Thursday, 21 June 2007

To Kill-A-Watt or Not?

So last week I posted about some of the things we've been doing to ease up on our energy consumption, etc. One of the things was to unplug assorted appliances, lamps, radios when they were not in use. I wanted to get some hard data on how much electricity this would save, because I have to admit, going around unplugging things was not very convenient, but I would keep doing it if it were to make a reasonably significant reduction to our energy use.

I had heard about a gadget, the Kill-A-Watt, you could buy to measure how much power something was using while it was turned off, but still plugged into the electrical outlet. But in the spirit of not buying something I don't really need, I asked my dad if there was an alternate way to measure this type of power usage. He said yes there was, and promptly retrieved the pictured gauge and plugger-inner thing to show me how.

The gauge measures volts and amps and stuff. First, you plug the stripped wire cord into the outlet and then plug your electrical device into that. Then, with the gauge turned on to measure Amps, you open the caliper thing and close it around the black or white wire to measure how many amps are flowing. Then, since Watts = Volts X Amps, and the typical voltage of a North American electrical outlet is 120 V, you can easily figure out how many Watts are being used.

Here are some of the measurements I took while these appliances were turned off:

Amps Watts

TV combo

0.15 18.00
0.00 0.00
Cell Phone Charger
0.00 0.00
Phone/Fax combo
0.09 10.80
Ikea Lamp
0.00 0.00
0.00 0.00

0.02 2.40
0.06 7.20

So from this experiment I can stop worrying about unplugging the toaster and the cell phone charger, and I don't need to get too worked up about the microwave either, I don't think. But what about the biggest of these power leeches, the TV/VCR/DVD combo?

According to the gauge and cord device, the trio were using 0.15 Amps. To find out the wattage as noted in the chart, I multiplied this by 120 Volts to get the listed 18 Watts. To obtain kiloWatts I divide by 1000 and get: 0.018 kW. So lets say I leave the TV combo off, but plugged in, for 24 hours. This results in the usage of 0.018 X 24 hours = 0.432 kWhs of power. If I did this for the entire month of June I would use 12.96 kWh of power. According to my last electric bill, we are paying about 10.22 cents per kilowatt hour. So the TV combo will cost me 4.4 cents per day to leave it plugged in, or $1.32 per month. It costs more as soon as I turn the TV on, of course.

So is unplugging the TV worth saving a maximum of 13 kWhs of electricity per month, or 155 kWhs per year? That translates, at current electricity prices, to about 16 bucks a year? I'm not sure. At most I would unplug it overnight, which would save us, say, 12 hours of power leeching a day, or about 2.2 cents. It seems like it would be worthwhile to unplug things like the TV and computer combos when we go away on a trip or something, but probably not when we are home everyday. I think I can make more of a difference by just not turning on the TV or the computer as much!

1 comment:

Lori said...

This is neat Theresa! I had no idea that things still used energy when they weren't on!