Heating Properties of Firewood by Tree Species

Heating Properties of Firewood by Tree Species Firewood performance can differ from species to species. The type of tree you use for burning can vary widely in heat content, burning characteristics, and overall quality. I have created a table that presents several important burning characteristics for many species used in North America. The chart ranks each tree species by its density which is a good indicator of overall heating effectiveness. Wood Characteristics Influencing Quality Heating and Ignition Density of Wood - density is the amount of space a volume or mass of firewood occupies. The denser the wood, the less space its given mass takes up and the greater a particular volume of firewood weighs.  For an example,  hickory is about twice as dense as aspen, so a cubic foot of hickory weighs approximately 50 pounds while a cubic foot of aspen weighs only about 25 pounds.   Green Vs. Dry Wood - Firewood should be dried (seasoned) to 10% to 20% moisture content for best burning performance. Much of the energy generated from burning green firewood actually goes toward evaporating the water held in the wood. Green firewood only gives off about 40% of the energy of dry firewood. To get the most heat production out of your firewood, you should season it by first cutting into short log bolts. Split these bolts and stack in a dry,  well-ventilated  area for at least six months before burning. Available Heat by Wood Species  - Available heat is a measure of the heat given off when wood is burnt and measured in million British Thermal Units. Hardwood trees give  off more energy in BTUs than a comparable volume of softwood because it is denser. It should be noted that  the volatile oils in some softwoods can increase the heat output of some species but only for a short time. Ease of Splitting - Wood with a straight grain is easier to split than wood with a tighter more complex grain. Knots, branches, and other defects can also increase the difficulty of splitting firewood. Remember that dry wood is generally easier to split than green wood. Ease of Igniting Firewood - Ignition ability is an important factor wood factor. Low-density wood is easier to light than denser wood. Woods with higher levels of volatile chemicals in their structure, such as conifers, will ignite  and burn more readily than those with less volatile chemicals. These woods should be used to start fires where dry  high-density woods will provide the heat. Definitions of Chart Terms Density - woods dry weight per unit volume. Denser or heavier wood contains more heat per volume. Note that hickory ranks at the top of the list.Green Weight - the weight in pounds of a cord of freshly cut wood before drying.mmBTUs - million British Thermal Units. The woods actual available heat measured in BTUs.Coaling - wood that forms long-lasting coals are good to use in wood stoves because they allow a fire to be carried over a longer period effectively. Wood Heating Values Chart Common Name Density-lbs/cu.ft. Pounds/cd. (green) Million BTUs/cd. Coaling Hickory 50 4,327 27.7 good Osage-orange 50 5,120 32.9 excellent Black locust 44 4,616 27.9 excellent White oak 44 5,573 29.1 excellent Red oak 41 4,888 24.6 excellent White ash 40 3,952 24.2 good Sugar maple 42 4,685 25.5 excellent Elm 35 4,456 20.0 excellent Beech 41 NA 27.5 excellent Yellow birch 42 4,312 20.8 good Black walnut 35 4,584 22.2 good Sycamore 34 5,096 19.5 good Silver maple 32 3,904 19.0 excellent Hemlock 27 NA 19.3 poor Cherry 33 3,696 20.4 excellent Cottonwood 27 4,640 15.8 good Willow 35 4,320 17.6 poor Aspen 25 NA 18.2 good Basswood 25 4,404 13.8 poor White pine 23 NA 15.9 poor Ponderosa Pine 3,600 16.2 fair Eastern Red Cedar 31 2,950 18.2 poor