Ventilation-limited minimum supply fraction calculator

Minimum supply-to-design flow fraction is calculated as V_OA_required / (f_OA × V_design). Use the stated system boundary and matching input units.

Units

f_{\text{min}} = \frac{V_{\text{OA required}}}{f_{\text{OA}} \times V_{\text{design}}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

f_{\text{min}} = \frac{300}{0.25 \times 2000} = 0.6

Symbol	Meaning	Unit
$f_{\text{min}}$	minimum supply-to-design flow fraction	—
$V_{\text{OA required}}$	required delivered outdoor airflow	cfm
$f_{\text{OA}}$	constant outdoor fraction within well-mixed supply	—
$V_{\text{design}}$	design maximum supply	cfm

Symbol	Meaning	Unit
$f_{\text{min}}$	minimum supply-to-design flow fraction	—
$V_{\text{OA required}}$	required delivered outdoor airflow	L/s
$f_{\text{OA}}$	constant outdoor fraction within well-mixed supply	—
$V_{\text{design}}$	design maximum supply	L/s

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.