Do you turn off your Mac at night?
Posted by Dennis Sellers 
Jun 20, 2007 at 6:45am
Do you turn off your Mac at night? I don’t; after all, that’s when the good gremlins do the under-the-hood maintenance. But, according to a new survey, maybe I should put ‘me on a different schedule and power down my Mac.
According to a survey released this week by 1E (a provider of power management software) and the Alliance to Save Energy (a coalition of businesses, government, environmental and consumer leaders), nearly half of all corporate computers in the US are not regularly switched off at night. This means a conservative estimate of 31.2 million work computers are being left on overnight; wasting energy, spewing carbon emissions into the air, and costing US businesses $1.72 billion to supply power to machines that aren’t even in use.
The folks at 1E and the Alliance to Save Energy say that all these computers being left on overnight are also needlessly pumping 14.4 million tons of carbon dioxide (CO2) into the atmosphere. According to recently released PC Energy Awareness report, preventing that amount of CO2 from reaching the atmosphere would have roughly the same impact as taking 2.58 million passenger cars entirely off the road—more cars than exist in the entire state of Maryland (2.48 million cars).
The data shows that American businesses are wasting energy while we sleep. A mid-sized company, which includes about 10,000 computers, wastes more than $165,000 a year in electricity costs for computers left on overnight, according to Sumir Karayi, chief executive officer, 1E. In addition, by turning these computers off, an employer can keep more than 1,381 tons of CO2 out of the atmosphere, he says.
According to the report, some people assume their IT departments need their machines to be left on overnight in order to deploy security patches and software updates. Others believe an on-board “sleep” or hibernation mode kicks in—which isn’t usually the case. And, an alarming number of respondents admitted that they just don’t care. The study says that:
° Energy costs—typically 10 percent of the corporate technology budget—could rise to as much as 50 percent in the next few years.
° Power management software can reduce a computer’s power consumption by 80 percent, allowing companies to save $25-$75 per desktop computer. Beyond automated shut-down, power savings are derived during the day by automating monitor shut-off after a period of inactivity.
The Macsimum News headquarters hardly has 10,000 computers. But we have a few, and I’m certainly interested in helping the environment. So maybe I should consider powering those Macs down at night.

Thoughts? Write me at daseller@earthlink.net
CHO Says:
My only computer is my laptop and I leave that on at night. By “leave on” I actually mean it’s in sleep mode.
Posted on June 20, 2007
Ken2 Says:
I also run Folding @ Home most of the time - I only turn it off during the day if I’m working on pictures. Between folding and system maintenance I get value from the system running all night, but I do turn the display on the iMac off.
Posted on June 20, 2007
Cjj Says:
It has been over twelve years since I had a Microsoft network IT guy (help desk or troubleshooter) NOT yell at me if I turned off a work PC!! This is at three different major IT companies, USAF and US Army bases. Once, during prep for a test in 2004, one of the IT guys shut down the “test” network of 200 various PCs for the weekend and it took almost two weeks to get it back up and stable enough to run the preliminary test. My Unix experiences are all with Sun, Silicon Graphic and other workstations and mainframes that had people working in shifts, although some of the small labs of 6 to 15 workstations and a mainframe would be shut down for long holiday weekends.
Posted on June 20, 2007
Brett Johnson Says:
I rescheduled my /etc/periodic cron ^H^H^H^H launchd jobs to go off at lunch time rather than the middle of the night. But I don’t shut my machines down at night. I put them to sleep. This preserves all my working state.
Posted on June 20, 2007
ToWS Says:
Switching off alone is not enough.
Forget the power used by the computer; consider the wall-mounted power supplies that nearly every peripheral uses. On standby they consume a tiny amount of power, say 1 watt. The amount of electricity used is so small it doesn’t even figure on the electriciy bill.
But then consider just how many of them there are, each wasting ‘just’ one watt.
Here in the UK we have 50 million people. If each person leaves just one piece of equipment on standby that’s 50 MegaWatts simply wasted. That’s a whole, large, power plant’s worth of pollution for absolutely nothing.
Shut down and UNPLUG everything that you’re not using.
Posted on June 20, 2007
David Says:
A few months ago our local power company held a one day “turn it off” event to show people how easy it is to save money and do something for the environment. All in all it was a big success and hopefully changed a few bad habits.
Ironically, a TV news crew drove to the power company’s headquarters at 2:30am where a high percentage of the lights were on and several computer displays could be seen shining brightly through the windows.
Sadly it would take hundreds of people making small changes like unplugging their power bricks to make up for the waste in that one office alone.
Posted on June 20, 2007
Neil Anderson http://www.cyclelogicpress.com Says:
I put my laptop into sleep mode overnight. How else would I be able to brag about getting over a hundred days of uptime between reboots? :)
Posted on June 24, 2007
Martin Says:
I never leave my mac switched on, why Climate Change! Its the absolute minimum I can do to reduce my energy use and greenhouse gas emissions. I’ve just bought a new imac and its interesting that the hand book says “If you wont be using your imac for more than a few days, shut it down”.
I have my TV, VCR and DVD plugged into a power board with a built in master switch. This gets turned off when ever the TV set is switched off so that we don’t use energy for clocks or stand by modes.
I also always turn off my work PC which is encouraged in my work place. We have a work environment group which does checks from time to time and leaves chocolate bars for those who do the right thing.
Posted on June 29, 2007
Hendrik Says:
I think you can just put your mac to sleep if you want to. When my iMac sleeps it consumes 20 Watts. When I turn it off it consumes the same! (I measured this using one of those devices.)
One of the reasons the iMac still consumes 20 watts is that nice fancy power switch, it needs power by itself, I guess. My old Mac plus has an button that takes some muscle to operate, at least the plus can be left in power socket without consuming energy.
I think Apple should not put in its manuals that you should turn off your Mac when this has no effect whatsoever. What a waste of paper.
Posted on July 06, 2007
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Dennis Sellers
Dennis has been a newspaper editor/reporter (seven years) and teacher (seven years). He has over 4,000 magazine, newspaper and online articles to his credit. He has also covered the Mac and tech industries for over a decade for such online publications as MacCentral, MacMinute and now MacsimumNews.
Frank Petrie Says:
I leave my Mac on at night. But it’s not sitting there idly. I have it working on the Folding @ Home project.
If these corporations insist on leaving their computers on all night, they could at least working on such projects?
Posted on June 20, 2007