Air Flow Calculation for Ventilation

Air Flow Formula:

\[ Q_{cfm} = \frac{V_{room} \times ACH}{60} \]

Air Flow (CFM):

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1. What is Air Flow Calculation for Ventilation?

Definition: This calculator determines the required ventilation air flow in cubic feet per minute (CFM) based on room volume and desired air changes per hour.

Purpose: It helps HVAC professionals, engineers, and building designers ensure proper ventilation for indoor air quality.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q_{cfm} = \frac{V_{room} \times ACH}{60} \]

Where:

\( Q_{cfm} \) — Air flow rate (cubic feet per minute)
\( V_{room} \) — Room volume (cubic feet)
\( ACH \) — Air changes per hour

Explanation: The formula converts air changes per hour to air flow rate by accounting for the 60 minutes in an hour.

3. Importance of Proper Ventilation

Details: Adequate ventilation removes contaminants, controls humidity, and provides fresh air for occupant health and comfort.

4. Using the Calculator

Tips: Enter the room volume in cubic feet and desired air changes per hour (default 6 ACH for general ventilation). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ACH values?
A: General spaces: 4-6 ACH, Kitchens: 7-8 ACH, Bathrooms: 8-10 ACH, Laboratories: 10-12 ACH.

Q2: How do I calculate room volume?
A: Multiply room length × width × height (all in feet).

Q3: Does this account for occupancy?
A: No, for occupied spaces, also consider ASHRAE Standard 62.1's cfm-per-person requirements.

Q4: What about ductwork losses?
A: This calculates ideal flow. Add 10-20% for system losses in real-world applications.

Q5: How does this relate to fan selection?
A: The calculated CFM helps select appropriately sized ventilation fans or HVAC equipment.