Heating Up: The Evolution of Data Center Temperature Recommendations
With Machines Running Hotter, New Issues Arise
The arrival of summer may bring the joy of imminent vacations, barbecues, and days at the beach. But for Data Center managers, summer can easily become the season of trepidation. As the hot weather increases, so do the challenges of keeping hardware cool and energy bills low.
Current standards & best practices for keeping a data center cool
While the traditional wisdom has been to keep hardware nice and cool—with some operators going as low as 55 degrees Fahrenheit—most centers ranged between 68 and 72 degrees. But the guidelines have been changing. In 2008, Google, arguably the most data-focused company on the planet, announced it was letting the environments in its massive server farms heat up to 80 degrees. That same year, the American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) adjusted its recommended maximum high-end heat target from 77˚ Fahrenheit to 80.6˚.
On the surface, these changes were good news for anyone looking to reduce expenses. According to the U.S. General Services Administration (GSA), data centers can save 4% to 5% on energy bills for every one-degree increase in temperature. That said, the increase of temperature often results in the increase in fan speeds to circulate the air, which can sometimes detract from savings.
The heat is on
Roger Schmidt, IBM’s chief engineer for data center energy efficiency, who worked on ASHRAE’s recommendations, called the fan power increases “minimal” for the 80.6˚ threshold. But he noted that going beyond that level “may end up diminishing returns for saving power at the whole data center level.”
Still, the threshold for higher temperatures may be rising yet again. In 2012, a test of a high temperature ambience system incorporating a chilled water loop designed by Intel and the Korean company KT had reportedly allowed machines to run in an 86˚ environment.
Cons to consider
One argument against having a warmer temperature is based on concerns about power failures and backup systems. A center that operates with 65˚ baseline temperature will have more time to troubleshoot a power failure than a center that operates at 80˚. Of course, for those with backup power systems, this issue may not be a large concern.
Another issue regarding higher temperatures and increased fan usage is the accompanying rise in noise levels. A 20% increase in speed (e.g., 3000 to 3600 rpm) equates to a 4 dB increase in noise level. Since noise levels above 85% require special monitoring, testing and education, increased fan usage may also erode any savings accrued by reduced cooling costs.
Balancing these issues—not to mention striving to keep uptime at 100%—is why summers don’t necessarily mean vacations for anyone in the Data Center business.
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