Computer Room Air Conditioning

Definition of Computer Room Air Conditioning

Computer Room Air Conditioning (CRAC) refers to a system specifically designed to maintain the temperature, humidity, and air circulation within data centers or server rooms. These specialized air conditioning units help to dissipate heat generated by servers and other network equipment, ensuring optimal performance and reducing the risk of overheating. CRAC units maintain a consistent and controlled environment, critical for efficient operation and longevity of electronic devices.


The phonetic pronunciation of “Computer Room Air Conditioning” is:/ kəmˈpyo͞otər ro͞om ɛr ˈkənˌdiSHəniNG /

Key Takeaways

  1. Computer Room Air Conditioning (CRAC) units are specifically designed to regulate the temperature, humidity, and airflow in server rooms and data centers, ensuring optimal operating conditions for sensitive electronic equipment.
  2. CRAC units can use various methods to cool the air, including direct expansion, chilled water circulation, or air handling, providing versatile and efficient climate control solutions for different data center requirements.
  3. Proper maintenance, monitoring, and management of CRAC systems is crucial for preventing equipment failures, optimizing energy efficiency, and extending the lifespan of both the CRAC units and the technology infrastructure that they support.

Importance of Computer Room Air Conditioning

Computer Room Air Conditioning (CRAC) is a vital technology in ensuring the optimal performance and longevity of computer systems and servers by regulating temperature, humidity, and air distribution within designated spaces.

These specialized air conditioning units are crucial in maintaining a stable environment for critical electronic equipment.

Overheating or exposure to excessive humidity can lead to hardware failures, system downtime, and potential data loss, all of which can disrupt operations and result in significant costs for businesses and organizations.

By utilizing CRAC systems, businesses can efficiently manage the environmental factors within their computer rooms and data centers, ensuring that their IT infrastructure remains reliable, secure, and operational at all times.


Computer Room Air Conditioning (CRAC) units play a crucial role in maintaining a stable and optimal environment within data centers and server rooms, where large amounts of electronic equipment operate continuously. These facilities generate a significant amount of heat as a byproduct of their operation, which can lead to equipment failure, reduced efficiency, or even catastrophic data loss if left unchecked.

Consequently, the primary purpose of CRAC units is to ensure that the sensitive electronic devices within these rooms operate at their preferred temperature and humidity levels, by constantly regulating and maintaining the necessary environmental conditions, thus extending the lifespan and reliability of the equipment and securing the integrity of the digital data they process. While traditional air conditioning systems focus on achieving a comfortable climate for people, CRAC units are specially designed to cater to the unique needs of computer equipment.

They achieve precise thermal management by monitoring temperature and humidity, and by adjusting the cooling capacity accordingly. The cooling process works by drawing in warm air from the room, filtering it to eliminate dust and contaminants, and then supplying cool air back into the space via an efficient heat exchange system, such as chilled water or refrigerant-based mechanisms.

In addition to temperature regulation, CRAC units also help to maintain appropriate humidity levels, ensuring that the air is neither too dry nor too moist, so as to prevent static electricity build-up and condensation, respectively. In summary, CRAC units are essential for safeguarding vital equipment and data in data centers and server rooms, providing protection against both heat-induced equipment failure and other environmental risks.

Examples of Computer Room Air Conditioning

Data Centers: Large-scale data centers require precise temperature and humidity control to maintain optimal operating conditions for servers and other IT equipment. A computer room air conditioning (CRAC) system plays a crucial role in achieving this, ensuring that cooling is efficiently distributed and maintained. For instance, the Google data centers use CRAC units to maintain an ideal operating environment for their thousands of servers.

Telecommunication Facilities: Telecommunication facilities, such as network operation centers and switching stations, house sensitive electronic equipment that generates a significant amount of heat. These facilities employ CRAC units to maintain a stable temperature and humidity level, ensuring optimal performance and preventing equipment failures. An example is the AT&T Global Network Operations Center, which employs a state-of-the-art CRAC system to manage its critical infrastructure.

Financial Institutions: Banks and other financial institutions have specialized IT rooms where servers, storage, and networking equipment are housed. These rooms require exact temperature and humidity control to safeguard the sensitive data contained within and to maintain the smooth operation of the facility. For example, the New York Stock Exchange (NYSE) uses CRAC systems in its massive data centers to keep equipment at precise temperatures, ensuring uninterrupted trading and data processing.

Computer Room Air Conditioning FAQ

What is Computer Room Air Conditioning (CRAC)?

Computer Room Air Conditioning (CRAC) is a specialized air conditioning system designed to maintain temperature, humidity, and air quality in computer rooms, data centers, and other IT environments to ensure optimum performance and longevity of electronic equipment.

Why is CRAC important for computer rooms and data centers?

CRAC is essential for maintaining precise temperature and humidity levels, as well as appropriate airflow in computer rooms and data centers. Proper cooling prevents overheating and ensures the reliability and efficiency of electronic equipment, while maintaining the proper environment reduces the risk of costly downtime, data loss, and hardware damage.

What are the key components of a CRAC system?

A CRAC system is typically composed of several key components, including compressors, evaporators, condensers, fans, air filters, and a variety of sensors and controls. These components work together to manage temperature, humidity, and airflow, as required to maintain a stable and efficient environment for IT equipment.

How does a CRAC system maintain accurate temperature and humidity levels?

A CRAC system utilizes sensors to constantly monitor and analyze environmental conditions, such as temperature and humidity. Based on this data, the system’s controls adjust the operation of compressors, fans, and other components to maintain optimal temperature, humidity, and air quality within the defined parameters.

What are the recommended temperature and humidity ranges for computer rooms and data centers?

According to ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers), the recommended temperature range for computer rooms and data centers is between 64.4°F (18°C) and 80.6°F (27°C). The recommended relative humidity range is between 20% and 80%. However, it is ideal to aim for 45% to 55% to minimize the potential for electrostatic discharge (ESD) and corrosion.

Related Technology Terms

  • Precision Cooling
  • Data Center Cooling Systems
  • Temperature and Humidity Control
  • Air Distribution
  • Hot and Cold Aisle Configuration

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