What's the cheapest form of heating: central air or other electric heating options?

November 16, 2007 10:07 PM

Which costs more: keeping my thermostat at 69 all winter, or using an electric blanket and radiator-style space heater in one room?

In the first case, assume that the thermostat would be set to 64 when we're not home (14 hours), and only go up to 69 when we're here. In the second case, we'd only use the electric blanket and space heater at night.

posted by bjork24 to home & garden (16 comments total)

If the space heater is electric, it's probably going to cost more (unless your house heat is also electric.)
posted by ook at 10:10 PM on November 16, 2007

In the second case (electric radiator and blanket) what are you going to keep the thermostat set to? Will you just keep the house heat off completely? (Probably not OK if the weather gets down near freezing, unless you like broken pipes.)

I have done the whole house vs spot heating experiment myself, and found that if I was good about only heating the room I was using, and keeping doors closed, the electric spot heating was cheaper. (Compared to very expensive gas heat.) I think it would have been a wash with oil. We were looking at the difference between $300/mo in gas to keep the whole house at 65 versus under $100/mo additional in electricity to spot-heat, if we were careful.

If you can keep the house heat completely off, and you're only going to use the electrics at night, and only in one room (and you can keep the door closed and it's not a huge room), I suspect that will almost certainly be cheaper.
posted by Kadin2048 at 10:12 PM on November 16, 2007

(emphasis on probably; I'm guessing, which is something I promised myself I wouldn't do in askmetafilter. Moment of weakness.)
posted by ook at 10:14 PM on November 16, 2007

Read Michael Bluejay's excellent page about saving money on heating. He would tell you that the best way to answer this question is to test. My guess, based on my own research, is that you'd save money by turning down the thermostat.
posted by jdroth at 10:15 PM on November 16, 2007

You have to compare the heat loss of the room you'd be heating to the heat loss of the house as a whole. If you're space heating a small room with a small window and only one outside wall in an otherwise huge house with huge windows, space heating obviously wins. On the other hand, if you are space heating a huge room with lots of windows in a small house, space heating probably doesn't win.

And ya, be really careful you don't let the rest of the house get too cold to be serviceable. Trying to heat it up for use takes a huge amount of energy, which will waist most of the savings, and you can't allow it to freeze.

So, depending on your climate and house.. You probably need to have a very cool central heat setting combined with space heating as needed, in a properly selected room. And, watch energy use bills carefully to see how your changes effect them.
posted by Chuckles at 10:39 PM on November 16, 2007

As a raw answer to your question, 64 in winter seems ok from a born and raised Iowa boy. You just put on thicker socks! In turn I'll answer with what I did.

From your description I'd just use a blanket. I don't know where you live, so I'll relate my story of Iowa winters. My restriction was money.

In college I couldn't afford heat. I also couldn't afford to take a shower in a 100 year old house with no heat. I went to my church and some wonderful lady made me a thick quilt for my bed. I took $30 and bought a space heater that was big on fan and little on heating element. It blew hot air like a champ and had all the safety features. Also didn't even make a dent in my electric bill.

I made sure to move it to my bathroom every night and set a timer for 20 mins with this little Black & Decker heating devil and it was like stepping into Florida every morning.

If pennies are at that much of a premium, use a workspace heater like that, the radiating ones are a huge haste of power. Also go to your local church or Goodwill and get a good blanket.

Invest in sweatpants and thick socks.
posted by sanka at 10:41 PM on November 16, 2007

Thanks to the intersection of my recent need to, quite literally, build a fire to warm a room and my truly incomporable laziness, I've turned to keeping warm at night with a combination of either comforter/sleeping bag or comforter/slanket, both of which work quite well. If you're looking to go cheap, such solutions work pretty well, provided you don't get up to pee frequently during the night. (This is, btw, NO HEAT and bedclothing, so if you're keeping it at 64, theoretically it would work pretty nicely.)
posted by the luke parker fiasco at 10:43 PM on November 16, 2007 [1 favorite]

Hey, whichever one you choose, could you send me the difference (in data terms) between last year's and this year's? I'd love to have it, as I have clients who are working on that exact same data pool and need real world examples.
posted by parmanparman at 11:43 PM on November 16, 2007

I should have mentioned.. When comparing to last years bills, it is very important to factor in Heating Degree Days.
posted by Chuckles at 12:10 AM on November 17, 2007

This question isn't as easy as all that. As mentioned, there are issues of degree days, the size of your house, whether your primary furnace is gas, electric, or electric + heat pump and what its respective effeciency rating is. Your windows matter, the direction they face matters, your floor coverings matter, you shades/blinds matter, and how much you're home matters. Also, the cost of gas and electricity per therm matters as well. The construction materials used in your home, the amount of insulation in the walls and ceiling...there's no instant answer.

