Thursday, February 22nd, 2007
Electrify Your Night
Here’s the Thing:
Use an electric blanket or mattress pad on your bed.
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Plug in your bed! |
This one comes to us from Jonathan in Boston, who’s too busy setting technology policy for MIT (and raising my niece and nephew) to write a silly little blog post. (For anyone who can find some time to write with us occasionally, click here!)
Many of the ideas on this blog focus on ways to minimize energy use, so pushing an electric blanket might seem a bit out of character — until you consider the savings to be had on the back side of this move, when you turn down the thermostat!
The truth is, I don’t know how well this equation works out. I’ve poked around on the Internets a bit and haven’t come up with too much on the difference between energy consumed by electric blankets and energy saved by lowering the home’s heat. My intuition tells me the blanket is probably a good idea, because you’re focusing a bit of heat on your body rather than heating lots of space around the house that nobody’s using. But alas, I can’t prove it. If anybody has any insight on this, please post!
Perhaps an even better idea is to just get a really really warm blanket for the bed that isn’t electric. No worries about safety, no worries about energy use, just good, clean, old-fashioned coziness.
Oh, and here’s a little history on bed warmers, from Wikipedia:
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The electric mattress |
A bed warmer was a common household item in cold countries, especially Northern Europe. It consisted of a metal container, usually fitted with a handle and shaped somewhat like a modern frying pan, with a solid or finely perforated lid. The pan would be filled with hot coals and placed under the covers of a bed, to warm it up and/or dry it out before use.
After the invention of rubber, the classical bed warmer was largely supplented by the hot water bottle, which is still widely used. In the late 20th century, electric blankets and then the electric bed warmer were invented to fulfill the same need.
on Friday, February 23rd, 2007 at 9:50 am:
Next week we’ll plug our voltmeter thing into our electric blanket so we can say how much electricity it is using during the night. Not sure how you’d convert that to energy used by heating the house, but it’s a start. It also definitely depends on how high you set the blanket. We tend to keep it on low, and I sometimes even turn it off during the night, once I’m warm enough.
on Monday, March 5th, 2007 at 4:16 pm:
I plugged in our Kill a Watt to measure the actual usage of electricity over a week of nights. After 5 nights, we had used 0.77 kWh, so about 0.154 kWh per night.
The estimates from the electric matress pad manufactures is that you can save 10-15% on your heating bill by using these devices at night which is probably not too far off.
Since we have twin 2 year olds that we can’t rely on to turn down or up such a device on their own, we do not lower our own house temperature as much as someone who doesn’t have kids in the house could. With the kids bundled up, we have the house temperature down 2 degrees at night and use the electric matress pad.
So how do these compare. Several sources indicate that you can save upwards of 5% of your heating bill per degree you lower your thermostat in the winter. I’ve seen one site that says 2% so I’ll include that as a low end estimate.
If you lower your themostat by 10 degree for 8 hours a night you could save 6.7%. Average consumption and prices for the midwest are 708 Therms at $1.55 for the October to March timeframe when we typically heat our houses. A 6.7% savings over that would be just over $70 per year.
That compares to the electricity usage using the electric matress pad during the same time period (my actual measurements included using it for more like 9 hours a night and they have automatic shutoffs after 10 hours) of around $4.50 (0.154 kWh X 182.5 days X $0.16/kWh). Even at max power (122 W) for 10 hours a night, this would only be about $35 and that is a LOT of heat in the bed.
Even for the modest at night decrease of 2 degrees we do and using the actual gas usage (761 Therms) and price ($1.91/Therm) we had for last year, our estimated savings were over $40. And my wife is much happier now with the electric matress pad when her preferred heat source (me) is late going to bed.
The thermo dynamic comparison of heating even just the bedroom with gas versus the bed with electric will have to wait for someone more ambitious, but I’m sure it will point in the same direction. Using an electric matress pad or blanket to heat the bed is far more efficient and money saving than heating the room with any form of energy (well except maybe radiant floor heat fed by a solar hot water system).
on Tuesday, March 6th, 2007 at 12:10 am:
Jon, I think you nailed the real advantage of the electric mattress pad there: “my wife is much happier now.”