A data center has IT equipment consuming 800 kW, cooling facilities consuming 280 kW, and power facility losses, lighting and so on amounting to 120 kW. When the cooling method is improved so that only the power consumption of the cooling facilities is halved, which is the PUE?

Answer: C. 1.325

PUE is the power consumption of the whole data center divided by the power consumption of the IT equipment. Before the improvement it is (800 + 280 + 120) ÷ 800 = 1.5. When the cooling facilities consume 140 kW, the total is 800 + 140 + 120 = 1,060 kW, and the PUE becomes 1,060 ÷ 800 = 1.325. The closer the PUE is to 1, the less power is used for anything other than the IT equipment.

• A. This is the inverse ratio, the IT power divided by the total power (800 ÷ 1,060 ≈ 0.75).
• B. This halves not only the cooling but also the power losses and lighting.
• C. Correct. (800 + 140 + 120) ÷ 800 = 1.325.