Consumer Reports, February 2002
Up in smoke
How economical is heating with wood? Split wood sells for roughly $150 a cord (delivered). If it's a true cord--a stack 8 feet long, 4 feet deep, and 4 feet high--the price is 40 percent cheaper than natural gas or fuel oil for equivalent energy, national average prices suggest. A "cord run," however, is a single stack of 16-inch logs that is one-third the volume of a true cord. A $150 cord run is 75 percent pricier than other heating fuels, assuming the stack of hardwood is 70 percent solid, contains 12 percent moisture, and provides 7,700 Btu/lb.
Burning wood can be inefficient. At best, 25 to 30 percent of the heat energy from a wood-burning fireplace goes toward warming the room. The rest is lost up the chimney. A fireplace insert or a wood stove might reach 70 percent efficiency, but you lose the coziness of the fire. By contrast, a new gas or oil boiler or a furnace is 80 percent efficient or more. Bottom line: A central heating system is typically the cheapest way to heat.

Fuel Monetary Values: Equivalent Cost of Fuels: CMF Engineering 2001