Wood Burning = Green Heat?

Heat-Kit.comPhoto Credit: Heat-Kit.com
Heating your house with firewood is completely retro. I mean, cutting up trees and burning them, that’s just so old fashioned and inefficient, and not green at all.

Right?

What do you mean, wood burning can be green?

In fact, masonry heaters (which are also sometimes called “Finnish heaters” or “Russian heaters”) can be a green source for heating a home. While a traditional fireplace may be only 10% efficient (which is to say not!), a masonry heater can be 90% efficient. A well insulated house (even in a cold, Canadian location) can be heated on a single cord of wood per season. In a sense, a masonry heater is to a traditional fireplace what a compact fluorescent (or, even better, and LED light) is to an incandescent bulb.

The key, as is the case with passive solar heating, is thermal mass. When heating is taking place, you want to capture and store as much of that energy as you can, so that you can use it throughout the day. The masonry heater does this with a large structure containing a series of baffles, all of which gets heated up from a fast, hot-buring fire. By using a series of baffles in the structure, the heater ensures that most of the heat goes into the stone of the heater itself, rather than shooting up the chimney to be wasted, as is the case with a traditional fireplace.

Once heated, the thermal mass of the heater slowly radiates heat into the surrounding space over the course of a day. Because the heat radiates from the thermal mass in a straight line, spaces in direct line of sight to the heater are going to be better served than small closed-off rooms away from the heater. A masonry heater is not likely to be something that can easily be added to an existing home. The design of the entire house needs to be considered in order to get the best use from a masonry heater.

The carbon impact with this kind of wood burning is actually fairly benign. Firewood contains recently sequestered carbon, carbon removed from the atmosphere during the life of the tree. This carbon is re-released to the atmosphere when the wood is burned, where it can be reclaimed by other trees and plants. Fossil fuels, on the other hand, have had their carbon sequestered for millions of years. By burning fast and hot, the masonry heater produces less of the soot, creosote and other by-products that are formed when a fire smolders and burns slowly. This makes it less polluting as well as more efficient.

A masonry heater doesn’t make sense for every location (nor does any other technology). It would make no sense to have one in a city where the firewood needed to be trucked in from a distant source. But for a location where firewood is a readily available local resource, it can be worth considering. And with a masonry heater, burning wood can be a green heating method.

Sources:
Alternative-Heating-Info
Green Mountain Soapstone
Heat Kit
Tulikivi


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  • Another Lisa

    I got to sleep on one of these in Russia for one night. The heater was the center of a hand-built dacha ("code?" what's a building code?), so all three ground floor rooms had part of a "heater wall." Two of the rooms were bedrooms, and the heater had a "shelf" in each room that you could sleep on for a cozy night's sleep.

  • Another Lisa

    I got to sleep on one of these in Russia for one night. The heater was the center of a hand-built dacha ("code?" what's a building code?), so all three ground floor rooms had part of a "heater wall." Two of the rooms were bedrooms, and the heater had a "shelf" in each room that you could sleep on for a cozy night's sleep.

  • Don't forget woodstoves! The house I grew up in was heated entirely by passive solar and one little Vermont Castings woodstove, located strategically at the center of an open floorplan. According to their web site, several of their woodstoves are more than 80% efficient:http://www.vermontcastings.com/content/products/productdetails.cfm?id=136

  • Don't forget woodstoves! The house I grew up in was heated entirely by passive solar and one little Vermont Castings woodstove, located strategically at the center of an open floorplan. According to their web site, several of their woodstoves are more than 80% efficient:

    http://www.vermontcastings.com/content/products/productdetails.cfm?id=136

  • Philip Proefrock

    The comparative disadvantage of woodstoves is that they don’t store the heat the way a masonry heater does. A woodstove needs to be fired more often and use more fuel, whereas a heater can oftentimes be fired just once a day to provide heat throughout the day.

  • Philip Proefrock

    The comparative disadvantage of woodstoves is that they don’t store the heat the way a masonry heater does. A woodstove needs to be fired more often and use more fuel, whereas a heater can oftentimes be fired just once a day to provide heat throughout the day.

  • Unregistered Userersfdhg

    Thermal mass has nothing to do with efficiency, but a lot to do with convenience. Masonry is certainly an option, but many good systems use water. Not only does it have lots on thermal mass, but it can also be piped to radiators far away from the furnace.

