sustainability

Efficiency Peak in the Rockies

Photograph courtesy Patrick H. Corkery, NREL

The U.S. government’s clean energy research team now works on a campus in the Rocky Mountain foothills that aims to showcase the promise for better buildings. With Colorado’s night air and intense sunlight helping to cool, heat and light the space for more than 800 workers, the new $64 million National Renewable Energy Laboratory (NREL) Research Support Facility uses half the energy of a more typical office building.

“It is, to our knowledge, the world’s most efficient building,” says Dan Arvizu, the laboratory director.

The H-shaped edifice in Golden, Colorado (map) is at the vanguard of an effort by the federal government—the largest single energy consumer in the U.S. economy—to prove that it is possible to use far less power, even with complex and diverse jobs to do. (Related: Overview Story) Following is a collection of U.S. government buildings that exemplify that efficiency drive, in many cases overcoming daunting obstacles with creative design.

NREL’s Research Support Facility, opened in June, houses the people who analyze U.S. research data on solar, wind, and other renewables, as well as advances in building energy. They also do the difficult job of moving that technology to commercialization.

The building’s long sides face north and south, allowing maximum daylight, while concave devices in the window glass reflect sunshine onto the white, highly reflective ceiling to provide diffuse, even light for all the building’s workspaces.

The ceiling also contains 42 miles (68 km) of plastic tubing, where cool water circulates in summer and warm water in winter. But the radiant cooling and heating gets a big assist from outdoors. Windows open to let in cool night air. For warmth, fans draw air in during the day through a transpired solar collector wall—an innovation developed by NREL’s own scientists. The perforated dark metal sheets capture enough solar energy to heat the air as much as 49ºF (9ºC) in the sunshine. Thick, heavy concrete walls and an innovative subterranean thermal labyrinth, or crawl space, beneath the first floor, help regulate the indoor temperature.

The building received the highest possible score in the U.S. Green Building Council’s LEED Certification program, and is expected to earn a Platinum rating later this year. But NREL senior engineer Otto van Geet says the building should be considered an “evolutionary” use of proven technologies, rather than a revolutionary facility that will be unique. “Every one of these strategies is very replicable, and many of them are appropriate for all buildings and all locations,” he says.

—Candace Adorka

A Building Skin that Breathes

Photograph by Lee Foster, Alamy

A structure’s outer shell is traditionally known as the “building envelope,” but designers of the slender 18-story federal office tower at Mission and Seventh Streets in downtown San Francisco instead sought to surround the space with a “living skin” that opens to the elements.

With Bay Area temperatures hovering in a predictable 49º to 65ºF (9º to 18ºC) range year-round, it was an ideal location for natural ventilation. The cross-ventilation from the windows on the building’s northwest side and the glass curtain walls on the southeast side naturally cool about 70 percent of the space for the 1,700 federal employees who have worked here since 2007.

Bob Peck, now commissioner of public buildings for the U.S. General Services Administration, which manages the facility, remembers when the design idea first was floated near the end of the Clinton administration. “When the architects said they were proposing a building where most of the floors wouldn’t have air conditioning, we all kind of gasped,” he recalls. “Then, a couple of seconds later, we thought, ‘Why do they have AC in San Francisco, anyway? What have we been thinking?'”

(Quiz: What You Don’t Know About Air Conditioning)

Philip Haves, a building technology specialist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, which modeled the natural ventilation for the building, says the San Francisco building’s strategy of pre-cooling the building structure at night could be applied in other climates. Although natural ventilation alone won’t suffice in humid regions that don’t cool much at night, Haves says much greater use could be made of passive cooling. “With care and forethought that starts right at the beginning of the design process,” he says, “in homes and office buildings, for example, you can substantially reduce, or even eliminate, conventional air conditioning energy use in many U.S. climates.”

Natural ventilation reduced projected cooling costs for the $144 million project by 86 percent—saving an estimated $500,000 in operational costs annually.

—Austin Lewis

On the Roof: Postal Progress

Photograph courtesy Gerald Merna, USPS

There aren’t many places in midtown Manhattan to carve out a new 2.5-acre (1-hectare) park, but the U.S. Postal Service found a spot seven stories above street level—on top of the sprawling building where 12 million pieces of mail are sorted for New Yorkers each day.

