EGEE 102
Energy Conservation for Environmental Protection

Fuel Choices


Various fuels such as natural gas, electricity, fuel oil, and so on, are used to heat a house. Click on the graph below to see the percent of households that use each type of heating fuel.

Choice of Fuels by Percent of Households
Fuel Type Percentage used
Natural Gas 49%
Electricity 34%
Fuel Oil / LPG 11%
Other 6%

As you see, about 50 percent of the households in the United States use natural gas as their main heating fuel, and about 35 percent of the households use electricity to heat their homes. Another 11% use fuel oil, and the last 6% use something other than natural gas, electricity, and fuel oil.

Capacity and Consumption


The amount of heat a furnace can deliver is called its capacity. Heating units are manufactured and sold by their capacity. The heating capacities of Natural Gas, Propane and Fuel Oil are measured according to BTU/h, and the capacity of Electricity is measured in kilowatts.


The amount of energy a furnace actually uses is called consumption. In other words, we pay monthly bills for the consumption of a particular heating fuel. Heating Fuels are sold to consumers in different units of measure. For example, Natural gas is sold by cubic feet (ft3).

Press play to see the difference between capacity and consumption in a gas-heated home.

Capacity and Consumption

Fuel Comparison

Capacity, consumption, and other information about various types of fuel
Fuel Capacity Consumption Additional Information
Natural Gas Measured in British thermal units per hour (BTU/h). Most heating appliances for home use have heating capacities of between 40,000 and 150,000 BTU/h. In the past, gas furnaces were often rated only on heat input; today the heat output is given. Consumption of natural gas is measured in cubic feet (ft3). This is the amount that the gas meter registers and the amount that the gas utility records when a reading is taken. One cubic foot of natural gas contains about 1,000 BTU of energy. Utility companies often bill customers for CCF (100 cu. ft) or therms of gas used: one therm equals 100,000 BTUs. Some companies also use a unit of MCF, which is equal to 1,000 cu. ft One MCF equals 1,000,000 BTUs (1 MM BTUs).
Propane or Liquefied Petroleum Gas (LPG) Measured according to BTU/h. Consumption of propane is usually measured in gallons; propane has an energy content of about 91.300 BTUs per gallon. Can be used in many of the same types of equipment as natural gas. It is stored as a liquid in a tank at the house, so it can be used anywhere, even in areas where natural gas hookups are not available.
Fuel Oil The heating (bonnet) capacity of oil heating appliances is the steady-state heat output of the furnace, measured in BTU/h. Typical oil-fired central heating appliances sold for home use today have heating capacities of between 56,000 and 150,000 BTU/h. Oil use is generally billed by the gallon. One gallon of #2 fuel oil contains about 140,000 BTU of potential heat energy. Several grades of fuel oil are produced by the petroleum industry, but only #2 fuel oil is commonly used for home heating.
Electricity The heating capacity of electric systems is usually expressed in kilowatts (kW); 1 kW equals 1,000 W. A kilowatt-hour (kWh) is the amount of electrical energy supplied by 1 kW of power over a 1-hour period. Electric systems come in a wide range of capacities, generally from 10 kW to 50 kW. Electricity is sold in kWh (kilowatts per hour). The watt (W) is the basic unit of measurement of electric power.

Heating Values of various fuels

Each unit of fuel when burned gives different amounts of energy. The energy that is released when a unit amount of fuel is burned is called the heating value. The heating value of a fuel is determined under a standard set of conditions. A comparison of approximate heating values of various fuels is shown in the table below.

Heating values of commonly used heating fuels
Fuel Unit Heating Value (BTU's)
Natural Gas CCF (100 Cu. ft) or Therm 100,000
Natural Gas MCF (1,000 Cu.ft) 1,000,000
Fuel Oil Gallon 140,000
Electricity kWh 3,412
Propane Gallon 91,300
Bituminous Coal Ton 23,000,000
Anthracite Coal Ton 26,000,000
Hardwood Cord 24,000,000
From the table above, it should be noted that if a gallon of fuel oil is burned, one would get 140,000 BTUs. Similarly, a CCF of natural gas would fetch 100,000 BTUs.