Electricity Use

[freeztar]

I decided to purchase a Kill-A-Watt unit to test my electricity consumption. It's a very nifty device, capable of measuring volts, amps, hertz, KWH, etc. I plugged it in today (in KWH mode) and plugged my laptop computer's power strip into the unit. Below are some semi-cursory results:

Time..... KWH
16:21.... 0.00 (start)
16:27.... 0.01
16:34.... 0.02
16:41.... 0.03
16:48.... 0.04
...
18:25.... 0.17

Assuming an electricity rate of 9.85 cents/KWH in Georgia Jul-07:

~7.3 minutes per one-hundreth KWH
~730 minutes (~12.2 hours) of laptop computer usage = 1 KWH
10 KWH = ~122 hours of laptop computer usage = ~$1.00

That really took me by surprise!
I expected it to be much, much higher.

I'll be testing more electrical objects such as a space heater, refrigerator (1/4 size), microwave, etc.

Does anyone have their own results to post?

Laptop specs:
Sony VAIO PCG-K37 (sucks, don't ever get one)
P4 3.2GHz 1MB CD\DVDRW 40GB EIDE 
USB 4-port hub with: 2 USB drives, wireless mouse reciever, 
  and a laptop cooling pad with three fans
Power supply: 19.5V

[Jay-qu]

I dont have any results I just remember running some similar calculations and been equally surprised as you are

My mum was complaining about people leaving lights on and how it was costing us more, so I went and calculated how much it would cost to leave all the lights on in the house for the duration of the billing period its nothing compared to what the microwave, fridge and computers use.

[Turtle]

Waste not, want not. It all adds up. I don't have a meter, but I do keep tabs on what the rated wattage/amperage is for our juice-hungry friends. The refer is the first thing I'd downsize if I lived on my own, and I would unplug Micro, vcr, etcetera things that use a "little" juice all the time. I'm a freakin' miser OK!? I turn off lights behind roomies(sometimes I don't even wait for them to leave a room!), turn the thermostat down, & burst into the occasional "I'm not payin' for your waste" rant, among other miserations.


Any body remember Reddy Kilowatt?

Have you found any great variance between rated power-use and actual? :

[freeztar]

Originally Posted by Jay-qu

I dont have any results I just remember running some similar calculations and been equally surprised as you are

I thought the unit was not working for the first seven minutes until I saw the LCD display change from "0.00" to "0.01". It was a momentous, and illuminating moment.

My mum was complaining about people leaving lights on and how it was costing us more, so I went and calculated how much it would cost to leave all the lights on in the house for the duration of the billing period its nothing compared to what the microwave, fridge and computers use.

Indeed.
I'm sure most lamps pale in comparison to "heavy loaders" such as washers, as far as energy consumption is concerned. Nonetheless, it is prudent, IMHO, to turn off lights that are not being used. Less is more in this case!

I'm now at time 21:45 and showing KWH 0.44.

[Jay-qu]

Originally Posted by freeztar

I thought the unit was not working for the first seven minutes until I saw the LCD display change from "0.00" to "0.01". It was a momentous, and illuminating moment.

Indeed.
I'm sure most lamps pale in comparison to "heavy loaders" such as washers, as far as energy consumption is concerned. Nonetheless, it is prudent, IMHO, to turn off lights that are not being used. Less is more in this case!

I'm now at time 21:45 and showing KWH 0.44.

Of course I would not condone wasting power for the sake of it - it may be cheap but it is still pumping CO2 into our atmosphere.

[palmtreepathos]

My past wanton extravagance was the use of LIGHT! wonderful, beautiful lamps and lights! I feel that a well lit home is a welcoming place. I grew up with the meter miser, harp harp harp! I AM WORTH IT! I need it and of course, it is cheaper than a shrink... and meds...

Also I am in the process of adjusting to new energy lights UGH! ugly color casting swirls. But I am trying. In the reading room we had a 500 watt halogen lamp, ahh sweet light! It is being replaced with a combo of regular 26 watt swirls and true color 26 watt swirls, 2 each so far for 104 watts, it is not the same but we are getting used to it. I am trying to do my part. And I like the idea of these lights...

YouTube - Hybrid Solar Lighting

Sorry, but sometimes you just gotta "lighten up!"

[Ganoderma]

cool video, those types of lights were a long time coming. i am so glad this sort fo thing is starting to be sold..

when i lok a tmy powers usage, aside form looking at the label, i always think in my head "Hot=lots of power". things like heaters, stoves, dryers etc i really try to cut back on. so things like hanging clothes to dry, using high L/W lights (i replaced all my lights in the house/school with 91L/W flouros! ohhh yea lol.


where did you get that meter? i always looks at the meter on the house that goes round n round. but i think it would be cool to measure the actual power usage of individual things (cause i am sure at least one of the labels on our stuff is misleading haha)

[CraigD]

Originally Posted by freeztar

I decided to purchase a Kill-A-Watt unit to test my electricity consumption. It's a very nifty device, capable of measuring volts, amps, hertz, KWH, etc.

