Which Fireplace Is Best for the Environment? Wood, Gas, Electric, Pellet or Alcohol?

Free hovering fireplace in a white and glass room

Dominique Imbert

It's that time of year when peoples' thoughts turn to staying warm, fireplaces often come up as a method of doing so. There are many kinds, and all have their strengths and weaknesses. In North America, one of the weaknesses is that it is really hard to find units that don't look like something grandma had, so this post will be illustrated primarily with European designs that demonstrate what a good designer can do.

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Wood burning fireplaces

Free floating fireplace in a glass and white room

Dominique Imbert

Like this one, the Gyrofocus, designed by Dominique Imbert in 1968, that is in design museums around the world and in 2009, was voted "The world's most beautiful object." But like all open wood burning fireplaces, it is hopelessly inefficient. An open fireplace can draw as much as 300 cubic feet of heated room air up the chimney every minute. They also produce a lot of particulate pollution, so much so that the City of Montreal has banned them and wants them all eliminated by the end of the decade. Fireplaces can be improved by bringing in outside air for combustion and having glass doors, but they still are pretty ineffective.

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Wood Stoves

Black vertical wood stove against a graffitied brick wall

 Stuv

A far better choice is an engineered wood stove. The new EPA certified ones are a huge improvement and reduce the fine particle pollution significantly. However the new EPA stoves can get expensive; according to the US Department of energy they work hard to get those high efficiencies and low pollution numbers.

Advanced combustion woodstoves provide a lot of heat but often only work efficiently when the fire burns at full throttle. Also known as secondary burn stoves, they can reach temperatures of 1,100°F—hot enough to burn combustible gases. These stoves have several components that help them burn combustible gases, as well as particulates, before they can exit the chimney. Components include a metal channel that heats secondary air and feeds it into the stove above the fire. This heated oxygen helps burn the volatile gases above the flames without slowing down combustion.
Others meet the new standards by adding catalytic converters. However a lot of people are fighting the new regulations, claiming it is all an Agenda 21 plot to take away their right to live self-sufficiently.
When Barack Obama’s EPA arrogantly moves to make every wood burning stove in America illegal,” the blog Right Wing News wrote, “he’s basically saying to those people, ‘You can go ahead and freeze for all I care.

Given that Republican senators are saying things like ”What they’re doing is unnecessary, and it comes against our American values and our traditions,” I suspect that the rules might well change again with the recent change in the Senate.

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Masonry heaters

Gray stone fireplace in a beige and white room

Tulikivi

You don't have to be Catholic to celebrate mass; you just have to be rich enough to afford one of these beautiful masonry heaters, used for centuries in Scandinavia. The nicest ones are built out of soapstone but others are made of more conventional masonry and even rammed earth. According to Wikipedia, they are:

a vented heating system of predominantly masonry construction having a mass of at least 800 kg (1760 lbs), excluding the chimney and masonry heater base. In particular, a masonry heater is designed specifically to capture and store a substantial portion of the heat energy from a solid fuel fire in the mass of the masonry heater through internal heat exchange flue channels, enable a charge of solid fuel mixed with an adequate amount of air to burn rapidly and more completely at high temperatures in order to reduce emission of unburned hydrocarbons, and be constructed of sufficient mass and surface area such that under normal operating conditions, the external surface temperature of the masonry heater (except in the region immediately surrounding the fuel loading door(s)), does not exceed 110°C (230°F).

In short, they have the thermal mass to radiate heat long after the fire has gone out. However there is a lot of mass in them, and they are expensive to build.

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Pellet Stoves

Gray rectangular pellet stove against a white wall

 RIKA Pellet stove

Pellet stoves were becoming very popular in the early years of TreeHugger, people couldn't get enough of them. They are quite efficient, (75 to 90%) and have low emissions, a fifth of EPA certified stoves and a 50th of older uncertified stoves. The pellets, made from waste sawdust, are consistent and convenient. According to Popular Mechanics,

Pellet fuel offers many advantages over cordwood: It has a moisture content of less than 8 percent, compared to 20 percent or more for seasoned wood and 50 to 60 percent for unseasoned wood. (Btus are wasted in vaporizing moisture.) Dry pellet fuel is inert and nontoxic. It has an infinite shelf life, and it doesn't harbor bacteria, fungus, bugs or mice. Its energy density rivals that of coal, but it doesn't produce as much ash as either coal or wood.

However, when the Great Recession hit, the drop in housing production and manufacturing dried up the supply of waste sawdust and the price of pellets doubled, to $250 per ton. The stoves also need electricity to operate the feeder and the fans inside, so it won't keep you warm in a blackout unless you have backup power. They are popular in Europe for space heating needs where the heating season is short; the pellets are easier to carry and store than wood. There are lots of designs as lovely as the  RIKA one shown.

