Fuel-Cost Calculator

Some heating fuels that used to be quite affordable, such as heating oil, have risen in price dramatically, making competing energy sources such as electricity relatively less expensive. In parts of the Northeast and Upper Midwest, even the most expensive form of electric heat — electric-resistance baseboard heat — is now less expensive than fuel oil. The challenge in comparing fuel costs is the fact that most fuels are purchased by volume or weight, rather than energy content. It's hard to compare gallons of fuel oil with hundreds of cubic-feet (ccf) of natural gas and kilowatt-hours (kWh) of electricity. Adding to the complexity, there are big differences in how efficiently energy sources are converted into heat and how efficiently that heat is distributed throughout a building.

To accurately compare the costs of different energy sources, we need to look at the price per delivered unit of heat. If we compare fuel costs on the basis of dollars per million British thermal units (Btus) of delivered heat, we are comparing apples to apples. BuildingGreen's online fuel-cost calculator considers the heat content of each fuel, the efficiency of combustion by the heating equipment, and the efficiency of distribution. With furnaces and forced-air distribution, there are often very significant distribution losses that raise the cost per million Btus of delivered heat. The BuildingGreen calculator provides default (average) efficiencies but allows users to enter different values if they are known. Because the prices of most fossil fuels are rising faster than the price of electricity, which is regulated, some homeowners and businesses are likely to switch from oil, natural gas, or propane to electricity. "There has been very little attention paid to this issue by utility companies and public utility commissions," according to Alex Wilson, president of BuildingGreen, "but the likelihood of fuel switching to electricity may have very significant implications on electricity demand and safety — especially if homeowners begin using portable electric heaters more widely." In an editorial called "Get Ready for Fuel Switching" in the July 2008 issue of Environmental Building News, Wilson cautions that fuel switching could cause capacity shortages this coming winter, potentially leading to brownouts and blackouts. In addition, the use of portable electric heaters in homes with outdated wiring may cause a rash of house fires.