How the Cleanroom Design Calculator Works
Our calculator uses your room dimensions and classification requirements to determine the critical components needed for a compliant cleanroom environment.
What We Need From You
- Room Dimensions: Length, width, and height tell us the total air volume that needs to be controlled.
- ISO Classification: Your required ISO class (5, 6, 7, or 8) is the primary factor determining filtration and air circulation needs.
- Process Considerations: Whether your process generates significant particles from machinery, materials handling, or operations.
What the Calculator Determines
Using industry-standard engineering calculations and ISO 14644 guidelines, our calculator provides:
- Total Airflow (CFM): Cubic feet per minute of HEPA-filtered air required to maintain your classification.
- Air Changes Per Hour (ACH): How frequently the entire air volume must be replaced with filtered air.
- HEPA Filter Quantity: Number of standard 2' × 4' filter modules needed for your ceiling.
- Low Air Returns: Number of return air grilles needed for proper airflow patterns.
- Lighting Fixtures: Quantity of cleanroom-rated LED fixtures for specified illumination.
Understanding Your Cleanroom Requirements
Air Changes Per Hour (ACH)
Air changes per hour represents how many times your cleanroom completely replaces its air volume with fresh, filtered air every 60 minutes. Think of it as the "refresh rate" for your cleanroom environment.
The impact of ACH rates:
- An ISO 5 cleanroom at 300 ACH replaces air every 12 seconds
- An ISO 8 cleanroom at 20 ACH replaces air every 3 minutes
This constant air movement rapidly removes particles introduced by personnel, processes, and materials before they can settle on products or surfaces.
Higher ACH rates aren't just about moving more air—they fundamentally change how your cleanroom operates. Very high ACH (200+) enables unidirectional or laminar airflow, where air moves in parallel streams from ceiling to floor, sweeping particles directly downward. Lower ACH creates turbulent or mixed airflow, where air circulates throughout the space.
HEPA Filter Modules
HEPA (High-Efficiency Particulate Air) filters are the heart of your cleanroom, removing 99.97% of particles 0.3 micrometers and larger from supply air.
Standard specifications:
- Module size: 2' × 4' (8 square feet each)
- Airflow capacity: 400-600 CFM per module
- Service life: 3-5 years with annual testing required
The quantity needed depends heavily on ISO classification. An ISO 8 cleanroom might need just 2-3 filters providing 10-15% ceiling coverage with mixed airflow. An ISO 5 cleanroom of identical size could require 15-20 filters covering 80-100% of the ceiling to achieve unidirectional flow.
What this means for you: More filters mean higher upfront costs but also more maintenance—each filter requires annual integrity testing and eventual replacement.
Lighting Fixtures
Cleanroom-rated LED fixtures are sealed units that integrate into ceiling systems without compromising contamination control.
Why specialized lighting matters: Standard ceiling lights shed particles, accumulate dust, and create contamination risks—completely unacceptable in controlled environments.
Cleanroom fixtures are designed to:
- Resist harsh cleaning chemicals
- Produce minimal heat generation
- Provide long service life without in-room maintenance
- Integrate seamlessly with HEPA filter ceiling systems
Illumination requirements:
- Standard work (50-75 fc): General cleanroom operations
- Detailed work (75-100 fc): Inspection and assembly tasks
- Precision work (100+ fc): Microscopy and critical inspection
A 200-square-foot cleanroom requiring standard lighting might need 4-5 fixtures, while the same room needing precision lighting for inspection work could require 7-8 fixtures for proper coverage.
Low Air Returns
Return air grilles positioned 6-12 inches above the floor complete the airflow circuit, exhausting contaminated air back to the HVAC system for filtration and recirculation.
Why returns matter: While HEPA filters supply clean air from the ceiling, returns create the airflow patterns that actually remove contamination from your workspace.
The number and placement of returns directly affects performance:
- Too few returns: Creates turbulent zones and high face velocities
- Proper distribution: Creates sweeping airflow carrying particles away from critical work areas
- Strategic placement: Typically on opposite walls from supply air for optimal air patterns
In ISO 5 cleanrooms with unidirectional flow, returns often cover entire floor perimeters to allow air flowing straight down through the work zone.
Additional function: Returns also maintain room pressurization, preventing outside contaminated air from entering through doors and other penetrations.
Next Steps for Your Cleanroom Project
Our cleanroom design calculator is a starting point, not a final design tool. It helps you get a general sense of what your space might require, from airflow to filter counts and lighting needs. Use it to explore options and develop a rough budget estimate, but remember that it cannot replace professional engineering.
Why Professional Design Matters
While the calculator can give you ballpark numbers, a cleanroom engineer considers factors it cannot, including:
- Optimizing airflow patterns for your specific processes
- Managing temperature, humidity, and pressure control
- Integrating specialized equipment that generates heat, moisture, or particles
- Addressing structural or HVAC limitations in existing buildings
- Ensuring compliance with ISO standards, GMP, FDA, or other regulations
These details are critical for creating a functional, compliant, and safe cleanroom.
Turning Estimates Into Reality
Building a cleanroom is more than numbers—it’s about performance and reliability. That’s where we come in. With decades of experience and many certified cleanroom builds, we make the process easy.
We handle every detail—airflow, filtration, HVAC, layout, and compliance—so you don’t have to worry. Working with us ensures your cleanroom performs exactly as needed for your processes, now and in the future.
Ready to move forward?
If you want to turn your calculator results into a real, fully engineered cleanroom, our specialists can guide you every step of the way. Contact us today to discuss your project.
