A small Harvard study found people performed significantly better on cognitive tests when in green building conditions. The Impact of Green Buildings on Cognitive Function
Green design gets a lot of attention for its energy- and money-saving aspects, but determining the buildings impacts on health isn’t always easy to quantify. But a team of researchers from Harvard, Syracuse University, and SUNY Upstate Medical Center conducted a study to help shed light on how the built environment can change our ability to think.
The team recruited 24 participants to work for six days in an environmentally-controlled space in the lab. Over those six days, the researchers changed the air quality to mimic three scenarios: a typical office building, a green office building, and a green office building with enhanced ventilation. These air states were achieved by increasing or decreasing the amount of volatile organic compounds (VOCs) and CO2 in the air, as well as the amount of outdoor-quality air per person.
The human guinea pigs were never told what kind of air they were getting, and at the end of every day they were given a test that measures cognitive function.
On average, cognitive performance was 61 percent higher in the green-building condition and 101 percent higher in the green-building-with-enhanced-ventilation condition. The amount of VOCs, CO2, and ventilation all had independent affects on how workers thought.
“Because this study was designed to reflect indoor environments encountered by large numbers of people every day, these findings have far ranging implications for worker productivity, student learning, and safety,” says the study. “Green building design that optimizes employee productivity and energy usage will require adopting energy efficient systems and informed operating practices to maximize the benefit to human health while minimizing energy consumption.”
The indoor built environment plays a critical role in our overall well-being. We spend about 90 percent of our time indoors, and buildings have a unique ability to positively or negatively influence our health. This study was designed to simulate indoor environmental quality conditions in green and conventional buildings and evaluate the impacts on an objective measure of human performance cognitive function.
With a gift from United Technologies, the Harvard T.H. Chan School of Public Health’s Center for Health and the Global Environment worked with leading academic research institutions:
Harvard T.H. Chan School of Public Health
- Joseph G. Allen, DSc, MPH, Principal Investigator, Assistant Professor of Exposure Assessment Science
- John D. Spengler, Ph.D., Co-Principal Investigator, Akira Yamaguchi Professor of Environmental Health and Human Habitation
Syracuse University Center of Excellence The Total Indoor Environmental Quality Laboratory (TIEQ)
- Suresh Santanam, ScD, PE, Co-Investigator, Director, Industrial Assessment Center, Associate Professor, Biomedical and Chemical Engineering
SUNY Upstate Medical School
- Usha Satish, PhD, Director, Strategic Management Simulations Institute for Human Performance
Twenty-four participants spent six full work days in an environmentally-controlled office space at the TIEQ lab at the Syracuse Center of Excellence. They were exposed to conditions representative of conventional and green office buildings in the U.S., as well as green buildings with enhanced ventilation:
- Conventional: typical (~500 ppm) volatile organic compound (VOC) levels and 20 cfm outdoor air per person
- Green: VOC levels reduced to approximately 50 1/4g/m3 and 20 cfm outdoor air per person
- Green with enhanced ventilation: VOC levels reduced to approximately 50 1/4g/m3 and 40 cfm outdoor air per person
Researchers also artificially elevated CO2 levels independent of ventilation. Participants were blinded to indoor environmental quality status each day.
At the end of each day, participants were administered a cognitive test using the Strategic Management Software Executive Decision tool, which tests live decision making performance by simulating real-world scenarios. It has been used by more than 70,000 participants worldwide over the last six decades.
This validated method enabled us to understand any changes in cognitive function that might be attributable to building design features.
Cognitive function scores were better in green building conditions compared to the Conventional building conditions across nine functional domains, including crisis response, strategy, and focused activity level.
On average, cognitive scores were:
- 61 percent higher in green building conditions
- 101 percent higher in enhanced green building conditions
CO2, VOCs, and ventilation rate all had significant, independent impacts on cognitive function.
Because this study was designed to reflect indoor environments encountered by large numbers of people every day, these findings have far ranging implications for worker productivity, student learning, and safety.
Green building design that optimizes employee productivity and energy usage will require adopting energy efficient systems and informed operating practices to maximize the benefit to human health while minimizing energy consumption.
Learn More and Connect
Join the conversation on Twitter using #TheCOGfxStudy
Joseph G. Allen
via Harvard School of Public Health