Atrium
F-1 Atrium Requirements
a) In order for an atrium to be permitted in buildings, the following shall be complied:
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Atrium shall be permitted in buildings of Type 1 and Type 2 construction only.
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The use of combustible furnishings and decorations on the floor of the atrium shall be limited and sparsely distributed.
b) Smoke detectors shall be provided on the underside of each floor protruding into the atrium, at the atrium roof and adjacent to each return air intake from the atrium. Within atrium space, beam type or aspirating type smoke detectors shall be used to ensure detection of smoke, considering factors such as stratification of smoke.
c) Where the ceiling of the atrium is more than 17 m above the floor, water based protection (automatic sprinklers) at the ceiling of atrium is not required.
d) Hydrants shall be available at the floor of
the atrium and also at the adjoining upper spaces/floors of the atrium.
Sprinklers are required to be installed for coverage of glass areas of retail, tenant and other areas adjoining the exit access corridor and atrium. Sprinklers shall be at a distance of 450 mm to 600 mm enabling cooling of such glass and limiting the extent of fire and smoke to the atrium (see Fig. 16). This provision does not allow similar sprinkler installation arrangement to offset fire compartmentation requirements, in which case fire barrier is required as per relevant provisions of this Part.
Atrium in business occupancy shall be planned with 6 air changes per hour (ACPH) while atrium in hotels and assembly occupancy shall be planned with 8 ACPH smoke extraction system.
Such air changes shall be planned in atrium for a height of from the top.
f) Smoke exhaust fans shall be capable of operating effectively at C for 120 min.
PART 4 FIRE AND LIFE SAFETY
FIG. 16 SPRINKLER PROTECTION OF GLASS FOR FLOOR OPEN TO ATRIUM
g) Makeup air supply points shall be located beneath the smoke layer and on the lower levels connected by the atrium.
h) Makeup air shall be provided by fans, openings to outside to allow infiltration, or the combination thereof.
j) It is recommended that makeup air be designed at 85 percent to 95 percent of the exhaust flow rate, not including the leakage through these small paths.
k) The makeup air shall not cause door-opening force to exceed allowable limits.
m) The makeup air velocity shall not exceed where the makeup air could come
into contact with the plume unless a higher makeup air velocity is supported by engineering analysis.
n) Atrium smoke management system fans shall be provided with emergency power.
p) If so required by the Authority, an engineering analysis should be performed which demonstrates that the smoke system for the atrium is designed to keep the smoke layer interface 1 800 mm above the highest occupied floor level of exit access, open to the atrium, for a period equal to 1.5 times the calculated egress time or 20 min, whichever is greater.