Are Smart Speakers and Streaming Devices Energy Efficient?
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- Aug 13, 2019 6:30 am GMT
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Ever wonder how much energy is consumed by the almost 100 million new smart speakers installed in America’s homes, such as the Amazon Echo and the video-streaming devices hooked up to our televisions? The good news is that even though these devices are always connected to the internet, ready to accept and quickly respond to the next command, our groundbreaking report published today shows they are very energy efficient. The picture can change dramatically, however, when a smart speaker is used to wake and control a television through voice commands instead of a remote control.
NRDC and our consultant Pacific Crest Labs completed the first in-depth study of the power used by each of the leading smart speakers (also sometimes referred to as voice or digital assistants) and video streaming products on the market, and performed modelling on the national impacts of their energy use.
Fortunately, these devices used low levels of power both when doing their main job—like playing a requested song, finding the answer to a question, or streaming a favorite show, sporting event or movie—and also when sitting idle waiting to be used. Due to their efficient designs, each one only consumes a few dollars ($1.50-$4) of electricity per year.
However, we also found that linking a smart speaker to some of the 2018 model year televisions in order to wake and control them without a remote caused the TV’s standby power use to skyrocket from less than 1 watt to around 20 watts continuously. This can cause a TV’s overall annual energy use to more than double, with an increase from 106 kilowatt-hours per year (kWh/yr) to 248 kWh/yr. Over the 10-year life of the TV, this adds up to almost $200 in extra electricity costs.
If this trend continues without TV design improvements, national television energy use could grow by the equivalent of three to six large power plants’ worth of electricity and increase consumer electricity bills by $1.3 billion to $2.5 billion per year. Fortunately, with design improvements, some of which are just entering the market, it’s possible to still deliver this great consumer experience while keeping TV standby power levels to 1 to 2 watts, avoiding most of the incremental energy use and related pollution from the additional power generation.
Amazon popularized the smart speaker product category with the Echo, the cylindrical-shaped speaker that is connected wirelessly to the internet and responds to voice inquiries that begin with the word “Alexa.” Apple, Google, and many others have introduced similar products, as well as miniaturized versions. As of early 2018, there were more than 50 million smart speakers installed nationally and together they consumed 783 gigawatt hours of energy per year (as shown below), which translates to $102 million in annual electricity costs.
|Product||On-Mode Power (Watts)||Standby Power (Watts)||Annual Energy Use (KWh/Yr) Per Model|
|Google Home Mini||1.7||1.4||12.3|
|Amazon Echo (2nd Gen.)||2.4||1.6||15.2|
|Harman Kardon Invoke||4.2||3.8||33.4|
Video Streaming Devices
Video streaming devices can dramatically expand the range of content that can be viewed on televisions. These devices connect directly to a television and come in the form of a small box or a thumb drive-shaped “dongle.” Each of the devices we tested—Amazon Fire TV, Apple TV, Google Chromecast Ultra and Roku Ultra—receives content via a wireless internet connection for viewing on a TV. Their on-mode power levels were very similar, between 2.3 and 3.3 watts. While the Amazon Fire TV and Apple TV had standby power levels of less than 1 watt, the Google Chromecast Ultra and Roku Ultra had slightly higher standby power levels of 2.2 and 2.7 watts, respectively, which can add up over the course of a year as these devices spend most of their time in standby mode.
The annual energy use for these devices ranged from 11 to 25 kilowatt-hours per year (kWh/yr). National annual video streaming device electricity consumption is approximately 727 gigawatt hours (GWh/yr)—or $94 million in annual consumer electricity costs.
However, these streaming devices use much less power than traditional set-top boxes provided by cable, satellite, and telephone companies to their customers for viewing pay TV services. (An old DVR, for example, uses roughly 10 times more electricity per year.) If consumers can access the same services via an “app” loaded onto their streaming device or directly onto their smart (internet-connected) TV, they should return their set-top boxes to their service providers. The switch from conventional set-top boxes would result in significant national energy savings, lowering electric bills for consumers and reducing power plant pollution.
Connecting a Smart Speaker to a New TV Can Dramatically Increase TV Energy Use
Many of the newest TVs on the market offer the ability to be linked with an adjacent smart speaker via a home wireless network. The speaker allows a user to control a TV (e.g., change volume, change channels, search for a show) and in some cases wake it from standby mode, simply via their voice, eliminating the need to find and use a remote control. Our testing looked at the impact this linkage had on the standby energy levels of 2018 model year televisions.
Almost all TVs on the market today use less than 1 watt in standby mode, waiting for a signal from the remote control, and many models need only 0.2 watts. Much to our surprise and dismay, some of the TVs we tested consumed between 18.8 and 22.9 watts of standby power continuously after being linked to a smart speaker. (Note: This increase only occurred with TVs that can be awakened and controlled by voice command. Those that could not be awakened by voice maintained low standby power levels.) The decision to link a smart speaker to a new TV can easily double its energy use.
After our initial testing, we relayed our findings to the leading TV makers and learned that a few had been working to achieve much lower standby power levels than the ones we recorded. Our limited follow-up testing showed that some of the new models will be able to achieve standby power levels of only 1 to 2 watts while still able to quickly wake a TV and respond to a user’s voice commands.
With smart speaker use expected to continue to mushroom, we hope our report serves as a wake-up call and that TV manufacturers make the necessary design changes to achieve low standby power levels when their TVs are connected to a smart speaker. This way we all can enjoy the convenience of waking and controlling our TVs with just our voices and avoid wasting massive amounts of energy and needlessly increasing consumer energy bills.