Space heaters are typically not an efficient means of heating, especially compared to a central heat pump, geothermal heating, or solar energy. Small electric heaters can use about 3,000 watts (about 10,000 BTU/hr) and larger ones may use over 11,000 watts (about 40,000 BTU/hr). Fuel powered portable heaters are often less expensive to run, using about 2,300 watts (7,848 BTU/hr) to 4,100 watts (13,990 BTU/hr). Electricity is one of the most expensive energies to use to heat an area, costing about twice as much as natural gas to produce the same amount of heat.
Compared to Other Heat Sources and Appliances
Running an electric space heater that uses around 1,500 watts for 24 hours a day for a month would take about 1,070 kWh per month. In comparison, running a baseboard heater for the same amount of time would take between 100 and 500 kWh/month, while running a heat pump could use anywhere from 1,000 to 2,000 kWh/month. It's important to remember, however, that a space heater can only heat a small area, while a heat pump can do the same for an entire house.
In terms of comparisons to other household appliances, running a microwave takes about 25 watts (85 BTU/hr), while an oven uses about 5,000 watts (17,061 BTU/hr) and a refrigerator uses about 780 watts (2,672 BTU/hr). This means that a person could run a refrigerator for about four hours before using up the energy it would take to run a small space heater for one hour.
Electric vs. Combustion Heaters
Since fuels like natural gas are typically less expensive than electricity, combustion heaters are often less expensive to operate than electric models. Even so, they are not recommended for regular residential use since they require very good ventilation. Combustion heaters can produce poisonous fumes that build up and become a danger to people in the area if they aren't vented properly. They can run on natural gas, diesel, or kerosene, but never gasoline. Typically, these devices are only used in residential settings during an emergency power outage.
Using Space Heaters Cost-Efficiently
Even though space heaters do consume a great deal of energy, in some situations they are both practical and cost efficient. With a central heaters, every room is heated equally, even if some rooms do not require the same amount of heat. The advantage of portable heating is that warmth is easily directed towards a single area. If the central heater is set to low temperature, and a single room or portion of a room is warmed with a portable heater, it can be more energy efficient than using the central unit.
It is important to note that portable heaters are rated for specific room sizes. If a small heater is used in a large room, it will use a great deal of energy without providing enough heat. A large heater in a small space will use excessive energy and provide too much heat.