Electric ceramic space heater
by Karen
(Woodward, OK)
I have gas heat. Is it more efficient to turn my thermostat down and use an electric ceramic space heater in the room I am in rather than heating all rooms? I have a house with 2200 square feet.
Answer from Green Energy Efficient Homes
That's a very good question and many people have successfully cut their overall energy use as well as their energy budget by doing exactly what you propose.
You will definitely save energy, in terms of the overall BTU consumption for your home heating, if you close off the one room and heat it to a comfortable temperature with your electric ceramic space heater, while keeping the other rooms colder, rather than keep the whole house at a comfortable temperature.
For example, a 10x10 foot room that is moderately well insulated might take 1,200 to 2,400 BTU per hour to keep comfortably warm in a cold climate, and perhaps 900 to 1,800 BTU/h to heat to a lower temperature. Assuming a house with 8 such rooms, you'd be consuming 9,600 to 19,200 BTU if you keep the entire house warm, and only 7,500 to 15,000 BTU to keep one room comfortable and the others cool.
The two complicating factors are relative energy cost between the electric ceramic space heater energy cost and the furnace energy cost, and whether you're trying to save just money, or actually reduce your energy use for environmental reasons. Although you'll use quite a bit less energy by using your space heater in the one room and keeping the other rooms cool, the financial savings may be non-existent. I did some very rough calculations for the above scenario and found that, in an 8 room house where electricity cost $0.09 per kWh (at 100% efficiency, since all electric heaters are 100% efficient at converting electricity to heat) and natural gas cost $0.82 per CCF (hundred cubic feet), which is what I paid on my last natural gas bill, with a furnace operating at 80% efficiency, it's actually marginally more expensive to heat one room with electricity and seven others with natural gas. The reason is that electricity costs so much more per unit of heat output. Of course, the more you lower the whole house temperature relative to the temperature of the one room you are heating with an electric ceramic space heater, the more likely you will realize at least some level of savings.
From an environmental perspective, don't forget that your electricity, if produced from coal or other fossil fuels, actually consumes roughly three times as much source energy at the power plant as it delivers to your power meter - mainly because thermal engines such as those used in power plants have a peak efficiency around 35-40%, and there are transmission losses along the way. (That's partly why it costs more to heat with electricity, because only a third of the heat energy from the fossil fuel source at the power plant makes it to your house.) So unless your electricity is from a completely green source, you're not doing the environment much good by heating with electricity instead of natural gas, unless you are keeping a huge differential between the one warm room and the seven cooler ones.
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