Tuesday, July 17, 2007

Understand Your Electricity: Sleeping your work Computer

From the Alliance To Save Energy

New Report Highlights the Power of Powering Down

A new report on personal computer usage and power consumption released this month suggests US business could be saving billions of dollars simply by shutting down machines at night. The survey, commissioned jointly by the Alliance to Save Energy and power management software company, 1E, found that nearly half of all corporate computers (roughly 31 million PCs) are not regularly switched off at night. According to the study, this lack of inactivity is costing US businesses $1.72 billion annually and adding over 14 million tons of carbon dioxide to the atmosphere per year.

Comment: pulling out my handy calculator, and borrowing a few PC numbers from Mr. Electricity, we can estimate that an average workplace computer uses about 100 watts just sitting there. The Alliance estimates that as many as 31 million PCs are left on at night. Forgetting about weekends, let's assume each of these is on instead of off or asleep for 10 hours every day, four nights a week; each one would thus waste 1 kWh per day, or 208 kWh per year. For 31 million computers that adds up to more than 644 million kWh per year, or a year's electricity for 586,181 homes. (Using my 11,000 kWh/year average). Each computer that is left on for 60 hours over the weekend wastes another 312 kWh per year. If 15 million of these were left on over the weekend year round, they would waste more than 4.68 billion kWh, or enough electricity to power more than 4.25 million homes.

Let's hope that these companies are sensitive to the other green, cost: according to the EIA, the average commercial cost for electricity this year is 9.28 cents/kWh. Using my numbers, each computer left on overnight during the work week wastes about $19 a year and each one left on over the weekend wastes another $30 a year.

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