I recently borrowed a "watt meter" to test the power consumption of various devices around my house. It was very educational and fun. I made a few changes as a result of my tests (I plugged just about everything I could into the meter to test it).

You can calculate how much a device costs to run knowing how much power it draws, how long it is powered on, and what you pay per killowatt hour (kwh). I pay 7.125cents/kwh with Pacific Power (for the first 500 kwh, then the price goes up slightly).

For example, I have one lightbulb outdoors that is on 24/7. It's about 13 watts. Multiple it out and it costs about 2.2 cents a day [( 13w/1000) * 0.07125 $/kwh * 24hours ]or $8.11 per year in electricity.

Some devices - especially older ones - draw a lot of passive power when plugged in but not powered on. I was surprised that a rarely-used old laserdisc player (1993-ish) draws 10 watts passive!!! By contrast, a newish DVD player draws only 0.5 watts passive. My 1993 GE microwave draws 3 watts passive, and I don't use it every day. My Dell laptop charger draws less than 0.1w (nothing registered) when plugged in but not charging (I have a spare at home that is always plugged in). So I'll never unplug that. Same with my cell phone charger: draws less than 0.1 watt when not charging.

I have a floor halogen lamp that I had forgotten had a 300w bulb in it! I measured it anyway; even at about 80% power it draw the expected 250w. I've since replaced that with a 20w floor lamp with a compact florescent bulb - surprisingly bright.

Other measurements:

- desktop tower computer, Pentium 4 2.66GHZ (no monitor): about 103watts at idle. It was just a backup tower anyway but it was on 24/7. I set it to turn on once a day for 20 minutes to backup my web server, then shut itself off til the next day (so saving about $60/year).
- Newer 2.2GHZ Core 2 Duo system that is a lot faster than the P4 draws only about 55 watts with about the same configuration. It's on and off randomly as needed for photo work.
- laptop draws 25 watts with no battery in it; 45 watts when charging the battery.
- 1990 Sony 27" TV (yeah, still going) draws between 110 and 150 watts (less than I expected) - just seems to vary for no discernible reason.

How about you? Ever considered how much your home appliances and electronics draw?

Andrew

"Phantom loads" can add up.
I got fed up with all the dang 'wall warts' under my desk,so I wired up a 10W solar panel to a battery bank,and replaced a bunch of those damn wall-warts with solar power!!
It's nice to have an outlet available if I need it,those wall-warts take up two(sometimes three)outlets,plus they draw power 24/7,if the device they are connected to is powered on or not.
My DSL modem,router,and a couple of other things are running from the 12V battery bank,and have been running 24/7 for a couple years straight.

The power drawn by a CRT TV can vary with the brightness of the picture. I hadn't thought about this until I read an article about building pedal-powered generators out of old stationary bikes. The author said that when powering a TV, maintaining sufficient pedaling speed during a brightly lit scene was challenging.

I'd like to try the watt meter experiment some day. I think that the most interesting load to analyze would be a window fan. If the wind blows against the direction that the fan is trying to push the air, I would expect the wattage to go up. However, if the wind blows in the opposite direction, the fan might (in theory) push a small amount of power back into the house wiring.

I tried one variable speed window-type fan and it hit about 95w at highest speed. No wind - I used it only inside. :-)

The phantom loads can add up but they vary. That 10w phantom load from the laserdisc player drain was silly, but my 0.5w DVD player isn't worth unplugging.

Andrew

I have found that it is also helpful to measure the total consumption... read your power meter and plot the reading on a daily basis. The little "kill-a-watt" meters are great for evaluating small appliances that can be plugged in, but the big users are the 230 volt devices; dryers, heat pumps, water heaters. Reading the total power, and matching it it to behavior patterns, such as temperature settings, hot water use, using extra "wrinkle touch up" time in the dryer, can reveal opportunities for saving energy and $$$$.

laserdisc player?????

You living in the 80's still?

Andrew and Junior, care to tell us which devices you're using? I've been thinking about this for a while now, but never got up to look at these devices and how much they cost.

