Thursday, November 20, 2014

Where There’s Oak, There’s Fire - Heating a House with Wood

By Adam Bonislawski
WSJ, Nov. 19, 2014

How much wood would a woodchuck chuck if a woodchuck had a 3,000-square-foot house to heat?

Well, that depends—are we talking white oak or ponderosa pine?

Roughly 2.4 million households use wood as their primary heating fuel, according to the Census Bureau’s 2013 housing survey. And, no doubt, there’s a certain rustic charm to a wood-burning stove that, say, an electric heat pump is hard pressed to match.

On the other hand, wood involves a bit more in the way of logistics than other, more commonplace fuels.

“It’s real easy to go to the thermostat and dial it up or down with natural gas or electric,” says Jim Reeb, associate professor of forestry and natural resources at Oregon State University. “Wood is a little tougher to handle. It takes a little [work] to find a place to put it. You need to keep it dry.”

You also need to make sure you have enough to take you through till spring. A typical 3,000-square foot home uses roughly 65 million BTUs over the course of a winter, according to the Energy Information Administration, part of the Energy Department. Of course the amount varies across regions and based factors like sun exposure and insulation levels.

Breaking it down by region, homeowners in the Northeast will use around 79 million BTUs, those in the Midwest will use around 76 million BTUs, and those in the South and West will average around 47 million BTUs.

What that equals in terms of wood consumption depends on what kind of tree you plan to burn.

“In general, your dense hardwoods have more energy because there’s not as much air” in the wood, Prof. Reeb notes. For instance, a cord (128 cubic feet) of white oak contains around 30 million BTUs worth of energy—the equivalent of 214 gallons of heating oil. A cord of the softwood ponderosa pine, meanwhile, has about 17 million BTUs.

Then there’s the matter of your stove’s efficiency. EPA-certified catalytic wood stoves are 72% efficient, meaning they convert 72% of the wood’s energy into heat for warming your house.

Add it all up and the average homeowner can expect to use just over three cords of hardwood or just over 5¼ cords of softwood in the course of a typical winter.

Better get chopping.

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