"Home Energy Cost", Variables.

Natural gas is generally the least expensive fuel-after daylight has ended obviously, and wood and coal in some regions. In rural areas without gas pipelines, liquefied petroleum (LP) gas takes the place of natural gas. A new gas furnace, hot-water boiler, or space heater operated with either natural or LP gas are among the least expensive choices in heating equipment because oil, coal, and wood require more costly fireboxes and chimneys.

Oil is generally, but not always, more expensive than gas as a heating fuel, and an oil fired furnace is the most expensive you can buy. Even so, in some places ( usually at the end of a pipeline or near a port or refinery), oil is cheaper than gas, making an oil burner the wiser choice.

Electricity is used for heating in two ways; resistance heat and heat pumps. A resistance heat system has baseboard heaters around the house with wires inside that warms and glows like that of a toaster. The heaters of a resistance heat system are generally much less expensive to buy than is equipment for other systems, but the consume large amounts of electricity and are expensive to operate. Consequently, a resistance heat system is not recommended unless (1) your home is near a hydroelectric plant, where the electric rates are low; (2) the system is used in small spaces, such as bathrooms; or (3) the system supplements solar, wood, or coal heating.

Heat pumps use electricity to operate a compressor.

A heat pump compressor, like that of an air conditioner, compresses a refrigerant from a gas to a liquid.

In the process of changing from a gas to a liquid, the refrigerant loses heat, which is released indoors to a duct system that routes the warm air to the rooms of your home. In summer, the process is reversed, so that the is released outdoors; indoors, heat is absorbed from indoors air, making the heat pump an air conditioner.

Using electricity to operate a compressor is two to three times more efficient than using it to heat wires. The efficiency drops when the outside temperature dips close to freezing, however. For this reason, heat pumps are best used year round temperatures are not often outside the range of 40 degrees F to 90 degrees F. In places where the weather is consistently colder, it is possible to use a heat pump with a heat exchanger buried in the ground, but presently, these systems cost more than conventional ones. Still, the prices are decreasing and if these newer types are available in your area, they are worth investigating.

Over the long run, heating with a heat pump cost about as much as heating with gas. This is true even considering the higher maintenance costs of operating a heat pump, which needs to be serviced annually and have its compressor rebuilt every 12 to 14 years