What percentage of electricity used to power IT equipment is typically converted into heat?

Question

Options

• A85%
• B90%
• C95%
• D99%

• A
  12% (4)
• B
  3% (1)
• C
  6% (2)
• D
  79% (27)

Explanation

Option D (99%) is correct because electrical energy consumed by IT equipment follows the first law of thermodynamics: virtually all of it is ultimately dissipated as heat. Whether energy powers processors, memory, or storage, the work performed at the transistor level generates heat through resistance and switching, meaning almost none of the input energy escapes as light, sound, or other forms in any meaningful quantity. Options A (85%), B (90%), and C (95%) are incorrect because they significantly underestimate the conversion rate - these figures might seem plausible but reflect common misconceptions about how much useful "work" escapes the system in non-heat form, which in practice is negligible. For the exam, remember the phrase "electricity in, heat out": IT equipment is essentially a very expensive space heater from an energy perspective, and the 99% figure is the standard used in data center thermal planning and efficiency standards such as those from ASHRAE and the Green Grid.

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