# How to Calculate the Cost of Operating a Gas Furnace

If you don’t already heat your home with a gas furnace and you’re thinking about installing one, you may be wondering what the cost of operating one is. While it differs in every region, there are many factors that can impact operation costs.

Factors Affecting Efficiency

The price of gas is a major factor when calculating the cost of operating a furnace. Other major factors include how efficient your home is and the efficiency (annual fuel utilization rate, or AFUE) of your furnace,

How do you know if your home is efficient? Consider these factors:

• Is your insulation the correct R-value for your region’s climate, and is it properly installed?
• Is your home airtight?
• Is ductwork properly sealed and insulated?
• What’s the orientation of your home and windows in regards to the sun?

Calculating the Annual Cost of Gas

The average household in the U.S. uses between 50 to 150 million British thermal units, or BTU, of heat every winter. To calculate operating costs, you might assume 100 million BTU of heat use in an average Southwest Oklahoma home, and then find the current price per therm (a therm is the unit natural gas is sold in, and is equivalent to 100,000 BTU) for our state.

Then, use the following formula:

• Unit cost of fuel times 1 million BTU divided by the amount of BTUs per unit of fuel (100,000).
• Divide that result by the AFUE of the furnace, and then multiply by 100 million BTU for the probable annual cost of fuel.

An HVAC contractor can help calculate the correct amount of BTUs used in your home to plug in to this formula.

Future Cost of Gas

Right now, the cost of natural gas is reasonable. Will it remain this way? This is unknown, but the supply is abundant, and it’s available domestically, so the prospect is good that prices will stay modest in comparison to other fuels.

For more information about the cost of operating a gas furnace, contact Davis Air Conditioning in Southwest Oklahoma.

Our goal is to help educate our customers in the Lawton and Duncan, Oklahoma area about energy and home comfort issues (specific to HVAC systems).