How High is High Enough?

Questions regarding methods of optimal cooling are limitless. What should be the size of my data center to ensure there are no hot spots? How should I align my racks to provide efficient cooling? How many CRAC units should I install? What method of airflow management should I adopt? How are raised floors helpful? I could go on and write a whole book just by listing the frequently asked question; but what I would like to address in this post is how ceiling height can affect data center cooling.

Yes, the height of the room does play a vital role in effective heat disposal. But the ceiling height majorly depends on how well the data center planning is done. If the designer has spared his attention to proper detailing of the hot and cold aisles, then even a 9 feet high ceiling, which is the minimum requirement for a data center, is more than sufficient. If not, then increasing the height of the room will help in providing a better and low resistance path to the hot air returning to CRAC. Some data center experts also suggest that the CRAC returns be raised to at least two feet below the ceiling so that it is easier to collect the hottest air.

A higher ceiling is highly advantageous in case of a cooling system failure. It is believed that a higher ceiling height increases the cold air volume, thus reducing the rate of temperature increase. This will give enough time for the operator to fix the cooling system or make alternate arrangements to bring down the room temperature before the systems start shutting down due to high temperature. Although there seems to be no significant impact of a higher ceiling in a cold- aisle containment, the effects of a high ceiling in a hot- aisle containment are still being studied.

Of course, one has to keep in mind that a high ceiling is not an alternative or a replacement option to airflow management. It just provides a helping hand in cooling the data centers.

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