Power Usage Effectiveness (PUE) is the ratio of total facility power to IT load. PUE 1.0 is ideal; the global average sits near 1.55 (Uptime Institute, 2024). The book includes a calculation and improvement forecast.
14.1 Power Usage Effectiveness (PUE)
The formula
Benchmark reference values
PUE
Meaning
1.0
Theoretically perfect; impossible in practice
1.10
Hyperscale (Google, Meta) annual average
1.55
Global enterprise average (Uptime Institute, 2024)
2.00
Poorly run facility; large efficiency opportunity
Worked calculation
Variable
Before
After (with controls)
Total facility (kWh/hr)
100
85
IT equipment (kWh/hr)
65
65
PUE
1.54
1.31
Savings: 15 kWh per hour x 8,760 hours/year = ~131,400 kWh/year. At PHP 10/kWh (illustrative) that is PHP 1.31m / year on energy alone.
The levers that move PUE
Lever
Effect
Cooling
Hot/cold aisle, air-side economisation
Airflow
Blanking panels, containment, floor seal
Power
Efficient UPS topology; eliminate headroom
IT equipment
Modern servers; virtualisation density
Setpoint
Allow higher inlet temp within ASHRAE band
Workload
Shift to lower-PUE regions where possible
Worked example - PUE improvement forecast
Year
Actions
New PUE
Today
Baseline
1.65
Year 1
Containment + airflow audits
1.50
Year 2
Economisation + setpoint raise
1.40
Year 3
UPS replace + virtualisation
1.30
Beyond PUE
Metric
Name
WUE
Water Usage Effectiveness
CUE
Carbon Usage Effectiveness
ERE
Energy Reuse Effectiveness
PUE alone misses water and carbon. Mature operators report all four.
Mentor’s tip: PUE = total / IT. Global average ~1.55; hyperscale ~1.10. Containment + airflow + setpoint are the cheapest wins. Track WUE, CUE, and ERE alongside PUE for the full picture in the tropics.
Discussion
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