Electricity Consumption

Submitted by Ben on Tue, 11/11/2008 - 16:15

[Note: this article was written in 2008, and we have different appliances now. See the comments for updates.]

Here is the electricity consumption of each of our appliances, measured by Kill A Watt unless otherwise noted.  "Typical usage" indicates how much power a device uses when we use it the way we usually do; cost per year assumes we use the device that way every day.  In reality, of course, we don't run any of these devices in any of these modes all day, every day, or even all year.  Costs are estimated based on $0.124 / kWh, which includes all our utility's fees and charges.

It's hard to classify the operating states of some electronics... for the purposes of this chart, "off" means no lights are showing and a power switch or button is required to turn it on; "standby" means a light is on and/or the device can be awakened by a button other than the power button; "idle" means it is fully turned on but not doing anything; and "on" or "running" means it is doing its main function.  Some devices do not turn off unless they are unplugged; others have both an off and standby mode; some consume the same amount of power whether running or idle; others save power while idle. Very low numbers should be taken with a grain of salt, since the Kill A Watt meter itself (as its name might imply) consumes a Watt!

device typical usage kWh/day cost/yr
Battery charger 20 Wh to charge 2 batteries 0.02 $0.91
Cable modem 3 W continuously 0.07 $3.26
Cell phone charger (Ben's) 3 W for about 3 hours, then 0 W 0.01 $0.41
Clock radio (either on or off) 1W continuously 0.02 $1.09
Computer, Apple laptop (charging) 35W for 2 hours 0.70 $3.17
Computer, Apple laptop (running) 32W for 2 hours 0.64 $2.90
Computer, Apple notebook (running) 15 W for 8 hours 0.12 $5.43
Computer, Dell notebook (running) 20 W (even with fan on) for 8 hours 0.16 $7.24
Computer, Dell notebook (standby) 2 W for 3 hours 0.01 $0.27
Computer, Gateway laptop (running) 40-55 W for 2 hours 0.08 $3.62
Computer, Gateway laptop (standby) 1 W continuously 0.02 $1.09
Computer, HP laptop (running) 30-35 W for 2 hours 0.06 $2.72
Computer, HP laptop (standby) 1 W for 1 hour 0.00 $0.05
Computer, media center (off) 2 W continuously 0.05 $2.17
Computer, media center (running) 140 W continuously 3.36 $152.07
Computer, media center (standby) 3 W continuously 0.07 $3.26
Crock pot (low setting) 169 W for 9 hours 1.52 $68.84
Dehumidifier 546 W average (on humidistat) 13.10 $593.09
Dryer 5.5 kW (estimated) for 20 minutes 1.80 $81.47
Fan, box 73 W (low speed) continuously 1.80 $81.47
Fan, Vornado 31 W (low speed) continuously 0.70 $33.67
Monitor, 17" LCD (running) 29 W for 8 hours 0.23 $10.50
Monitor, 17" LCD (standby) 1 W continuously 0.02 $1.09
Percolator 180 Wh per pot (about 20 minutes) 0.18 $8.15
Power tool charger 80 Wh per charge (about 24 hours) 0.08 $3.62
Printer, inkjet (off) 1 W continuously 0.02 $1.09
Printer, inkjet (on) 3 W continuously 0.07 $3.26
Printer/copier/scanner (off) 1 W continuously 0.02 $1.09
Printer/copier/scanner (idle) 5 W continuously 0.12 $5.43
Refrigerator 80 W average (on thermostat) 1.90 $86.90
Space heater (full power) 200 Wh during 15 min shower 0.20 $9.05
Speakers, stereo (on or off) 1 W continuously 0.02 $1.09
Speakers, surround (running or idle) 25 W for 2 hours 0.05 $2.26
Speakers, surround (standby) 4 W continuously 0.10 $4.34
Toaster 20 Wh for two slices 0.02 $0.91
TV (19" CRT, running) 40 W for 2 hours 0.08 $3.62
TV (19" CRT, standby) 1 W continuously 0.02 $1.09
TV (32" LCD, maximum backlight) 180 W for 2 hours 0.36 $16.29
TV (32" LCD, minimum backlight) 60 W for 2 hours 0.12 $5.43
Vacuum cleaner (handheld) 50 Wh per charge (about 24 hrs) 0.05 $2.26
Vacuum cleaner (HEPA) 1.2 kW for 15 minutes 0.30 $13.58
Vacuum cleaner (wet/dry) 880 W for 15 minutes 0.22 $9.96
VCR (idle) 9 W continuously 0.22 $9.78
VCR (standby) 1 W continuously 0.02 $1.09
VCR/DVD, bedroom (standby or idle) 2 W continuously 0.05 $2.17
VCR/DVD, office (off) 3 W continuously 0.07 $3.26
VCR/DVD, office (idle) 6 W continuously 0.14 $6.52
VGA Box (standby) 2 W continuously 0.05 $2.17
VGA Box (running) 3 W for 2 hours 0.01 $0.27
Washing machine 100 Wh per load (about 20 minutes) 0.10 $4.53
Wi-Fi router 3 W continuously 0.07 $3.26
Wii (idle - green light, no game) 15 W for an unknown time 0.36 $16.29
Wii (off - red light) 1 W continuously 0.02 $1.09
Wii (running - game in play) 30 W for approx. 1 hour 0.03 $1.36
Wii (standby - orange light) 9 W for an unknown time 0.22 $9.78

