Burning firewood isn’t a risk to anyone’s health if it is properly seasoned and burned responsibly. People need to have an efficient air-tight firewood stove (or appliance) and dry, clean firewood to burn.
Whether firewood is safe and environmentally friendly source of home heat is a big debate since many people enjoy the feel of a home heated by firewood and firewood prices don’t fluctuate as much as oil prices do. People have been using firewood to heat their homes for years and they will continue to do so with no identifiable repercussions. Environmental groups are advising that burning wood is creating harmful exhaust that threaten the welfare of the surrounding population.
Burning firewood is carbon-neutral, meaning that burning it releases the same amount of carbon as leaving it to decay. Firewood is a renewable resource that can be locally grown and harvested. Firewood can come from fallen trees or overgrown forests and the wood used for firewood isn’t (generally) of the same quality as wood used for lumber, so using it to heat our homes is environmentally beneficial simply by using wood that might otherwise be wasted.
So, who is right? Does burning firewood create an environmental and health risk?
There are a hundred opposing articles that investigate the subject, but at the crux of both arguments are two major questions. How efficient is your wood burning stove? What type of wood are you burning and how dry is it?
The efficiency of the wood burning stove is very important. An inefficient stove will allow for a fire to burn at a much lower temperature. This causes the wood to smoke and smolder, creating very little heat and allowing the fire to produce and release air pollutants. The more smoke that is produced from low temperature fires and smoldering, the larger the amount of chemical compounds (nitrogen oxides, carbon monoxide, and particulate matter) that can be released into the air. Ideally, a fire will be hot enough to burn off as many residual combustible gasses and microscopic particles that can be carried in the smoke.
To maximize the efficiency of burning wood, a stove should be sized properly to heat the building that it is meant to heat. If the stove is too small, it will not provide sufficient heat. The US Department of Energy wrote an article stating that when the fireplace is too large for the home it is in, people tend to keep the wood burning at a lower temperature to keep the heat output low. This wastes fuel and it allows for the release of all of the particulate matter that didn’t get consumed by the flame. To estimate the stove size required to heat your home, you should look at stoves that can produce approximately 31 British Thermal Units (BTUs) for each square foot of your home. To determine the necessary size and type of wood burning stove that is needed, the Department of Energy and the National Fireplace Institute recommend hiring a certified industry professional to choose and install the best stove/appliance for your home. With the right equipment and installation, firewood is a much smaller threat to you and the environment.
The U.S. Environmental Protection Agency certifies wood burning appliances to identify which produce the most effective source of heat and the least environmental impact. They label stoves that can burn combustion gases (part of the exhaust) at lower temperatures. This cleans these gases out of the exhaust by burning them off and creating less particulate matter to be released in to the atmosphere. The more that can be burned off inside of the stove, the less that is emitted as air pollution. The Department of Energy published a great resource to help guide people through the process of finding an appropriate and safe wood burning stove or appliance. The Department of Energy’s article can be found here. People who are looking for a wood burning stove should only look for EPA certified appliances.
The second major factor which effects the efficiency and the environmental impact of burning wood for home heat is the wood itself.
Burning unseasoned, green, or wet wood will cause the fire to smoke and smolder more. Lighting it can be brutally difficult and that should tell you that it probably shouldn’t be burned. When this is ignored, burning wood that is unseasoned will allow for the build-up of creosote in your chimney. For a great resource discussing creosote, please visit mastersweep.com. They state that, “The "smoke" of unseasoned wood is heavily laden with unburned creosote. Because unseasoned wood causes the whole system to burn cool, the creosote laden flue gas [smoke] quickly condenses on the surface of the flue”. Effects of creosote is the largest danger that burning firewood can create and it is a result of negligent maintenance of firewood burning system and the use of wet wood. It tends to clog the exhaust and cause the particles to re-enter the home.
Creosote is a flammable, tarlike material that collects inside the chimney if its components aren’t burned off inside the stove. Creosote can cause your home heating system to have very ineffective exhaust. Creosote builds up inside the chimney and restricts the exhaust from exiting your home. Even worse, Creosote is very flammable and can cause chimney fires which can be simple, small and unnoticed, or they can erupt and devastate your chimney and home. A chimney fire will become more of a possibility once creosote builds up a ¼” thick layer or more. For more information on the impacts of creosote build-up, please consult this article concerning the three stages of creosote by High’s Chimney Service in Gaithersburg, Maryland.
The species of wood being burned also plays a major component in the fire that is produced. By using dense, hardwood species as firewood, the fire will be hotter and will produce more heat. This will give the fire a better opportunity to burn off more of the residual compounds identified as pollutants. Burning hardwood species will heat your home better.
So, there is a reason to be concerned with air pollution if you are burning unseasoned wood with an inefficient home heating appliance. However, if fully-seasoned hardwood is burned and an EPA approved wood burning stove (or appliance) is used, there is little to no threat to your welfare.
This is good news for New Englanders looking forward to a winter warmed the old-fashioned way (with fully-seasoned, hardwood firewood). If you have any questions or are looking for seasoned hardwood firewood to heat your home, please contact us.