Chasing Away Server Room Heat

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Study: Cooling Technology Can Tap Enormous Efficiency Potential of United States’ 2.5 Million Small Data Centers

Variable refrigerant flow (VRF) heat pumpsVariable refrigerant flow (VRF) heat pumps can reduce energy use in small data centers by up to 29%, according to an EPRI study.

While companies such as Google, Facebook, and Apple apply significant resources to reduce the massive energy consumption of their warehouse-scale data centers, the 2.5 million small data centers in the United States present enormous untapped efficiency potential. Representing about 1% of total U.S. electricity consumption, these network closets and server rooms are often located in commercial buildings—such as offices, hospitals, banks, and schools—that were not designed for data centers. Cooling typically accounts for about 40% of energy consumption in small data centers. Many best practices for cooling large data centers are not applicable because of space limitations.

As a potential energy savings solution, EPRI evaluated a VRF heat pump in its Innovations in Datacenter Efficiency Advances (IDEA) Laboratory in Knoxville, Tennessee. The system was configured to cool a server room while recovering server heat to condition an adjacent laboratory occupied by EPRI research staff. For 14 months, researchers compared its performance with that of a conventional heat pump system.

Key insights:

  • In heat recovery mode, the VRF system yielded 10–12% energy savings.
  • When cooling the server room and occupied space, energy savings were as high as 29%.
  • At low outdoor temperatures, VRF indoor units may shut down to prevent freezing, limiting cooling capacity. This suggests that the technology may not be suitable for larger data centers in cold climates.

Utilities can use these results as a technical basis in considering the technology in energy efficiency programs.

Artwork by Kirk Anderson