Power Usage Effectiveness (PUE)
How efficiently a data centre uses energy, versus overhead like cooling.
Formula
Variables
Example
1.5 MW total for 1 MW of IT → PUE = 1.5
How it works
Power Usage Effectiveness (PUE) compares the energy a data centre receives from the grid to the energy actually delivered to its computing equipment. Since a server room also needs cooling, power conversion, lighting, and other support systems, the total facility energy is usually larger than the IT equipment energy alone. A lower PUE means a smaller share of energy is going to overhead, so the site is using electricity more efficiently.
When to use it
Use PUE when evaluating or comparing the energy efficiency of data centres, server rooms, or cloud facilities. It is especially useful in facilities management, sustainability reporting, and planning upgrades to cooling or power infrastructure.
Worked example, step by step
A data centre uses 2,400 MWh of total facility energy in a year. Its IT equipment consumes 1,800 MWh in the same year. PUE = Total facility energy / IT equipment energy PUE = 2,400 / 1,800 PUE = 1.33 So the data centre’s PUE is 1.33, meaning for every 1 kWh used by IT equipment, about 0.33 kWh is used by overhead systems.
Common mistakes to avoid
- Using the IT load as the numerator instead of the denominator
- Mixing power and energy units without matching the time period, such as kW with kWh
- Assuming PUE measures how efficient the servers themselves are rather than the whole facility
Did You Know?
A perfect PUE is 1.0; modern hyperscale data centres reach around 1.1.
Share this formula
More in Media & Data
View allGross Rating Points (GRP)
IntermediateTotal advertising weight of a campaign against the whole audience.
Target Rating Points (TRP)
IntermediateAdvertising weight counted only within the specific target audience.
Television Rating (TVR)
BasicShare of all potential viewers watching a particular programme.
Cost Per Mille (CPM)
BasicThe cost of reaching one thousand impressions.
Cost Per Rating Point (CPP)
IntermediateHow much it costs to buy one rating point of audience.
Click-Through Rate (CTR)
BasicPercentage of ad views that result in a click.