Cold Rooms Help Control Energy Costs
At NetApp's Global Dynamic Laboratory, air containment plays an important role in saving energy. The data center includes tunnel-like enclosures, or cold rooms, that prevent the hotter exhaust air from mixing with the cooler supply air.
This design enables the data center to set its supply air at a warmer temperature (70 to 80 degrees F) than traditional supply air temperature settings (50 to 60 degrees F). Setting a higher thermostat temperature, reduces the energy required to cool the supply air and the runtime of the chilled water system because the facility can use ambient air more often. It also lowers overall fan horsepower by about 3 percent because warmer air is lighter and easier to move.
Similarly, another cost-saving aspect of the design involves locating two air handlers above each cold room. This placement takes advantage of the fact that cool air falls, thus saving energy over a traditional raised floor, which consumes extra fan energy to push cool air upward.
In addition, the facility can use higher chilled water supply temperatures. Cooling water to 55 degrees F instead of 44 degrees F increases the efficiency by about 20 percent.
The energy savings are considerable, given the size of the data center. Its 36 cold rooms each hold 60 cabinets, for a total of 2,136 racks of equipment. At full load, this represents a n energy bill of roughly $36 million per year.