Which appliance is the energy hog? It’s not your air conditioner

August 16th, 2011 by Philip Brasor & Masako Tsubuku

See that red button on the right...

Actually, in terms of overall electricity usage in households, air conditioners use the most on a continual basis, followed by refrigerators. But on a unit per hour basis, air conditioners are not that bad, even though they’ve been made the villain by the media.¬†Broadcasters, in particular, are offering tips to households on how to cut down on energy consumption and the main suggestion is to set your air conditioner at 28 degrees centigrade. Because so many people, in particular the elderly, have fallen victim to heat stroke, no one is saying to turn off the air conditioner any more, but the general consensus is that the average air conditioner in the average home uses about 130 watts of energy and, overall, accounts for a bit less than a fourth of the summer electricity bill, which gives you some idea of the savings potential.

What the media doesn’t say, according to an article in the most recent issue of Shukan Post, is that there is another appliance in your house that actually uses more electricity. A typical large screen (over 37 inches) LCD television set uses on average 220 watts, or 70 percent more energy than the air conditioner if both are being used continuously, but, of course, media companies aren’t going to suggest you turn off the TV because that would hurt their business.

And according to the Nomura Research Institute, since air conditioners work on something akin to fuzzy logic, they save more energy the longer you keep them on. The point is not to turn them off and on. If a room is, say 32 degrees and you turn on an air conditioner set to 27 degrees, it requires 800 watts right at the beginning, but after only a minute the energy consumption drops to 600 watts and then after 17 minutes it can drop to as low as 80 watts. What tends to be the concern of energy producers is not so much that households use their air conditioners, but rather that they don’t all turn them on at the same time. By the time an air conditioning unit is maintaining its set 27-degree temperature it may be using as little as 20 watts. The problem is, once you turn the air conditioner off, you have to start from zero again. Also, it should be noted that these figures are for rooms that are fully insulated.

In comparison, three incandescent 60-watt light bulbs use 162 watts, continuously. And TVs are worse: 220 watts isn’t a whole lot better than the old CRT TVs. Though LCD and plasma displays are touted as being more energy efficient by the industry, the comparisons are being made for equivalent screen area. For sure, a 28-inch CRT TV uses about 87 watts, and a same-size LCD screen only uses 42 watts, but the energy consumption increases exponentially from there. When you get to 40 inches, the LCD consumption jumps to 230 watts. And the whole point of flat screen TVs is that they take up less room and thus families are buying larger and larger ones. A 50-inch plasma screen uses 400 watts.

Also, there’s a big difference in manufacturer specifications. Some makers are much more energy efficient than others, but the point is that the TV is not only using a lot more electricity than your aircon, it’s also heating up your room, making more work for your aircon. Even when the TV is on standby it’s consuming about 3 watts of power. So turn it off. There’s nothing to watch anyway.

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2 Responses

  1. This is a brilliant post, and one I will be showing to my Japanese wife with whom I am forever arguing about the air-conditioning temperature. Thank you!

  2. Good post

    I noticed a while ago that the the area close to my large flat screen TV is considerably hotter than the rest of my room.
    This made me think a bit. And in I guess that since almost all of the energy used by my TV is converted into heat in the room, a proportional amount of AirCon energy would be needed to counter this effect.
    Which means, that Turning of your TV might actually save you on your AirCon bill as well.

    Id love to see some calculations on it.


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