I have an inexpensive networked laser printer (Brother HL-2070N). Other than occasional paper misfeeds it's a decent printer. It's ultra-fast and the consumables are inexpensive. Since it's networked, it's plugged into my wireless router. As long as the printer is on, anyone on the wireless LAN can print. The printer has a low-power "sleep" mode in which it draws minimal power and is ready to print.

But how much does it cost to let this laser printer "sleep" for one year? If it's too much I'll turn on the printer when I need to print, and leave it off otherwise. But having the printer always ready to print would be a major convenience. According to the manufacturer the printer draws 7 Watts when asleep. Here are my yearly cost calculations:

7 Watts * 1 Kilowatt/1000 Watts * 24 hours/day * 365 days/year = about 61 Kilowatt hours / year

According to my latest utility bill, last month I paid $46.15 for 542 Kilowatt hours, so 1 Kilowatt hour costs about $0.09. The yearly cost to let this printer sleep is about:

$0.09 / Kilowatt * 61 Kilowatt hours / year = about $5.50 / year

$5.50 seems like a reasonable cost for the convenience, so I'll leave the printer on in sleep mode. Also, I should mention that I had the printer on the same power strip as my desktop computer. Consequently, every time I turned on that computer, the printer went through its full power-up sequence which I'm sure consumed a lot of electricity.

I've ordered a Kill-A-Watt to measure electrical consumption. I've heard that many appliances consume significant amounts of power while "asleep". After the Kill-A-Watt's delivered I'll be able to check out my electrical devices myself.