The Power Office

How much energy does your home office actually consume? That’s what I tested with the help of a little gadget called the Kill-A-Watt. It’s a simple device that plugs into your wall outlet; plug your Mac and peripherals into it, and it’ll tell you how much electricity they’re pulling. So one Sunday, I plugged it in and then went about my usual business. You’ll see the results in the table below.

To give its readings some context, I then multiplied those energy readings by the numbers of hours in a year and the cost per kwh from my last electrical bill. The Mac mini, when in active use, consumes about 3 watts. Multiplying that by my cost per kilowatt hour and the hours in a year yields an overall cost of $25.20 per year.

That figure is, of course, inflated: It's based on running the devices in “active” mode 24 hours per day, 365 days per year. So none of them reflect actual usage patterns; they're for the sake of comparison only. Still, they should give you some idea about how energy-intensive your various peripherals and Macs can be.

Home Office Power Consumption

Product Watts Consumed Cost per Year
Off Sleep In Use In Use
Mac Mini/1.66 GHz 1.0 2.0 29.7 $25
Mac Pro/2.66GHz 4.0 7.0 237.0 $201
Power Mac G5/2.0GHz 1.0 13.0 157.1 $134
MacBook Pro 15-inch Core 2 Duo/2.16GHz 1.0 2.0 23.5 $20
PowerBook 12-inch G4/1.33GHz 0.5 1.0 15.8 $13
Brother laser printer 0.0 8.0 750.0 $637
Brother multifunction printer 1.5 4.0 10.0 $8
Canon Pixma ink-jet printer 0.0 3.0 14.0 $12
Apple 23-inch Cinema Display 2.0 3.0 35.7 $30
Sony 20-inch LCD 0.0 3.0 33.0 $28
Netgear Internet router 0.0 N/A 3.2 $3
Apple AirPort Extreme Base Station N/A N/A 6.0 $5
Netgear Fast Ethernet switch N/A N/A 3.5 $3
Yamaha speakers (desk) 1.0 1.0 3.0 $3
Yamaha speakers (subwoofer) 2.0 2.0 6.0 $5
LaCie 500GB Big Disk (over FireWire 800) 0.0 19.0 22.0 $19
Maxtor 200GB 5000DV
(over FireWire 400)
0.0 11.0 13.0 $11
Epson Perfection 1660 scanner 1.0 3.0 14.0 $12
Desk lamp
(compact fluorescent)
0.0 0.0 22.0 $19
Paper shredder 0.0 3.5 134.0 $114
Sony PlayStation 2 0.0 1.5 17.0 $14
TOTALS 17.0 90.0 1581.6 $1,317

N/A = not applicable. For "active" Mac tests, the Flurry screen saver (with default settings) ran for an hour or so. The paper-shredding test consisted of shredding one 8.5-by-11-inch page.The printing test consisted of printing one 8.5-by-11 page from a browser; the cost is based on a rough average of watts used to print. The hard-drive test consisted of copying a large file and noting the watts used; sleep means "not doing anything."

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