Efficient Cooling of Data Centers with CRAC Units

Posted by James Ball on Sep 25, 2018 9:00:00 AM

Cooling plays a crucial role in data center operations and costs. Inefficiencies in the cooling systems can lead to more power used for cooling than the equipment itself. CRAC (Computer Room Air Conditioners) are one of the many methods that can be used to cool down data center facilities. We’ll explore how they work here.



Exploring the Pros and Cons of CRAC Units         

CRAC units are used to maintain consistent temperature and humidity according to the thermal guidelines recommended by committees like ASHRAE (American Society of Heating, Refrigeration and AirConditioning Engineers), which makes understanding the basics of CRAC essential for any data center manager.


Data Center Cooling’s Effect on Power Usage 

Cooling systems can be responsible for up to 40% of the power consumption of a data center. Depending on the efficiency of the system, this percentage can vary from 24% to 61%. CRAC systems with a well-defined and long track record can help data center managers provide high-quality cooling without worrying about reinventing the wheel.


How CRAC Units Work 

CRAC cooling systems use refrigerants not unlike home air conditioner systems do. Power usage depends on the efficient management of the heated air, so data center equipment is organized with air circulation efficiency in mind.


In and of itself, using a CRAC system to maintain the same temperature throughout the data center is not the most optimal in terms of power use, so data center designers organize server racks to create hot aisles and cold aisles. In the cold aisles, the fronts of the servers face each other, while the hot aisles are used for the backs of the servers. This configuration allows servers to consume cold air from the cold aisles, use the air to cool down the server components and then exhaust the heated air through the backs of the servers to the hot aisles.


The CRAC units are usually positioned on the sides of data centers. As air is exhausted into the hot aisle, the warmth of the creates a natural buoyancy (think hot air balloon) and rises to the top of the room. CRAC units then collect the hot air from the ceilings and recirculate it through the CRAC units and cools down the air and then redistribute it to out to the cold aisles using the raised floor system and perforated tiles in the cold aisle.


The efficient circulation of hot and cold air ensures that CRAC cooling systems can maintain ideal temperature and humidity while staying power-efficient. Using a well-designed hot or cold aisle containment system in conjunction with the cooling system can greatly increase its efficiency and reduce its energy usage. Learn more about Instor’s containment solutions here.


Benefits of Using CRAC Cooling Systems 

Here are some of the reasons data center managers like using CRAC systems:

  • Established Technology: Facilities have been using CRAC cooling systems since the early days of data centers, so there is a lot of operational data, experience and expertise available. Data centers can easily set up a CRAC system without wasting too much time on research and development.
  • Reliable Vendors Available: Reliable designers, suppliers and installers can help data centers create and install an efficient CRAC system. Data center owners always have multiple options to choose from.
  • Newer CRAC Units with Variable Speeds Save More Power: Older CRAC units could only turn on and off depending on the temperature needs of a server room. Newer units have variable speed options which can further help with power efficiency and thus savings.


Other Considerations with CRAC Units 

There are some things to consider with CRAC units, however.

  • Higher Maintenance Costs: CRAC maintenance can be costly and time-consuming. Regular inspection and maintenance are essential. Technicians have to keep track of refrigerant levels, filter conditions, and multiple mechanical components.
  • Fixed Speed Power Wastage: Older CRAC units that use fixed speed cooling are less efficient with power because they only have the ability to turn on and off at certain temperature and humidity set points rather than responding real time to load variations from the servers. Replacing or retrofitting older units with variable speed components can resolve this issue. Fortunately, there are many newer, more efficient solutions on the market. Explore Instor’s product partners here.


Data centers use CRAC cooling systems due to convenience. It’s easy to set up with a lot of help available. But it’s important to remember to design the most efficient system to meet your data center cooling demands, and that CRAC systems require routine preventative maintenance to identify potential problems and replace or service the components. Otherwise, it might lead to inefficient cooling and higher power bills than are necessary.


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Topics: Cooling, Products