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Air Change per Hour Calculator
Quickly determine the air change rate for any space. Enter room dimensions and ventilation details to get accurate ACH values for optimal airflow and energy efficiency.
Calculate the airflow (CFM) required for your space based on industry standards.
PLASTEC Ventilation - ACH Calculator
Calculate the airflow (CFM) required for your space based on industry standards.
Enter Room Dimensions (in feet):
ACH Value:
Please enter valid, positive numbers for all dimensions.
Calculation Results
Room Volume:
0.00 cu. ft.
ACH Value Used:
≥20 (occupied); ≥4 outdoor air changes per hour
Required Airflow (CFM):
0 CFM
Additional Information:
Reference Standard: ASHRAE 170 (Health Care Ventilation)
Important Notes: Operating rooms require high ventilation rates to control infection and maintain sterility. At least 20 total air changes per hour must be supplied, with at least 4 ACH from outdoor air. Rooms are maintained at positive pressure relative to adjacent spaces. During unoccupied periods, the total ACH can be reduced, but positive pressure must be maintained, and the full 20 ACH restored before re-occupancy.
What is Air Changes Per Hour?
Air Changes Per Hour is a measure of how many times the total volume of air in a room is replaced in one hour. It's a critical parameter for maintaining indoor air quality, meeting code requirements, ensuring infection control, providing occupant comfort, and optimizing energy efficiency.
Why Use Our Air Changes Per Hour Calculator?
Accurate Air Changes Per Hour calculations are fundamental to proper ventilation system design. Our calculator provides industry-standard Air Changes Per Hour values for 20+ different applications, instant CFM calculations based on room dimensions, compliance references to ASHRAE and CDC standards, and application-specific guidance with important notes and considerations.
Benefits of Accurate Air Changes Per Hour Calculations
Select the right fan capacity to meet ventilation requirements, ensure regulatory compliance with building codes and industry standards, optimize energy consumption by avoiding over-ventilation, and maintain proper indoor air quality for occupant health and safety.
Understanding Air Changes Per Hour Requirements by Application
Different spaces have vastly different ventilation needs.
| Space Type | Required Air Changes Per Hour (ACH) | Primary Purpose |
|---|---|---|
| Operating Rooms | ≥ 20 ACH | Sterility, infection control |
| Cleanrooms ISO 5 | 240–600 ACH | Ultra-clean environments |
| Laboratories | 6–12 ACH | Safety and fume control |
| Offices | 4–6 ACH | Occupant comfort |
| Restrooms | 8–10 ACH | Odor control |
| Commercial Kitchens | 15–20 ACH | Heat and moisture removal |
| Data Centers | 30–60 ACH | Equipment cooling |
Our calculator automatically applies the appropriate standard for each space type, eliminating guesswork and ensuring compliance.
Selecting the Right Plastec Fan
Once you've calculated your CFM requirements, Plastec polypropylene fans offer the ideal solution for corrosive and demanding environments.
Why Choose Plastec Fans?
Our fans feature corrosion-resistant non-metallic polypropylene construction that eliminates rust and chemical degradation. We offer a complete CFM range from small inline fans to large centrifugal blowers with precise airflow control to match your exact Air Changes Per Hour calculations. The lightweight design reduces structural loads and simplifies installation. Our fans are durable with UV-resistant HALS additives and UL94-V0 flame retardant compliance. We provide smart controls integration with CONTROL E-SEAT, L.COM, and CAPTUR monitoring systems, explosion-resistant options using Carbon-Impregnated Polypropylene (CIP) for hazardous locations, and quick delivery with manufacturing within 48 hours.
Fan Selection Process
Start by calculating CFM using our Air Changes Per Hour calculator above, then determine system pressure using our Duct Pressure Loss Calculator. Next, select the optimal Plastec fan that meets both CFM and static pressure requirements, and verify compatibility with control systems and project specifications.
Supported Applications & Industries
Our calculator includes Air Changes Per Hour standards for a wide range of applications.
- Healthcare Facilities include Operating Rooms (ASHRAE 170), Hospital Patient Rooms, Hospital Isolation Rooms (AII), Hospital Protective Environment (PE) Rooms, and Hospital Corridors.
- Laboratory & Research applications cover General Laboratories, Pharmacy Cleanrooms (USP <797>), and Animal Research Facilities (Vivariums).
- Cleanrooms include both ISO 7 Cleanrooms for moderate cleanliness and ISO 5 Cleanrooms for high cleanliness requirements.
- Commercial & Industrial spaces include Commercial Kitchens (Prep/Cooking & Dishwashing), Data Centers, Offices, Classrooms, and Gyms / Fitness Centers.
- Specialized Spaces cover Natatoriums (Swimming Pools), Pool Mechanical Rooms, Restrooms & Toilet Rooms, and Archives / Libraries (Rare Books).
Important Considerations
Many applications require a minimum amount of outdoor air (fresh air) in addition to total air changes. For example, operating rooms need ≥4 Air Changes Per Hour outdoor air out of ≥20 total Air Changes Per Hour to ensure fresh air supply while allowing recirculation for efficiency.
Different spaces require specific pressure relationships. Positive pressure is required for operating rooms and cleanrooms to prevent contamination entry, while negative pressure is needed for isolation rooms and restrooms to contain contaminants.
Always verify local building codes and industry-specific standards, as requirements may vary by jurisdiction and application.
Additional Resources
For comprehensive ventilation system design, explore our other calculators and tools including our Duct Pressure Loss Calculator to calculate system pressure losses, Lab Fume Hood Flow Calculator for quick airflow sizing for fume hoods, Fan Selection Guide with our complete range of polypropylene fans and blowers, Technical Documentation with installation guides and technical datasheets, and Industry Applications showing solutions specific to your sector.
Plastec Ventilation - Global leader in corrosion-resistant ventilation solutions with 20+ years of experience serving 80+ countries. Rapid manufacturing (48 hours) of polypropylene fans and blowers for demanding environments.
Need Assistance?
Our team of experienced ventilation engineers is available to support your projects. Whether you need help with Air Changes Per Hour calculations for complex spaces, fan selection and sizing, system design and layout, code compliance verification, or control system integration, we're here to help.
Contact us today to discuss your ventilation requirements and discover how Plastec Ventilation can deliver the perfect solution for your corrosive environment applications.