By Toby Velte, Anthony Velte, Robert C. Elsenpeter, McGraw-Hill |  Green IT, energy consumption

This excerpt is from the book Green IT: Reduce Your Information Systemâ€™s Enviornmental Impact While Adding to the Bottom Line , by Toby Velte, Anthony Velte, Robert C. Elsenpeter.Â

Initial Improvement Calculations

Letâ€™s say youâ€™re overweight and one day you decide, "Thatâ€™s it. Iâ€™ve had enough. Iâ€™m losing weight tomorrow!" For the next 6 months you eat right, you exercise, you get plenty of rest, drink lots of water, and the weight is just pouring off. Itâ€™s coming off so nicely that a friend comes up to you and says, "My gosh, you look great. How much weight have you lost?"

It feels good to have lost weight, but because you didnâ€™t step on the scale for a starting weight, you have no idea how much weight youâ€™ve lost.

Itâ€™s the same way with greening your organization and IT department. If you donâ€™t know how much power youâ€™re consuming, you wonâ€™t be able to compare it to results as you proceed. But unlike someone who has lost weight, itâ€™ll be harder to see the benefits of your efforts. True, you can compare electrical bills from when you started to when you finished, and youâ€™ll see results there, but you can also take advantage of other opportunities to track your progress.

Selecting Metrics

Thereâ€™s a lot you can measureâ€”and a lot of it isnâ€™t even that difficultâ€”to see you how youâ€™re doing in your efforts to go green. Letâ€™s take a closer look at the metrics you can use.

Power Usage Effectiveness and Datacenter Efficiency

Two metrics have recently been introduced that help measure data center efficiency: Power Usage Effectiveness (PUE) and Datacenter Efficiency (DCE). PUE is defined as

PUE = Total facility power/IT equipment power

whereas DCE is defined as

DCE = IT equipment power/total facility power

Total facility power is the power as it is measured at the meter for the datacenter. IT equipment power is defined as the power needed to manage, process, store, or route data within the datacenter.

This excerpt is from the book Green IT: Reduce Your Information Systemâ€™s Enviornmental Impact While Adding to the Bottom Line , by Toby Velte, Anthony Velte, Robert C. Elsenpeter.

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