Monday, July 16, 2007

Understand your Electricity: Vampires Part 2

I just read yet another site that recommends that we unplug our electronic appliances: this writer claimed that 75% percent of household energy use goes to power items in standby mode—the site credits the Department of Energy of all places. Considering that according to the most recent Energy Information Administration figures available (2001), all household electronics—TVs, stereos, computers, peripherals, everything—accounted for just 7% of U.S. household electricity use, that number is not just incorrect but utterly insane.

The writer may have wanted to claim that 75% of the total power use of our electronics is used to power items on standby—that could be true: is your printer on all day? how much time do you spend printing? Is your VCR on right now? Is anyone watching it? So we could probably cut a significant proportion of that 7% by shutting these items down.

But let’s get a little proportion. Here are a few numbers from my trusty Kill-a-watt to cut through the green haze we are living in.

The computer system I am currently writing at includes the following components all plugged into a single power strip:
Apple desktop
cable modem
HP printer
external hard drive

That entire system uses between 90-115 watts of electricity, including when I am printing. Starting up, the whole system draws about 105 Watts. The printer draws 21 watts on standby and 27 watts when it is starting up. The cable modem, which many people leave on all the time, draws 7 watts.

That is to say, my whole computer system uses about the power of a single 100 watt bulb or 1.5 60 watt bulbs.

My Energy Star Air-conditioner uses between 700 and 1000 watts whenever it is cooling. It saves energy by alternating its cooling mode with a 0-watt low-energy mode.

As I noted in my previous "Vampire" post, unplugging standby appliances might save you about 72 kWh a year. Turning off your window air-conditioner could save you twice that each week. A central system running at full blast uses 3.5 kWh every hour.

The problem with the internet is that this misinformation tends to take on a life of its own: how many internet start-ups were funded because of the widely repeated but utterly baseless factoid that the number of people on the internet was doubling every three months?

Standby power is a problem on a national not a household scale. Its real solution is efficiency standards. It makes much more sense for the government to revise the codes to minimize standby power draw than for individual consumers to have to research the power use of a dozen electronics that use only a few watts each, or for them to have to walk around turning them off--something that only a small number of people are ever going to do.

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