Airtight Buildings: Are We Trading Energy Conservation For Cognitive Impairment?

In an effort to conserve energy, buildings have become more airtight: Cracks are sealed, weather stripping applied and much effort is maintained to use heating and cooling systems most efficiently. New research published in Environmental Health Perspectives claims that the airtight buildings have a negative effect on our cognitive abilities. Reportedly, when people work in well-ventilated offices with below-average levels of indoor air pollution and carbon dioxide, their cognitive ability is significantly increased.

A team of scientists from the Harvard T.H. Chan School of Public Health, led by Prof. Joseph Allen, say that indoor working environments found in airtight buildings adversely affects cognitive functioning and that when the air inside buildings is fresher, cognitive ability of workers is significantly increased. Energy-efficient building design has been progressing since the 1970s and buildings have become more airtight, but this leads to the potential of indoor air pollution. In the 1970s, air exchange rates in homes happened at approximately one air change per hour. New homes experience between 0.1-0.2 air changes per hour. During the early 1980s, after people were experiencing “sick building syndrome,” which included poor health attributed to indoor environment factors like humidity, ventilation rate, and chemical-emitting materials, builders started working on green design, which included ventilation and filtration of chemicals and pollutants while still focusing on energy efficiency. These buildings strive to lower nitrogen dioxide, volatile organic compounds (VOCs), and allergens, but carbon dioxide and air exchange rates have never been top priority in these green building designs.

VOCs, the research indicates, definitively are associated with lowered cognitive scores. Interestingly though, greater levels of carbon dioxide found in airtight buildings are also associated with lowered cognitive scores. So, while cognitive functioning is improved in green building designs where air pollution is lowered, it can be improved even more if the air is ventilated more to reduce carbon dioxide levels. The greatest improvements were seen in crisis response, information usage, and strategy skills like planning, prioritizing, and sequencing.

Indoor pollution in airtight buildings really can reduce cognitive ability, the researchers say. In airtight buildings, VOCs are most often found from pesticides, paints, fabric conditioners, cleaners, and air fresheners. These compounds in airtight buildings can cause headaches, respiratory infections, nervous system problems, liver and kidney damage and even cancer, according to Medical News Today.

The research was a double-blind study, in which participants performed standard work activities three days a week, during normal office hours for two weeks. They were randomly assigned cubicles in one of two almost identical environments. Near the end of every day, the workers performed cognitive tests by using Strategic Management Simulation (SMS) software designed to assess nine cognitive areas. The green building environments that also improved ventilation doubled the cognitive scores of conventional buildings, while the typical green building environments that would simulate an airtight building were only 61 percent higher than conventional buildings, the researchers said. In ventilated green building environments, information usage and strategy were nearly tripled over conventional buildings while just under doubled over conventional building when the green improvements didn’t also include attempts to increase ventilation.

Carbon dioxide isn’t normally considered an indoor air pollutant, but higher levels found in airtight buildings that approached 950 ppm, levels considered acceptable and typical of indoor air conditions resulted in decreased scores in seven out of nine of the cognitive tests. Interestingly, in Texas classrooms where students breathes in carbon dioxide over 1000 ppm, more absences were recorded, according to Medical News Today. The Harvard scientists said this research indicates we should investigate the air quality within homes, schools, airplanes, and other buildings where decision-making and other cognitive functioning areas would have significant impacts on people’s learning and safety. Prof. Allen explained the implications in a press release.

“We spend 90% of our time indoors and 90% of the cost of a building are the occupants, yet indoor environmental quality and its impact on health and productivity are often an afterthought. These results suggest that even modest improvements to indoor environmental quality may have a profound impact on the decision-making performance of workers.”

“The major significance of this finding lies in the fact that these are the critical decision making parameters that are linked to optimal and productive functioning. Losing components of these skills impacts how people handle their day to day lives,” Prof. Usha Satish, of the Department of Psychiatry at SUNY Upstate Medical University, explained.

Improved air quality in buildings that would be airtight for efficiency would greatly increase the cognitive function performance of students and workers, the research indicates.

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