1. What is AHU CFM Calculation?

The AHU (Air Handling Unit) CFM calculation determines the required cubic feet per minute of air flow needed for proper ventilation in a space. It's essential for HVAC system design and ensuring adequate air changes for indoor air quality.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( Area \) — Floor area in square feet (sq ft)
• \( Ceiling\ Height \) — Height from floor to ceiling in feet (ft)
• \( ACH \) — Air changes per hour (recommended for the space type)

Explanation: The formula calculates the volume of air that needs to be moved each minute to achieve the desired number of complete air changes per hour in the space.

3. Importance of CFM Calculation

Details: Proper CFM calculation is crucial for designing efficient HVAC systems, ensuring adequate ventilation, maintaining indoor air quality, and meeting building code requirements for various space types.

4. Using the Calculator

Tips: Enter the floor area in square feet, ceiling height in feet, and the required air changes per hour (ACH) for your specific application. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ACH values for different spaces?
A: Residential spaces: 4-6 ACH, offices: 6-8 ACH, hospitals: 12-15 ACH, laboratories: 15-20 ACH. Specific requirements vary by building codes and space usage.

Q2: Why divide by 60 in the formula?
A: The division by 60 converts the hourly air volume requirement (cubic feet per hour) to the required minute rate (cubic feet per minute).

Q3: How does ceiling height affect CFM requirements?
A: Higher ceilings increase the total volume of the space, requiring more CFM to achieve the same number of air changes per hour.

Q4: What factors influence ACH requirements?
A: Occupancy density, activity level, pollutant sources, building codes, and specific space用途 (kitchen, bathroom, bedroom, etc.) all influence ACH requirements.

Q5: Is this calculation sufficient for complete HVAC design?
A: While CFM calculation is fundamental, complete HVAC design also considers heat load calculations, duct sizing, static pressure, and equipment selection.