What I'd recommend is that you go to the store and buy a programmable thermostat and install it. They are VERY easy to install if you know how to operate a screwdriver and they cost no more than about $25. They'll pay for themselves within a month. Set it to ONLY be on about 20 minutes before you get up, to go down as soon as you leave, and to only turn on about 20-30 mins before you get home. Forget 64, go for 60 as your low. Forget 69 as your high, go for 67/68. Each DEGREE represents ~5% in energy cost difference above the previous degree.

Now, your house is going to fall to 60 degrees at night. For me, that's PERFECT sleeping weather, so I wouldn't worry about an electric blanket or a space heater.

In my house, there's no heat on the second floor, and I'm an energy nazi, so I don't mind that my room gets to...oh...probably 45-50 degrees at night, I sleep like a baby. I DO have an electric blanket on my bed for the winter for the nights it gets stupid cold.

Long story short---Only heating the immediate area where you ARE is much, much, much more efficient than heating your entire house, especially while you're not moving and not conscious.
posted by TomMelee at 5:54 AM on November 17, 2007

I read that you need to keep a house at least 55 degrees to keep the pipes from freezing.
posted by cda at 6:06 AM on November 17, 2007

Definitely more efficient to heat only the space area than the whole house. But I'm not sure an electric blanket is really necessary. A good quilt should do the trick. Our bedroom goes down to 55f in winter and our quilt keeps us warm and toasty.
posted by bluefrog at 6:53 AM on November 17, 2007

This is a bit off the main point, but I find that an electric mattress heater is much nicer than an electric blanket. I never turn the heat on in my house (disclaimer: I live in San Francisco, where it virtually never freezes) and my old Victorian has little or no insulation, so it gets pretty chilly in here (drafty, too). But the mattress heater keeps me delightfully warm without feeling stiff and rubbery like an electric blanket. Also, the regular blankets retain the heat from the mattress heater, whereas I imagine much of the heat from an electric blanket would be lost to the air.

Anyway, my utility bill (combined gas and electric) is about $30/month during the warm season and rarely goes above $50/month during the cold weather. Presumably most of the difference is the cost of running the mattress heater.

Once you get accustomed to it, you can tolerate pretty chilly temperatures in your house, and even come to prefer it that way. I stay comfortable in my house with lots of layers and down-filled slippers, and I find other people's houses uncomfortably stuffy and dry.
posted by Quietgal at 9:54 AM on November 17, 2007

It is cheaper to heat a small area than a large area. The only wrinkle is that electric heat may be more expensive than a gas furnace, but that is mitigated to some extent by the fact that electric heaters are 100% efficient and your furnace is likely only 80% efficient. It is very likely that heating only one room with electricity is cheaper than heating the whole house with a gas furnace.

On the other hand, if comfort is more important, then heating the whole house to 69 while you are home might make more sense. But it does not make sense to keep the house at 64 when you aren't home. Set it to 55 when you are gone. Generally you don't want the furnace to ever be on when you aren't home. A setting of 55 degrees should ensure that your pipes don't freeze if the weather gets extremely cold.

Even better, get a modern timed thermostat and have it start warming up the house about 30 minutes before waking and 30 minutes before returning in the evening. During the day while you are gone and at night when you are sleeping the thermostat will automatically turn the furnace off.

Chuckles: Be really careful you don't let the rest of the house get too cold to be serviceable.Trying to heat it up for use takes a huge amount of energy, which will waste most of the savings.

This is a common fallacy. It does not waste energy to heat up a cold house. The cost of heating a house is equal to the energy that escapes through the walls and ceiling to the outside. This is simply proportional to the temperature difference between the inside and outside multiplied by the time at that temperature. Any time spent at a lowered temperature decreases the flux of energy to the outside, reducing your energy loss. Heating up a cold house takes less energy than maintaining a house at a steady temperature.

In addition frequent cycling of a gas furnace to maintain a steady temperature wastes more energy than having it stay on for longer, less frequent cycles because, for many furnaces, warm air continues to to escape up the flue each time the furnace cools.
posted by JackFlash at 11:53 AM on November 17, 2007

If you want to save money on heat, turn the thermostat way down. You'll get used to it in a week, and be much more comfortable when you go outside. Right now it's 60 in my house, and wearing one layer of lightweight clothing with sandals.
posted by yohko at 12:01 PM on November 17, 2007

You don't have to keep a house at 55 degrees to keep the pipes from freezing. Below 55 degrees you start to see depredation in stored chemicals, paints, and other liquids, though. If freezing pipes are a concern, put pipe insulation around them, or really any other material (crumbled newspaper works) to separate them from a wall. Generally for long term emptiness, a furnace is kept ~50 degrees.

Part of my job is helping low income families stay warm while keeping their energy bills affordable--if you need more data or resources my email is in my profile.
posted by TomMelee at 1:06 PM on November 17, 2007