Selecting the correct sizeventilation fanis key to achieving optimal air quality, energy efficiency, and comfort in any space — whether residential, commercial, or industrial.
In this guide,AOSAIRexplainshow to size a ventilation fanstep-by-step, helping you make informed decisions for your next project.
Why Fan Sizing Matters
✅ Ensures adequate air exchange
✅ Maintains indoor air quality (IAQ)
✅ Prevents moisture buildup and mold
✅ Enhances occupant comfort
✅ Reduces energy waste
✅ Helps comply with building codes
Key Concepts: Airflow & Air Changes
✔️ Airflow Rate (CFM / m³/h)
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CFM= Cubic Feet per Minute (used in US)
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m³/h= Cubic Meters per Hour (used in Europe/Asia)
These units measure how much air the fan moves.
✔️ Air Changes Per Hour (ACH)
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ACH refers to how many times the air in a room is replaced per hour.
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Recommended ACH depends onroom type and use(see table below).
Step-by-Step: How to Size a Ventilation Fan
1️⃣ Measure the Room
Forrectangular rooms:
Length × Width × Height = Room Volume
Example:
A 5m × 4m × 2.5m bathroom →
5 × 4 × 2.5 =50 m³
2️⃣ Determine Recommended ACH
| Room Type | Recommended ACH |
|---|---|
| Bathroom | 10–15 |
| Kitchen | 15–30 |
| Office | 6–12 |
| Living room | 6–10 |
| Bedroom | 4–8 |
| Warehouse | 6–20 |
| Workshop | 15–30 |
| Gym / Fitness | 10–20 |
3️⃣ Calculate Required Airflow
4️⃣ Convert Units (if needed)
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To convertm³/h → CFM:
CFM = m³/h ÷ 1.699
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To convertCFM → m³/h:
m³/h = CFM × 1.699
5️⃣ Select a Suitable Fan
Choose aventilation fanrated for at least the required airflow:
✅ Factor in duct losses (add ~10–20%)
✅ Consider noise level requirements
✅ Ensure compatibility with duct size
Practical Tips
✅ Always round up airflow to ensure sufficient ventilation
✅ For long duct runs → select fans with higher static pressure capability
✅ For noise-sensitive spaces → choose low-noise or EC motor fans
✅ For retrofit projects → verify available installation space
Common Mistakes to Avoid
❌ Using undersized fans → poor ventilation, mold risk
❌ Oversizing excessively → noise & energy waste
❌ Ignoring duct layout → airflow loss
❌ Not accounting for special equipment (e.g. in kitchens, workshops)
How AOSAIR Supports Fan Sizing & Selection
AOSAIRassists:
✅ HVAC contractors
✅ Architects and designers
✅ Builders and developers
✅ OEM partners
We provide:
✅ Fan sizing consultation
✅ Technical data sheets
✅ OEM customization
✅ Project-based product recommendations
Need Help Sizing Your Next Ventilation Fan?
👉 Explore ourProducts pageorcontact us here.
Our team can help you:
✅ Select the optimal fan for your space
✅ Customize airflow performance
✅ Ensure compliance with project requirements
Conclusion
Proper fan sizing ensureseffective, efficient, and compliant ventilation— saving you costs and ensuring occupant comfort.
AOSAIRis ready to support your ventilation projects — contact us today for expert guidance!
