Trip Summary Calendar - Where we went and when

September 16, 2005

So what does it cost to watch that huge TV?

Kill-a-WattAfter receiving ever-increasing electric bills, I decided to do something about it. No, not conserve silly - analyze! Ok, the eventual goal is to conserve but how does one know what in the house is using the most juice? After a bit of research I bought a cool toy called a Kill-a-Watt (heh, cute name). The idea is you plug this into the wall, then some electrical item into the Kill-a-Watt. It provides instant readings like the current wattage, and measurement over time like KWh. KWh are the Kilowatt Hours your electricity bill is based on. Here we pay about 11.6 cents for every KWh we use. One nearly needs a PhD to understand how this is calculated, but that's another story.

The first big test for the new toy is our home theater system. We have a nice system but not that far off from what others are buying these days. We've got a 61" rear-projection TV, a Tivo/Satellite receiver, a receiver/amplifier, and the usual collection of CD/DVD/VCR/tape/etc players. The Tivo is always on, as it is always recording. The receiver is always on as it's the main switcher for the whole system. The other devices are on when we use them - most often the television. So what does this all cost to use?

I also wanted to answer a question I've had for a while, which is how much electricity does the receiver/amplifier use when powered on, but not in use (volume down). When I wired the system I had to use the receiver because the TV I had at the time didn't have enough inputs. The 61" beast has plenty, so a viable option is to use the TV as the video switcher. What's the cost benefit?

So here's what I've learned thus far... If the TV is turned on 24 hours a day, it would cost us 76 cents a day or $22.88/month. With the TV off, that drops to 29 cents a day or $8.72/month. Remember, I'm measuring the whole system - not just the TV. So the system costs $8.72/month just to sit there.

In bare watts, the system uses 104 watts with the TV off, and 273 with the TV on. If I use the main amplifier's volume to get surround-sound, wattage goes up another 50-80 watts depending on volume (most often we just use the TV's speakers so that rarely applies).

Turning off the Tivo/Satellite receiver makes no difference. Even when "off" it's really on recording two simultaneous Satellite channels and/or anything we have programmed in. Powering it off saved a mere one watt. So leaving that on all the time is fine. I didn't measure how much it uses because I know we'll leave it on anyway.

Turning off the receiver/amplifier, though, dropped the 104 watt usage of the idle system almost in half. It uses 47 watts while powered on and idle. That's a cost of $4/month, or $47/year! So yes, there's a financial benefit in rewiring, especially because I have most of the cables I need.

The last 57 watts is apparently used by everything while powered "off" - many electronic devices, especially televisions, use power even when off. I suspect much of this is the Tivo - I'll figure this out later.

As a test, I turned everything on - two CD players, a DVD changer, a VCR, and a tape deck. 320 watts. With the amp's volume cranked half-way, just over 400 watts. Ouch.

What about cumulative actual use? I've had the Kill-a-Watt monitoring our system for 58 hours thus far. This 58 hours has cost us 99 cents. At this rate the system as-is contributes about $12.35 to our monthly electric bill. Once I remove the receiver/amp this should drop below $9.

Next up will be the laser printer (which is always on, often in "sleep mode") and my main computer which is always on.

Imagine the spreadsheets I'll be creating!

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Posted by Mitch at September 16, 2005 08:55 AM
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