The Green Grid recommends the Power Usage Effectiveness (PUE) metric for data centres in order to benchmark and compare energy consumption between data centres and to baseline consumption against which improvements in energy efficiency may be measured.
PUE is defined as:
Total Facility Power
IT Equipment Power
Most data centres operate at PUE = 2 to 3 and some at PUE > 3. PUE = 3 means that for every watt consumed by the computers, 2 watts are being consumed by data centre (or computer room) air-conditioning (CRAC), lighting and power delivery equipment. The goal is thus to get PUE to approach 1. Google, operator of the world’s largest data centres, reports that current state-of-the-art data centres can attain a PUE of 1.2. (more…)