After learning it costs about $14.00 USD per month to run a bare-bones PowerMac G5 (that’s $170/year!), I have been thinking of how to minimize electricity costs at the abode.

According to Apple, a dual 1.8 Ghz G5 Idles at 140W. That’s like keeping a very powerful light bulb on all day.

I estimate that electricity costs about 8¢/kwh. There are 24 * 30 = 720 hours per month, translating to 720/1000 * 8 = 5.76 ¢ to run a 1W device continuously for a month.

Thus in the case of a G5, averaging say a meager 180W of usage: (180 * 5.76)/100 = 10.368, or roughly $10 per month. If you are good at keeping your processor busy, then perhaps the G5 consumes 250W, equivalent to (250 * 5.76)/100 = 14.4, or $14 dollars a month.

So as you can see there we should all have some concern for device power consumption, as running a “tight ship” should yield lower energy bills, and more money in the pocket to take to the local Mac store.

At the moment I am running a web server from home on an older 667 MHz PowerBook G4, which supposedly idles at 18W. The cost of keeping this running all the time is roughly 18*5.76/100 = 1.037, or a paltry $1.00 a month, at least a 10-fold savings over the desktop.

Interestingly, it seems someone’s MacMini draws a similar 25W as a laptop, showing its efficiency as a home device.

This page lists wattage estimates of various common electrical equipment. Notably, an HP Inkjet printer idles at 4W.