6 Differences Between Cleanroom Air Conditioning and Regular ACs

Air conditioning systems are generally divided into comfort air conditioning (regular systems) and process air conditioning (such as cleanroom systems).

Cleanroom air conditioning refers to systems with built-in purification functions. These are commonly used in industries and facilities that demand high air quality, such as pharmaceuticals, chemicals, hospitals (operating rooms and negative-pressure wards), laboratories, medical equipment production, food and beverage processing, electronic manufacturing, and constant-temperature and humidity laboratories.

The main goal of cleanroom air conditioning is to maintain air cleanliness, prevent external contamination, and ensure a stable indoor environment.

Although cleanroom air conditioning systems are based on comfort air conditioning principles, they differ significantly in several aspects.Below are six key differences between the two systems:

1. Air Handling Process

Cleanroom units first cool the air to its dew point temperature, then reheat and humidify it before supplying it to the clean area through fans and ducts. In contrast, regular systems simply cool air to the dew point and deliver it directly, without maintaining constant temperature or humidity.

2. Air Filtration Requirements

Regular air conditioning systems generally include only basic filtration, such as a primary filter or, in some cases, an additional medium-efficiency filter.

Cleanroom systems use three-stage filtration—primary, medium, and high-efficiency filters (HEPA)—and may even include adsorption filters for specific contaminants.Moreover, cleanroom systems place the high-efficiency filter at the terminal air outlet, while general systems usually do not filter the air at this stage.

3. Indoor Pressure Control

Regular air conditioning systems do not control indoor pressure. Cleanroom systems, however, must maintain a positive pressure differential (typically ≥10 Pa) between clean and non-clean areas to prevent cross-contamination. Different cleanliness classes require specific pressure levels, achieved through specialized system designs.

4. Airflow Organization

Regular air conditioning focuses mainly on temperature and humidity control, using low air exchange rates and turbulent airflow that causes strong secondary circulation. Cleanroom systems, in contrast, prioritize controlling dust and particles. They minimize turbulence and secondary airflow to ensure contaminants are quickly removed.

Thus, while general systems often use top-supply, top-return layouts, cleanroom systems typically adopt top-supply, bottom-return or top-supply, floor-return configurations to achieve better airflow control.

5. Air Change Rate

Regular air conditioning typically provides about 10 air changes per hour (ACH).Cleanroom air conditioning must meet much higher standards:

Higher air change rates enhance cleanliness but also significantly increase energy consumption.

6. Energy Consumption

Regular air conditioning systems are designed for energy efficiency, using the smallest possible airflow to meet cooling or heating needs. Cleanroom air conditioning systems, however, require large air volumes such as Purification AHU to maintain cleanliness, resulting in higher cooling, heating, reheating, humidification, and fan loads. This leads to substantially greater energy consumption.

Summary

In short, while both cleanroom and regular air conditioning share similar basic principles, cleanroom systems involve far stricter control over air quality, temperature, humidity, pressure, and airflow patterns—ensuring a contaminant-free and stable environment for sensitive processes.