Indoor Air Quality is
a function of several factors of which temperature is the most
important thermal comfort measurement. It is typically controlled
between 68°F to 70°F and (20°C to 25°C), and sudden
temperature changes can cause discomfort, and indirectly affect
other comfort parameters such as relative humidity. By following
the air temperature for a week, it is possible to follow a building’s
air handling behavior.
Relative Humidity (Rh)
and dewpoint (absolute humidity) measurements verify conditions
are within a comfortable range for occupants. They also provide
data ensuring the environment is not conducive to microbial growth
or verify that laboratories, computer rooms, storage areas, etc.
have acceptable moisture levels. A low % Rh is not an answer to
all IAQ problems since if the % Rh is too low, eye irritation,
skin irritation and respiratory tract problems may arise. Dust
is generally more of a problem in low humidity situations. Most
viruses grow best in low temperature/high humidity conditions.
Formaldehyde emissions also increase when both temperature and
Rh increase. Hence, Rh limits for IAQ purposes are usually specified
as being between 30% and 60%.
The Carbon Dioxide (CO2)
concentration level is an important parameter to measure as it
provides a practical basic indicator of ventilation, and accurately
calculates outdoor air ventilation and air dilution rates. As
a surrogate indicator of air quality, CO2 provides
a natural tracer through the building’s ventilation system.
Carbon Monoxide (CO) levels
provide an indication of improperly ventilated combustion processes
to verify occupants are not at risk from this potentially lethal
specific pollutant. This is particularly important where direct-fired
heat exchangers are used. Mechanical damage or corrosion to the
heat exchanger causes mixing of the combustion gas with the return
air, resulting in a buildup of CO inside the building. Inhalation
of CO is highly toxic even at relatively low concentrations, and
in high concentrations can cause immediate collapse and death.
Any concentration in excess of a few ppm should be investigated.
The IAQ Surveyor instruments
can be used for quick spot-checks, walk-through surveys, or left
to monitor over time; storing days, weeks, or even months of data.