EPRI Research Releases Energy Efficiency in Data Centers Findings

Owners of data centers have multiple options for reducing their energy bills, extending the life of assets, and increasing the reliability of their servers.

To reduce the power consumption of an ever-expanding population of high-density data centers, EPRI investigated the potential for energy reduction at multiple fronts. This included reducing the number of voltage transformations in power distribution systems, retrofitting ordinary power supplies with highly efficient “80 PLUS” power supplies, intelligently managing airflow in server aisles, using state-of-the-art software to enable servers and air conditioners to work in concert to reduce the energy consumed by the servers and the cooling systems, and operating servers in higher temperatures. This demonstration highlights that owners of data centers have multiple options for reducing their energy bills, extending the life of assets, and increasing the reliability of their servers.

An electric utility in the Southwest United States commissioned an airflow-management and cooling-control system at its main data center. With the advanced control system, the utility managed the cooling of 6,000 sq ft of raised floor and more than 50 racks of servers. It also installed dozens of meters and a wireless mesh network to collect measurements over a wide area.

An electric utility in the Northwest United States hosted a demonstration at its data center, which upgraded to 80 PLUS server power supplies. These highly efficient power supplies yielded a significant reduction in power consumption. The utility also in­stalled dynamic power-management soft­ware, which is used to capture CPU per­formance and reduce power levels.

An electric utility in the Southeast United States installed a 30kW DC rectifier/UPS and three IT equipment racks capable of run­ning on AC or DC power feeds. Results show a significant decrease in power con­sumption using DC versus AC. The util­ity also commissioned a comparison be­tween DC power supplies and high-efficiency AC power supplies. Labo­ratory tests indicated that the tested DC power supplies were 2% to 3% more efficient.

Key findings include:

  • By employing power supplies that comply with 80 PLUS protocols, data centers can profit from significant energy savings, as high as 20% according to EPRI field tests. Moreover, because these energy-efficient power supplies run cooler, an attendant reduction in air-conditioning bills is likely.
  • Airflow in even the most modern data centers can be unruly, cooling objects that do not require cooling and bypassing objects that do. By managing airflow velocity to maintain an adequately low server temperature, data centers can shave up to 77% from the energy consumption of unregulated fans and reduce the total energy consumption by as much as 17%.
  • Thermal maps may provide enough high-resolution evidence for operators of data centers to raise the temperature of their cold isles by five degrees F (for example, from 72°F to 77°F). This temperature increase will enable the chillers to work less, resulting in a significant energy savings (3% to 5% in some scenarios).
  • Replacing the standard AC power system used to electrify modern servers with DC systems, data centers can reap the benefit of eliminating multiple AC-to-DC and DC-to-AC power conversions, resulting in a potential energy savings of 15%.
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