Nerval's Lobster writes that a survey from the Uptime Institute "suggests something it calls 'green fatigue' is setting in when it comes to making data centers greener. 'Green fatigue' is exactly as it sounds: managers are getting tired of the increasingly difficult race to chop their PUE, or Power Usage Effectiveness. The PUE is a measure of a data center's efficiency. The lower the PUE, the better — and Microsoft and Google, with nearly limitless resources, have set the bar so high (or low, depending on your perspective) that it's making less-capitalized firms frustrated. Just a few years ago, the Uptime Institute estimated that the average PUE of a data center was around 2.4, which meant for every dollar of electricity to power a data center, $1.4 dollars were spent to cool it. That dropped to 1.8 recently, an improvement to be sure. But then you have companies such as Google and Microsoft building data centers next to rivers for cheap hydroelectric power in remote parts of the Pacific Northwest and reporting insanely low PUEs (below 1.1 in some cases). The Institute latest survey of data center operators shows only 50 percent of respondents in North America said they considered energy efficiency to be very important to their companies, down from 52 percent last year and 58 percent in 2011."