Data Center Cooling

Apple is using solar arrays, including a 100-acre solar energy farm in Maiden, N.C., to help power a data center there. Apple allowed NBC's Today show inside the facility this week, and during the tour, a reporter asked what the temperature was there. "It's about 103 degrees in here," said Lisa Jackson, Apple's vice president of environmental initiatives and a former Obama administration EPA chief. What wasn't explained is that Jackson and the reporter were walking down a hot aisle, and feeling the fan exhaust. The experience might have been different if they had walked down the cold aisle, where the rack fronts face the aisle. Apple isn't disclosing details about its Maiden data center operations, except at the 30,000 foot level, so it's unknown exactly what temperatures it's operating at. But it is possible to estimate a range. The American Society of Heating, Refrigerating & Air-Conditioning Engineers (ASHRAE) sets temperatures and humidity guidelines for data centers based on what it knows about the equipment inside them. It recommends that data centers operate between 64.4 to 80.6 degrees Fahrenheit. The recommended limit concerns the air intake temperature. The exhaust temperatures will be higher, how much higher will depend on the density and the quality of the air management, according to the Uptime Institute vice president Keith Klesner. But the temperature could be approximately 15 to 30 degrees Fahrenheit higher, he said in an email. Dave Kelley, director of application engineering at Emerson Network Power's Liebert Precision Cooling, narrowed it down further. Typically, he said, "if you have 80 degrees Fahrenheit entering the IT equipment in the cold aisle, you will have 100 to 105 degrees Fahrenheit leaving in the hot aisle. All of these values are functions of how much [...]