Indoor building environment has significant impact on cognitive function: Study

Improved indoor environmental quality doubled employees' scores on cognitive function tests, according to a new study. The Impact of Green Buildings on Cognitive Function study found that employees' cognitive performance scores averaged 101 per cent higher in green building environments with enhanced ventilation compared to a conventional building environment.

"When it comes to the decision-making ability of green building occupants, intelligence is in the air," said John Mandyck, sustainability officer for United Technologies, the company that supported the study. "We know green buildings conserve natural resources, minimize environmental impacts and improve the indoor environment, but these results show they can also become important human resource tools for all indoor environments where cognitive abilities are critical to productivity, learning and safety."

The double-blind study evaluated the cognitive performance of 24 participants who experienced conditions in a laboratory setting that simulate those found in conventional and green buildings, as well as green buildings with enhanced ventilation. Researchers measured cognitive function for nine functional domains, including basic, applied and focused activity levels; task orientation; crisis response; information seeking; information usage; breadth of approach; and strategy.

The largest improvements in cognitive function test scores occurred in the areas of crisis response, information usage and strategy.

Crisis response scores were 97 per cent higher for the green environment and 131 per cent higher for the green environment with enhanced ventilation and lower carbon dioxide levels compared to the conventional environment.

Information usage scores for green and enhanced green environments were 172 and 299 per cent higher than in the conventional environment, respectively.

For strategy, green and enhanced green scores were 183 and 288 per cent higher than the conventional environment.

The results are provocative for three reasons, said Joseph Allen of Harvard's School of Public Health and principal investigator for the study.

First, they suggest that the levels of carbon dioxide and volatile organic compounds that are commonly encountered in conventional office buildings are associated with decreases in worker performance compared to when those same workers are in green building environments.

Second, when ventilation is enhanced and indoor environmental conditions optimized, there are improvements in the cognitive function of workers.

And third, these results fill important knowledge gaps in existing research about the relationship between green buildings and occupant health.

The study was conducted in an environmentally controlled lab at the Syracuse Center of Excellence in Environmental and Energy Systems in Syracuse, N.Y., and took place over the course of six workdays spread across a two-week period.

"Participants spent each day during the test period conducting their normal work activities in indoor environments that are encountered every day by large numbers of workers," said Suresh Santanam, associate professor of biomedical and chemical engineering at Syracuse University and study co-investigator.

At the end of each six-hour workday, participants completed a 1.5 hour cognitive assessment using a well-validated, computer-based cognitive assessment test.