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  1. Monitoring your electric usage

    December 30, 2011 by Karl

    Electric Meter berry berry berry berry berry

    Learn how to monitor your own home electric usage from minute to minute.

    Many people have heard of, or become familiar with the Kill A Watt electric meter.  This is the first step in taking charge of your electric bill, and building a true understanding of how much electricity different appliances in your house are using.  It can be purchased at, but also many libraries have them available for loan.  Check with your local public library to see if they have one available.

    This meter plugs into a standard outlet (US) and then an appliance is plugged into the device.  The Kill A Watt meter gives you an instant view of how many watts (power) the appliance is using at the moment, but many appliances use more or less power depending on what it is doing at the moment.  For example a computer reads different at start-up than it does during normal running, and different again in sleep mode, which is less.  To get a good solid reading for the appliance, you want to leave it plugged in for at least 24 hours on a day of typical use, to get the best kilowatt-hour reading.  Kilowatt Hours (KWH)  are what the electric company tracks to figure out what to charge you.  One Kilowatt Hour is the amount that a 1000 watt light bulb would use in one hour,  or what 10 – 100 watt light bulbs would use in one hour.  When you look closely at your electric bill, it doesn’t look like it should cost too much to light a house at 10-20 cents (US) per KWH, but it adds up very quickly.  Keeping these same  10-100 watt light bulbs on 24 hours a day for 30 days (24 x 30), uses 720 KWH.  That means that you may be spending $72 to $144 per month to light those bulbs depending on the electric cost per KWH in your area.  Of course this is an extreme example, but it gives you a simple illustration that is easy to understand.  Naturally these lights are going to be turning on and off throughout the day and night, which makes this more complicated.  Next we need to look at all the other things in the house that use electricity.  The more we can choose not to use, or to turn off as soon as we are done, the more we will save.

    The Kill A Watt is good for discovering how much single appliances cost on average, but it is limited.  It cannot measure the amount of power that ceiling lights are using for example.  It is not good at measuring what high power devices are costing you, such as your hot water heater, electric range, electric clothes dryer, well pump, or heating and cooling system.  These devices do not plug-in to a standard outlet, making the Kill A Watt useless for measuring these devices.

    There is another device out there that fits the bill.  It is called the EnviR SmartR Monitor it is also called the Current Cost monitor depending on what you search on the web (they need to work on their branding a little bit).  This device has some simple clamps (they look like chip clip type clamps) that clamp over the main power wires coming into your house.  These clamps plug into a small radio transmitter that sends a signal to a monitor that you place somewhere in the living space of your house.  It monitors the electric in your whole house, and updates every 6 seconds.  It reports how many KWH you have used in the past day, week, and month.  It gives you a real-time reading of the overall power you are using.  You can watch it change as you turn lights on and off.  You can get a sense of what is drawing the most power in your house, and how that can be reduced.

    Within the first two days of having this monitor in our kitchen, my 9-year-old daughter (unprompted) started turning things on and off to see how much is was costing.  This is the daughter who left the lights on all the time.  Now her behavior is starting to change!