Residential Energy Consumption

Here is a link to the 2009 Residential Energy Consumption Survey done by the U.S. Energy Information Administration (EIA). I find it a positive development that heating and cooling no longer the majority of U.S. home energy use. On the other hand there is an 44% increase in energy consumption of appliances/electronics/lights since 1993: 55% of the total energy consumed is now spend on these items.

Residential Energy Consumption in US homes

Here is a link to a per item energy consumption estimation by the U.S. department of energy. The problem with this list is that it does not contain any information about how long any of these items are in use. In particular a Refrigerator (frost-free, 16 cubic feet) is listed with 725W. The article mentions:

Note: To estimate the number of hours that a refrigerator actually operates at its maximum wattage, divide the total time the refrigerator is plugged in by three.

That would result in 24/3 = 8 hours of operation per day. Luckily there is another factor that can be put into the estimation: The 725W might only be consumed to start the compressor in the refrigerator, once it is running the wattage drops again.

Here is some real testing data I collected from my refrigerator. The plate reads: 6.5A, 110V. That would result in 715VA which is about 708W for a refrigerator (because the power factor was 0.99). The measured surge power used to start the refrigerator was about 1000W – which is about 140% of the listed value but as soon as it is running it only consumed 150W which is only 20% of what is listed.

Some other items which I did measure:

  • regular UPS with IP-Phone and cable modem plugged in: 18W (permanent)
  • 55″ TV with adaptive background light: 75 – 450W (in use)
  • CD-Player: 3W (standby)
  • Audio Amplifier: 3W (in use, low sound volume)

Here is a list of standby power of many products. Standby power adds up to a huge amount and it is will most likely grow since we all buy more and more electronic items.

Not all appliances are as complex as a fridge but to really measure the consumption of any household item there is the Kill-a-Watt device available which can measure household appliances up to 1500W.

Recommended also: Manifesto.

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