I was using a "Watts Up" meter, the more expensive competitor to the "Kill-a-Watt" brand of meters that can be had for $30. I was using the very basic one, but it worked well. It had the ability to monitor power use over time and thus let you see real kwh over a set period rather than just guesstimating from an immediate reading.

It does make sense to look the high-drawing appliances like your fridge, dryer, and water heater. My water heat is gas (I am considering getting a tankless model). My fridge is 10 years old, and I did monitor it, thinking it could make sense to replace it with a more efficient model. I was surprised that the compressor was not always running while the fan was; power use peaked at 700w but didn't stay there all that long, dropping down to about 30w quickly with the fan still on. I'm not so sure I'd get much bang out of replacing this thing with a new model.

And the dryer - I just use the basic modes, and I have a front-loading washer that extracts a lot of water from my clothes, so I don't think there's much room for savings for me there.

My little window A/C unit for my bedroom draws just under 400w when on, surprisingly low. No wonder my electric bill in the summers never gets that high, even when I use the A/C a lot.

(And Trixter, I said rarely-used old laserdisc player. I still have a bunch of old laserdiscs, a few of which have never been released on DVD in that exact version. I have some great audio commentaries by people like Martin Scorsese for "Raging Bull" and "Taxi Driver" that he never did again for DVD.)

Andrew

"Kill-a-Watt":

http://www.amazon.com/P3-International-P4460-Electricity-Monitor/dp/B000RGF29Q/r ef=pd_bbs_sr_2?ie=UTF8&s=electronics&qid=1229238188&sr=8-2

But the PGE service power meter is free and already attached to the side of your house.

Ditto on the laserdisk player, lots of titles that never have been issued on dvd ! I hope to transfer many to DVD before the old LD700 craps out!

Thanks guys. Andrew, is your device measuring 220 v. as well?

Does your meter take into account the power factor?

I received my Kill-a-Watt a couple of weeks ago.

So far, I've determined that at approx. $0.10 per KWh, it takes about a penny to make coffee in the morning (690W, .07KWh),

My wife's space heater averages 1KWh per day ($1.68 per week).

I had it on in my office (two to three notebooks running during the day) 2.67 KWh per day @ $1.87 per week.

I now have it on my primary tower PC/Media Center and it's drawing about 160W.

Monkeyboy,

I've thought seriously about doing the solar thing with my Cable Modem & AP. Can you provide more details on your setup?

Skep, I don't have my device anymore - but it had only a standard 110v AC plug, so I don't think it can measure 220v. Maybe with an adapter?

Amus, have you ever considered getting a Media Center server based on the newish Intel Atom CPU? It's an extremely low power CPU but with quite decent performance. The latest offering is dual core and runs at 1.6GHZ. You can get the motherboard + CPU for about $80:

http://www.buy.com/prod/mitx-mbd-dc-atom-330-ddr2-sata-aud-geth/q/loc/101/208661 725.html

The CPU is passively cooled and draws under 10w; the chipset on this board draws more (and requires a fan), but a system based on this should draw under 50w total - and be far quieter than a conventional PC. I'm thinking about building one.

Andrew

Andrew,

The subject of Media Center PC's was touched on here last January. Maybe we should start a new thread on this, but have you decided on a Media Center App?

Concerning Power usage...
This year we're using LED Christmas lights.
We have about 100 lights on our house.
100 x 9W (C9 bulbs) = 900 Watts.
100 x .25W (C-9 equivalent) x 100 = 25Watts

Edit - I can also repair the bulbs if I need to!

From the Kill-a-Watt description on Amazon, linked above:

"Also check the quality of your power by monitoring Voltage, Line Frequency, and Power Factor"

This has been one of the most excellent threads. I'm seriously thinking about one of these meters. I'm wondering about the cost of cooking various foods!

A little "how-to" on reading utility power meters:

http://www.geocities.com/mistertippy/howto/pwrmeter.html

It is a little tricky if you have never done it before because alternating dials turn in opposite directions.

>>I'm seriously thinking about one of these meters

wheres the best place to purchase/get that next unique Christmas gift!?????

I got mine at Smarthome.com for $25.