Facts about DVRs and Energy Consumption

There has been a lot of hype about the energy consumption of DVR units provided by cable and satellite television companies. Sensational headlines scream that DVRs are destroying your budget and melting the glaciers. These are quickly followed by sarcastic rebuttals and disparaging comparisons to Al Gore. An example from Popular Science: Your Set-Top Box Is Murdering Your Electric Bill. The headline literally screams murder and is followed by text like: “the biggest energy drain in your house…is, unbelievably, the TV set-top box.” The comments that follow the article are an exercise in acidic snark: “Can’t PopScience find writers that finished grade 3 arithmetic?”, “Does the writer not possess any common sense whatsoever?”, “Biggest load of tosh I’ve ever read.”

Those are the comments I can quote without bleeping…

So what is the real deal? How much do these things consume? Are they evil vampires or just the latest thing for silly people to be paranoid about? They’re Like Light Bulbs… The deal is this: Data shows that set-top boxes consume energy at about the rate of your average incandescent light-bulb, between 30 and 50 watts. By contrast, articles like the one I’ve cited claim that cable and satellite DVRs use as much power as a refrigerator or a/c unit. So there’s nothing to it, right? Fridges and a/c units obviously use more power than that.dvr energy consumption Yes and no.

DVRs That Never Shut Off

DVRs use much less energy than refrigerators or a/c units do when their compressors are running. According to this table from GE, a refrigerator/freezer uses about 450W, and a window unit a/c approximately 1000W. The problem is that unlike these appliances DVRs never turn off. Even when they are “off” they consume nearly as much power as they do when on. By contrast, refrigerators and a/c units do not run their compressors 24 hours a day. Now, DVRs need be ‘on’ enough to maintain a connection with the service provider and to receive software updates; it would be impractical to have them completely power down when they are not being used. Remember how long it takes to get a connection when you install service? You don’t want to have to wait that long every time you turn on the TV. However, this ‘always on’ requirement is entirely compatible with a low power ‘sleep’ mode that only keeps essential components on while the box isn’t being used. Cable and satellite companies are loath to build in such a sleep mode for reasons mostly related to their competitive environment. Namely, there isn’t demand for it from consumers sufficient to justify (in their view) putting the money and time into changing practices, and they are afraid that consumers will get annoyed having to wait for DVRs to power back up from a ‘sleep’ mode, resulting in a competitive disadvantage with rivals who can be expected to hype their “instant-on!” machines. By comparison, European markets have DVRs that sleep, due to government regulations. Much of the overheated rhetoric about DVR power consumption is aimed at either spurring regulations, or exciting consumer demand for such settings so that the providers will be motivated to provide them. How to Really Compare DVRs with Refrigerators So how do DVRs compare to refrigerators? It turns out that the comparisons trumpeted by the alarmists and the sarcastic rebuttals of the critics are both partially accurate. At 40W, DVRs obviously don’t consume energy nearly as quickly as a fridge (450W) or a/c unit (1000W) when it is running its compressor. But fridges and a/c units turn on and off as regulated by a timer or thermostat, while DVRs are constantly on. (NOTE: The most modern and energy efficient refrigerators have consumption rates below 150W even when the compressor is running, but most homes are not yet equipped with them. The number I’m using is an average of the most currently used models of fridge).

What’s a Watt?

To make sense of any comparison between the energy consumption of different appliances, we need to distinguish between two measures of energy that are often run together in debates and cause a lot of confusion, Watts and Kilowatt Hours. The one (Watts) measures power, the other (Kilowatt Hour) measures total energy. What does that mean? We can compare electricity to water flowing through a pipe and out of a spigot. Asking “How many Watts?” is like asking how fast water is coming out of the pipe; asking “How many kilowatt-hours (kWh)?” is like asking how much water came out of the pipe in total. In other words, Watts (W) indicate the rate of consumption, and kWh indicates the amount of energy consumed. So how much energy does a DVR consume? The average DVR plugged into the wall consumes energy at a rate of 40W nearly constantly. Consuming 40W constantly for an hour translates to 40 “watt hours” of energy, or .04 kWh. Thus, the average DVR consumes 960 watt hours per day – 40W times 24 hours – which is .96 kWh, a little bit less than one kWh. By comparison, the average modern refrigerator run at full power (450W) 24/7 would consume 10.8 kWh per day. That’s a whole lot more than the DVR. But for how much of the day does a fridge run at full power?

The answer is…it depends.

Of course it depends. It depends on where you live and how you use the appliance. Are you running your refrigerator in a house that’s 70 degrees F, or 90? Do you open the door a few times a day, or over and over? Do you tend to stand in front of the open door trying to figure out what to eat, or open and close it real quick? How much food is in it? Etc. For this reason it’s much more useful to compare appliances based on measures of average annual energy consumption. Here’s an example. According to the table in the link a standard refrigerator built between 2001 and 2010 consumes an average of 600 kWh per year, while the most modern and energy efficient models consume on average 425 kWh per year. Your mileage will vary, depending on whether you live in an environment warmer than average or colder than average, and on how you use your fridge. So let’s just use the averages and compare them to the DVR. With our assumptions, the average DVR consumes .96 kWh per day, which translates to (.96×365=) 350.4 kWh per year. This is getting close to the energy consumption of the most efficient refrigerators at 425 kWh, and is approximately 58% of the average annual consumption of a standard 2000’s era fridge at 600 kWh.

What to Take Away From This?

The alarmists are clearly exaggerating this issue. But their sarcastic critics are severely underestimating it. If your concern is your energy bill, it’s probably not that big of a deal. Having a DVR will cost you something on the order of a few tens of dollars per year, depending on your energy rates. However, if your concern is the economic and environmental effects of the overall energy consumption of millions of consumers, it is a big deal, and improving the efficiency of DVRs is certainly worth promoting. More importantly, however, neither side has talked about what’s really shocking about all of this: keeping a 40W light bulb burning all the time is like having a second refrigerator in your house! => Help us Invite your Friends on Facebook to inteercommunication.blogspot.com!!!