Winter 2013

Close to Home | Tips to Warm Your Hearth

Tips to Warm Your Hearth

It’s no surprise that traditional wood-burning fireplaces are major energy wasters. According to the Department of Energy, a blazing fire sends about 300 cubic feet of air up the chimney every minute, along with up to 90 percent of the fire’s heat—plus some of the heat produced by your home’s furnace too. Furthermore, the smoke ftrom older fireplaces contains fine particulates that can aggravate asthma, allergies, and other health conditions.

Thankfully, modern stoves and fireplace inserts that use wood or other fuels can heat your home while saving energy and reducing pollution. (Bear in mind that all fuel-burning stoves and fireplaces produce global warming emissions; emissions vary based on the type of fuel, its source, and the energy used in producing it.)

Wood-burning units are available in a variety of configurations, ranging from about $2,000 to $3,000 installed, that meet stringent emissions limits set by the Environmental Protection Agency (EPA):

  • Catalytic stoves employ a ceramic catalyst coated with platinum or palladium to burn much of the fire’s exhaust gas rather than letting it escape, generating more heat while reducing the buildup of creosote (which can lead to chimney fires). Certified units emit no more than 4.1 grams of particulates per hour, compared with the 40 to 60 grams per hour generated by an older fireplace. The catalyst must be replaced every few years (at a cost of $75 to $150) to keep emissions in check.
  • Non-catalytic stoves have slightly higher emissions (7.5 grams per hour maximum) but maximize heat output and minimize pollution via an insulated firebox and holes at the top of the firebox that enhance combustion. Non-catalytic stoves can be cheaper than catalytic units, but burn wood more quickly.
  • Traditional fireplaces can qualify under a voluntary EPA program if the unit emits no more than 5.1 grams of particulates per kilogram of wood burned—about 70 percent less than an older fireplace. While qualified fireplaces generate more heat than older units, they may not generate enough to serve as your primary heat source.

If you do opt to burn wood, minimize your environmental impact by using only dry, seasoned wood (wet or “green” wood requires more energy to burn and can generate more smoke).

Pellets made of compressed sawdust and other wood/plant waste can be burned in stoves that produce very little pollution; look for an EPA-certified stove that has the highest efficiency rating possible (independently verified ratings are available on some manufacturers' websites). Because they do require electricity (about 100 kilowatt-hours per month under normal usage) to feed pellets into the combustion chamber, they will not work during a power outage unless connected to a backup power source. Pellet stoves range from about $1,500 to $3,000 installed.

Natural gas (or propane) fireplaces, which range from approximately $2,000 to $4,000 installed, offer instant, easily adjustable heat and avoid the mess and storage requirements associated with wood and pellets. And because gas fireplaces do not require a chimney, they can be placed almost anywhere in the house (though the EPA does not recommend unvented units due to air quality concerns). No EPA certification exists for these units because they are all highly efficient (converting up to 80 percent of the fuel into heat) and produce minimal particulates, but look for direct-vent units, which reduce interior heat loss by using outdoor air for combustion.

Before you make a decision, be sure your home is well insulated and any air leaks have been sealed. Then, contact a retailer or National Fireplace Institute-certified installer to help you determine the best, cleanest model for your needs. To learn more, visit the EPA website at

Also in this issue of Earthwise:

Ask the Scientist

Natural gas is often described as “clean-burning,” especially compared with coal, but I’ve read that methane can leak from natural gas operations. What are the climate implications of this leakage?