Soaking up the sun to squeeze bills to zero

Meanwhile,the photovoltaic roof array was beating a retreat in the fading,low-angled light. It had until 1:35 p.m. been producing more electricity than the building could use—a three-hour energy budget surplus— interrupted only around noon by a passing cloud formation. For Duffield,62,it was just another day in what was designed,to be the largest net-zero energy office building in the nation. He’s still adjusting,six months after he and 800 engineers and managers and support staff from the National Renewable Energy Lab moved in to the $64 million building,which the federal agency has offered up as a template for how to do affordable,super-energy-efficient construction. The energy lab’s Research Support Facility building is more like a mirror,or perhaps a sponge,to its surroundings.

This is the story of one randomly selected day in the still-new building’s life: January 28,2011.It was mostly sunny. The sun rose at 7:12 a.m. The photovoltaic panels kicked in with electricity at 7:20 a.m. As employees began arriving,electricity use—from cellphone chargers to elevators began to increase. Total demand,including the 65-watt maximum budget per workspace for all uses,lighting to computing,peaked at 9:40 a.m.

Meanwhile,the basement data center,which handles processing needs for the 300-acre campus,was in full swing,peaking in electricity use at 10:10 a.m.,as e-mail and research spreadsheets began firing through the circuitry. The data center is the biggest energy user in the complex,but also one of its biggest producers of heat,which is captured and used to warm the rest of the building. There is no giant,expensive solar array that could mask a multitude of traditional designs but rather a rethinking of everything,down to the smallest elements,all aligned in a watt-by-watt march toward a new kind of building. “It’s all doable technology,” said Jeffrey M. Baker,the director of laboratory operations at the Department of Energy’s Golden field office.

People print less paper when they share a central printer that requires a walk to the copy room. Rethinking work shifts can also contribute. Here,the custodial staff comes in at 5 p.m.,two or three hours earlier than in most traditional office buildings,saving on the use of lights. At 5:05 p.m.,the solar cells stopped producing. Declining daylight in turn produced a brief spike in lighting use,at 5:55 p.m. Five minutes later,the building management system began shutting off lights in a rolling two-hour cycle

Duffield,whose work space is surrounded by a miniature greenhouse of plants he has brought,said his desk has become a regular stop on the group tours. If the building is a living experiment,he said,then his garden is the experiment within the experiment. Co-workers stop by,joking in geek-speak about his plants,but also checking up on them as a measure of building health. “They refer to this as the building’s carbon sink,” he said. And Duffield’s babies—amaryllis,African violet,a pink trum—are very happy with all the refracted,reflected light they get,he said.KIRK JOHNSON