Supplement to Cut Your Utility Bills “Home energy checkup”
The following technique is one way you can rate the energy efficiency of your house.
Use your gas and electric utility bills, oil or propane deliveries, firewood, etc. Use the following factors to convert to Btu equivalents: 1 kilowatt-hour of electricity equals 3,414 Btu, one cubic foot of natural gas equals 1,025 Btu, 1 gallon of propane equals 91,000 Btu, 1 gallon of oil equals 138,700 Btu, and 1 cord of wood equals 19 million Btu.
Now, divide the total annual Btu used by the square footage of the living area of your house. To adjust this for your climate, divide this result by the sum of the heat and cooling degree days for your area. Degree days are the number of degrees the outdoor temperature is above or below 65 degrees. At an outdoor temperature of 65 degrees, it is assumed you don’t have to heat or cool your home. Your local weather service can give you monthly figures, which you can total for the year.
If the final calculated result is 10 or less, you can consider your house to be reasonably efficient. If it is between 10 and 20, there is room for improvement. If it is greater than 20, your house needs major improvements. Keep in mind, this is just an estimate for a typical family of four.
To read the March 2007 Cut Your Utility Bills column that goes along with this supplement, click here: Home energy checkup