Last year, the largest green roof in New York City opened atop the Morgan mail processing facility at Ninth Avenue and 30th Street.

(Related, from National Geographic Magazine, “Up on the Roof“)

The park—complete with benches, an art wall, and drought-tolerant native perennials—helps to cool the workspace for the 1,800 people who handle virtually the bulk of letters and packages delivered in Manhattan and the Bronx.

Air conditioning can be a major cost in a city facility with such a large workforce. So when it was time to replace the building’s black asphalt roof in 2007, the Postal Service began exploring ways to reduce the surface temperature. It turned out that the facility could support the weight of soil and vegetation, and would benefit in numerous ways from a park-like installation.

(Related, from National Geographic Magazine, Green Roof Photos)

The green roof is designed to last 50 years, twice as long as the roof it replaced. And the vegetation—including drought-tolerant ground covers like coral carpet, Immergrunchen, and John Creech—will suck down storm water. That will reduce runoff into the New York municipal water system by as much as 75 percent in the summer and 40 percent in winter, the Postal Service says. The Postal Service also was able to recycle and reuse 90 percent of the old roof in the new project.

Surrounded by a Healthy Commons

Image courtesy TVS Design

A greenscape with walking paths surrounds the curving 12-story Atlanta tower that is home to the U.S. government’s lead public health agency—a design meant not only to encourage physical fitness, but to save energy.

The campus of the $115 million headquarters of the U.S. Centers for Disease Control and Prevention, which opened in 2006, was planned to diminish the heat island effect that can grow oppressive in this hot Southern city. Tree-lined paths and permeable paving at ground level, sunscreens on the windows, and reflective roofing material all work together to take the edge off the Georgia sunshine for the more than 1,000 workers here. Also on the roof, a heat-exchanging energy recovery system cools incoming air in the summer, and warms it in the winter.

“The key to the success of this project was holistic approach,” says Micah Rosen, project manager, of the Atlanta architectural firm tvsdesign. The building features low-emissivity glass, made of a microscopically thin metal layered inside and outside the panes, to absorb sunlight and insulate. The rounded aluminum curtain wall allows maximum daylight to enter, while an indoor light management system dims artificial light when natural light is adequate for work activity.

The building, named for Senator Arlen Specter, the Pennsylvania Republican-turned-Democrat who formerly chaired the CDC’s budget subcommittee, is outfitted for a post-9/11 world with a large emergency operations center. The project budget included sitework, design, construction, commissioning, and equipment. Even with all the technology needed for agency officials to manage any type of public health crisis—from anthrax scare to flu outbreak—the headquarters is 20 percent more energy efficient than a typical office building.

—Yewon Kang

History as the Outer Wrapping

Photograph courtesy Naval Facilities Engineering Command

The U.S. Navy’s first effort at green building was ambitious—remaking a structure near the Anacostia River in Washington, D.C., that was originally designed as a manufacturing shop in the decade before the Civil War.

Fittingly, the service’s own building engineers and designers—the Naval Facilities Engineering Command (NAVFAC)—are now housed in the very space they retrofitted in 1998. Known simply (in prosaic military style) as Building 33 in the Washington Navy Yard, the red brick structure is considered a model of the possibilities for energy-efficient renovation of an historic preservation site.

The Navy couldn’t make any changes to the exterior of the building, and had to take many steps to maintain its original character—a requirement of numerous overlapping authorities that oversee historic preservation in the nation’s capital. Case in point: All of the old, drafty, single-panel windows in the building had to stay intact. The solution: The Navy created a “super-window” effect, by installing double-glazed insulating glass on the interior side of the existing windows.

Indeed, because the edifice originally was a 45-foot-high (14-meter-high) open-bay factory, later used as a warehouse, the large open space was suited for a building-within-a-building. A four-story structure, with new insulated walls and roof assemblies, was constructed within the existing shell. It now provides office space for about 400 people, as well as a library, storage, and mechanical space.

The challenges were all worthwhile, says Michael Chapman, NAVFAC’s senior architect in the office of the Chief Engineer. “Using an old building is the greenest way to go,” he says.

