The concept of
indoor air quality (IAQ) is not new. Publications as far back as the
early 1800s discuss the subject and suggest ventilation as the
solution.
These early
writers mostly recommended a minimum of 5 ft3 /min of outdoor air per
person, but later writers increased that number. The present ASHRAE
Standard 62 value is 20 ft3 /min for
normal situations.
Most of this early
work was done in England, where a number of public buildings were
provided with heating and ventilating systems, including the House of
Commons. Centrifugal fans were developed, using small steam engines
for motive power.
Schools were a
prime target for ventilation, and by the early part of the twentieth
century the schoolroom unit ventilator was developed and advertised.
Electric motors were available by then. A three-story elementary
school, built in 1916, included an outdoor air-ventilation system
with a direct current motor-driven supply fan (rheostat control
provided manual variable volume!) and cast iron steam-heating coils
in the ventilation air for winter use.
When the new
science of air cooling came along, the value of introducing outdoor
air through the cooling/heating system was obvious. And, as the
material in the previous parts of this book shows, present technology
allows us to control outdoor air ventilation very accurately.
Negative Effects of Poor Air Quality
Two terms are important: building
related illness (BRI) and sick building syndrome (SDS). BRI relates
to individual illness due to poor IAQ. Much of this relates to
allergens, to which some people are more sensitive than others.
SBS means that many people become sick
in the building environment, and this, of course, causes loss of
production and, perhaps, lawsuits. In addition, there are problems
with odors (including those caused by smoking) and problems with high
or low humidity.
High humidity may allow mold growth and
deterioration of the building or furnishings. Excessive air movement
(drafts) is a common complaint. When people are sick or complaining,
they are not producing.
Positive Effects of Air Quality
Many studies have shown an increase in
productivity of 10 percent or more, when the air quality and other
environmental factors are optimized, and there is less time off for
sickness and fewer complaints.
Housekeeping and cleaning are made
easier and less expensive. Thus, good IAQ is economically
advantageous, and it improves the morale of the people who work and
live in the building.
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