Berkeley Lab

In Your Home

If you don’t have an expensive meter, it is still possible to estimate your home’s total standby power. Here are two approaches:

1) Use Our Data Tables

Electromechanical Meter

Our data tables show the range of standby power requirements for most common appliances. Consult the list and familiarize yourself with appliances that typically have a standby mode. Then survey your home’s appliances and list how many you have of each kind. Use the average value listed in the Summary Table to estimate standby for each of them. (NOTE: Some appliances, such as computers, may be unplugged for several hours per day because they are on a power strip. In those cases, multiply the values by the fraction of time which you believe that they are actually leaking.) Sum the entries. This is your home’s leaking electricity. It will probably be between 25 and 150 Watts. If it isn’t, you may want to go back and check your calculations.

2) Shut the House Down (briefly)

CAUTION!! Don’t do this without an adult’s close supervision and only after careful preparation!

This technique employs your home’s built-in meter that is provided by your electric utility. You can measure electricity use with this meter just like the utility does. The goal is to make a brief measurement of your home’s electricity while all the appliances are switched off. This is more difficult than you might at first think because many appliances operate all the time or automatically. Some tricky appliances include:

  • refrigerator
  • freezer
  • water bed heater
  • aquarium lights and bubbler
  • well pump
  • sump pump
  • air conditioner crankcase heater
  • pool or hot tub pump
  • heat exchanger
  • other thermostatically controlled fans

If any of these appliances come on during the measurement period, then you will greatly overestimate standby power. Refrigerators are a real problem because they also have small electric heaters and motors inside that you can’t hear turning on and off. Therefore, to measure the standby power in your home, you will have to unplug these appliances. It is important to make a list of all the appliances that you unplug. The danger here is that you will forget to plug back in critical appliances like refrigerators, sump pumps, or well pumps before you notice the damage. Other appliances are hard wired into the house’s electrical system and can’t be unplugged. Fortunately most of them make noise when they switch on or can be switched to a “minimum” setting so that they won’t switch on during the measurement period. (Record all original settings on these appliances before you change them!)

Unfortunately, the smallest dial on most electromechanical meters go around once for every 10 kWh consumed. Since leaking electricity is typically on the order of one-twentieth of a kW (50 W), it will take about 200 hours for it to go around. You can’t switch off all of the appliances in the house for that long, so you’ll need to use one of two special measurement procedures, depending on whether you have an electromechanical or digital meter on your home. Most homes have an electromechanical meter like the one shown here.

It’s best to perform both methods discussed above because method 1 is likely to underestimate standby power (because appliances are overlooked) and method 2 is likely to overestimate standby power (because some appliances were on, not in standby).

Studying standby power makes an excellent science project. Here are some questions to answer along the way.

Please let us know what you find!