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    Why Computers Must Sleep

    Written by

    Emanuel Maiberg

    Contributor

    Do computers dream of electric sheep?

    Not unless we program them to, but the important thing is that they're sleeping in the first place. Idle electronics may waste as much as $19 billion in energy costs annually in the United States, according to study from the Natural Resource Defense Council.

    “Personal computers use roughly the same amount of energy as all the data centers in the US,” Pierre Delforge, who advocates for energy efficiency in the high tech sector for the NRDC, told me. “Individually, they don’t use that much energy, but because there are so many of them in homes and offices, in aggregate they add up to about 2 percent of energy use in the US.”

    Most of that energy, studies have shown, is used when you’re not even using the computer. It’s a huge waste—like leaving the refrigerator door open—which is why practically every consumer electronic device has a sleep mode.

    Sleep mode, or some variety of automatic power-down mode, has been around for as long as we’ve had computers. The earliest example I could find is now at the National Museum of Computing in the UK. A spokesperson for the museum told me that it’s Harwell Dekatron computer, which first ran in 1951, had an auto-power down feature.

    The Harwell Dekatron. Image: The National Museum of Computing

    If users don’t touch their computer for a set amount of time, the system assumes they’re away, cutting power to unneeded subsystems while keeping just enough powered on so the machines can pick up where they left off.

    It’s a simple solution that didn’t really gain popularity until the ‘90s—not because engineers were trying to save the planet, but because of the spread of laptops and other mobile devices where longer battery life is key.

    In theory, this solves one of the biggest energy waste problem with consumer electronics (at least until we can do away with sleep modes entirely), but in practice, it’s much more complicated. In fact, in some cases sleep modes can waste more energy than they save.

    The best example of this is the Xbox One, which has an “instant on” mode. Microsoft’s game console will go to sleep if you leave it idle for a certain time, but it will keep listening via the Kinect camera and microphone, so you can turn it back on with a voice command. It’s a convenient feature, but it also means that the Xbox One is drawing 12 watts of power in sleep mode. According to Delforge, that’s way too much power. By contrast, many countries follow the One Watt Initiative, which limits the power a device can use in sleep mode to that amount.

    “There’s no reason a single product on the market should be allowed to have a 5 or 10 watts of sleep mode power when we have technology to keep it at one watt,” Delforge said.

    The previous iteration of the console, the Xbox 360, didn’t have a sleep mode, meaning it would waste a lot of energy if you left it on, but the Xbox One’s default sleep mode adds up. It amounts to 44 percent of the Xbox One’s annual energy consumption, which overall is more than twice the annual energy consumption of the Xbox 360.

    “It’s certainly not an isolated case,” Delforge said. “More devices have this always-on mode because they’re connected 24/7, or they have some function like voice control. That function, if not designed properly to use very low power, because it’s on a lot of the time, adds up to a lot of energy.”

    Another good example of this is connected light bulbs you can control with your smartphone. They can help save energy because you can turn them off when nobody’s around, but if every light bulb uses just 1 watt to do this, even if that bulb is very energy efficient when it’s on, it could still use more energy overall.

    Delforge said that doesn’t mean we can’t have connected light bulbs. They just need to be better designed. Sam Naffziger, an AMD corporate fellow and an expert on low power technologies in microprocessors, agrees.

    “In engineering every feature requires time and energy so we gotta pick and choose which one to invest in, and I don't think [Microsoft] necessarily knew that feature would be so important,” Naffziger said. “The thing to keep in mind is the big trade off is power saving versus overhead of getting in and out. The deeper the sleep mode is, the longer it takes to wake up, and there's an analogy to biology there to some extent.”

    He’s been working on making sleep modes more efficient for more than a decade, and while the innovation that takes place in this space is largely invisible, it’s kind of amazing.

    Naffziger said that one of the more advanced things he’s working on these days are specialized sleep modes for certain activities, like watching videos. If all you’re doing is watching Netflix, the computer will put everything it doesn’t need for that activity to sleep.

    Image: NRDC

    “We're even going into the levels where we take advantage of the 33 milliseconds between frames, which is a really long time in processor world,” he said. “We've realized we can do all the computation for that video frame in like 5 to 10 of those millisecond, and then we go to sleep for the remaining 20ish milliseconds and that reduces video playback power by quite a lot.”

    Naffziger calls this type of “short idle” sleep mode dozing or napping modes, but you can also think about it like sleeping with your eyes open. Your screen is displaying something, but it’s not doing much else.

    According to Energy Star, an energy efficiency standard for consumer products created by the Environmental Protection Agency and the Department of Energy in 1992, technological innovation in this area prevents billions of pounds of greenhouse gas emissions every year.

    When the EPA started looking into how to save power in the information technology industry and set the Energy Star standard, Naffziger said, it found a direct correlation between the average power a PC consumed over a year and these short idle power modes. Active power, like when your pimped-out gaming PC is firing on all cylinders, is negligible.

    “Now, we in the processor community are beating that idle power down,” Naffziger said. “ We still have a way to go, but when we’re done, the only power we’re gonna burn is active power. That’s where we want to get.”

    As important as that goal is, Energy Star can only do so much to compel manufacturers to improve energy efficiency in sleep modes. Qualifying for Energy Star is a selling point for consumers who consider energy consumption while shopping, and not qualifying for Energy Star can prevent companies from selling a huge number of products to government agencies, but the standard Energy Star sets isn’t mandatory. Even Naffziger admits that while better sleep modes can reduce fan noise and heat--things PC power users care about--manufacturers aren’t as motivated to improve sleep modes on desktops as they are with mobile devices.

    The Energy Star standard is also not as good as it can be. For example, the European Commission's Ecodesign program has clear regulation for “standby and off modes” which forced Microsoft to ship the Xbox One with a more energy efficient default configuration. Xbox One users in Europe have the option to turn on the wasteful voice activation feature if the wanted, but it wasn’t set up that way out of the box.

    For Delforge and the NRDC, getting manufacturers to optimize their software and hardware for more energy efficient sleep modes, even when they don’t have to do it for the sake of battery life, is crucial.

    It’s making some progress, at least in California, where the California Energy Commission set its own appliance efficiency regulations.

    “Everything that has a battery that is sold in California today—cell phones, laptops, cordless phones—to meet a certain level of sleep power,” Delforge said. “There's still a long way to go. It needs to be expanded to many more product categories, and beyond California. That's one initiative we're working on.”

    Last spring, the NRDC gave a demonstration to the California Energy Commission where it took an off-the-shelf PC, and changed some of the settings in Windows and bios, reducing the energy it consumed in sleep mode by 60 percent, without sacrificing wake up times.

    It’s one of many, relatively easy things consumers and companies can do to seriously cut down energy waste. They just have to do it.

    You’ll Sleep When You’re Dead is Motherboard’s exploration of the future of sleep. Read more stories.