Space heaters are considered energy hogs with very good reason. The smallest electric space heaters can use about 3000 watts (10,236.43 BTUs) per hour. Larger electric space heaters may use over 11,000 watts (37,533.56 BTUs) in an hour. Using space heaters instead of central heating may increase your overall energy costs for heating by about 70%.

Some people also use propane-based space heaters, called combustion models. These may be good for emergencies when electricity is not available but they do need to be properly vented so as not to release dangerous carbon monoxide into a home’s air. For these, one purchases either propane or diesel fuel, but never gasoline. Many combustion model space heaters are measured by British Thermal Units (BTUs) only.

Essentially a BTU is a measurement of the amount of energy needed to heat one pound of water by one degree. It is transferable to watts, but costs of energy will depend largely on the source. If you happen to live in an area where propane is inexpensive, propane based space heaters are often considered less expensive to run. They may use about 2300 watts (7,847.93 BTUs) to 4100 watts (13,989.78 BTUs) in an hour.

Combustion models are certainly cheaper, and do by and large use less energy. A large combustion model heater uses about the same energy as a small to mid-size electric space heater. However, neither kind of space heater is without its dangers.

Space heaters should always be used in very safe settings. They should be kept away from children, and combustion models, unless they are rated as safe for indoor use, must be ventilated. Space heaters account for numerous fires each year in the US, about 25,000. These often result from improper use.

On the other hand, even though space heaters do consume more energy, if they are used sparingly, and safely, they may ultimately use less energy than central heating. This is because central heating heats all the rooms in one’s home. If one only wants one room heated for a short period of time, it may prove more economical to use a recently built, small space heater.

One can also save money and energy by carefully reading the manufacturer’s recommendations on space heaters. One should purchase a space heater that is large enough, but not too large for a particular room’s dimensions. It does not make sense to purchase space heaters that are supposed to heat larger spaces than one has, and it will cost more in energy. It will also be more expensive to run a space heater that is too small for the room one wishes to heat. The space heater will have to run longer to provide the ideal temperature.