One of the most costly and important factors in building a cleanroom is air control. Cleanrooms are pressurized and use advanced filters that remove contamination-causing particulates. These airborne contaminates are not the only environmental issue in the cleanroom, though.
Humidity control is of the utmost importance in a cleanroom. Too much humidity can encourage bacteria growth. Additionally, some products made in cleanrooms, like sutures, are moisture-activated and can start to degrade if the humidity is too high. Too little humidity can cause static electricity. Static electricity is a major issue in cleanrooms, especially those for electronics. Electrostatic discharge can render some parts useless. Also, accidental static shocks to humans can distract workers (and they can hurt!)
Outdoor air has a direct effect on the humidity level in a cleanroom. Finding the right equipment to adjust for this can be difficult. Many states experience weather that is both humid and below freezing, depending on the time of year. This means that air filter systems for these locations have to be able to both cool and heat air from the outside as it goes into the building. Whether the air is hot or cold, temperature control can cause a number of problems, including coil ice that can melt and cause water damage.
As sensors detect changes in humidity, the system will turn on and off accordingly. This often creates an uncomfortable situation for the cleanroom workers. Many cleanroom workers complain that the room is either too humid or not enough; there is no happy medium.
Discomfort in the cleanroom is a distraction for employees. Mental faculties suffer when a person is stressed by humidity. Attempting to adjust controls to fix the problem just makes it worse. The controls are set to ensure the humidity is within a safe range, so changing them can be dangerous.
As a result of this challenge, there are many products and systems on the market to help with temperature and humidity control. They can be quite costly, so it is imperative to know the needs of a particular cleanroom as well as future budget estimates when researching the right control system.