Controlled environment vs. Cleanroom

  • 11, 04, 2021

Cleanrooms and controlled environments are very much alike, but the specifications for each differ in severity. While controlled environments largely entail the control of factors such as air pressure and temperature, cleanrooms require these environmental controls plus decontamination and filtration. For this reason, cleanrooms require a great deal of specialized design and equipment that is not necessary in a controlled environment.  


A controlled environment, also known as a critical environment, is a space with precisely regulated environmental factors. Air temperature, temperature, and humidity are regulated to meet operational needs, and the critical area is isolated from other operations within the facility. The level of particle contamination is not measured and controlled environments are not required to meet the same high decontamination standards as cleanrooms. 


Cleanrooms are used to create a particulate free environment free of contaminants such as dust, mold, and microorganisms. They are actually a type of controlled environment and must still maintain rigorous environmental control and segregation from external environments.

However, the environmental conditions within the cleanroom must adhere to much more stringent regulations. For example, cleanrooms are required to meet certain standards for the acceptable volume of particle contaminants in the air. This means that specialized filtration and cleaning technology must be employed to different degrees, depending on the application and industry for which the cleanroom operates.

The level of decontamination is determined based on the classification required for the industry and application. Cleanroom standards come from a variety of sources, including;

  • Good Manufacturing Practices (GMP)
  • Food and Drug Administration (FDA)
  • Deutsches Institut für Normung (DIN)
  • European standards (EN)
  • International Organization for Standardization (ISO) 14644-1 

ISO 14644-1 establishes 9 classifications for particle contamination, wherein Class 1 is the most stringent and Class 9 the least. Depending on the application and industry, standards and regulations will establish the level of acceptable particles per cubic meter, and the acceptable size of those particles, measured in micrometers (μm). 


Cleanrooms for controlled environments are tailored to meet the specific needs of the industry and application they serve. Cleanroom contractors will consider a wide range of factors when determining the construction materials and environmental regulating equipment. In order to ensure that the facility is accurately and thoroughly equipped, the contractor will consider the following:

  • Level of required cleanliness (i.e. ISO class, FDA regulations)
  • Types and placement of filters (HEPA or ULPA)
  • Environmental conditions 
  • HVAC requirements
  • Spatial specifications
  • Construction materials
  • Air showers and/or pass-thru units
  • Fire protection
  • Light and air supply and filtration
  • Electrical and plumbing requirements
  • Equipment hookups and special equipment

Choosing the best cleanroom for your needs means understanding the specific requirements for your industry. Cleanrooms are used in a wide variety of industries and applications, including:

  • Pharmaceutical
  • Aerospace
  • Medical
  • Biotechnology
  • Food & beverage

Each industry must adhere to the requirements of its own regulatory bodies, broader industry standards for cleanrooms, and accepted best practices.

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