I recently purchased a Kill-A-Watt electric meter, which is a device you can use to measure how much energy an electrical appliance is using. I used my kill-a-watt around both my and my parent's house (my Dad was really interested too), and took some readings. Some were surprising, others were not. It's worth noting that large appliances (TVs, refrigerators, computers) often have a spike in power usage immediately when they are turned on, but usage quickly drops once the startup time has passed. I have tried to note the startup spike where I can, but it is brief and it can be hard to get a reading.
I found it interesting that on a CRT TV screen, the power usage changes depending on what is on the screen. For example, an image with a lot of bright white uses more power than a dark image. For a rear projection, LCD, or plasma TV, this situation is probably different.
We tested my parent's refrigerator for an hour to measure how many kilowatt-hours (kWh) it used. Because it cycles on and off, this gives a better understanding of it's usage over time. Over 60 minutes, keeping the door closed the whole time, the compressor cycled on and off twice, and overall it used 0.08 kWh.
I've decided to keep monetary cost out of the equation, because the real cost of energy goes way beyond how much you pay your electric company each month.
Here's a table of my readings. I'll be adding more as I take them. If you have an idea for something you'd like measured, let me know!
Device | State | Watts |
---|---|---|
40W incandescent bulb | on | 40 |
Torch-style halogen lamp | on | 266 |
LED night light | on | 0 |
20" CRT TV w/ built-in VCR | off | 3-5 |
20" CRT TV w/ built-in VCR | on | 50-70 |
32" CRT TV | off | 5 |
32" CRT TV | on | 65 |
32" CRT Sony Wega TV | off | 1 |
32" CRT Sony Wega TV | startup | 89-262 |
32" CRT Sony Wega TV | black screen | 86 |
32" CRT Sony Wega TV | blue screen | 103 |
32" CRT Sony Wega TV | green screen | 99 |
32" CRT Sony Wega TV | red screen | 120 |
32" CRT Sony Wega TV | white screen | 130 |
Panasonic 42" Plasma | Standby | 19 |
Panasonic 42" Plasma | Startup | 133 |
Panasonic 42" Plasma | Picture | 100-151 |
Panasonic 42" Plasma | Black | 60 |
Panasonic 42" Plasma | Blue | 265 |
Panasonic 42" Plasma | Cyan | 342 |
Panasonic 42" Plasma | Green | 252 |
Panasonic 42" Plasma | Magenta | 350 |
Panasonic 42" Plasma | Red | 210 |
Panasonic 42" Plasma | White | 360 |
Panasonic 42" Plasma | Yellow | 330 |
Stereo head unit | off | 1 |
Stereo head unit | startup | 52 |
Stereo head unit | idle | 34-36 |
Stereo head unit | playing music | 36-40 |
Powered sub-woofer | idle | 7 |
Powered sub-woofer | playing music | 7-11 |
Digital cable box (no DVR) | standby | 13 |
Digital cable box (no DVR) | on | 13 |
Refrigerator | fan only | 23 |
Refrigerator | compressor startup | 225 |
Refrigerator | compressor running | 190 |
TiVo (Series 2 standalone unit) | startup | 40 |
TiVo (Series 2 standalone unit) | on | 28 |
Linksys WRT54G (Wireless/ cable router) | off | 1 |
Linksys WRT54G (Wireless/ cable router) | on | 4 |
Motorola cable modem | on | 4 |
Computer speakers (stereo + subwoofer) | muted 1 | 2-3 |
Computer speakers (stereo + subwoofer) | idle 2 | 6 |
Computer speakers (stereo + subwoofer) | in use | 6-10 |
Dell Inspiron 4150 laptop | off | 3 |
Dell Inspiron 4150 laptop | standby | 2 |
Dell Inspiron 4150 laptop | hibernate | 3 |
Dell Inspiron 4150 laptop | startup | 40-50 |
Dell Inspiron 4150 laptop | idle | 28-30 |
Dell Inspiron 4150 laptop | high CPU usage | 49-55 |
Dell Inspiron 4150 laptop | LCD power save | 18-20 |
Dell Inspiron 4150 laptop (linux) | startup | 30-47 |
Dell Inspiron 4150 laptop (linux) | idle | 28-29 |
Dell Inspiron 4150 laptop (linux) | high CPU | 49-55 |
Dell Inspiron 4150 laptop (linux) | LCD power save | 20 |
Dell Inspiron 8600 laptop | off | 0 |
Dell Inspiron 8600 laptop | on | 20-33 |
Shuttle SN25P Computer | hard off 3 | 0 |
Shuttle SN25P Computer | soft off 3 | 9-12 |
Shuttle SN25P Computer | startup | 126-155 |
Shuttle SN25P Computer | idle 2 | 83-84 |
Shuttle SN25P Computer | file copy (disk to disk) | 87-89 |
Shuttle SN25P Computer | video card demo | 160-180 |
Shuttle SN25P Computer | high CPU load | 144-155 |
Cell phone charger | charging | 1 |
Bluetooth headset charger | charging | 1 |
Alarm clock | on | 1 |
Carbon Monoxide Detector | on | 0-1 |
Philips LED Rope Light | on | 1 |
Dell 2001FP 20" LCD Monitor | Off | 0 |
Dell 2001FP 20" LCD Monitor | Standby | 4 |
Dell 2001FP 20" LCD Monitor | On | 48 |
HP dv9000t laptop | idle | 35 |
HP dv9000t laptop | heavy disk use | 40 |
HP dv9000t laptop | dvd burning | 42 |
HP dv9000t laptop | off | 1 |
HP dv9000t laptop | startup | 55 |
HP dv9000t laptop | arithmetic test | 55 |
HP dv9000t laptop | multicore efficiency | 57 |
HP dv9000t laptop | multimedia test | 63 |
Specs on the Shuttle SN25P are: