Power Usage Effectiveness & Efficiency Flashcards

A data center reports a PUE of 1.0. What does this indicate?

Answer: All power is used exclusively by IT equipment with zero overhead

A PUE of 1.0 is theoretically perfect, meaning 100% of power goes to IT equipment with no overhead losses.

Which metric is the mathematical reciprocal of PUE?

Answer: DCiE (Data Center Infrastructure Efficiency)

DCiE equals 1/PUE and expresses infrastructure efficiency as a percentage, where higher values are better.

A colocation facility has total power draw of 8 MW and IT load of 5 MW. What is the PUE?

Answer: 1.6

PUE = Total Facility Power / IT Equipment Power = 8 MW / 5 MW = 1.6.

What does a PUE measurement taken only at peak summer load fail to capture?

Answer: Seasonal variation in cooling efficiency across the full year

PUE varies with ambient temperature and load, so a single peak-load measurement misses the more efficient winter and shoulder-season periods.

Which of the following is NOT included in the IT equipment power denominator when calculating PUE?

Answer: Computer room air conditioning (CRAC) units

CRAC units are facility infrastructure overhead, not IT equipment, so they belong in the total facility power numerator only.

What PUE improvement technique involves using outside air directly for cooling without mechanical refrigeration?

Answer: Economization or free cooling

Economization (free cooling) uses ambient outdoor air or adiabatic cooling to eliminate compressor energy when temperatures permit, significantly lowering PUE.

The Green Grid recommends measuring PUE at which boundary?

Answer: At the utility meter entering the facility

The Green Grid's standard boundary for total facility power is the utility meter, capturing all power consumed by the data center.