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Part 2: The Advantages And Disadvantages Of Hot-Aisle, Cold-Aisle Containment Strategies
By Travis Steinmetz and Thomas Squillo
November 2013 -
Data Centers Article Use Policy
Each of the three containment solutions, if applied correctly, can be equally effective in separating the exhausted heat from the cool air and preventing bypass and recirculation. However, they do have distinct advantages and disadvantages. Here are the advantages and disadvantages of hot-aisle and cold-aisle containment strategies.
• Cold-Aisle Containment involves enclosing the cold aisles within the data center. Cold supply air is then delivered directly to each cold aisle and can be matched to the server airflow requirements with proper controls. The physical barrier, which can be solid metal panels, plastic curtains, glass, or plexiglass, is added to the ends and at the top of the cold aisle. Making the barrier transparent enables the cold aisle to remain visible for monitoring or to work with existing room lighting.
One advantage of cold-aisle containment is that it can be used with raised floor supply plenums or overhead ducted supply with no raised floor. If controls are designed correctly, it may offer some efficiency advantages by providing greater ability to control supply air to match server airflow.
But there are some disadvantages to cold-aisle containment. Allowing the discharge air from the hot aisle to fill the room results in temperatures anywhere from 80 to 100 degrees F throughout the majority of the data center. This can create perception issues for company executives or for tenants of a co-location data center. It also may create operational issues if any non-contained equipment, such as low-density storage or communication racks, is installed in the general data center space. Also, in many cases, cold aisles have intermediate ceilings over the aisle. This may affect the overall fire protection and lighting design, especially when added to an existing data center.
• Hot-Aisle Containment encloses the hot aisles within the data center. The discharge air from the IT equipment enters the enclosed hot aisle and is returned directly to cooling equipment through a ceiling plenum or ductwork. The cool supply air is introduced into the room through a raised floor, directly into the general space from the AC units, or through ductwork.
The main advantage of hot-aisle containment is that the general data center space remains cool, eliminating the perception by visitors that the IT equipment is not being cooled sufficiently and allowing for some low density areas to be un-contained if desired. Also, accurate distribution of supply air throughout the space is less critical. As long as the cool air is introduced into the general space, even far from the server intakes, and hot air is properly returned, expensive raised floor supply distribution systems and extensive supply ductwork can be avoided.
But there are disadvantages to be aware of. When data center technicians need to access the equipment and its infrastructure, a contained hot aisle can be a very uncomfortable place to work. While this problem can be mitigated using temporary local cooling, the high hot-aisle temperatures need to be considered, especially for a facility that needs frequent access to its equipment.
Part 1: What To Know About Hot-Aisle, Cold-Aisle, And Chimney Data Center Containment Strategies
Part 3: How Chimney Containment Can Help Manage Temperatures In Data Centers
Part 4: Four Factors To Consider When Developing A Data Center Containment Strategy