Minnesota’s quiet energy pigs

A study finds 75 percent of desktop computer electricity use occurs when no one is actually using their computer.


Are we saving much electricity by weatherproofing our homes and converting lighting to more energy-efficient bulbs? Sure, but much of the energy saved is being wasted by a sharp increase in the number of electronic gadgets in the house sucking up electrons while waiting to be used, according to a survey of Minnesota homes.

The report, from the Energy Center of Wisconsin, says plug-in devices consume 15-30 percent of a home’s energy consumption, and 4 percent of it is wasted merely by the devices’ stay-warm feature.

The biggest energy hog is the computer, the report said.


Our analysis — which was based on metering data as well as occupancy-sensor data showing when someone was at the computer — suggests that simply enabling sleep/hibernate mode for these computers could reduce electricity use among these systems by about 50 percent (nearly 300 kWh per year). In other words, in two of every three Minnesota homes, a simple change to computer settings could reduce home electricity by about 3 percent.

About 30 percent of energy savings “opportunities,” comes from four devices, according the Energy Center: Compact stereo systems that drew 20 watts or more continuously and were rarely used; older CRT TVs drawing 10 watts or more of standby power; computer printers drawing 4-8 watts of standby power that were only used a few minutes a week; and TV peripherals — especially VCRs and VCR/DVD players that were rarely used.

The study found that 75 percent of desktop computer electricity use occurs when no one is actually using their computer.

“Most computers are set up to turn the monitor off after about 20 minutes,” researcher Scott Pigg told the Milwaukee Journal Sentinel. “So we turn it on and use it and walk away and come back into the room and see the monitor’s off. We think: ‘Well, my computer is managing its power and it’s shut down.’

“What they don’t realize is that two-thirds of the electricity draw is the thing that’s sitting on the floor – not the thing that’s sitting on the desk,” he added. “And the only visual indication that you have that computer’s on is a little fan noise and a little green light somewhere.”

(h/t: Ken Paulman)

  • Bob Moffitt

    Good article, Bob. It’s true. We have a older Mac and a newer laptop. While we keep the laptop powered up all day, we keep the juice off on the Mac until needed.

  • Tyler

    I don’t have a link, but a recent study compared a Sony flat-screen, Xbox 360, and old CRT TV when powered down. The CRT actually took the least amount of electricity since it was physically switched off, and the Xbox soaked up the *most* juice.

    YMMV