Remaining to be measured:

  • Air conditioner
  • Cell phone charger (Jessie's)
  • Dishwasher:
  • Furnace (blower)
  • Microwave oven (high power)
  • Microwave oven (standby)
  • Printer, inkjet (printing)
  • Printer/copier/scanner (printing)
  • Printer/copier/scanner (copying)
  • Printer/copier/scanner (scanning)
  • Stove:
  • VCR (running)
  • VCR/DVD, bedroom (playing VCR)
  • VCR/DVD, bedroom (playing DVD)
  • VCR/DVD, office (playing VCR)
  • VCR/DVD, office (playing DVD)

Implications:

  1. The most room for improvement is in the basement -- pretty much any means to reduce the amount of time the dehumidifier runs would pay for itself, from replacing the windows to running box fans.
  2. The second biggest improvement would be to reduce the amount of time the media center is turned on.  Since it tends to turn itself on, this means unplugging it when no recordings are scheduled.
  3. The refrigerator is almost 7x more efficient than the dehumidifier, and so is not a candidate for early replacement, despite being one of the least efficient models on the market 9 years ago.
  4. Even on its lowest backlight setting, the LCD TV uses 50% more power than the CRT. (It also has more than twice as much screen area.)
  5. The LCD TV and cell phone chargers use less than one Watt while on standby.
  6. The media center uses nearly as much power while turned off as it does on standby, so we may want to consider unplugging it when it is not due to record a TV show.
  7. The crock pot does not reduce its power consumption after it reaches peak temperature (boiling).  We may want to put it on a timer so it can cool off by dinnertime.
  8. The handheld vacuum cleaner is a real bargain, whenever we can use it in place of either of the other vacuum cleaners.
  9. The clock radio and stereo speakers do not use measurably more power when on than off, but the surround-sound speakers use more than 5 times as much.
  10. The 17" LCD monitor uses more power than the Dell or Apple notebooks, even though the notebooks have their own 13" LCD screens (admittedly, half the screen area)
  11. Leaving the Wii on standby all day consumes more power than playing a game and then unplugging it.  Even leaving it turned off (but plugged in) all day consumes nearly as much as playing a game and unplugging after.
  12. Jessie's Gateway laptop uses more than twice as much power as Ben's Dell or Apple notebooks, despite being 8 years newer than the Dell and having only 1.5 times the screen area of either of them.  It's not a huge expense or anything, but it's an interesting fact.
  13. The percolator uses almost twice as much power as the washing machine in the same amount of time, and a tenth as much as the dryer.

Comments

A few days ago we got fed up with the dehumidifier and bought a new one, a Frigidaire 70 pint model.  In addition to being quieter and running less often, it also consumes about 63% of the power of the one listed above (which is a Comfort-Aire 65 pint model).  The new one averages 341 W, which comes to 8.20 kWh per day or $371.33 per year, which means it will pay for itself in the first yearMore on this in another post.

We have replaced our Media Center PC (listed above in the chart) with a digital video recorder (DVR) rented from the cable company.  I expected its power consumption to be less than that of the Media Center, but so far the readings are discouraging: although it uses only 44 Watts when turned on (even while recording!) it uses 42 Watts on standby.  Since it will spend most of its time on standby, waiting to record, it will cost us a minimum of $46 in electricity per year.

To be fair, though, the Media Center didn't spend as much time on standby as we wanted it to, because it had a habit of turning itself on and requiring a person to put it back to sleep, so particularly when we were out of town (sometimes for weeks at a time), it was running and using 140 Watts instead of 3.  So the DVR with its 44 W maximum may still represent a savings compared to the insomniac Media Center.

In other news, the cable box in the bedroom (which we now need because we have upgraded to digital cable, but which does not include a DVR) uses 19 Watts ($20.80 per year) regardless of whether it's turned on or on standby.  Ugh!  The TV and VCR/DVD in the bedroom together consume only 3 Watts on standby, but with the cable box added into the mix we may have to use a power strip.  :-(

admin

Tue, 02/19/2013 - 15:59

In reply to by admin

We got rid of the DVR shortly after we got it, probably September of 2009, but the comment above is still relevant because DVRs are more popular than ever.

Just a quick note to say that our pet fountain appears to use 2 Watts, or about $2.30 per year (plus filters).  What a bargain, to keep the cats hydrated and the floor dry!

Our food "and jerky" dehydrator uses 1.07 kWh in about 5.5 hours of use, or an average of 194.5 Watts at indoor temperatures.  (Its heating element cycles on and off with a thermostat, while the fan runs constantly.)  My mother pointed out that it would maintain the same temperature with less energy if we put it on the back porch in the summertime instead of indoors where it fights the air conditioner.  But it wouldn't smell as good!

We recently replaced the 19" CRT TV listed above with a 21" LED-backlit LCD TV which uses only 4 Watts -- one tenth the power of the TV it replaced.  And its standby power consumption is not measurable by the meter, that is, closer to 0 than 1 Watt.  So let's hear it for Energy Star!  And thanks to Wal-Mart for showing the power consumption of all their TV models on the rack so we could buy the most efficient one available.