The Homeowners Column

The Homeowners Column

Firewood usage

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

"Chestnuts roasting on an open fire. Jack Frost nipping at my nose" Jack can keep his nips to himself but an open fire can warm our homes and hearts. However a few pointers should be kept on the front burner when it comes to using firewood.

According to John Church, University of Illinois Extension Educator in Natural Resources, before using wood as a source of heat, first consider necessary safety precautions and proper equipment maintenance to avoid fires and chimney problems. For instance be sure to have the chimney professionally cleaned. Secondly if heat, not just entertainment, is the goal investigate types of wood burners and fireplaces to ensure that the use of wood is really more efficient and economical for your home than the use of routine fuel sources. The "Illinois Forestry" website on the University of Illinois Extension homepage at http://web.extension.uiuc.edu/forestry/timber_harvest/firewood.html contains excellent information regarding harvesting, buying and burning firewood for heat.

Forestry economists estimate that approximately two million cords of firewood are harvested annually from Illinois woodlands. Almost 43 percent of all annual wood removals are used as firewood and nearly 75 percent of all firewood is cut from dead or downed trees. When considering the use of wood for heat, remember that all species of wood have the same Btu (British Thermal Units) per pound of wood; roughly 8600 Btu per pound at 15% moisture content. As the moisture content goes up in the firewood, the heating value goes down (less Btu's) because more energy (heat) is needed to dry off the moisture in the wood before it will burn. Therefore firewood should be seasoned at least 6 to 9 months before it is burned. Freshly cut wood is not very efficient for heating use.

The difference in the heating value of different species of trees is due to the density (weight per unit of volume) of the wood species. If comparing two pieces of wood that are of identical size (volume) and moisture content and one is oak and one is cottonwood, the piece of oak firewood will contain more Btu's (heat) in it than the cottonwood because the density of oak is much greater than cottonwood. Oak is a heavier wood than cottonwood, so oak will have more potential energy than cottonwood if the same size piece or stack (volume) of wood is compared. The variety of wood and total Btu's should be considered when purchasing and pricing cords of wood for heating purposes.

In addition to our personal economics and safety we also need to consider the economics and safety of our trees by paying attention to the source of the firewood. Several devastating insects can be unknowingly moved in firewood. Emerald Ash Borer, a relatively new pest to Illinois, is underlining the problem. People should use local sources of firewood, especially ash wood to slow the spread of this diabolical beetle. Even if you purchase the wood locally, ask the supplier where the wood originated. Also when purchasing packaged wood at gas stations etc., look for the USDA inspection shield. Emerald Ash Borer's presence was confirmed this year just down the road in the Bloomington area. McLean County is now part of the EAB quarantine.

The Illinois and U.S. Departments of Agriculture are working with communities and industry to try to control the spread. Since the borers do not fly far, reducing human transport of the pest can help slow their spread. Beetles don't travel 65 mph down the road on their own. Areas identified with the Emerald Ash Borer are officially quarantined to restrict the movement of all firewood, wood products and the borer.

For more information about emerald ash borer http://www.agr.state.il.us/eab/

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