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Reducing the amount of propane you use per square foot can help save money and reduce your carbon footprint. According to Home Energy: Advancing Home Performance, 39.4 percent of homes using propane heating use between 5 and 10 British Thermal Units (BTU) per square foot. Only 12.2 percent use under 5 BTUs per square foot. Home Energy Saver reports 1.2 billion tons of greenhouse-gas emissions, such as carbon dioxide, are emitted into the environment every year as of 2010.
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Total the amount of propane your family consumes in a year. Add the total gallons of the last 12 months' worth of bills. There are 95,475 BTUs in every gallon of propane. If you do not have access to your propane usage, call your local propane provider; they will have your yearly consumption numbers in your account file.
Multiply total gallons by 95,475 to figure total BTUs of usage. To figure the total propane for your home, multiply total gallons of propane for the year by 95,475. The result is the total BTUs your family consumes in a year.
Example: 800 gallons * 95,475 = 76,380,000 BTUs.
Measure the square footage of each room in the home. To figure the square footage of a room, measure the length and width of the room and multiply those two numbers.
Example: 10 feet * 12 feet = 120 square-foot room.
Add the square footage for the entire home. Add the square footage of every room in your house. Include bathrooms, walk-in closets, playrooms, kitchen, living room and any other living space in your home. It is not necessary to measure regular closet space or the garage, so those numbers do not need to be included in the total square footage for the home.
Calculate the total heating degree days (HDD). This number is available on monthly utility bills or available through the National Weather Service. Heating degree days are basically the cumulative amount of heating degrees a community consumes for a year. The mean temperature for HDD is 65 degrees. For example, if it is 40 degrees outside, the heating degrees for that day is 25 HDD, which makes the total 65 degrees.
Estimate propane use per square foot for your home. Divide the total BTUs you figured in step 2 by the total square footage of your home figured in step 4. Divide that answer by the total HDD you figured in step 5. The answer is your average BTUs per square foot per HDD. This gives you the most accurate estimate of your propane usage per square foot for the weather conditions and home location.
Example: 76,380,000 BTUs divided by 1,500 square feet divided by 2,500 HDD = 20.368 BTUs per square foot per HDD.