The Kill-A-Watt plugs into a wall outlet and will measure the actual electricity usage of any appliance. I've been wanting one of these things for years, to the point of seriously considering manufacturing one myself. I'm glad someone has finally done it for me. It looks like my computer costs me something like $216 a year to run. Trouble is, I have five of them. Something's gotta go.
Street price for this device is about $30. I should save that much in the first month.
An additional idea that I thought of would be combining these units with that cheesy home-network technology that communicates via your home's electrical system. (Or use WiFi) That way several wall units could communicate with a PC and give you a running total of your energy consumption. The system could automatically retrieve your electrical rates from the Internet and even give you a running total in dollars of what you're spending.
Reader comment: Dom Padden says,
We have a device in Australia called the Cent-a-meter that measures your whole household electrical consumption in real time — not weeks later when you get a bill. Mine paid for itself immediately. I just bought it and placed it on the kitchen counter. The other people in my house took interest, calculated the cost of every appliance in the house (by elimination) and changed their habits. Our computers are surprisingly inexpensive to run but the whole TV-DVD-VCR stack gets turned off at the switch every night now, and the coffee machine is not turned on 24/7.
Reader comment: Rob Henderson says,
The Watts-Up meter from Electronic Educational Devices is similar to the Kill-A-Watt, but includes data logging and a serial interface. Link
Reader comment: angrygoatface says,
That Kill-a-watt that you mentioned in the update today — it's commonly used by techies to measure the usage of power supplies. As a general rule, the higher the wattage and the lower the useage, the better the power supply's efficiency.