1. What is Exhaust Fan Air Flow Calculation?

The Exhaust Fan Air Flow Calculation determines the required cubic feet per minute (CFM) of air movement needed for proper ventilation in a space. This calculation is essential for selecting appropriately sized exhaust fans for bathrooms, kitchens, workshops, and other enclosed areas.

2. How Does the Calculator Work?

The calculator uses the exhaust fan sizing formula:

Where:

• \( CFM \) — Cubic Feet per Minute (air flow rate)
• \( Room\ Volume \) — Volume of the room in cubic feet
• \( ACH \) — Air Changes Per Hour (recommended ventilation rate)

Explanation: The formula converts the hourly air change requirement into the minute-based CFM rating needed for exhaust fan selection.

3. Importance of Proper Ventilation Sizing

Details: Correctly sized exhaust fans ensure adequate air exchange to remove moisture, odors, and contaminants while maintaining energy efficiency. Oversized fans waste energy, while undersized fans fail to provide sufficient ventilation.

4. Using the Calculator

Tips: Calculate room volume by multiplying length × width × height in feet. Common ACH values: bathrooms 8-10, kitchens 15-20, workshops 6-8, living areas 4-6 changes per hour.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ACH values for different rooms?
A: Bathrooms: 8-10 ACH, Kitchens: 15-20 ACH, Workshops: 6-8 ACH, Living Areas: 4-6 ACH, Garages: 6-8 ACH.

Q2: How do I calculate room volume?
A: Measure length, width, and height in feet and multiply: Volume = Length × Width × Height (all in feet).

Q3: What if my room has irregular shape?
A: For irregular rooms, divide into regular shapes, calculate each volume separately, then sum them for total volume.

Q4: Should I add safety factor to the calculation?
A: Yes, adding 10-20% safety factor is recommended to account for duct resistance and future conditions.

Q5: What about noise considerations?
A: Look for fans with low sones rating (1-3 sones for quiet operation) while maintaining required CFM.