For many people, the only thing they know about electricity is that they use it and get a monthly bill for that use. Volts, amps, watts, and kilowatt hours are a foreign language. In order to start reducing your electric bill, it is helpful to find out how much energy different parts of your house are using. Watt meters are very helpful devices to accomplish this.
There are two basic types of Watt meters. The first type is a plug meter designed to measure individual appliances. Simply plug your appliance into the meter, and plug your meter into the wall. With this information, you can quickly identify inefficient items. The second type of meter is a whole house meter which can be located in a convenient place in your home (the kitchen countertop for example), and will show you how much energy your home is using at any specific time, as well as cumulatively for the day and for the billing cycle.
A watt meter tells you how much power is being used. If you plug a 60 watt reading light into a watt meter, it should read something close to 60 watts. If you use that reading light for 3 hours a day for a month, you will have used 60 watts x 3 hours/day x 30 days = 5,400 watt hours. A good watt meter will allow you to leave something plugged in and will tell you both current watts and accumulated watt hours. You buy electricity from the utility company in units of 1000 watt hours or one kilowatt hour (kWh). Kilowatt hours are usually abbreviated kWh. If your utility charges you $.10/kWh, using the reading light for 3 hours a day for a month would cost 5.4 kWh * $.10 or $.54 per month.
What people do not realize is how much energy some devices use when they are off or on standby. For example, a computer uninterruptible power supply (UPS) backup battery with monitor, printer, computer, rechargeable phone, and computer speakers may draw 50 watts even when the system is off. In this case, 24 hours * 50 watts * 30 days * .10 /1000 = $3.60/month to run a computer that is turned off. Most homes have many devices that draw power when they’re off, and this is referred to as a “phantom load”. If your home has 10 devices that draw a 50 watt phantom load all the time, this starts to really add up. In the example above, you’d be spending $36 each month for things that were off or on standby. Not only is this an unnecessary cost, it causes unnecessary pollution as well. Once you’ve identified a phantom load, simply unplug the device when you are not using it, or put it on a power strip and switch the power strip off.
In addition to an instantaneous reading, some watt meters will project monthly kWh and/or cost. This is particularly useful for appliances such as refrigerators with compressors that cycle on and off. You can plug a refrigerator in for several days and the meter will estimate how many kWh the refrigerator will use for an entire month.
There are several brands of Watt meters on the market that will make your home energy audit go faster. The meters we found to do the job best are the “Kill-A-Watt (TM)” plug meter, the” Watts UP? (TM)” Plug meter, and the “TED (TM)” whole house meter. The Kill A Watt is a good plug meter if you want to mainly measure watts and kWh. It is an inexpensive way to start getting the big picture of how your house is using electricity.
The Watts UP? plug meter adds a power cord to make it easier to use and has many more features such as the ability to project monthly kWh and cost. It also keeps track of many more values such as maximum and minimum. The Watts UP? PRO adds data logging to the Watts UP meterand will record data every second. Once memory fills up, it starts recording every two seconds. You still get good data resolution even after collecting data for a month. The data can then be downloaded into a computer and graphed for a visual of how your energy usage is going.
The TED meter will give second-by-second and daily feedback on energy use for the entire house. Part of the meter is set up inside your breaker box. There is a display unit that can be plugged into any outlet in the house. Most people do not know how much or little energy they are using until the monthly bill comes in. It is too late then to make adjustments. A TED meter is a great way to immediately see how changes in habits and devices affect the entire house energy usage. You might want to think about turning the television off before you go to bed.