All of the sustainable architecture features are estimated to have added just $85,000 to the cost of the $21 million project. With building energy savings estimated at $58,000 per year, the payback for the efficiency measures was less than two years.

—Austin Lewis

Cooling Towers in the Desert

Photograph courtesy NREL

In a narrow slot canyon in the southern Utah desert, the National Park Serviceseized a chance to tap into the energy of a unique environment.

At Zion National Park in Springdale, Utah (map), where sandstone cliffs change in gradient from cream to pink to red against a cloudless blue sky, two downdraft cooling towers rise from the visitor center that opened in 2000.

(From National Geographic Travel: Zion National Park)

Desert heat evaporates water pumped onto a honeycomb media at the tower tops. Evaporatively cooled air falls through the towers under its own weight and gusts into the building. No fans needed. It’s an architectural feature that echoes not only the look of the scenery, but its cooling quality.

“We started looking at the climate,” says Paul Torcellini, principal group manager at the U.S. Department of Energy’s National Renewable Energy Laboratory, which collaborated with the park service on the project. “As you go up in the canyon, you get a lot of weeping water down the canyon walls that naturally evaporated and helped cooling.”

To help with heating (temperatures range from 20º to 60ºF (-6.6º to 15.5ºC) in winter), there’s a thick, dark sun-facing Trombe wall. Named for French architect Felix Trombe, who popularized the passive solar energy absorption technique, the wall gives off heat as the building cools, warming the building into the night. The visitor center also can fall back on electricity if needed, with a set of radiant ceiling panels that can provide heat. But together, the systems save more than 90 percent of the energy of a typical heating and cooling system—a savings of $16,000 per year.

The facility has transformed the experience for Zion’s more than 2.5 million visitors. Previously, on a typical summer day more than 3,000 private vehicles would traverse the two-lane road to a parking lot with only 400 spaces. Congestion not only hampered the visitor experience, it threatened wildlife and vegetation in the canyon. At the intersection of three separate ecosystems, it is home to 900 plant species not found anywhere else in Utah. Integral to the park’s design is a new shuttle bus system that runs on clean-burning propane. The $24 million cost of the project included purchase of the 30 buses and a bus maintenance center. Energy-saving features were incorporated into the building itself at a cost in line with that of a typical visitor center, says Torcellini.

—Catherine Ngai

(From National Geographic Travel: Zion National Park Photos)

Southern-Style Sustainability

Photograph courtesy U.S. Department of Energy

An expansive front porch gives the low, white Environmental Protection Agency building on Sabine Island, Florida, (map) the look of a Southern plantation. But in reality, it’s a computational and geospatial sciences (CGS) research lab, and the veranda is just one of the energy-saving features incorporated into the design.

The building, opened in 2008, houses about two dozen scientists in the EPA’s Gulf Ecology Division who conduct research on the impact of human activities on marine, estuarine, and wetland ecosystems. They help develop strategies to degrade toxic chemicals in the environment. Because their modeling work requires energy-intensive computer systems, the EPA worked to maximize energy efficiency by focusing on other areas of energy use, including cooling and lighting.

The light color and the large porch help deflect heat. And the building has numerous windows and skylights to reduce the need for artificial lighting. But all that glass posed a challenge for this location on a barrier island off the Florida panhandle. In 2004, Hurricane Ivan tore through Florida’s Gulf Coast, destroying six of the 40 buildings on the 16-acre campus where the CGS building now sits. So the many windows are made of high-impact glass, and aluminum was chosen as the primary roofing material because traditional shingles tend to come loose in tropical storms.

Water conservation also was an important concern in the design of the building on the fragile Gulf Coast. The building’s urinals and toilets use 100 percent recycled water gathered from a rainwater cistern on the roof. The building earned a LEED Silver designation from the U.S. Green Building Council.

“I think it’s important [to work toward sustainability] because it reflects our vision,” says Clay Peacher, facility manager at the EPA’s Gulf Ecology Division. “You’re walking the walk.”

—Catherine Ngai

Candace Adorka, Yewon Kang, Austin Lewis and Catherine Ngai are reporters for Medill News Service in Washington, D.C.