A: Stanford, California, United States

3/2011

Energy and environmental scientist Jonathan Koomey of Stanford University, and Stephen Berard, Maria Sanchez, and Henry Wong published “Implications of Historical Trends in the Electrical Efficiency of Computing” *Annals of the History of Computing*, **33**, no. 3, 46-54. This historical paper was highly unusual for its enunciation of a predictive trend in computing technology labeled by the press as “Koomey’s Law.”

“Koomey’s law describes a long-term trend in the history of computing hardware. The number of computations per joule of energy dissipated has been doubling approximately every 1.57 years. This trend has been remarkably stable since the 1950s (R2 of over 98%) and has actually been somewhat faster than Moore’s law. Jon Koomey articulated the trend as follows: ‘at a fixed computing load, the amount of battery you need will fall by a factor of two every year and a half.’

Because of Koomey’s law, the amount of battery needed for a fixed computing load will fall by factor of 100 every decade. As computing devices become smaller and more mobile, this trend may be even more important than improvements in raw processing power for many applications. Furthermore, energy costs are becoming an increasingly important determinant of the economics of data centers, further increasing the importance of Koomey’s law” (Wikipedia article on Koomey's Law accessed 11-19-2011).