The Amazing Waste from Turning Off Computers Each Night

I saw an article that illustrates why it's good for me to teach students about economic cost as opposed to raw accounting cost:

I leave my laptop running overnight because I know it'll take five minutes or more to get things going in the morning -- not just booting up, but launching the various apps I start the day with, downloading my overnight email, filtering out the spam, and otherwise "getting settled."

But all the power wasted while computers are sitting idle overnight adds up, and one study has finally tried to measure it. The tally: An estimated $2.8 billion wasted on excess energy costs each year in the U.S. alone....

The full report is available for download here (scroll down to "PC Energy Report US 2009")....

If you run a company with 1,000 PCs left on overnight, you can save about $28,000 a year if they are turned off after hours. That's not chump change.

One advantage of the economic way of thinking is that it makes one think of a question here. Why are companies so stupid as to not mandate that their employees turn off computers, if companies could save so much money? The economist naturally wonders if there is something that high-paid corporate executives know that the journalist is missing.

Let's do the full calculation. 1000 PCs * 5 minutes of employee time * 200 days per year * $60/hour or $1/minute = $1 million/year saving from leaving the computer on all night. That compares with $28,000 in energy savings costs.

You can adjust my numbers if you think they're wrong. Suppose its only 1 minute of employee time that it takes them to boot up, 100 days per year that they work, and $6/hour that your company pays them. Then the benefit in labor costs from leaving on the computers is only $100,000 per year, a mere four times the extra cost in electricity.