It sure is!

I got a Kill-A-Watt last year, and used it to check various stuff around my house. I also took it with me when I shopped for and eventually bought the below mentioned LCD TV. There are some surprising differences between similar-specification TVs, some drawing more than twice the power of one of the same size and display type.

Originally Posted by freeztar

Does anyone have their own results to post?

Interesting measurements from around my house include:

• Sony CFD-E90 “boom box” Radio/Tape/CD player, using AC power
  • Off: < 1 W
  • Radio on, low volume: 1 W
  • CD on, low volume: 5 W
  • Max volume: 9-14 W
• 2004 Toshiba A65-S126 laptop, 2.8 Ghz Celron, 1 GB RAM, w/ 2-fan cooling pad
  • Hybernating: 0-1 W
  • Sleeping: 29-30 W
  • CPU ~ 0%: 41-45 W
  • CPU 100%: 76-78 W
  • CPU ~30%, disk write bottlenecked: 49-55 W
• JVC AV-27D303 27” CRT TV
  • Off: <1 W
  • On, no signal: 55 W
  • On, signal: 60-90 W
• DCT2224/1161/ACDEQ Cable TV receiver box
  • Off: 18 W
  • On: 20 W
• 40” Samsung a900 LCD TV
  • Off: <1 W
  • On, no signal: 70 W
  • On, signal: 180-240 W (The whiter/brighter the picture, the greater the power)
• Mr Coffee 12 cup coffeemaker
  • Brewing: 950 W
  • Warming: average about 200 W, in 15 s bursts of 950 W

Light bulbs of all kinds (incandescent, florescent, etc.) all appear to draw almost exactly their rated power.

A typical personal electronics (cellphone, etc) charger draws a few watts when charging, essentially 0 when not.

Originally Posted by freeztar

I plugged it in today (in KWH mode) and plugged my laptop computer's power strip into the unit.

For most use, I prefer the Kill-A-Watt’s “Watt” setting to the “KWH” one – it gives quicker results, and a better sense of a device’s variable power consumption. Also, a short (~ 30 cm) cord works better for me than plugging directly into outlets and power strips.

Originally Posted by Ganoderma

where did you get that meter?

I got mine via mail order from smarthome.com – they add US$8 to the cost for shipping and handling in the US, and will ship internationally, through possibly at crazy rates. Searching for the phrase “kill-a-watt” will probably turn up a better merchant for non-US delivery.

[freeztar]

Originally Posted by CraigD

I got a Kill-A-Watt last year, and used it to check various stuff around my house.

It was actually a post you made, Craig, that led me to purchase one.

I also took it with me when I shopped for and eventually bought the below mentioned LCD TV. There are some surprising differences between similar-specification TVs, some drawing more than twice the power of one of the same size and display type.

I have no doubt that this single use will find the unit paying for itself very quickly.

Interesting measurements from around my house include:[list][*]Sony CFD-E90 “boom box” Radio/Tape/CD player, using AC power

• Off: < 1 W
• Radio on, low volume: 1 W
• CD on, low volume: 5 W
• Max volume: 9-14 W

...

Awesome, thanks Craig.

A typical personal electronics (cellphone, etc) charger draws a few watts when charging, essentially 0 when not.

That was one of the items I most wanted to test as I typically leave my cell phone charger plugged in for convenience.

For most use, I prefer the Kill-A-Watt’s “Watt” setting to the “KWH” one – it gives quicker results, and a better sense of a device’s variable power consumption. Also, a short (~ 30 cm) cord works better for me than plugging directly into outlets and power strips.

Very good advice. I did not consider variable power consumption, but that will be very useful when testing my devices, such as the refrigerator. I also found it a bit akward to read the LCD when plugged directly into the wall, so the extension cord idea seems prudent.

I got mine via mail order from Smarthome - Home Automation, X10, Remote Control, Lighting, Wireless Security – they add US$8 to the cost for shipping and handling in the US, and will ship internationally, through possibly at crazy rates. Searching for the phrase “kill-a-watt” will probably turn up a better merchant for non-US delivery.

I got mine through ebay for about $23 with shipping. Since the company is based in the US, I would expect high fees for international transportation. But even at $40+ it is well worth it in the long run.

[Ganoderma]

thats one thing i always wonder about is how much power things are using when not turned on, but plugged in. many things like our tv, dvd charges etc all say they use "minimal" power when off, whatever that is. we just unplug everything when we don't use it, the only thing that stays plugged in is the fridge, which is surprisingly only 175 watts....

thanks for the link, i know what i am looking for now!