Sleep your PC to Save Energy

Personal computers account for about 1% of the total carbon emissions in the world according to the PC Energy Report 2009. Almost every family in the US has at least one computer at home and the sad fact is that most of the electricity used by computers at home is wasted.  Not because the computer is inefficient or an energy hog, but rather because it sits idle most of the time.  This is especially true for computers at home which are used by one or more parents that work outside the home and kids that go to school for a good chunk of the day.  If your computer is on when no one is using it, then it is wasting energy.  Fortunately you can do something about it and modern computers make it really easy to set once and then save energy without having to think about it.

Do Once Sidebar!
I am a big fan of things that you can configure once and then not have to think about again.  I find them far more effective at saving energy because you can’t forget to do them or consider them not worth the effort at some later point.   I put configuring PC power management at home in the set and forget category.  In GLC we are labeling those as “do once.”

To enable PC power management on your home computer, follow the instructions at the Energy Star web site.  About half way down the page you will find individual instructions for Windows 2000, Windows XP, Windows Vista, and Macintosh.  Or you could use the EZ Wizard.  Energy Star even provides an Excel spreadsheet to estimate your energy savings, though I think it may be a bit too aggressive in estimating savings. 

I suggest starting with the following settings and tweak them to until they work for you:

  • Sleep/Standby after idle: 15 minutes
  • Display sleep after: 10 minutes

The right settings are the ones that work for you.    It is far better to have a longer time to sleep than to disable PC power management.  I also prefer using the sleep/standby setting for desktops and laptops because they power up much faster, a few seconds compared to a few minutes.  Another tip is to use hibernate for a laptop if you are not going to use it again for at least 4 hours to save on battery life.

I’ve measured how much power computers consume with my kill-a-watt, for example, my Dell Optiplex 745 desktop uses 2-3 Watts (W) powered off and the same in Standby.  The reason most PCs still use a few Watts when off is that they continue to provide power to the network card (NIC) so that the computer can be remotely administered through various protocols like Wake-on-LAN.  Only extreme techies use that on their home computers.

To use the savings calculator from the Energy Star site, download and open the Excel spreadsheet.  You fill in your information on the “Start Here” worksheet.  Be sure to select your state and switch it to “Residential” to get a more accurate estimate for $ savings.  Then go to the “Results” worksheet.

According to the spreadsheet, for a single desktop computer in Massachusetts, you could save just under $90 per year when switching from never turning the computer off to using the settings above.  I think that estimate is about double what you could realistically save and I’ve calculated it for my machine to be about $40 per year more that it would be costing me if I left it on all the time.

Regardless of how much or how little you save, with a few minutes of time, you can avoid wasting electricity and still have your computer ready to use within seconds.

A couple caveats for those using computers as DVRs or providing services that need to be accessible remotely.  If you don’t know what I’m talking about, you probably don’t have any of these to worry about. These systems typically need to be on all the time to record shows and so forth, so be careful when considering power management on these systems.  Also, before making changes at work, please check with your IT folks.

You can go even further by using a smart strip to automatically power off your peripherals when your computer goes to sleep, but that is a topic for another post.

Happy Greening,

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