by Ty Newell
Our wine was being sent back for the third time in the 5-star restaurant located on Istanbul’s busy Taksim Square. Ole Fanger and I had been invited to give keynote addresses at the Turkish ASHRAE society’s annual meeting, and we were being treated to some of the most delicious cuisine in the world. Our hosts and I let Ole know that he would not be sending the wine back for a fourth time. Fortunately, his pocket thermometer finally registered a temperature within his palate’s acceptance range.
Professor Fanger’s wine temperature precision was a reflection of his carefully crafted experiments that defines our modern concepts of indoor air quality and comfort. Ole Fanger was a pioneer, working at the interface of human sensory perception and building science decades before others realized the economic significance of being a bit chilly or warm, and the importance of maintaining fresh air within buildings.
Ole’s address to the Turkish ASHRAE society presented his latest results showing that human productivity can be degraded by air quality that humans find satisfactory. He described tests in which office workers were unknowingly, periodically exposed to a bundle of used carpeting and drapes. Surveys showed that the workers could not detect any odors or change in air quality, but his data showed significant changes in productivity. What our noses can’t smell can degrade our ability to think! Ironically, Ole’s presentation was in a heavily carpeted and draped auditorium with several smokers in the audience.
Professor Fanger was a faculty member at the Technical University of Denmark, an institution that continues to be a leading institution studying human-environment interactions. He gave us the “olf” (olfactory unit) and the “decipol”, a unit of air flow. Ole’s research showed us that one cannot quantify air quality by simply adding up all of the chemical components in our air, but instead, must use human sensory perception to help guide us.
The olf is the smell of a sedentary (office work activity), recently showered, average-size human who is wearing clean underwear and clothing, and in a comfortable room with one decipol of air flow (10 liters per second or 20 cubic feet per minute per person). Someone who smokes, who is exercising, or doesn’t shower often may produce 3 or more olfs at one decipol. At an olfactory level of 1 olf, 80 percent of us are not dissatisfied with the air quality. We may not think the air quality is good, but for the most part, we don’t complain about it. And this odor-based sensing is the origin of today’s ventilation standards.
To make the olf and a decipol more understandable, 40 pounds of air are inhaled into our lungs each day. At one decipol, 2000 pounds of air must flow through a building for each human in order to keep the air quality at one olf. Recent research, including one of Professor Fanger’s last publications (“What is IAQ,” Indoor Air, 2006, pp328-334, P. Ole Fanger), shows us that we need to double our current ventilation rates to a level that is beyond human olfactory sensitivity in order to reduce a mental degradation caused by both carbon dioxide from our respiration and a soup of VOCs (Volatile Organic Compounds) that surrounds us in buildings.
Professor Fanger, thank you for your insight and for providing a path to improve our health and comfort!
