Wood Stove

Wood Stove


A wood stove works great in a home with an open floor plan. In addition to the ambience and comfort of a cozy fire, they have the advantage of using renewable, biogenic fuel with much lower life-cycle greenhouse gas emissions than fossil fuels.

Wood stove manufacturers are required to have their stoves tested to meet EPA standards based on their annual particulate emissions as measured in parts per million (PPM.) The EPA started requiring stove manufacturers to meet air emission standards in 1988 when annual PPM were over 280. The new 2020 standard for wood stoves is down to 2 PPM annually.

Stoves with catalytic converters and “non-cat” stoves

Stove manufacturers may meet the EPA standard through two different stove design strategies. Stoves with a catalytic converter burn clean by capturing the particulates in a honeycomb structure where they can be reburned. Non-cat stoves reburn particulates with secondary and tertiary airflows that are built into the stove design.

Catalytic converter stoves need to have their catalyst bypassed in order to create sufficient draft during initial light off. In order to achieve the clean burn EPA standard, the stove operator needs to place the catalytic converter back in position once the fire is going. Additionally, catalytic converters need to be replaced periodically. Non-cat stoves achieve the clean emissions standard without requiring the operator to keep track of the position and condition of the catalytic converter, which, if not properly maintained, could lead to much higher emissions.

Wood stoves’ clean burn and safety is in the hands of the operator:

  • Draft must be sufficient, especially during initial light off.
  • Stoves burn cleaner when the operator maintains a high heat, typically between 290 and 560°F. Use a wood stove thermometer .
  • Cordwood should be dry before burning. Season wood for six months prior to burning.
  • The chimney must be periodically swept to remove creosote, which could cause a chimney or house fire.

Engineered Wood Bricks

Engineered wood bricks like Biobricks and Fiber Fuel are an alternative to burning cordwood in your wood stove and they have a few advantages. They’re made from the waste of furniture and other woodworking operations, which means the sawdust is from lumber that has already been kiln-dried. No glue or additives are used, they are manufactured using high pressure to hold the brick’s shape. The very low moisture content in engineered wood bricks means they burn very hot and cleanly, resulting in magnitudes less ash and creosote. Because they are a uniform shape and size, they stack tightly so you can fit a lot of BTUs in a small area compared to cordwood.

State incentives

In order to incentivize clean burning wood stoves, some state governments offer incentives for replacing your older model polluting wood stove for one that meets the latest EPA standard. If your state has an efficiency utility, it would be a good place to start your research; if not, google “(state name) wood stove incentive”.

Fresh air intake

If you take a close look at figure 1 above, you can see that combustion air is drawn into the stove’s firebox as indicated by blue dotted lines. Using heated room air for combustion cuts down the overall efficiency of the appliance. Some stoves are designed with the ability to have fresh (cold) outside air piped to the burn chamber which increases its total efficiency.

Smart storage & conveyance

They say that wood is the fuel that warms you twice: once when you cut it and stack it and once more when you burn it. Heating with wood will be more convenient when planned in three stages: long-term drying, easy undercover storage near the door, and a one-day supply next to the stove.

Installing a wood stove

Wood stoves must be chimney vented. Installing a new wood stove will require connecting to an existing chimney or adding an exterior metalbestos chimney. See your local building codes for construction details when venting through walls, floors, or the roof.

Inside at the stove location, beware of the need for clearances from combustible surfaces, the hearth extension at the front of the stove, and proper heat shields. Your particular installation details will be dictated by the stove manufacturer’s specifications and local/national building and fire codes.

Wood stove summary

A wood stove is great if you’re going to be around to enjoy the fire and don’t mind feeding and stoking. Follow best practices for burning wood that has been properly dried and seasoned in order to minimize creosote, ash buildup, and pollution. If reducing pollution is the primary driver of your decision, keep in mind that pellet stoves heat cleaner than wood stoves.

For a deep dive into all things wood stove, visit our nonprofit partner, the Alliance for Green Heat.


Heat Loss

The two variables of of heat loss are a) geographic location, and b) building performance. Together they will determine the quantity of heat needed to maintain comfort.

Geographic location drives the building's “design day." Your design day is the difference in temperature between the inside and outside of your house on the theoretical coldest day of the year; so in the northeast we calculate a day that is -10ºf outside and comfortable 68ºf inside. This is referred to as the “delta-T” value. A typical delta-T for the northeast is 78º.

Building performance is the big one because there’s nothing we can do about geographic location. Today we can build a really tight thermal envelope, but most of our heating pollution comes from the millions of homes built over the last 100-150 years. We are getting better at buttoning-up those old buildings with insulation and weather sealing but weatherization is still  never going to be enough to overcome the heat loss from a 78º delta-T. That means we need heating systems that can quickly put a whole lot of heat back into those old houses on the days that are really cold.

Annual Particulate Emissions for Residential Heating Systems