Equation 12 · Part 10 · The Physical Plant: Power, Cooling, and Networks in an AI Datacenter

Numerator: E_cooling + E_distribution + E_other

\mathrm{PUE} = \frac{E_{\mathrm{facility}}}{E_{\mathrm{IT}}} = 1 + \frac{E_{\mathrm{cooling}} + E_{\mathrm{distribution}} + E_{\mathrm{other}}}{E_{\mathrm{IT}}}.

E_{\mathrm{cooling}} + E_{\mathrm{distribution}} + E_{\mathrm{other}}

What this part means

The complete quantity above the fraction bar.

Its job in the formula

$E_c$ ooling + $E_d$ istribution + $E_o$ ther occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Full expressionNumerator: E_cooling + E_distribution + E_otherArticle meaning

The passage around this formula

Power usage effectiveness is the industry’s one universally reported number: $\mathrm{PUE} = \frac{E_{\mathrm{facility}}}{E_{\mathrm{IT}}} = 1 + \frac{E_{\mathrm{cooling}} + E_{\mathrm{distribution}} + E_{\mathrm{other}}}{E_{\mathrm{IT}}}$ . Uptime Institute, which has collected the metric since its introduction by The Green Grid in 2007, reported a weighted average annual PUE of 1.54 across its 2025 respondent sample, “marking the sixth consecutive year that this headline figure has virtually stood still.” Beneath that flat average the sample separates: facilities commissioned within five years of the survey averaged 1.48, facilities of 20 MW and above averaged 1.44 globally, and 15% of respondents reported 1.3 or better [ 3 ] . Google, disclosing its own fleet, states that “in 2025, the average annual power usage effectiveness for…

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Learn the underlying idea

A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.

Open the illustrated fractions: division written vertically guide →

Sources cited in the surrounding passage

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