Computes Power Usage Effectiveness (PUE) — the ratio of total facility energy to IT equipment energy — and its reciprocal, DCiE, from a measured energy period (e.g. a month or a year). Breaks out the non-IT 'overhead' energy (cooling, power distribution losses, lighting, etc.) and its estimated cost, and classifies the result against the commonly-cited Green Grid PUE efficiency scale.
Standards followed
ISO/IEC 30134-2 (PUE metric definition & measurement methodology)The Green Grid PUE/DCiE white paper (originating definition)
What it can do
- PUE = Total Facility Energy / IT Equipment Energy.
- DCiE (%) = 1/PUE — the reciprocal, expressed as IT equipment's share of total energy.
- Non-IT overhead energy and its estimated cost at a given electricity rate, over the same measurement period as the inputs.
- Efficiency-band classification (world-class to very inefficient) against the commonly-cited Green Grid PUE scale.
Example problem
A data center measures 1,500,000 kWh total facility energy and 1,000,000 kWh IT equipment energy over a year, at $0.12/kWh.
- PUE = 1,500,000 / 1,000,000 = 1.50.
- DCiE = 1/1.50 = 66.67% — the IT equipment consumes about two-thirds of total facility energy.
- Overhead energy = 1,500,000 − 1,000,000 = 500,000 kWh, or 33.3% of the total.
- Overhead cost = 500,000 kWh × $0.12/kWh = $60,000 for the period.
PUE = 1.50, DCiE = 66.67%, $60,000 of overhead energy cost for the period — classified as 'Moderate' on the Green Grid scale.
Want the full step-by-step version?
The efficiency bands (world-class <1.2 through very inefficient ≥3.0) are the commonly-cited informal Green Grid scale from its original 2007 guidance, not a formal ISO/IEC-mandated classification — ISO/IEC 30134-2 standardizes the PUE metric and measurement methodology itself, not efficiency bands. Enter total facility and IT equipment energy over the same measurement period and metering boundary for a meaningful result.