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Read here about Koomey's law, an invariant scaling factor relating computing power to energy consumption across 16 orders of magnitude.


Koomey's law, focuses on energy use in relation to computing cycles. Koomey’s Law states that the amount of power needed to perform a computing task will fall by half every one and a half years.

This description of improving energy efficiency was the conclusion of an analysis published in the IEEE Annals of the History of Computing 2010 with the title “Implications of Historical Trends in the Electrical Efficiency of Computing.” Jonathan G. Koomey, a consulting professor at Stanford University, collaborated with three Stephen Berard of Microsoft, Maria Sanchez of Carnegie Mellon University, and Henry Wong of Intel. (Mr. Koomey did not use the term “Koomey’s Law,” but others have.)

The analysis of the Koomey team goes back to 1946 and the Eniac, when computers used vacuum tubes rather than semiconductor chips, and traces the progress of computing energy-efficiency through 2009.

Koomey’s Law depends on Moore's law, as smaller circuits use less energy to accomplish the same computing tasks.

Koomey's Law Diagram


The chart shows computations per kilowatt hour (kWh) per time (1940-2010). The chart includes Eniac, EDVAC, Univac, DEC PDP, IBM PCs, up to 2009 laptops.