Burning Issues

Home Heating Facts and Figures

Home Heating Pollution in Pounds Per 24 Hours
Wood stove  0.825
New wood stove  0.434
Pellet stove  0.127
Oil furnace  0.001
  Gas furnace 0 .00005

Here we compare how many times dirtier a new wood stove is compared to natural gas. These numbers indicate the best of circumstances, but in fact the stoves do not achieve the expected emission reduction (McCrillis, 1990).

Here is a chart to show a rough comparison between fuel cleanliness.

How much dirtier is burning wood for heat compared to using gas or propane?
Old wood stove is approximately 16,500 times dirtier
New wood stove 8,500 times dirtier
Pellet wood stove 2,500 times dirtier

While we discuss the efficiency of different fuels we should be discussing the efficiency of the heating appliance that utilizes the fuel. By efficiency one means the percentage of the heat generated that is delivered to the surrounding space. In effect, the percentage of the generated heat that does not go up the chimney.

An electric heater is 100% efficient. A gas furnace is 95% efficient. A wood stove is 60% efficient. New Stoves claim to be 80% efficient however that efficiency soon dwindles, (McCrillis, 1990). You would have to burn more fuel and cause more pollution with a wood stove than with the other fuels to get the same amount of heat.

Heating Efficiency of Wood Burning Methods
Heating Efficiency  
Masonry Fireplace -10% to 10%
Manufactured Fireplace -10% to 10%
Freestanding Fireplace -10% to 30%
Antique Stove 20% to 40%
Fireplace insert 35% to 50%
Airtight Stove 40% to 50%
Masonry Heater 50% to 70%
Certified Stoves 60% to (80% temporary when new)
From Wood burning Handbook, California Air Resources Board 2001


Energy sources in terms of British Thermal Units (Btu).
Kind of Wood a cord of wood is 128 cubic feet. (8'x4'x4') or 3.625 cubic meters. Heat Value In a 60% efficient stove.
1 cord oak 22 Million Btu
1 cord maple, fir or cherry 19 Million Btu
1 cord of seasoned pine wood 12 million Btu

Form of Energy Heat Value
12.5 therms of natural gas One million Btu
13.6 Gallons Propane One million Btu
292 kilowatt hours of electricity One million Btu
A cost comparison of fuels is under Economics. "In most areas of California you will pay more to heat with wood than to heat with gas." CA ARB, 2001

Fireplaces don't heat well.
Note that we do not include a fireplace or wax logs as a home heater because they actually can have a negative effect on house interior temperature as they draw in air to support their combustion. You can see this in Heating Efficiency of Wood Burning Methods above.

"There are few energy advantages to the homeowner for burning wood or wax logs in fireplaces. Instead of heating the home, a fireplace tends to move the home's indoor air, along with the hot gases from the fire, up the chimney. Thus, most of the heat, along with the most of the particulate air pollution (but not all), leaves the home up through the chimney, moving out throughout the surrounding neighborhood and into other peoples' homes. Since fireplaces heat homes so poorly, the main reason for fireplace use in the Bay Area is the attraction of the flame itself. Some use of fireplaces may be caused by a misunderstanding from the 60's that fireplaces help bring about energy conservation. Unfortunately, their energy conservation effect is small, while their potential for producing deadly particulate air pollution is great (Ott, 2000)."

An example of questionable advertising was noted recently on a box of six pound wax logs sold at Costco. It read "20% more BTUs than the competitors' brand of a five pound log." Since the logs are most likely going to have a negative heating effect perhaps it should read "20% more pollution than our competitors log."

Burning Issues
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Tel: 707-882-3601
E-mail: pm10mary@mail.mcn.org

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