Mea Culpa – my math was wrong

In my previous blog post, I tried to refute the idea that TV set top boxes are the second largest consumer of energy in many US homes. I wrote: “According to the reporter’s own data, the average set top box (STB) uses about 35 watts per hour while on standby. There are 224 million STBs in the US, and about 110 million homes, meaning the average home has two of these ‘power hogs.’ At 24 hours per day times two devices, that is 1.68 kWh per day.”

Bad Duncan. That was NOT what the reporter said: “A set-top cable box with a digital recorder can consume as much as 35 watts of power…”

Please note his two qualifiers. First, not all of the 224 million STBs in America have PVRs: in fact, only about 50% of pay TV homes have even one PVR. Second, that phrase “as much as” should have gotten my spidey-sense tingling. Based on people who measure their own PVRs, 25 watts standby power is the norm, with non-PVR STBs running about 15 watts standby.

Therefore, let’s assume that about 35% of all the STBs in the USA have digital recorders, or 78 million, consuming an average of 25 watts per hour. That leaves 146 million consuming 15 watts. The blended average is about 18.5 watts.

Therefore, in all my comparisons to other sources of energy consumption, the number for an average home with two cable boxes is NOT 1.68 kWh per day, but 0.888 kWh per day, or 47% less.

Which makes the idea that set top boxes in standby mode are a significant part of household energy consumption even more ludicrous.

 

No, cable TV boxes are NOT the 2nd biggest energy users in many homes

Unless ‘many’ means about seven homes in all of North America.

As my friend Brian Piccioni likes to say, to many reporters the word “energy” is equivalent to “magic”: once they start talking about electrons, their brains turn to mush, and basic math and fact checking fly out the window.

This week’s version is from the LA Times, and the headline is not an overzealous contribution from some editor. The second paragraph ends with the sentence: “They [set top boxes] have become the biggest single energy user in many homes, apart from air conditioning.” There’s even an adorable little infographic showing the “power hog” devices. (I like the bit where the pig noses are power plugs: infographics #FTW!)

But it is almost impossible for that to be true. According to the reporter’s own data, the average set top box (STB) uses about 35 watts per hour while on standby. There are 224 million STBs in the US, and about 110 million homes, meaning the average home has two of these ‘power hogs.’ At 24 hours per day times two devices, that is 1.68 kWh per day. That’s not nothing, but how does it compare to other energy users?

There’s no question that air conditioners are huge consumers of energy. But so are refrigerators: the average (energy efficient!) fridge is around 750 watts per hour, and the average one runs 5-10 hours per day. That’s a minimum of 3.75 kWh per day, or more than four set top boxes. Do you have hot water in YOUR home? A water heater runs at 4,000 watts, and about 3 hours per day: 12 kWh daily, or over seven STBs. Clothes dryers are another culprit: at 3,000 watts per hour, if you spend even half an hour a day drying your clothes, that is more than the average home with two cable boxes.

We haven’t even touched the big energy use: space heating. Lots of homes have either all-electrical heating, or at least a few baseboards. They aren’t on year round, but when they are, the dials on your electric meter will be spinning: the average home uses nearly 30% of its total energy consumption for heating over an average year. That’s even more than air conditioning.

So it is technically possible that there are some American homes where STBs are the second biggest user of energy. But they would need to have a dozen cable boxes, be in Hawaii, not own a fridge, and bathe in the ocean. Or be this guy:

[To be clear, “vampire energy” consumption by set top boxes – or any appliance – is a serious issue. There absolutely need to be changes in how STBs run in sleep mode. But bad energy math is still bad energy math. Millions of Americans could start unplugging their set top boxes, and think they are saving the planet. At 35 watts per hour, STBs are nowhere near the top of the list of energy conservation measures that we should be thinking about.]