Heat output is typically measured in terms of Btu (British Thermal Unit) output.
One Btu is the amount of energy required to raise one pound of water one degree Fahrenheit

Factors That Effect Btu Output:

1) The efficiency of the heating appliance burning the fuel.

2) Improperly set controls or no settings to control the combustion air required to burn the fuel.

3) Most appliances Btu ratings and burn times are based on the burning high quality fuel!
This is not what typically is used as a fuel by the majority of consumers.

4) The potential Btu of the fuel being burned is also affected by
the moisture content of the fuel supply being burned:
a)Heat is consumed in the evaporation of moisture,
hence the more moisture in the fuel supply the less heat output.
b) If the fuel is too dry, the heating appliance is not be able to capture the heat as fast
as it is being produced, so excess heat is exhausted out the chimney.

5) Any incomplete burn of fuel, particles:
a) charcoal is high Btu fuel, you want burn it, not throw them out with the ashes and
b) exhaust gases -a well designed appliance will be designed so that it has a scondary burn
of the exhaust gasses - extracting additonal heat and creating a cleaner burn.

Our New Fuel Cost Calculator
calculates potential Btu output and costs of using various fuel sources.

All wood species have approximately 8200 Btu per pound of wood.
Higher density wood weighs more by volume, hence has a higher Btu value per cord.

A standard cord of wood (cord = 4'x4'x8') occupying 128 cubic feet of space
and contains 80 cubic feet of solid wood.