Smoke Control System Calculator

Calculate smoke exhaust and pressurization requirements per NFPA 92 for atriums, stairwells, and smoke management systems.

System Type

Atrium Floor Area (sq ft)

Atrium Height (ft)

Design Fire Size (Btu/s) Typical sprinklered: 5000 Btu/s; Unsprinklered: 2000-20000 Btu/s

Smoke Layer Height Above Floor (ft) Minimum 6 ft above highest walking surface (NFPA 92)

Sprinkler Protection

Ambient Temperature (F)

System Type	Key Requirement
Atrium Exhaust	Maintain smoke layer 6 ft above floor
Stairwell Press.	0.05" w.c. min, 0.10" max (doors closed)
Elevator Press.	0.04" w.c. min, 0.10" max
Makeup Air	Velocity < 200 fpm at door

Smoke Control Methods

Mechanical exhaust maintains smoke layer above occupants. Makeup air must be provided at low velocity (<200 fpm) to avoid disturbing the plume.

Positive pressure prevents smoke infiltration. Must maintain 0.05" w.c. with doors closed, while limiting door opening force to 30 lbf.