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Looking at this from the standpoint of a howeowner and not a utilities company I was trying to find a way to monitor and analyze the energy use in my home without relying on my providers bills.

So now I can check the current consumption via my iPhone or via a Web Page. The iPhone is best viewed on an iPhone/iPod Touch.



Once you have easily accessible information it is very enlightening. The cost of appliances in my home definitely did not reflect what I had expected. In fact 5 computers, a TV, PS3, FIOS receiver, 2 fridge freezers and a bunch of lights turns out to cosume less than half the energy of boiling an electric kettle.

The graph of results shows makes interesting reading. Peaks represent appliances such as the tumble dryer and washing machine. It definitely makes you think about being more efficient with the heavy duty appliances.

Technical Details

My first thoughts were to get an old electricity meter and add a STAMP module to it, however there are far simpler ways to do this. You can buy off the shelf units such as The Energy Detective.

There are also project options available that can work out a lot cheaper. The Adafruit Tweet a kit is a modification to the Kill a Watt meter that will tweet for individual appliances in your home.

I bought an energy detective. This requires the sender unit to be wired into your home with the circuit breaker. A remote unit then reads the signal embedded in the power supply and displays power consumption and voltage on a convenient unit. The unit has an USB port that you can connect to a windows machine and use the corresponding software to monitor your usage.

My initial goal was to take those readings and make them available on my iPhone. However once the link from the meter to the server was made it opened all sorts of opportunities.

The meter is read using a python script running on a Mac Mini (scanwidget). The script periodically reads the data via the USB port and posts it to a publicly available server via a PHP script. The readings are stored in a mysql database. The same time the readings are stored, any increase in the peak daily KW usage is tweeted.

The same server hosts

  • A web page showing some latest readings and current reading with some flash based UI
  • An iPhone Web Application

Other links

Once I was almost complete obviously then it was when I found out there are other initiatives ongoing for consumers to monitor their energy usage.

Google PowerMeter

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  1. Marilyn Pratt
    We can’t easily change what we can’t measure.  While no handy woman, I’m inspired by your examples to get me some home monitoring going and just in time for Earth hour.  What a perfect tribute to the occasion.  I’m watching a film right now called Kilowatt Ours which states: “It’s the smallest change that makes the largest impact”.  Thank you, thank you, thank you for answering the plea to get some practical steps documented and illustrated.  You totally ROCK John!
  2. Krishnakumar Ramamoorthy
    Cool app!!. We are working on initiatives around AMI (meter with two way communication) which opens up the door for many more applications like this. However, AMI is a bigger project in itself and benefits are not going to be realized overnight.

    Till then, apps like these are the way to go.

    Keep up the good work and thanks for sharing this with us.


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