The PlayStation 4 and Xbox One's standby modes and video capabilities are responsible for the vast increases in power usage over their previous-generation versions, according to a new report from the Natural Resources Defense Council.

The NRDC, a nonprofit environmental advocacy group, conducted extensive testing last month with the PS4, Wii U and Xbox One to determine the consoles' power consumption across a variety of functions. The organization collected its findings in a report called "The Latest-Generation Video Game Consoles: How Much Energy Do They Waste When You're Not Playing?" Prior to this report, the most recent NRDC paper on game console power usage came in 2008.

"The new consoles consume more energy each year playing video or in standby mode than playing games"

Headlining the new NRDC report is a staggering figure: If the PS4, Wii U and Xbox One replace the 110 million units of PlayStation 3, Wii and Xbox 360 consoles that were sold in the U.S. from 2005 through 2013, the total energy use of the three current-generation systems will top 10 billion kilowatt-hours of electricity per year — enough to power all of Houston, the nation's fourth-largest city. And that energy total would cost American households $1 billion in annual power bills, with 40 percent of it — $400 million — going to electricity that's wasted while the consoles are in standby mode.

Over the course of a year, the PS4 and Xbox One will consume two to three times as much energy as the latest models of the PlayStation 3 and Xbox 360, according to the NRDC. That's true even though both of the new consoles incorporate energy-saving features like improved power scaling (the ability to use only as much energy as a particular task requires) and options for automatically powering down after a certain amount of time.

"The new consoles consume more energy each year playing video or in standby mode than playing games," the report reads.

According to the NRDC's tests, the PS4 draws 8.5 watts in standby (3 watts with USB charging disabled), while the Wii U draws a mere 0.4 watts. The Xbox One, in its default configuration, consumes 15.7 watts in standby, largely due to Kinect voice control — the device is always listening for the phrase "Xbox on." The NRDC calculated that the Xbox One's standby power usage comprises 44 percent of its annual power consumption.

The Xbox One does use less energy than the PS4 when it's playing games (112 watts versus 137 watts) or streaming videos (74 watts versus 89 watts). However, the Xbox One's TV functionality requires the console to be on whenever a user wants to watch cable TV, which adds an extra 72 watts to TV viewing. The NRDC report recommends that Microsoft update the Xbox One to allow TV watching while the console is off.

The Xbox One's TV functionality adds an extra 72 watts to TV viewing

Sony and Nintendo didn't get away scot-free. The report suggests that Sony reduce the amount of standby power the PS4 requires with USB charging enabled but not in active use, and cut down power usage during streaming video playback. Nintendo, the report says, should change the Wii U's notifications so the console doesn't continually alert users that automatic power down is enabled — the nagging pop-ups can lead people to disable the feature, which would cause higher power usage.

The report notes that a combined 8 million units of PS4 and Xbox One consoles had been sold worldwide within two months of their launches in November. In their lifetime, those systems will use a total of 8,000 gigawatt-hours of electricity and be responsible for 3 million metric tons' worth of carbon dioxide emissions.

If neither Sony nor Microsoft change the way the PS4 and Xbox One currently run, the report warns, "Much of that energy will be consumed when no one is using the console but it is still listening for a voice command in the middle of the night and using higher power than necessary to keep USB ports active."

You can find many more details in the full NRDC report (PDF).