Application Note

3 Fluke Corporation Indoor air quality: Can your schools pass the test?
investigation shows the
unvented attic space above is
140 degrees. In winter, cold
walls and window surfaces
can have just the opposite
effect—occupants feel cold in
spite of air temperatures in the
comfort zone.
•
Cleanliness. “Typically in
schools the cleaning is based
on appearance, not on health,”
Prill says. “If it looks clean,
good enough. But we find that
carpets that look clean can
contain huge amounts of parti-
cles. Many of these particles
are allergy and asthma trig-
gers. So how do the custodi-
ans or janitorial staff keep
abreast of quality control? Are
you spending the time, money
and equipment where you
need to?
“By having some kind of a
particle measurement you can
look at various areas and sa
y,
“Gee, how c
ome this w
ing of
the building has ten times
more particles than the other
w
ing?” It c
ould b
e that one
custodian is not doing as good
a job, or his/her vacuum equip
-
ment isn
’t work
ing
. Maybe the
kids are tracking in too much
dirt from the pla
yg
round
. Mea
-
surement is just a wa
y to get a
handle on reality.”
Prill uses a laser particle
c
ounter to get real time c
ounts
of the number and size of
particles present and track
dow
n their sourc
e. Instead of
assuming high particle counts
are caused by dirty ductwork,
and spending thousands on
cleaning, Prill advises schools
Benchmarks
Both the walk-around inspection
and the subsequent IAQ manage-
ment program are focused on
five basic benchmarks of indoor
environmental quality.
•
Moisture. In addition to open-
ing the way for mold growth,
excess moisture can cause
unsightly stains and even
structural damage. “Add water
and you’ve got mold,” Prill
says. “If you’ve got any water
leaks, which most buildings
do, you need to address that
immediately. The “best” water
leak is one that is small
enough it doesn’t cause exten-
sive damage and big enough
that you find it in time. So we
suggest moisture meters to
locate wet materials. Bigger
districts can probably benefit
from a thermal imaging device
that
’s sensitive enough to
show the temperature differ-
enc
e b
etween wet materials
and dr
y materials
. That’s a
good way to find hidden mois-
ture, and track dow
n the
sourc
e of a leak
.”
•
Comfort. The right combina-
tion of temperature and rela-
tive humidity is essential, but
comfort is what people feel,
not what a thermometer or
humidity tester say it is. Prill
uses an infrared thermometer
to measure surface tempera-
tures and spot problems. A
room thermostat might read
72 degrees Fahrenheit, but
occupants feel hot. The
infrared thermometer reveals
that the ceiling surface may be
is 85 degrees, and further
to count the particles in air
from supply ducts. If the supply
air is cleaner than room air,
the HVAC system is likely not
the problem.
•
Ventilation. A key job for the
HVAC system is removing stale
or polluted inside air and
replacing it with cleaner out-
side air. ANSI/ASHRAE Stan-
dard 62-2001,
Ventilation for
Acceptable Indoor Air Quality
,
calls for 15 cubic feet per
minute of outside air supply for
each student
. Inadequate sup-
ply can allow levels of carbon
dioxide to climb above the
ASHRAE guideline of 1,000
parts per million (ppm). Excess
CO2 also suggests that other
pollutants and particulates are
also accumulating. The CO2
meter makes it easy to rou-
tinely tour the various zones
and note whether the proper
amount of outside air is being
supplied. CO2 measurement
also identifies over-ventilation
of zones. Over-ventilation can
waste energy, increase wear
and tear on equipment, and
create comfort problems.
Another significant benefit is
that the occupants can see for
themselves that they are get-
ting the fresh air they deserve.
The CO2 meter, particle
c
ounter and infrared ther
-
mometer help keep a check on
the cleanliness and tempera-
ture of air coming into the
room. An airflow capture hood
determines supply air volume.
•
Pollutant control. Point
sourc
es of pollutants must b
e
identified and controlled and
in general, air should flow
from clean to dirty
. That means
air moves from the hallway
into and through the restroom
to b
e vented outside. Air
moves into the chemistry lab
and storage areas 24/7 to
protect oc
cupants in adjac
ent
spaces in case of a mistake,
leak or spill. Prill uses a chem-
ical trac
er smoke to track the
direction of airflow, and carries
a carbon monoxide tester to
check for the presenc
e of
dangerous combustion gases.
Infrared thermometers are a c
onvenient way to check for temperature differences
along pipes that could indicate a moisture leak.