In the hills above Berkeley, Cindy Regnier steps into a small office with sweeping views of the bay and urges visitors to watch their feet.

"We are actively testing here," she says, her voice hushed. "Try not to knock over any sensors - please!"

The office looks like any other corporate nest, with nondescript desks and chairs arranged across a well-lit floor. But the desks are empty of papers or people. Instead, a series of slender poles - some knee-high, others reaching to the ceiling - hold instruments that constantly monitor air temperature and light levels. White metal tubes stationed near the desks give off a small amount of heat - the same amount as a human being.

The "office" is really a laboratory, created to help buildings save energy. It is the only facility of its kind in the world. And as California tries to cut the amount of electricity that buildings use, the Flexlab at Lawrence Berkeley National Laboratory could be a game-changer.

"This is about understanding the performance of a building before you spend millions of dollars on it," said Regnier, executive manager of the Flexlab project.

Researchers can easily swap out the lab's heating, air conditioning and lighting - even its windows. They can see how all of those elements perform together, not just one system at a time. A portion of the lab, resting on a concrete turntable that weighs a half-million pounds, can rotate 270 degrees to test how different angles of sunlight affect energy use. The sensors inside ensure that the space stays pleasant for workers, not too hot or too cold.

"We built Flexlab with reconfiguration in mind," Regnier said. "It's like a kit of parts."

Key goal

Slashing the energy use from buildings has become a key goal for both California's government and federal authorities.

The electricity and natural gas needed to keep America's buildings heated in winter, cooled in summer and lit year-round accounts for roughly 40 percent of the nation's greenhouse gas emissions, by most estimates. California this month enacted a tough new set of building codes in response. And by 2030, the state wants all new commercial buildings to produce as much energy - most likely through solar power or fuel cells - as they consume.

"That's a very big challenge," said Andrew McAllister, a member of the California Energy Commission. "The builders and the developers are going to put a lot of money into this stuff, and if they're going to do that, they need some certainty that it's going to work the way it's supposed to and their people are going to be comfortable."

Designed and built with $15.7 million from the U.S. Department of Energy, Flexlab isn't just an academic facility.

Genentech office

The Webcor development company is building a 250,000-square-foot office for biotech giant Genentech in South San Francisco. So Webcor has installed at Flexlab the same ventilation and lighting systems it plans to use for Genentech, as well as the same windows.

Tests will reveal, in detail, how well the systems work together to cut energy use while keeping office workers comfortable.

"Sometimes, energy saving would appear to be in conflict with comfort," said Webcor Vice President Phillip Williams. "Occupants, if they're comfortable, are going to be able to save more energy because they won't be overriding the building controls."

Genentech will incorporate the lessons learned into its next building project, whenever that might be.

Data trove

And that is considered Flexlab's most important feature. Over the years, it will build up a trove of test data that developers and others - including the companies that make heating and lighting systems - can use to refine their work.

"We'll be learning a lot that we can apply to future buildings," said Carla Boragno, Genentech's vice president for site services. "It's not a one-time effort."

©2014 the San Francisco Chronicle