Enclosure Ventilation Airflow Calculator
Estimate ideal airflow needed to remove a sensible heat load while keeping enclosure air below a user-entered target temperature.
Enter heat load and temperatures
Required ventilation airflow
About this calculator
Estimate airflow from an entered sensible heat load and the temperature rise available between ambient air and a maximum enclosure temperature.
Use a heat-load estimate for the actual operating condition and representative ambient temperature.
Method and assumptions
Airflow (CFM) = heat load (BTU/h) ÷ [1.08 × temperature rise (°F)]. Watts are converted to BTU/h before calculation.
The equation assumes ideal mixing and air properties near standard conditions. It does not size a fan against static pressure or account for altitude, filters, recirculation, or enclosure rating.
FAQs
What if ambient air is already warmer than the target?
Ventilation with ambient air cannot cool the enclosure below ambient. This calculator rejects that condition; consider an appropriately rated cooling method.
Does the calculated airflow account for filters or duct losses?
No. It is an ideal heat-balance estimate. Actual fan selection must account for system resistance, filter loading, altitude, and manufacturer performance.
Sources
Use enclosure and fan manufacturer engineering data for airflow performance, environmental limits, and installation derating.