In Depth: Phantom Energy

by NeilT, 2009-06-05

I recently purchased a Kill-A-Watt meter to check the energy use of various appliances around the house. We hear a lot about how appliances on stand-by use a lot of electricity, but rarely are we given real numbers. I wanted to find out how much was really being wasted.

I tried to take 4 measurements for each device:

  • On/Active - The device is being actively used, such as a computer while booting up.
  • On/Idle - The device is on but not being actively used, such as a computer sitting idle.
  • Standby - If the device has a dedicated standby mode, which is on but low-power.
  • Off - The most powered-down state of the device while still plugged in.

Not all devices had all 4 modes, so I've just left those blank.

All measurements are in Watts as read by the Kill-A-Watt. I intentionally left off the brand name of most items because my purpose is to show a realistic example, not precise measurements for just a specific model.

Energy use readings

Find ways to become more sustainable

Sustainable Action Recommendations
Discussion Forums
Track Your Home Energy Use
Desktop computer (2.66 Quad Core2 Duo)959066
Older desktop computer (AMD 2400+)9088 1
19" CRT monitor707011
Computer Speakers (Amplified)55 2
External USB hard drive enclosure188 0
Photo printer22 1
Scanner1313 1
Thinkpad Laptop851510
Floor rotating fan44 0
Coffee maker990111
Toaster oven820 0
Small led night light1 1
Video baby monitor3 1
Nintendo Wii181881
32" LCD TV151 1
DVD player1010 1
Portable mini stereo53 1
Cordless phone stand21 1
Vonage router4  
Cell phone charging4  

Wasted energy

Now we can look at a few different scenarios. Without unplugging the devices, the lowest phantom energy use that could be achieved, assuming the devices were never turned on, is 25 Watts (including the Vonage router but not cell phone charging). That's 219 kWh anually, which at $0.10/kWh is $21.90 plus 153 kg CO2 wasted.

That scenario is pretty unrealistic, so let's try to figure out what the average person might waste. Assume one of the computers is on but idle half the time and in standby otherwise. Assume the printer is normally left on (who actually turns them off?). Assume the Wii is in standby mode all the time (I didn't know until I got the Kill-A-Watt that there was a separate "off" mode rather than standby). Assume the laptop if always left in standby mode.

The new scenario shows a waste of 86 watts, which is 753 kWh, $75.33 and 527 kg CO2 anually.