Cleanroom Industry Guide

Filtration is the cornerstone of cleanroom performance. Two primary filter types dominate the industry:

HEPA (High-Efficiency Particulate Air)

HEPA filters capture a minimum of 99.97% of particles at 0.3 micrometers (the Most Penetrating Particle Size, or MPPS). HEPA filtration is the standard for ISO 5 through ISO 8 cleanrooms and is sufficient for most pharmaceutical compounding, medical device assembly, and general manufacturing applications. HEPA filters are categorized as H13 (99.95% efficiency) and H14 (99.995% efficiency) under the EN 1822 standard.

ULPA (Ultra-Low Penetration Air)

ULPA filters achieve 99.999% efficiency at 0.12 micrometers, making them essential for ISO 3 and ISO 4 environments found in semiconductor fabrication and nanotechnology research. The higher efficiency comes at the cost of increased pressure drop, requiring more powerful air handling units and higher energy consumption. ULPA filters are rated as U15 (99.9995%) or U16 (99.99995%) under EN 1822.

Dual-Filtration Systems

Some modular cleanroom units feature both HEPA and ULPA filter stages, allowing operators to achieve progressively cleaner environments. Pre-filter stages (MERV 8-14) extend the life of terminal HEPA/ULPA filters by capturing larger particles upstream.

Airflow pattern is a critical design parameter that directly impacts particle removal efficiency and cleanroom classification capability.

Unidirectional (Laminar) Airflow

Laminar flow delivers filtered air in parallel streamlines, either vertically (from ceiling to floor) or horizontally (from wall to wall). This pattern provides the most consistent particle removal and is required for ISO 5 and cleaner environments. Vertical laminar flow is most common in pharmaceutical applications, while horizontal laminar flow is often used in semiconductor and electronics manufacturing.

Non-Unidirectional (Turbulent) Airflow

Turbulent airflow mixes filtered supply air with room air through dilution. While less effective at maintaining ultra-clean conditions, it is adequate for ISO 6 through ISO 9 environments and significantly reduces the cost of air handling equipment. Higher air changes per hour (ACH) compensate for the less efficient particle removal pattern.

Air Changes Per Hour (ACH)

ACH measures how many times the total volume of air in a room is replaced in one hour. ISO 5 cleanrooms typically require 240-600 ACH with laminar flow. ISO 7 rooms commonly operate at 30-60 ACH, while ISO 8 environments may function at 15-25 ACH. Higher ACH rates increase energy costs but provide better particle control and faster recovery from contamination events.

Softwall Cleanrooms

Softwall cleanrooms use flexible, transparent vinyl or anti-static curtain panels suspended from an aluminum frame with integrated ceiling-mounted fan filter units (FFUs). They are the most affordable modular option and can be deployed in hours. Best suited for ISO 6-8 applications where a fully sealed enclosure is not required. Advantages include easy reconfiguration, expandability, and visual access to the work area.

Hardwall Cleanrooms

Hardwall units feature rigid panel construction (steel, aluminum, or composite panels) with sealed joints. They provide superior pressure control, are better suited for ISO 4-6 classifications, and support positive or negative pressure differentials. Hardwall rooms accommodate pass-throughs, airlocks, gowning rooms, and integrated monitoring systems. Installation typically requires 1-4 weeks depending on complexity.

Hybrid Cleanrooms

Hybrid designs combine hardwall structural elements with softwall access points, balancing cost efficiency with performance. Common in pharmaceutical settings where some walls must be sealed while others benefit from curtain access for material flow.

Mobile Trailer Cleanrooms

Mobile cleanrooms built into standard or custom trailers are fully self-contained with integrated HVAC, filtration, electrical distribution, and monitoring. They can be transported to any site and operational within hours. Ideal for disaster recovery pharmacy operations, field-deployable semiconductor inspection, temporary production surges, and construction-phase cleanroom needs.

Inflatable Cleanrooms

The newest modality in the market, inflatable cleanrooms use pressurized membrane structures to create controlled environments. They offer the fastest deployment time and the most compact transport footprint. Primarily used for emergency response and field operations where ISO 7-8 conditions are sufficient.

