Berkeley library branch a 'zero net energy' building
By: David R. Baker
San Francisco Chronicle
Monday, December 30, 2013
Article Link: http://www.sfgate.com/business/article/Berkeley-library-branch-a-zero-net-energy-5100368.php
Bright light floods the main room of Berkeley's newest library branch. Cool, comfortable air surrounds the stacks.
But listen carefully, and you won't hear the usual whoosh of an air conditioning system trundling in the background. Look carefully during the daytime, and you won't see many switched-on lights.
The new West Berkeley branch of the city's public library system was designed to save energy. Its heating, cooling and lighting systems use so little electricity, in fact, that solar panels on the roof generate more than the building needs.
The branch is a "zero net energy" building, meaning it produces more electricity over the course of a year than it draws from the state's power grid. As such, it's a rarity. While the concept has been around for years, few zero net energy buildings have been built. Berkeley boasts that the $7.5 million branch, which replaced a building dating to 1923, is California's first zero net energy library.
But the state has big plans for such buildings, seeing them as a potent weapon against climate change. California officials have set a nonbinding goal that by 2020, all new residential construction will be zero net energy. The same standard will apply to all new commercial construction by 2030.
"California's clearly staking out some very aggressive goals," said Steve Malnight, vice president of customer energy solutions at Pacific Gas and Electric Co. The utility consults with companies designing zero net energy buildings, including the firm behind the new West Berkeley library branch. PG&E also helped start an annual zero net energy design competition, called Architecture at Zero.
The state's goals are attainable, Malnight said. But getting there will take effort.
"The broad conclusion we've come to is it's feasible for the vast majority of buildings in California, but in the near future," Malnight said. "It's not here today with technologies you can buy off the shelf. But we can see a clear path in that direction."
Almost every element of the West Berkeley library branch was designed to tread lightly on the power grid. Its clean modernist lines hide systems that tap the wind for cooling in summer, while broad windows and long skylights nearly eliminate the need for artificial lighting during the day.
"A lot of care went into this building," said Gerard Lee, an associate with the Harley Ellis Devereaux architecture firm that designed the branch. "Almost everything you see isn't just for looks. It has a specific function."
Often, multiple functions.
The wall of triple-glazed windows facing University Avenue, for example, doesn't just let in light - it also blocks traffic noise far better than would ordinary glass. A front entrance that requires visitors to pass through two sets of doors helps screen out noise while preventing heated or cooled air from escaping.
Removing hot air
The roof features a raised wall on its southern side. Winds blowing off the bay flow over the wall and create a space of negative air pressure just behind it. That negative pressure, in turn, sucks hot air out of the library through a series of large vents behind the southern wall. Lee calls it a "wind chimney."
An automated system linked to sensors opens and closes windows as needed to help manage heat. Pipes embedded in the concrete floor circulate warm water in the winter and cold water in the summer, keeping the rooms comfortable.
"We've relied on forced air for far too long," Lee said recently, on a tour of the building. "It actually gets noisy and uncomfortable. Here the heat travels through the space, as opposed to having pockets of hot air blowing on you."
Banks of solar panels on the roof generate electricity, while a separate solar system heats water. Harley Ellis Devereaux will monitor the building's performance during the coming year to see if the building lives up to its zero net energy promise.
"When we did our initial design models, we showed a net-positive, that this building would actually generate more (energy) than it would use," Lee said. "But once you get people in here, the results can be very different."
'We all really like it'
The building cost about as much per square foot, Lee said, as the Berkeley library system's new South Branch, which opened in May and wasn't designed for zero net energy use. Smaller than the West Berkeley branch, the South Branch cost $6.5 million to build.
So far, the West Berkeley building is drawing favorable reviews from employees and patrons.
"I think we all really like it," said Amanda Myers, supervising librarian at the branch. "I've had, like, 10 patrons come up and say, 'Can we have a tour?' "
David R. Baker is a San Francisco Chronicle staff writer. E-mail: firstname.lastname@example.org Twitter: @DavidBakerSF
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