A Multi-Scale Problem, In Your Living Room

The previous post, on the topic of how to wrap your head around a multi-scale problem, provides a general framework for conceiving of a problem on multiple scales, ranging from the individual button press to global policy. A convenient example of a multi-scale problem which is in nearly every living room is the cable box.


It seems innocuous enough, the cable, satellite, or telecom company rents it to you and it makes the telly gets a crisp HD signal. Sure it complicates the remote situation, and it adds a few bucks to the cable bill and the electric bill every month … wait, how much does it tack on to the electric bill? About 25-50W, continuously, 8760 hours a year, which adds up to about 200kWh/year, or at my rate of about 10c/kWh I pay about $2/month for the cable box electricity consumption (that’s a slightly more stinging $24/year, per box). Two of them consume as much electricity as the fridge! (which consumes an average of 415kWh/yr, or $45.65). And all it’s doing is … a lot.

What the cable box is not so silently doing

If it’s a DVR, it has a hard drive in it, which you can often hear spin up and hack away while recording, or at conveniently quiet times to defragment or update the guide. That uses energy. It also has a nice little clock, and a few LEDs to tell you it’s on or (still on but pretending to be) off. It never really turns off, and most don’t even throttle back a significant amount. The reasons it stays powered up all the time is that it has a lot of communicating to do, and people expect near instant action when they turn the TV and the box on.

It has to stay in contact with the cable office or satellite, and keep the channel and program listing synced up. It has to record when you want it to record (and therefore it needs to keep the hard drive defragmented (if you haven’t defragmented your computer’s drive lately, you should do that soon). It may have to do other things too—like get real time messages from upstream—some can be controlled from the web or from a smartphone application, or offer other features.

Why does it use so much electricity?

The quick answer is the most telling quote in the article: “Nobody asked us to use less.” Now, engineers shave grams off bike frames and milliwatts off the draw of cell phones, but without external pressure on multiple levels—from the government (105), on the corporation (103), to the boss (102), to the engineers (101) things won’t be prioritized. A cable box has to offer at least acceptable ergonomics, high reliability, and *instant performance*. People expect it to start instantly—and certainly not take an hour to update. If you’ve ever plugged in a factory fresh one, it can take up to an hour to set itself up—not exactly useful.

The system itself operates at multiple levels, which is why it has to stay booted (sort-of). The cable box (100) has to communicate with the local network (103), and possibly with a higher level network (104) or satellite network (106). That’s a little more complexity than just picking up the carrier wave from the local network affiliate and demodulating the Indian Head.

What to do

The engineers at Motorola or Cisco or Samsung (large manufacturers of set-top boxes all) need to work with the network designers to design more efficient ways to get the data to the box so that it doesn’t need to download so much data to get itself ready to go, and can power up and down as needed, such as waking on external signal or having a higher data rate to get its work done faster before powering back down. And of course better electronics can help to some degree.

One partial solution is to get rid of the cable box, and make the television smarter—modern TVs already have some equipment that’s always powered on—the remote receiver, possibly some other functionality—1..5W worth of something, which isn’t inconsequential when summed over the whole of the US. This would require a better solution than the failed CableCard, but something modular like that would be a start, eliminating a separate remote and batteries, power supply, cabling, box, and some circuitry.

There’s a behavioral component here as well—can you train users to expect a few second delay between button press and when the picture appears? That’s a fundamental human factors issue, fortunately people can put up with a few seconds of delay, although now being accustomed to instant action makes it harder to go to a less ‘perfect’ model of operation. The other part of the human dimension of this problem is that due to the delay in and diffuse nature of the feedback on power consumption (you get a single number at the end of a month), unless you read the Times or use an electric meter to figure out the STB is unobtrusively drawing a constant 25-50W, and then put that into context—and then get riled up enough to petition the government for redress.

Fortunately the EPA is extending the Energy Star guidelines to cover the set-top box, but that will take some time to come into force—and as consumers have almost no say over which box they get, the cable utility providers may not opt for newer higher efficiency units—it’s not their cost, so they don’t care other than wanting to be good corporate citizens.

What can you do, now?

You can try to see what happens if you power off the cable box with a power strip physical switch—some may resume quickly, some may take an hour. There’s going to be a lot of variability. And you can petition the government… or get rid of your cable/satellite service and read more books!

A Follow Up


Their estimate of 25 billion kWh of annual consumption, is incredible, especially if that results in 9 power plants worth of draw.   I’ve heard the figure bandied around of 5 power plants powering all of the devices which aren’t doing anything useful (like the charger not charging your cell-phone).  If it really is fourteen (14) power plants powering things which aren’t doing useful work, there’s a huge problem, and opportunity for electronics design and user education.


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