Monday, 7 December 2009

In Search of Net Zero

The National Renewable Energy Laboratory wants to be the greenest office building in the country. Here's how.

GOLDEN, Colo.—It takes a certain ruthlessness to create the greenest office building in the nation.
The Journal Report
The National Renewable Energy Laboratory, a unit of the U.S. Department of Energy, is midway through construction of a $64 million project that lays claim to that title. The architects and engineers have spent hundreds of hours calculating the energy use of every aspect of the building, from the elevator to the exit signs. They have tweaked the design again and again with the aim of getting the 218,000-square-foot building to perform at net zero—meaning it will consume so little energy that it won't need to draw a single electron from the grid.
Building Green
The NREL's $64 million, 218,000-square-foot research campus is being built to the highest green standards.
The calculations leave little margin for error, however, so project manager Eric Telesmanich is girding for a new role as energy enforcer next summer, once the lab's 750 employees move into the building, located on NREL's campus in this Denver suburb. No personal mini-fridges or microwaves or space heaters.
If he has to, Mr. Telesmanich says, he will do an outlet audit and unplug any unauthorized energy hogs. "We have to be the police," he says. "We're introducing our occupants to the new energy culture."
Nationally, 191 commercial buildings meet the most stringent standards for sustainability laid out by the U.S. Green Building Council, a Washington nonprofit that promotes and certifies green building practices. The NREL building is designed to go well beyond the highest standard—a designation known as LEED platinum—to reach net zero. No other commercial building of its size has achieved that goal in the U.S., according to the U.S. Green Building Council; just a few have made it in Europe.
A Smart Building
NREL began the project by setting an energy budget for the building based on British thermal units, a standard measure of energy, in addition to a financial budget. NREL told designers bidding on the project that the new building could use no more than 32,000 BTUs per square foot a year. A typical office building in the Rocky Mountain region uses 65,000 BTUs per square foot a year, says the U.S. Green Building Council. If the building stays within its limits, all its energy use should be covered by a one-megawatt solar array being built on the NREL campus.
To achieve that goal, the winning design-build team—which included the international architectural firm RNL; Haselden Construction LLC of Centennial, Colo.; and Stantec Consulting, a North American engineering firm—assembled a crew of 180 to rethink the concept of an office building, from the outside in. "Traditional architecture is design first, then figure out how to make it work," says Rich von Luhrte, president of RNL, which has offices in Denver. "This project reverses that mindset: Energy drives the design."

Instead of a blockish tower, Philip A. Macey, a senior associate at RNL, drafted plans for two long, narrow wings of office space positioned along an east-west axis to catch maximum light. A mirrored louver built into the building's south-facing windows will bounce that daylight toward the ceiling, where it should diffuse, creating a natural overhead light that Mr. Macey says will be adequate on all but the darkest days.
It had better be: Though employees will have 10-watt LED lamps on their desks, they will have no way to turn on overhead lights. The building will switch them on automatically when the daylight recedes.
The building, in fact, will control a good deal of the working environment. Some windows will open and close automatically as outdoor air warms and cools throughout the day. Other windows will be left to employees to operate—but the building will ping occupants with reminders, flashing alerts on their laptops (desktops use too much energy) when it is time to open or close particular panes.
Some windows will be shrouded to minimize glare and heat. Others will be coated with a reflective film developed by RavenBrick LLC of Denver. The glass darkens automatically as the temperature rises, so it reflects the sun's heat away from the building while still allowing daylight to penetrate.

"It's a smart building that knows what it needs," says Brian Livingston, a project executive with Haselden Construction.
Culture Shock
It's also an office building without, well, offices.
Putting up walls and ceilings to create individual work spaces impedes the flow of daylight and ventilation. So architects banned the traditional office. They did include a few semi-private rooms with walls that reach about halfway toward the exposed struts and girders that pass for a ceiling. Most employees, however, will work in cubicles with low dividing walls.
The cubicles were engineered to save energy down to the smallest detail; even the phones, for instance, are special models that use 2.8 kilowatt-hours of electricity a month, compared with 10.8 kilowatt-hours for standard models.
The lack of privacy—not to mention the shortage of storage space, since the cubicle walls are too low to hold shelves—has been a bit of a culture shock for NREL employees who reviewed the plans, says John Andary, a principal at Stantec Consulting. "It's hard to get people out of the mindset, 'I need an office with walls up to here,' " he says.
Another striking feature of the NREL building: It will have no central air or heat and no fixed thermostat. The temperature will fluctuate during the day, though it shouldn't go below 68 degrees or above 80.

Temperature is regulated through an age-old concept known as "thermal mass," which involves sheathing the building in concrete panels nearly a foot thick. In summer, the panels will absorb the sun's heat, keeping the interior of the building comfortable, much the way an old stone cathedral remains cool inside even on the warmest days.
In winter, the building relies on thin sheets of perforated metal that hang down south-facing walls. The metal is painted black, so it heats up quickly in the intense Denver sunshine. Air flowing through holes in the hot sheet metal is also warmed. A fan then sucks the warm air into an underground labyrinth—a crawl space crowded with a maze of concrete blocks. The labyrinth stores the warm air until it is needed elsewhere in the building.
A backup system of 42 miles of radiant piping runs through the building's hollow floors, using hot and cold water to keep work space comfortable even in the most extreme weather.
Higher Construction Costs
All of these techniques cost a premium. A run-of-the-mill office tower in Denver costs about $140 per square foot to design and build, according to an analysis by RSMeans, a unit of Reed Construction Data.

The NREL building costs about twice that, almost $280 a square foot unfurnished, according to Haselden Construction. But NREL says its building meets federal guidelines for government construction costs—federal buildings generally cost more because of added safety and security requirements—and is, in fact, no more expensive than a standard government office building that has fewer energy-efficiency features.
Though the building's energy use has been extensively modeled—the computer analysis fills 1,000 gigabytes of storage space—outside experts caution that few projects perform as advertised right off the bat. "It takes a lot of complex massaging," says Scot Horst, a senior vice president at the U.S. Green Building Council.
NREL plans to report on its setbacks, as well as its successes, in scientific journals and presentations to developers, architects and engineers. Office buildings account for 18% of U.S. energy consumption, so any lessons about efficiency learned here could "have a huge impact on our nation's energy security," says Jeffrey Baker, director of the Energy Department's local field office.
The federal government also plans to continue studying—and tweaking—the building's energy use long after construction is complete. "That is critically important," says Bob Fox, a partner at the New York firm Cook + Fox Architects, which focuses on green building. "We need more projects like this to push the envelope."— Ms. Simon is a staff reporter in The Wall Street Journal's Dallas bureau. She can be reached at