A Perfect Present for the Farns

Kendra gave me an awesome present this year for Christmas.


That's right, A Kill-A-Watt. It's an electricity usage monitor. You plug it in and then plug something into it and it tells you how many watts are being munched. And you can attach it for hours or days to find out how many kilowatt hours something uses over a period of time.

I think it's the greatest thing. You know why (or at least one reason)? Our electricity bill doubled when we moved into this apartment. We didn't change anything about our habits. The heating and cooking are natural gas in both apartments. So what the heck is the deal? At least when the dude who broke into our car and stole our GPS did it, we understood why and how. This electricity thief is so much more subtle.

So I did an electricity audit of the house. I calculate that the marginal cost of electricity according to our bill is just over 11 cents per kilowatt hour (not including the $10 fixed fee). This will tell me the influence of various household items on our electric bill.

I learned a lot. And now you are going to.

Ashley's computer (just the box, not the monitor), when idle, consumes 52 watts. My computer, on the other hand...89 watts. The two computers are nearly identical. Really there are only two differences: mine has a new power supply that I installed after burning the other one up (oops), and mine has a graphics card while hers uses onboard graphics. Quite a big difference. Actually both of these numbers look pretty good compared with the 110 watts my old computer consumes when on. Of course these are all idle numbers. I started encoding mp3's, and watched the wattage shoot up by about 40 watts. I bet when it's really working it goes up much beyond that. We looked into our operating system settings and realized you can set it so your computer will go into hibernate when you press the power button. It takes just a second and makes the electricity usage go down to almost nothing. Then when you press it again the computer is back in like 2 seconds. Since we often walk away from our computers for hours at a time and leave them on, we can save a lot of power by doing this habitually. And now we do. We used to try and actually turn them off when we did this, but it takes so dang long to reboot (especially with her computers...stupid windows). Now we just sleep them, and everyone's happy.

My study of these monitors is even more informative. My 22-inch LCD monitor consumes 20 watts of power. Clearly those monitor manufacturers have really worked on power consumption and the LED lighting really works. Think about it, an incandescent light bulb eats like 60-75 watts, right? Then I checked Ashley's monitor, which is nearly identical to mine. 38 watts. That's almost twice what mine consumed. I looked into the settings and realized I had my brightness turned somewhat down while hers was at 100 percent. You can't really tell by looking that my settings are different. We turned hers down and I literally watched the wattage go down from 38 watts to 17. If you want to save power on your monitor, turn down the brightness. On these monitors it doesn't make much difference in the user experience but it makes a big difference in power consumption. The other settings, like contrast, don't make any difference. Also interesting was that if we turned on my screen saver, which just turns the monitor black, the power usage goes up by 3 watts. I think maybe "blank screen" turns up the LED backlight or something. Anyway monitors don't really get burn in and it consumes power, so don't use a screen saver. One more thing of note: neither Ashley's monitor nor mine consumes any detectable power at all when off. And when you turn the computer off so the monitor goes into sleep mode it also uses an undetectable amount of power--nothing is gained by actually pressing the off switch. These monitors are very efficient. By the way I checked my old LCD monitor too. It's 25 inches and uses a halogen backlight instead of LED. That sucker pulls 98 watts when idle. Even when it's completely turned off it eats up 8 watts, which is about as much as my bedside lamp. There's a real difference between the old and new technology (though they are both LCD...who knows how much the old CRT monitors used).

It has been estimated that 11% of a household's electricity consumption goes to idle electronics. Almost all electronics consume power even when they are completely turned off. And there's a lot of variety in how much they consume. I haven't actually measured all my devices yet, but I will. Because they only consume a couple of watts or so when off they aren't as easily measured using the kill-a-watt. The best way to do it is to leave them plugged in for a long time and measure the watt-hours used. That takes time. I did find a couple of interesting ones, though. For example, my desktop speakers munch 10 watts when playing music, 9 watts when on but idle, and 5 when completely turned off. That's one thing I kind of wish I could unplug. For reference, 5 watts is also the amount my computer consumes when turned off...and that has to do a few random things like keep my ethernet card on so I can turn the computer on remotely. The stereo in my daughter's room eats just as much, when off. There are lots of such devices around the house. Every outlet is laden with these little guys, each eating 2 to 5 watts each all day every day. Better to unplug them when you can. Now I kind of want one of these babies

It's a smart power strip. It completely turns off power to peripherals when they are turned off. I'm not sure how well it works (how does it know whether 7 watts is a device that is on or off?), but I think it's a great idea. Of course, it would take a long time for the electricity savings to pay for the $30 the thing costs. But that doesn't make it any less of a great idea.

A few other interesting items: the compact fluorescent bulb lamp that lights our living room: 12 watts when on. Pretty efficient. Compare that to the 400 watts or so our hall lights use (no I couldn't measure, that's just adding up their wattages...they are the kind that dim).

The other thing I wondered about was our deep freeze. I have been toting that around for a while and I always wondered what the costs were in electricity. I tested it for hours and found an average usage of less than 30 watts. That comes to about 2 dollars a month in electric costs. I say it's worth it.

But I bet you are wondering what the answer to my big question was. Why did our electric bill go up so much? I tested our refrigerator (which came with the apartment). The average wattage was over 150. That's like 1300 kilowatt-hours a year, almost three times what a modern refrigerator consumes. On a monthly basis, that comes to about $12 dollars. Ok that doesn't completely resolve the question of electricity costs, though it contributes significantly to it. The freezer part of our refrigerator is always frigid even though we have it turned all the way to warm. And the refrigerator part is always quite warm, even though we have it turned all the way to cold. Probably a bad thermostat or something. Also we moved the grate and looked at our cooling coils and they were completely covered in a carpet of thick lint--a nice insulating blanked preventing the coils from doing their job. We probably can't get our landlord to get us a more modern fridge, but at least we can clean off the coils.

Looking at the difference in electricity usage between our two food cooling devices was quite shocking. I mean the deep freeze holds a lot more food and keeps it colder. From what I understand, deep freezes are more efficiently insulated and of course the cold doesn't always fall our when you open the lid. Also they aren't always trying to prevent frost formation. Some smart soul out there hooked a thermometer to a power switch and converted their deep freeze to an ultra efficient refrigerator (it turns of power to the freezer when the temperature gets down as low as desired). Apparently the thing consumes only like 37 kilowatt-hours per year! Given the low cost of deep freezes (mine only cost about $150) and the simplicity of the conversion, I got really excited about the prospect of making my own deep freeze refrigerator and just putting the one that came with this apartment outside or something. Alas, it turns out in marriage you only get to have things your way when you are the only one affected. Some day when we have a basement, I'll make a deep freeze refrigerator for it, and it won't make a noticeable difference on our power bill at all. My dream refrigerator:


In mean mean time, I wish I could figure out a way to pipe freezing air from outside into our freezer. It's like 10 degrees outside...why does my refrigerator work hard all day long? It's also just crazy that our fridge sits right next to the furnace. One tries to heat the air around it while the other tries to use that same air to cool itself.

Anyway, our inefficient refrigerator is a major portion of the variable part of our electric bill. The fixed costs here in Chicago are probably higher than up in Evanston and so are the taxes. That is probably the rest of the difference. But that fixed part is out of my control and therefore so much less fun than planning the ultimate do-it-yourself food cooling system. I think we can all agree on that.