A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION
(OSHA): the regulatory arm of the US Department
o f Labor, which promulgates safety and health
standards, facilitates training programs, and
enforces regulations on worksites. OSHA has developed
permissible exposure limits (PELs) for over 600
contaminants present in the industrial workspace.
OCCUPIED ZONE: The region within an occupied
space between planes 3 and 72 inches (75 and 1800
mm) above the floor and more than 2 feet (600
mm) from the walls or fixed air conditioning equipment
(see ASHRAE Standard 55-1981).
OCTAVE BAND (O.B.): A range of frequency where
the highest frequency of the band is double the
lowest frequency of the band. The band is usually
specified by the center frequency.
ODOR: A quality of gases, vapors, or particles
which stimulates the olfactory organs; typically
unpleasant or objectionable.
ODOR THRESHOLD: the lowest concentration of a
chemical that can be reliably detected by a panel
of untrained observers. Different investigators
for many chemicals have reported variations of
one to four orders of magnitude. This is due to
differences in test methods, such as temperature
and relative humidity control, and reporting methods.
OLF: (From "olfactory") A perceived
air quality term which attempts to quantify a
given pollution load. One person creates 1 olf
of bioeffluents. If there are 10 cubic meters
of floor space per person, then people create
0.1 olf per m² (olf/m²). Other sources
are compared and quantified by olfs. For example,
if 40% of the people smoke, this adds 0.2 olf/m²
to the load.
OMNIVORE: Animal that obtains its nutrients from
both plants and animals.
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OPERATIVE TEMPERATURE (to): The uniform temperature
of a radiantly black enclosure in which an occupant
would exchange the same amount of heat by radiation
plus convection as in the actual non-uniform environment.
Operative temperature is numerically the average,
weighted by respective heat transfer coefficients
(hc and hr), of the air (ta) and mean radiant
to = (hcta + hrtr)/hc+hr)
At air speeds of 80 fpm (0.4 m/s) or less and
tr less than 120 F,(50oC) operative temperature
is approximately the simple average of the air
and mean radiant temperatures and equal to the
adjusted dry bulb temperature.
OPTIMUM OPERATIVE TEMPERATURE: Temperature that
satisfies the greatest possible number of people
at a given clothing and activity level.
OUTDOOR AIR INTAKE: an opening in the building
exterior that is a planned entry point for outdoor
OUTLET, CEILING: A round, square, rectangular,
or linear air diffuser located in the ceiling,
which provides a horizontal distribution pattern
of primary and secondary air over the occupied
zone and induces low velocity secondary air motion
through the occupied zone.
OUTLET, SLOTTED: A long, narrow air distribution
outlet, comprised of deflecting members, located
in the ceiling sidewall, or sill, with an aspect
ratio greater than 10, designed to distribute
supply air in varying directions and planes, and
arranged to promote mixing of primary air and
secondary room air.
OUTLET, VANED: A register or grille equipped
with vertical and/or horizontal adjustable vanes.
OUTLET VELOCITY: The average velocity of air
emerging from the outlet measured in the plane
of the outlet.
OUTPUT: Capacity, duty, performance, net refrigeration
produced by system.
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OUTSIDE AIR OPENING: Any opening used as an entry
for air from outdoors.
OZONE: a highly reactive trivalent form of oxygen.
Ozone exposure can result in mucous membrane irritation
and potential pulmonary damage. The principal
source of indoor ozone is outdoor photochemical
smog, although come copier machines and laser
printers emit noticeable levels.
OZONE GENERATOR: an air cleaning device that
produces highly reactive ozone, which reacts with
volatile organic compounds to form non-hazardous
products and reduces the number of bio-contaminants.
these devices are controversial because their
touted benefits may only be accomplished at ozone
levels above recommended exposure levels.
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