Pharmaceutical Compounding (USP 797 & 800)

USP General Chapter 797 establishes standards for compounding sterile preparations. Primary Engineering Controls (PECs) such as Laminar Airflow Workbenches (LAFWs) must be placed in ISO 5 environments, located within ISO 7 buffer rooms that are accessed through ISO 8 ante-rooms. USP 800 addresses the handling of hazardous drugs, requiring negative-pressure ISO 7 containment areas with externally vented air. Modular cleanrooms provide a compliant pathway that avoids costly facility renovations.

Semiconductor & Microelectronics

Semiconductor fabrication demands ISO 3-5 environments to prevent sub-micron particle contamination on wafer surfaces. Modular cleanrooms serve as cost-effective alternatives to traditional fab construction for packaging, inspection, and testing operations. ESD (Electrostatic Discharge) dissipative flooring, walls, and work surfaces are critical in these applications.

Aerospace & Defense

Aerospace cleanrooms protect sensitive optical components, satellite assemblies, and precision instruments from particulate contamination. ISO 5-7 environments are common. Modular solutions allow defense contractors to establish controlled environments at distributed manufacturing sites without permanent facility investments.

cGMP Manufacturing

Current Good Manufacturing Practice (cGMP) regulations enforced by the FDA require controlled environments for the manufacture of pharmaceuticals, biologics, and medical devices. Modular cleanrooms designed for cGMP compliance include validated construction materials, integrated environmental monitoring, and documentation packages that support qualification protocols (IQ/OQ/PQ).

Key regulatory frameworks governing cleanroom design and operation include:

• ISO 14644-1:2015 - Classification of air cleanliness by particle concentration
• ISO 14644-2:2015 - Monitoring to provide evidence of cleanroom performance
• ISO 14644-3:2019 - Test methods for cleanroom characterization
• ISO 14644-4:2022 - Design, construction, and start-up
• USP 797 - Pharmaceutical Compounding: Sterile Preparations
• USP 800 - Hazardous Drugs: Handling in Healthcare Settings
• 21 CFR Parts 210/211 - FDA cGMP for Finished Pharmaceuticals
• EU GMP Annex 1 - Manufacture of Sterile Medicinal Products
• IEST-RP-CC012 - Considerations in Cleanroom Design

Temperature Control

Most cleanroom applications require temperature control between 64-72 degrees Fahrenheit (18-22 degrees Celsius) with a tolerance of plus or minus 1-2 degrees. Semiconductor fabrication may demand tighter control at plus or minus 0.1-0.5 degrees Celsius. Modular units achieve temperature control through integrated or external HVAC systems with precision thermostatic controls.

Humidity Control

Relative humidity (RH) is typically maintained between 30-60%. Pharmaceutical applications often target 45-55% RH to prevent moisture-sensitive degradation. Semiconductor environments may require 40-45% RH to control electrostatic charge accumulation. Humidity control prevents microbial growth (high RH) and static discharge events (low RH).

Pressure Differentials

Positive pressure cleanrooms (0.02-0.05 inches WG above surrounding areas) prevent external contaminants from infiltrating the controlled space. Negative pressure environments, required for USP 800 hazardous drug handling, ensure that aerosolized hazardous agents do not escape the containment area. Pressure cascades between adjacent rooms maintain the hierarchy of cleanliness.

Monthly Rental

Cleanroom rentals range from $2,000-$5,000/month for basic softwall ISO 7-8 units to $15,000-$40,000+/month for large hardwall ISO 5 systems with full environmental controls. Rental agreements typically include maintenance, filter replacements, and re-certification services.

Rent-to-Own Programs

Many providers offer rent-to-own structures where monthly payments build equity toward eventual ownership. This approach preserves working capital while providing a path to asset ownership. Typical rent-to-own terms range from 24 to 60 months.

Section 179 Depreciation

Modular cleanrooms classified as equipment (rather than real property) may qualify for Section 179 immediate depreciation under the IRS tax code. This could allow businesses to deduct the full purchase price in the year of acquisition rather than depreciating over the standard 7-year MACRS schedule. Consult a qualified tax professional to determine eligibility and applicability to your specific situation.