends are connected by a series of spaces that offer rich views of the Rocky Mountains. Retail shops inhabit the first floor; EPA offices on the remaining nine wrap around an atrium.

The design architects, Portland, OR-based Zimmer Gunsul Frasca Architects (ZGF), and architects of record, Minneapolis-based Opus Architects and Engineers, chose the double-L scheme because it delivers optimal daylighting along the perimeter and center of the building. But with the building situated at a 45-degree angle, each L had to be fine-tuned to face unique climate conditions. "By developing these two Ls separately, surrounding the atrium, the response to those solar and climate orientations merged," says Mark Perepelitza, AIA, associate partner, ZGF.

To block prevailing winds from the north, the northeast-northwest-facing L, at 129 feet, is slightly taller than the southeast-southwest-facing L's 117 feet. This height differential protects the south L and an eighth floor terrace. Like its counterpart, the south L's height is not without plan or purpose. Its short stature allows it to take advantage of its solar orientation, allowing daylight penetration into its inner recesses. 

"Quite often you'll hear people talk about daylighting; what they're really talking about is more glass in the building. But that's not really a daylighting solution, that's uncontrolled daylighting," says Rob Bolin, PE, LEED AP, senior vice president at the Chicago office of New York-based mechanical, electrical, and plumbing engineering firm Syska Hennessey Group. Working with the architects, Bolin used a daylight modeling tool named Radiance to guide an integrated design that maximized and managed daylighting throughout the 292,000-square-foot space.

Vertical "fins" mounted on the northern L's exterior harvest sunlight from the diffuse northern sky. On the south L, exterior horizontal light shelves help push daylight into office spaces and the atrium. This carefully articulated design results in a uniform, natural illumination.

Control, Comfort
Throughout office spaces, providing occupant control and comfort was a high design priority. "We put a lot of thought into creating a space conducive to high morale and productivity that also models what we'd like to see the rest of the building community doing," says Teter.

In the south L, automated horizontal blinds cover the 9½-foot windows at 7½ feet and above, the "daylight zone." Below 7½ feet, manually operated horizontal blinds offer occupant control. In the north L, fixed vertical blinds cover the daylight zone and are supplemented by manually operated horizontal blinds below. Occupancy sensors and light sensors control artificial light use throughout the Ls.

Pods of Herman Miller workstations, measuring only 60 inches high, allow daylight trespass deep into the space. Enclosed offices near the core of the building reap the benefits of this daylighting via clerestory windows.

In the workstations themselves, translucent panels offer an additional daylight avenue. Above each is a 30- by 30-foot dropped ceiling, or cloud, suspended from the exposed concrete ceiling, bouncing daylight farther into workspaces. Below, low-VOC carpeting and an underfloor air distribution system help occupants breathe easier.

Even with all of these sophisticated, highly integrated components, the atrium is where EPA Region 8's sustainable design takes center stage. 
Illuminate, Animate
The atrium is the heart of EPA Region 8. It is where technology, architecture, and nature culminate to create a glowing gathering place for the building's 750 employees and the community. 

To fill the corridor with light, designers needed to direct daylight coming through the atrium's skylight. Designers considered standing mirrors on top of the skylight, with the mirrors facing southeast and southwest to reflect daylight down into the space. They nixed that idea after a scale model they tested showed the mirrors would produce too much glare in office spaces on the eighth and ninth floors.

Ultimately, the parabolic profile of a fluorescent light fixture inspired another solution - a type of light reflector resembling a billowing sail. The curvaceous form would gently bend the light, guide it into the atrium, and alleviate glare issues. With the reflectors hanging from the skylight, they didn't have to be wind- and weather-resistant. And who better to construct this nautical-like apparatus than sailmakers.

In came Portland, OR-based North Winds Canvas. "We were a little nervous because they're not used to working in the architectural world where you do shop drawings and approvals," recalls John Breshears, AIA, associate partner, ZGF. "We showed them a paper model and we said, ‘Could you make nine of these things?'" 

Stainless steel tubing and fiber glass tensioning struts (both typical sailing components) sheathed in a coated, white woven polyester fabric made by Ferrari of France (not to be confused with the automobile manufacturer) form the 10-foot-wide by 10-foot-long by 12-foot-high reflectors. "We can actually see the light traveling around those curves throughout the day and bouncing down. It just creates a wonderful, almost artistic pattern," observes Teter.

And the artistry doesn't stop there. 

Below, a bamboo-clad "grand staircase" provides seating for meetings. A stone veneer water wall flanks the right side of the staircase, adding drama. "It sounds like a waterfall. Even though you're indoors, you feel like you're outdoors," says Teter.

Colorado water rights laws prohibited designers from implementing a rainwater harvesting system, so, instead, the feature draws from small pools of recirculated water at the base of the elevators. In addition to its aesthetic appeal, the water wall provides passive cooling throughout the atrium.

Live, Learn
The building has been a learning experience for both designers and end-users. "One of the things we're learning is you can't live in one of these buildings the way you do traditional buildings," explains Teter. With automated, integrated components throughout the LEED Gold building, Teter and her team are helping employees understand how the systems are designed and how they can maximize their own comfort yet allow the systems to operate as intended: to save energy.

As a living laboratory, EPA Region 8 Headquarters is a visible example of what intelligent sustainable design can be. It allows earth's elements to create a wholly natural experience for users that can be seen, heard, and touched.

Chelsea Houy ([email protected]) is the new products editor at ARCHI-TECH.

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