When you get your monthly natural gas bill, have you ever looked at it and wondered how much energy you're getting for all that money you pay? Gas is measured in cubic feet, but the measurement for the energy in that gas is measured in BTUs or British Thermal Units. Here is how to find out how many BTUs are in a cubic foot of natural gas.
Natural gas is odorless and colorless, but it's full of energy. It is composed of mostly methane, but it can also contain ethane, propane, butane and pentane. The gas that is used in most homes is almost pure methane. The energy in natural gas is released when the gas is burned. We use that energy to heat our homes, generate electricity and cook our food.
Before natural gas comes into your home, it passes through a gas meter. The meter measures the volume of the gas passing through it. The standard measurement is a CCF or 100 cubic feet.
BTUs or British thermal units measure the energy in natural gas. One BTU equals the heat required to raise the temperature of one pound of water 1 degree Fahrenheit. The amount of heat in a burning wooden match is roughly equal to one BTU. A cubic foot of natural gas has 1,015 BTUs. This compares to a gallon of propane that contains 91,700 BTUs and 1 kW of electricity that contains 3,413 BTUs.
Calculating Your Monthly Energy Use
You can calculate your monthly energy usage by taking the cubic feet you used during the month. If your usage is listed in CCFs, divide the number by 100 to get the number of cubic feet you used. Take this number and multiply it by 1,015 (the number of BTUs in a cubic foot of gas) and you will have the number of BTUs you used during the month.
For large numbers of BTUs, the number is converted into therms (100,000 BTUs). Here are some average monthly energy usages for gas-powered household appliances. Furnaces use 100 therms in a month. Water heaters and space heaters use 18 therms a month. A clothes dryer will use 3.5 therms and stove tops use 2 therms a month.