Peter was nice enough to loan me a Kill-A-Watt for a couple weeks to investigate power usage around our home.  I have thought about buying one before, but borrowing one is certainly better, though it is quite a bit of fun to test out devices to see how much power they use.

I first tried it on our dental water pik, and it is 30 watts when it is being used, and 0 when it is not.  In Pittsburgh (at 11.3 cents per kWh), a 50 watt device running for a minute costs just under a penny.  Our chest freezer runs at 83 watts when it is cooling, and 0 watts when it is not (pretty good, I think).  I let it run for a day and the grand total is 9.4 cents ($3/month).

I suspect our freezer is probably the most energy efficient thing in our house, but so far so good.  I'll have to try it out on our computers and stereo equipment.  Note that I test for the 0 watts when it is off, because lots of devices don't really turn off - Peter said his stereo uses 30 watts when it is on and 20 watts when it is off.

Posted by Jon Daley on September 25, 2007, 8:25 pm | Read 3032 times
Category Reviews: [first] [previous] [next] [newest]

Jon knows this, but for everyone else...

As soon as I caught my stereo burning 20W while turned off, I put it on a switched power strip, which does use zero Watts while off.

Posted by Peter on September 26, 2007, 9:37 am

I'm eagerly awaiting the results on your computing equipment, Jon. It looks like a pretty nifty device.

Do either of you know how much your television consumes (on and off)? We've only ever bought one TV in our lives, and that was more than 20 years ago. We were given the one we have now, however, so it's not quite that old, though it's old enough that we have to connect our DVD player through the VCR because there's no direct connection on the TV. A television set is about last on the list of devices we want to buy, but it may become a question of sanity. This one will often decided not to turn off.... You can hit the power button, and it sort of goes off -- the screen is blank, and the sound seems to be off, until the room gets quiet, and then you can hear the sound still going on. The only way to get it to shut up is to run it through the VCR, but then we have to have the VCR turned on (using how much power how much I don't know). We do have the TV plugged into a switchable power strip, and we've used that method to turn it off when we're out of town, but whenever we do that the TV has to go thorough a long boot-up procedure when it's turned back on, one that involves lots of input from us to get the setting right. Needless to say, we don't do that very often.

It would be nice to know how much power we're wasting, though it's my sanity rather than the power that's the real issue. :)

Posted by SursumCorda on September 27, 2007, 8:48 am

The next thing I tested was our phone. It looks like it uses about a half a penny a day. It didn't use hardly any power the first day, but Heather pointed out that no calls were made...

I talked for three hours yesterday, so that is what brought it up to a half penny. Pretty nice.

Posted by Jon Daley on September 29, 2007, 5:15 pm

I put it on the washer. Large load, regular (10) cycle: 0.26 kWh. Adding an extra rinse brings the total to 0.38 kWh.

We can't put it on the dryer because it's a 220V connection.

Posted by joyful on October 30, 2007, 4:54 pm

I finally put it on the computer. I actually put it on the UPS, since then I didn't have to turn off the computer just to test the wattage.

Our computer (and phone, phone-tree and wireless router) take 110 Watts ($9/month), when the monitor is turned off, which is most of the time. If it is power saving mode, the monitor takes 3 Watts, and when running, takes 50 watts.

For comparison, my new server (clementine, for those of you following along with the naming scheme - lemon, orange, tangerine, so far) takes 350 watts ($28/month), which is interesting, since I only pay $80-$100/month per server, and that includes network bandwidth, air conditioning, battery/diesel backup, and network hardware and maintenance.

My other servers are smaller (and quieter), so presumably don't use as much electricity, but still pretty impressive.

Posted by jondaley on November 1, 2007, 9:21 am

And since it was easy to calculate right now, I also checked that:

the wireless router takes 7 watts (57 cents/month)
the phone takes 4 watts (32 cents/month)
the phone-tree takes 2 watts (16 cents/month)
(not counting actually using the the phone equipment)

Posted by jondaley on November 1, 2007, 9:28 am

For the curious this is a phone tree, I make the calls for our church for the folks who don't have email.

Posted by jondaley on November 1, 2007, 9:30 am

A coworker had read an article that said that something like 90% of the electricity used by cell phone chargers was used when the phone wasn't being charged, but just because people left them plugged in all the time. I am happy to find out that our charger isn't one of them - it stayed on 0 kWh for the whole day.

However, our subwoofer for our stereo uses 12 Watts when it is "off" and 24 when it is "on", though hardly being used - I just turned on the radio.

The stereo uses 75 watts or so when on, at a reasonably soft volume. The VCR and cd player add 4 watts each. All of the stereo equipment and the TV use 10 Watts while off. It is sort of a pain to figure out which device uses what, so I don't know if I will take the time to figure it out.

I might look into a switch for the subwoofer, since it doesn't have one at all.

Posted by jondaley on November 1, 2007, 10:39 pm

Speaking of subwoofers, I plugged mine into the AC outlet of my stereo so it only draws power if the stereo is turned on.

Posted by Peter on November 2, 2007, 9:06 am

I actually realized as I was falling asleep that everything is already on a power strip, so it would be easy enough to turn the whole thing off when we aren't using it. Our VCR loses power often enough that I don't bother resetting the clock anyway, so we won't really be losing anything.

Posted by jondaley on November 2, 2007, 9:16 am
Add Comment
Add comment
E-mail me when comments occur on this article