    Efficiency is all about combustion gas cooling. To minimize pollutants and soot, the fire needs to burn hot, with plenty of oxygen. Then, the gasses need cooling, e.g. a heat transfer to some sort of accumulator. The goal is to have a fire as hot as possible and a chimney as cool as possible. This is difficult to achieve in many ways, and there are lots of different approaches.

    My entire condo building, and in fact most of my town, is heated by a biomass fueled area heating/electric plant about three kilometers away. It’t clean, and it works very well.

  • Unregistered Userersfdhg

    Thermal mass has nothing to do with efficiency, but a lot to do with convenience. Masonry is certainly an option, but many good systems use water. Not only does it have lots on thermal mass, but it can also be piped to radiators far away from the furnace.

    Efficiency is all about combustion gas cooling. To minimize pollutants and soot, the fire needs to burn hot, with plenty of oxygen. Then, the gasses need cooling, e.g. a heat transfer to some sort of accumulator. The goal is to have a fire as hot as possible and a chimney as cool as possible. This is difficult to achieve in many ways, and there are lots of different approaches.

    My entire condo building, and in fact most of my town, is heated by a biomass fueled area heating/electric plant about three kilometers away. It’t clean, and it works very well.

  • I don’t think this article was intended to argue against other forms of green/efficient heating, only to say that masonry heaters are a very efficient option for people interested in alternatives to gas and oil. The efficiency comes from how much of the heat produced by burning wood is transferred into the home and not lost out the chimney. In a masonry heater you have a very hot fire, with more complete combustion, making for cleaner emissions if you are interested in using wood for heating and effective transfer of the heat into the space.

    Then there is the comfort level of the type of heat: a wood stove is very hot while burning and dries the air and burns the dust where the radiant mass of a masonry heater is more steadily warm.

    Another bonus to masonry heaters is the esthetic pleasure of having a work of art in the center of one’s home or space, where friends and family can gather around the warm stones and be comfortable together, and enjoying the light and warmth of the fire. You can also heat water in a masonry heater using a stainless water coil and a thermo-syphon hot water system. And many masonry heaters have built in ovens for cooking as well! How about a warm bench to sit on and enjoy after coming in from the cold!

    Masonry heating is not ideal for every situation, but is a great option for people who would like to use wood for heating their home, and who enjoy building a fire once or twice a day.

  • I don’t think this article was intended to argue against other forms of green/efficient heating, only to say that masonry heaters are a very efficient option for people interested in alternatives to gas and oil. The efficiency comes from how much of the heat produced by burning wood is transferred into the home and not lost out the chimney. In a masonry heater you have a very hot fire, with more complete combustion, making for cleaner emissions if you are interested in using wood for heating and effective transfer of the heat into the space.

    Then there is the comfort level of the type of heat: a wood stove is very hot while burning and dries the air and burns the dust where the radiant mass of a masonry heater is more steadily warm.

    Another bonus to masonry heaters is the esthetic pleasure of having a work of art in the center of one’s home or space, where friends and family can gather around the warm stones and be comfortable together, and enjoying the light and warmth of the fire. You can also heat water in a masonry heater using a stainless water coil and a thermo-syphon hot water system. And many masonry heaters have built in ovens for cooking as well! How about a warm bench to sit on and enjoy after coming in from the cold!

    Masonry heating is not ideal for every situation, but is a great option for people who would like to use wood for heating their home, and who enjoy building a fire once or twice a day.

  • Great post I really enjoyed it. I will have to bookmark this site for later.

  • Great post I really enjoyed it. I will have to bookmark this site for later.

  • Yes, I agree Masonry Heaters are an excellent way to efficiently heat a home during the winter! These fireplaces burn about 60-70% less wood during the heating seasons compared to a woodstove, and nicely radiate a low level, gentle heat.

    As an employee who has constructed many of these efficient fireplaces, I can truly say there is no substitute for the beauty and warmth these fireplaces
    emanate.

    http://mastercraftmasonry.blogspot.com
    Portland/Vancouver Area

  • Yes, I agree Masonry Heaters are an excellent way to efficiently heat a home during the winter! These fireplaces burn about 60-70% less wood during the heating seasons compared to a woodstove, and nicely radiate a low level, gentle heat.

    As an employee who has constructed many of these efficient fireplaces, I can truly say there is no substitute for the beauty and warmth these fireplaces
    emanate.

    http://mastercraftmasonry.blogspot.com
    Portland/Vancouver Area

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