Power Usage Effectiveness (PUE)
Description: Ratio of total data center energy consumption versus IT energy consumption as an annualised average.
Purpose: Defines Power Usage Effectiveness (PUE) of a data center, introduces PUE measurement categories, describes the relationship of this KPI to a data center’s infrastructure, information technology equipment and information technology operations and provides information on the correct interpretation of PUE.
Calculation formula:
Components
E_dc – Total DC building energy consumption in kWh
E_it – IT energy consumption in kWh
Measurement points:
Locations of IT equipment energy consumption measurement – kWh:
- For PUE1 (simpler to measure, less accurate) – UPS output
- For PUE2 (intermediate accuracy) – PDU output
- For PUE3 (most accurate) – IT equipment input (Excludes impact of losses and non-IT equipment)
Actionable insights
This metric should be used to understand the power overhead imposed by a building during the process of delivering services to the IT equipment it hosts. PUE is not an overall measure of data center energy efficiency, however used correctly it can be very effective in reducing the building overhead resulting from the servicing of the IT load. It should be noted though that a reduction in PUE will not always result in an overall reduction in the number of kWh consumed by the building as it does not track potential increases in IT side demand.