The weeks energy data has been collected and the results posted in our article Energy Saving for a Laptop Computer We do encourage you to read it. Like us, you may be surprised at how energy efficient a recently purchased, energy star rated, laptop computer actually is.
We are examining the energy costs and energy savings opportunities of typical home office. As we wait for a weeks data (having applied our energy savings tips) to be collected, I thought we could post why "putting a laptop to sleep" saves energy over even the most stringent power settings.
The image to the right shows the energy profile of my original (default) power settings. Screen saver (bubbles) after 5 minutes of inactivity, display off after 15 minutes, and sleep after 25 minutes.
We discuss the energy to be saved by adjusting the default power management settings in the posting Energy Saving for a Laptop Computer This includes adjusting the screen brightness, removing the screen saver, and reducing the time elapsed for the power settings to invoke.
Although I am a fairly disciplined home worker, and my wife respects the office as if I was at work, there are times each day when I stop using the computer. They include the restroom, coffee, lunch, tea, more coffee, wife emergency, TV alert and such ...
When updating the power settings I noticed that I could set the function of the power button to invoke sleep mode. I must admit I was a little surprised to find how well it worked. One press and my laptop was asleep, one press and it woke up again, almost instantly and right where I was.
The energy saving is not challenging! Engage finger, press power button once, and then take break ....
It turns out that I get an average of 10 such opportunities each day. To be conservative, and recognizing that the breaks can be brief, I have limited the calculation to 20 minutes per break.
1) 5 minutes of inactivity @ 31 Watts = 9,300 Joules
2) 10 minutes screen saver @ 42 Watts = 25,200 Joules
3) 5 minutes display off @ 15 Watts = 4,500 Joules
Saving per manual sleep instance 38,800 Joules
10 times per working day, 5 days per week, 48 weeks = 25.87 Kwh
Cost saving using 11,5cents per Kwh = $2.98
If we use 20 million home office small business users, and assume most users have the default power settings in place, we could save 59,6 million dollars of domestic electricity each year.
Makes you think? It certainly gives new meaning to the idea of lifting a finger to help!
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