Environmental Engineering Reference
In-Depth Information
The IAQ Procedure is, in reality, a program of source control and ventilation
specification, design, and implementation.
iii. Perceived Air Quality Procedure. Ventilation requirements can
also be determined using the Perceived Air Quality (PAQ) Procedure, devel-
oped by Danish engineer/scientist, Ole Fanger. It is based on the premise
that sufficient outdoor air should be provided to reflect the pollution load
of the building and the resultant perceived air quality. The pollution load is
determined from the irritating/discomfort effects of building contaminants
generated by humans, tobacco smoking, and emissions from building mate-
rials on the olfactory and common chemical senses. The two olfactory senses
combine to assess perceived freshness or pleasantness or various degrees of
stale, stuffy, or irritating air.
Perceived Air Quality is expressed in units called decipols. One decipol
is the equivalent of the PAQ in a building space with a pollution strength
of one olf ventilated by 10 L/s (21 CFM) of clean air. Pollutant emissions
from a “standard” person are equal to one olf. Using the standard person
as a reference, other pollution sources are assessed relative to their effects
on PAQ. Olf ratings for sources indicate the number of standard persons
required to make air as unacceptable as their emissions. The effect of venti-
lation on perceived dissatisfaction (rated by a trained panel of judges) can
be seen in Figure 11.13 . These are expressed in L/s/olf (person). Equivalent
values in CFM/person can be approximated by multiplying each L/s/olf
value by a factor of 2. The curve in Figure 11.13 was derived from panel
ratings of the acceptability of bioeffluents from more than 1000 sedentary
men and women.
The PAQ procedure requires quantification of olf values of pollution
sources in building spaces. Olf values from different sources, including peo-
Figure 11.13
Relationship between ventilation rate and dissatisfaction with air qual-
ity. (From Fanger, P.O.,
Proc. 5th Internatl. Conf. Indoor Air Qual. Climate
, 5, 353, 1990.)
 
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