Five Percent: Conserve Energy

Climate Change Is Important: Energy Conservation is the First Step

September 14, 2008

Two More Big Electricity Savings (Thanks, Apple!)

Category: Conservation,Green Reviews,Save Electricity,Technology – Tom Harrison – 7:22 pm

Apple\'s Time Capsule

Apple's Time Capsule

Do you have a computer that runs all the time to be a “server”? If so, you’re a geek like me. But you’re also using more electricity than I bet you know. In fact, I calculate I will save $160/year in electricity expenses by replacing my PC with Apple’s Time Capsule.

We have a Windows PC setup in our broom closet. It holds a bunch of files; our pictures, digital music, backups, and other stuff we all use. It’s also a shared printer server. Finally, it runs a bit of software that works with several “Squeeze Boxes” that let us play our digital music on the kitchen radio, and in our living room and outside patio. There’s a small monitor, keyboard and mouse which are needed when updating the machine. We also have our wireless network router in there.

The only problem: when all of this stuff is on, my Kill-a-Watt meter shows that it uses 108 Watts of electricity. And it’s on all the time. No wonder the closet is so hot!

Apple to the rescue! We bought a Time Capsule, which is a terribly named thing, if you ask me. It’s actually: a wireless router, a 500GB (!) hard disk, a print server, and, get this, it can even let us play music from our music library in our kitchen and living room.

This single box uses only 12 watts when idle (18 when the hard disk is in use), and it can replace the computer and exiting wireless network router. All this in an elegant 8-inch square, 1-1/2 inch high case. And, it’s silent.

Net reduction of power: 96 Watts, 24 hours a day. So that’s 2.3 kWh saved every day, which at our rate of $0.19/kWh is 44 cents a day. So what, you say? That adds up to $13/month, or $160 per year saved.

Kill-a-Watt Meter

Kill-a-Watt Meter

The Time Capsule costs $300, so the payback period is a couple years. Except: I can sell my PC for $200, the monitor for another $50, and the router for another $30 on EBay. So, effective payback period: a couple months :-)

We can now store brooms and other things in our broom closet, and the house will be just a little bit quieter.

I can sell my SqueezeBox (wireless music player) and get an Apple AirPort Express (which also extends the wireless network and can be a print server too); I think the net cost here should be very small. I doubt there will be a significant energy use difference, maybe a bit less.

Our PowerCost Monitor (which measures all the electricity we use) reports that we’re using about 400 Watts of power … when everything is “off”. This is the sum of all of those “standby” modes, vampire transformers, phones, clock, cable box (well, TiVo, actually) … and the whole computer setup. So this represents about one quarter of our standby use.

Which, of course, makes me wonder, what other things are sucking up the other 300 Watts?!!


  1. Tom, have you figured out what’s using the 300 watts? Recently I knew some electricity was going somewhere. Discovered a cat had stepped on an outlet strip and turned on a computer and monitor that I rarely use.

    Comment by Paul Lambert — September 18, 2008 @ 8:38 pm

  2. Paul —

    Ah, it’s the old “the cat did it” theory! My cat prefers leaping down on the power strip of the computer I am using and turning it off (we’re all very energy conscious in our house :-)

    No, I haven’t yet found all the other things soaking up all those watts. But I am on the hunt. And if I find the cat is responsible, the fur will fly.

    Thanks for the great tip, Paul. I needed a little levity today.


    Comment by Tom Harrison — September 18, 2008 @ 9:16 pm

  3. Chime in 2+ years later….. In my experience it just couldn’t pull it off.

    My ultimate solution was a MacMini Server (MacMini would work) Idle power usage under 10 watts never observed more than 25 watts. I have mine set to sleep if no activity for 5 min and wake on lan activity. Power consumption while asleep 1.18 watts. And moving 30GB only takes a couple of hours not an entire day. It also acts as my Access Point/Router. The performance is significantly better and the additional power consumption minimal if any over time.

    Comment by Hamlin — January 20, 2011 @ 3:31 am

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