Natural Smoke Ventilation Calculator

Calculate natural smoke ventilation opening size for roof vents per NFPA 204

Input Parameters

Results

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Total Vent Area Required
m2
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Total Vent Area Required
ft2
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Area per Vent
m2
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Smoke Layer Temperature
C
Note: Natural ventilation relies on buoyancy of hot smoke. Effectiveness depends on smoke-ambient temperature differential and smoke layer depth. Provide adequate makeup air inlets at low level. Wind effects can help or hinder natural venting.

Reference

NFPA 204 Natural Ventilation: m_dot = 0.071*Qc^(1/3)*z^(5/3) + 0.0018*Qc dP = rho_amb * g * d * (1 - T_amb/T_smoke) A_vent = m_dot / (Cd * sqrt(2 * rho_smoke * dP)) Cd = 0.7 (typical discharge coefficient)