Environmental Comparison of Wood-Burning Stoves

Heating with Wood and the Environment – part 4: How Different Types of Wood Burning Appliances Affect the Environment

Earlier on in our series, “Heating with Wood and the Environment”, we discussed the pollutants and other environmental concerns in burning wood. We also discussed how what you burn and how you operate a fire can really reduce negative environmental impacts. In this article, we shall discuss how different types of wood burning appliances will affect your contribution to pollution rates.

Different types of wood burning appliances have different capabilities when it comes to how efficiently they maintain a flame and how complete the combustion is. Higher efficiency appliances require less wood is to provide heat and therefore produce less pollution, such as fine particulate matter. The main classes of indoor wood-burning appliances are listed below:

• Wood pellet stoves are generally the most environmentally friendly and efficient wood-burning appliance. Wood pellet stoves burns small pellets derived from dried wood and other biomass waste. The wood pellets are fed into the main burn area via a small electrical device.
• EPA-certified Wood stoves or fireplace inserts represent the next most efficient class. A wood stove generally consists of a solid metal closed fire chamber and has adjustable air control. A wood burning fireplace insert is basically a wood stove inserted into the fireplace, as opposed to a freestanding wood stove.
• Masonry Heaters are appliances which retain heat through a large masonry mass and a maze of heat exchange channels.
• Basic chimney and fireplace

However, note that the specific design and construction of an appliance has just has much impact on efficiency as the type of appliance.

The efficiency of wood stoves and inserts varies tremendously from model to model. One factor is whether or not the wood stove uses a catalytic converter; catalytic woodstoves are typically less polluting. Also, the difference in pollution between an EPA-certified woodstove and a non-EPA stove is tremendous. Even among EPA certified models, there are very large differences.  The environmental-friendliness of a wood stove is usually measured by two metrics: GMs/hr, or grams of particulate matter emitted per hour, and efficiency rating. For example the Regency Classic™ F1100 Wood Stove has a GMs/hr of 3.0 and is 77.7% efficient at optimal operation.

Thinking about replacing an old wood stove or fireplace insert? There may be government incentives for upgrading to a more environmentally friendly device. Be sure to check if your state has a changeout program or other incentive programs. Maryland for example, just started offering rebates for wood and pellet stoves.

Fireplaces also have a huge variety in efficiency. Typically, a factory-built fireplace, also known as a “low mass fireplace” will be more efficient. However, it is not uncommon for a family’s masonry fireplace to be more efficient than a neighbor’s prefabricated fireplace. Again, the design and construction plays a huge role in efficiency. The quality of the installation and the situation of the chimney also are important.

Learn what you can do to your chimney and fireplace to reduce pollution in part 5 of the Heating with Wood and the Environment series.