D. Faulkner et al., INDOOR AIR-FLOW AND POLLUTANT REMOVAL IN A ROOM WITH FLOOR-BASED TASKVENTILATION - RESULTS OF ADDITIONAL EXPERIMENTS, Building and environment, 30(3), 1995, pp. 323-332
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Categorie Soggetti
Construcion & Building Technology","Engineering, Environmental
A laboratory-based study of the performance of a floor-based task vent
ilation system designed for use in office buildings has been completed
. With the task ventilation system, occupants can adjust the flow rare
and direction of air supplied to their work space through floor-mount
ed supply grilles. Air exits the ventilated space through a ceiling-mo
unted return grille. To study indoor airflow patterns, the age of air
at multiple indoor locations was measured using the tracer gas step-up
procedure. To study the intra-room transport of tobacco smoke particl
es, cigarettes were smoked mechanically in one workstation and particl
e concentrations were measured at multiple indoor locations. Test vari
ables included supply flow rates, temperatures, supply directions, and
internal heat loads. Multiple floor supply units were in operation si
multaneously. During all tests, the ventilation system supplied 100% o
utside air. Our major findings are as follows. (1) Deviations from a u
niform age of air, and a uniform particle concentration, were generall
y less than 30%. (2) With two floor-supply units operating and supply
air directed toward the occupant, the age of air in the breathing zone
was about 20-40% less than the age of air that would occur in the roo
m if the air was perfectly mixed. (3) With two floor-supply units oper
ating, the air appears to travel from the floor to the ceiling in a pi
ston-like flow pattern. (4) With three floor-supply units operating, a
two-zone flow pattern, with a piston-like flow in the lower region of
the room and mixing in the upper region, was evident at some operatin
g conditions. (5) A strong (r(2) = 0.81) correlation was found between
the rate of change in the average age of air with height and two fact
ors hypothesized to be determinants of the indoor airflow pattern. (6)
Workstations without a cigarette smoking machine and with an operatin
g task ventilation system were not significantly protected from tobacc
o smoke in an adjacent workstation.