Wood Density and Heat of Combustion Values
Unfortunately for a many of those who live within city limits, restrictions are being placed on what kinds of fireplaces - if any - are allowed. Some ordinances ban all forms of wood heating while others allow only compressed wood pellets.
Benjamin Franklin famously said, "He who cuts his own wood warms himself twice." Anyone who has done gone into the forest to cut down a big maple or oak tree, cut it into fireplace size logs to pile into a truck bed, then take it home and split and stack it knows what he means. I did so often as a teenager. In the last few years I have cut down a lot of trees, but it has been to clear land of clutter; sometimes I even managed to sell the logs.
Here is a table of wood properties that includes BTU values. Pretty much the exact same table is reproduced all over the Web, so here it is again here. The information has not been verified against a reputable source, so be forewarned. Presenting a single value (especially to 3 significant figures), as opposed to a range of values, is unrealistic since wood typically varies widely in density based on water/sap content, growing conditions, and processing. Therefore, numbers should be regarded as an average value.
In the following table, 1 cord = 85 ft3 (the standard cord is defined as a densely stacked 4' x 4' x 8' = 128 pile ft3, so 85 ft3 assumes 65% wood and 35% air space) is used to convert between the "Density" and "Weight of Cord" column. Be aware that the densities used for the wood species varies significantly. The densities used above is for natural dried wood where the average moisture content is approximately 20%.
Heat values of Cords with dry wood can be estimated by adding the green wood cords values with approximately 10%.
1 ft (foot) = 0.3048 m
1 lb = 0.4536 kg
1 Btu (British thermal unit) = 1,055.06 J = 2.931x10-4 kWh = 1.055x1010 ergs = 252 cal = 0.293 watt hour
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