Crank up the datacenter heat -- with care

ASHRAE says it's OK to make the datacenter warmer, but a higher temperature could have unintended consequences

Datacenter experts often share a similar nugget of advice as to how to reduce energy bills for the datacenter: Turn up the heat. The reason is, some datacenter managers have their datacenter CRAC units running far colder than is necessary to keep their machines sufficiently cooled. There's a clear financial benefit to boosting the temperature in your datacenter: Increasing the set point temperature by just one measly degree can reduce energy consumption by 4 to 5 percent, which translates to lower energy bills. For the environmentally conscious company, that also means a reduction in carbon emissions.

[ Learn more tips about how to beat the heat in the datacenter. ]

The next question, however, is how hot is too hot for the datacenter? Many datacenter operators turn to ASHRAE (American Society of Heating, Refrigerating and Air-conditioning Engineers) for guidance there. As of last week, the group officially expanded its recommended datacenter temperature range [PDF]: Previously, it was 68 to 77 degrees Fahrenheit. Now, it's 64.4 to 80.6 degrees. (Those temperatures should be measured at the server inlets.)

Moreover, ASHRAE altered its recommended approach to measuring humidity levels: It should now be measured by dew point and fall within 41.9 degrees Fahrenheit to 59 degrees. Humidity was previously measured by relative humidity, and the temperature range was narrower.

Before you crank up the heat to 80.6 degrees in the hopes of reducing those monthly utility bills, take note: The datacenter is a complex environment, and adjusting the temperature can have some unexpected or unintended results. For starters, a higher set temperature point doesn't automatically mean less energy waste. As ASHRAE puts it, "Neither the 2004 nor the 2008 recommended operating environments ensure that the datacenter is operating at the optimum energy efficiency."

For example, some datacenter gear is designed to speed up its fans to compensate for the higher inlet air temperatures. This could potentially offset the gains in energy-efficiency that you'd enjoy from raising the datacenter's temperature. ASHRAE advises that datacenter operators "review and determine, with appropriate engineering expertise, the ideal operating point for their system. This will include taking into account the recommended range and their site specific conditions."

That means that ongoing measuring and adjusting is a must if you really want to see your datacenter operating at maximum efficiency.