High-Performance Computing Data Center Power Usage Effectiveness

When the Energy Systems Integration Facility (ESIF) was conceived, NREL set an aggressive requirement that its data center achieve an annualized average power usage effectiveness (PUE) of 1.06 or better. Since the facility opened, this goal has been met every year—and the data center has now achieved an annualized PUE rating of 1.036.

Studies show a wide range of PUE values for data centers, but the overall average tends to be around 1.8. Data centers focusing on efficiency typically achieve PUE values of 1.2 or less. PUE is the ratio of the total amount of power used by a computer data center facility to the power delivered to computing equipment.

Data center operators calculate instantaneous PUE using the following components:

  • Lights and utility plugs that are associated with the data center and dedicated mechanical room. The crank-case heater for the emergency standby generator is also captured as light and plug load.

  • Cooling, which captures the power used by fans and pipe trace heaters associated with outdoor cooling equipment. The dedicated tower filter pump power is also captured as cooling load.

  • Pumps that move water in the data center Energy Recover Water loop and the Tower Water loops, and also capture power used by the boost pumps that circulate water through the fan walls.

  • Heating, ventilation, and air conditioning (HVAC), which captures fan walls, fan coils that support the data center electrical rooms, and the make-up air unit.

  • IT equipment, which captures power used by the IT equipment on the data center floor.

All of the above measurement points are measured with electrical power meters except for:

  • Generator heat, which is calculated as a percentage of total generator heat power as the emergency generator is shared with the entire ESIF building.

  • The tower filter pump runs constantly to filter water from the data center cooling tower system, so 2.67 kilowatts are attributed to this pump.