It’s long been postulated by developers, building managers and sustainability consultants, but now there’s some research to back it up: Employees who work in “green” buildings are more productive than those who work in non-green buildings, says a study by the University of San Diego’s Burnham-Moores Center for Real Estate and CB Richard Ellis.

Findings from the report will be presented at a session on Friday morning at Greenbuild 2009, being held in Phoenix. And the study will be the first of many, says Norm G. Miller, a professor and director of academic programs at the University of San Diego, and a co-author of the report. “We will start repeating it every year,” Miller tells GlobeSt.com. “We still have a lot to learn.”

A 2003 study conducted by another institution surveyed just 2003 buildings. Miller and David Pogue, national director of sustainability at CBRE, surveyed 154 green buildings nationwide–defined as LEED-certified at any level or bearing the Energy Star Label– containing over 2,000 tenants, 534 of which participated in the study. Productivity was defined by two criteria: number of sick days and respondents’ reports of productivity changes after moving to a new building.

Of the respondents, 12% strongly agreed that employees are more productive, 42.5% said that employees are more productive, and 45% suggest no change. In addition, 45% agreed said workers were taking fewer sick days since moving to a green building, while 45% reported no change, with the remainder reporting more sick days. For tenants who did report greater productivity, it rose 4.88%, with an average value-add per worker of $5,204. Those reporting fewer sick days averaged a 2.88% productivity increase, for a value-add of $1,228.54.

“Healthier buildings reduce sick time and increase productivity,” the report says. “The steps required to provide a healthier building are not that much of a design and engineering challenge. Generally natural light, good ventilation and the absence of organic compounds ensure happier, healthier workers.”

However, creating a truly “green” office to properly measure productivity isn’t as easy as it might seem, he notes. New buildings, the study said, often had polluting chemicals from concrete, paint or carpeting.

“You can have a green building but [the tenant will] fill it with particle board, and that will still make you sick,” Miller says.

Other surprises were not related to productivity, but were significant nonetheless. Separate metering works: A separately metered building, where tenants pay for what they consume, will have lower energy costs by 21% on average even if the Energy Star score is the same.

“When people know what they’re spending, then they’ll save,” Miller says.

Other results from the survey indicated that green buildings’ vacancy were slightly lower–16.6% for sustainable structures versus 17.2% nationally–while rents are somewhat higher–$30.54 per square foot versus $27.00 per square foot nationally.

“Our results continue to support the notion of green paying off,” the reports stays. “We observe higher similar occupancy rates with higher rents. This more than offsets, on a present value basis, any reasonable cost premiums expected for either developing greener buildings or converting existing buildings and spaces into better workplaces.”