How to Get the BTU Value of Firewood
British thermal units, or BTUs, measure thermal energy, which is the energy that is released when a substance is burned. One BTU is roughly the amount of heat generated by one lit match. The BTU value of firewood varies depending on the species of wood and whether the wood is green or dry and seasoned. Typically, 1 lb. of dried firewood generates 7,000 BTUs when burned, and it takes about 2,500 BTUs to heat a 10 foot by 10 foot room. Firewood is measured in cords -- a cord is the amount of wood necessary to fill 128 cubic feet of space. Does this Spark an idea?
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Instructions
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Identify the type of wood that you have in your firewood stack. Visit a website that lists types of wood and their corresponding BTU values.
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Determine the value of 1 million BTUs per cord. BTU values are always based on a cord of wood.
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Determine the value for pounds per cord of dry firewood. Divide that value into the 1 million BTUs per cord. For example, 1 cord of dry white oak weighs 3,710 pounds and has 28 million BTUs. If you divide 28 million by 3,710, you get 7,547.170. Dry white oak generates roughly 7,547 BTUs per pound.
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Determine the value for pounds per cord of green firewood. Divide that value into the 1 million BTUs per cord. For example, 1 cord of green white oak weighs 6,290 pounds and has 28 million BTUs. If you divide 28 million by 6,290, you get 4,451.510. Green white oak generates roughly 4,452 BTUs per pound.
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Tips & Warnings
Wood that has been dried and seasoned properly should generate about 7,700 BTUs per pound.
Green wood has an average of about 5,500 BTUs per pound.
Live oak, eucalyptus and manzanita are among the hardwoods that give off the most BTUs.
Dry wood weighs less and creates more BTUs than green wood.
Green or wet wood weighs more and generates fewer BTUs than dry wood.
References
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