1. What is the Exhaust Fan Calculation Formula?

The Exhaust Fan Calculation Formula determines the required cubic feet per minute (CFM) of airflow needed to properly ventilate a space based on room volume and desired air changes per hour (ACH). This is essential for maintaining indoor air quality and removing contaminants.

2. How Does the Calculator Work?

The calculator uses the exhaust fan formula:

Where:

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

Explanation: The formula converts the hourly air change requirement into a minute-based airflow rate, which is the standard measurement for exhaust fan capacity.

3. Importance of Proper Ventilation

Details: Proper ventilation is crucial for removing odors, moisture, pollutants, and maintaining healthy indoor air quality. Inadequate ventilation can lead to mold growth, poor air quality, and health issues.

4. Using the Calculator

Tips: Enter room volume in cubic feet and desired air changes per hour. Common ACH values range from 4-8 for general rooms, 8-12 for kitchens, and 10-15 for bathrooms.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ACH values for different rooms?
A: Living rooms: 4-6 ACH, Kitchens: 8-12 ACH, Bathrooms: 10-15 ACH, Workshops: 15-20 ACH.

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

Q3: What if my room has irregular shape?
A: Calculate volume by dividing into regular shapes or use average dimensions for approximation.

Q4: Should I oversize the exhaust fan?
A: It's generally recommended to select a fan with 10-20% higher CFM than calculated to account for duct losses and ensure adequate performance.

Q5: What factors affect actual CFM requirements?
A: Duct length, number of bends, filter resistance, and static pressure can all reduce actual airflow, requiring higher CFM ratings.