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Gas fireplaces

Rectangular gas fireplace with a gray steel border

 phototropic / Getty Images

Gas fireplaces used to be pretty ugly, with hokey fake logs in hearths designed to look like wood burning fireplaces. Designers have improved the situation and come up with some very attractive designs. As a method of space heating, gas fireplaces can be effective; I used one for years in our poorly insulated drafty old house to make the living room habitable in winter. But they are certainly not an efficient way to heat with gas running at about 65%; the rest of the heat is going up the flue. A high efficiency furnace can be up to 95% efficient, a much better way to get your heat. They do look nice, and are relaxing, our dog is quite fond of it. However this past season we have renovated our house so that it is now properly insulated and sealed, which makes a lot more sense that heating it by a fireplace.

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Electric Fireplaces

Electric fireplace with white exterior detailing against a blue wall

 maxsime / Getty Images

Like the gas fireplace, these are really not the most efficient way to get heat of the fuel resource. All electric heaters are 100% efficient at converting the electricity to heat; the difference is how effectively they get the heat to you. An electric heater designed for that function is going to do a lot better job than this. Also whether you can call an electric fireplace zero-emissions depends on where you are and how you get your power; if it is from coal, like 47% of America, you are not burning a clean fuel. If you are just doing it for the looks, you are better off putting a video of a real roaring fire up on that big screen.

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Ethanol Fireplaces

A rectangular fireplace, with a black modern table in the foreground

A-Fire

The latest rage is the ethanol fireplace, which produce a real flame without any flue. That's because alcohol burns extremely cleanly, producing primarily water vapor and a little bit of CO2. But it does make that water vapor by taking oxygen out of the air. So this particular unit comes with all kinds of safety devices like a built in CO2 detector that shuts it off. And they say, "Running on bio-alcohol, an eco-friendly and renewable energy, these fire spaces do not produce smoke or smell. AFIRE Bio-fireplaces is the simplest way of appreciating a real fire." There are smaller units that sit on your table; these come with warnings that they should be in a minimum room size and that there should be adequate ventilation. I think that in a healthy home, you shouldn't be burning anything unvented and that these are not TreeHugger recommended. Studies agree:

As a rule, ethanol does not burn out completely. Rather, the incineration process results in CO2 – along with poisonous gases (like carbon monoxide, a respiratory toxin), organic compounds (like benzene, a carcinogen), and irritant gases (like nitrogen dioxide and formaldehyde), as well as ultrafine combustion particles.

When I have written about them in the past, people have disagreed with me.

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Flueless Gas Fireplaces

Silver fireplace inset into a black and white wall

 Ekofire

Another new fireplace is the catalytic flueless gas fireplace. These are legal in the UK and the United States but not in Canada. These units burn natural gas and then put it through a catalytic converter to theoretically remove noxious fumes. They have all kinds of safety devices from oxygen detectors to CO2 detectors. Some have makeup air vents, and others do not, relying on the leakiness of your house. The manufacturers claim they are safe, but others do not; including Lance O'Hearn, who put it nicely:

Anyone following the debates raging in the United States regarding ‘vent-free’, ‘ventless’, or ‘unvented’ fireplaces has to wonder how long the people on the pro-side of this debate have been inhaling the fumes from their own unvented fireplace. Whatever name you choose to call these appliances by, I call them “wit-free”, “witless” and “unwitting”. In fact, I can not believe there are grounds for a reasonable debate on this matter at all.

In the UK, where they are common, the advice from a building expert:

All gas heaters produce water vapour and carbon dioxide, and — in the event of an insufficient supply of oxygen – some carbon monoxide too. That’s why they need flues, to get all that stuff vented to the outside. Flueless gas heaters just chuck it all into the air inside the house. The water vapour produced will raise the relative humidity and increase the likelihood of condensation; the carbon dioxide will make you feel sleepy, and the carbon monoxide – if present – could damage your health.

Alex Wilson nails it at Green Building Advisor:

Even though we are largely blocked from banning unvented heating appliances through our regulations, we can at least exercise our good sense by not buying them. It’s more expensive, but we should only install combustion heating equipment that vents to the exterior. Period. End of story.
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So what should I buy?

Chart of clean energy options

Puget Sound Clean Energy Agency

Really, after looking at all of these alternatives, I think the only answer is a heavy sweater and some mittens. Failing that, the natural gas or propane stove is, from a pollution point of view, the best bet. From a fuel cost point of view, it's best to look at the cost per million BTU. Even Gillespie did the comparison in SFGATE,

At a fuel cost of $250 per ton and an efficiency rating of 85%, a pellet-stove heat costs about $18 per million BTU. At a 75% efficiency rating, the cost increases to more than $20 per million BTU. On a cost-per-BTU basis, pellet stoves are significantly more expensive than wood stoves, which cost about $13 per million BTU. Natural gas furnaces are almost as inexpensive as wood stoves, at $13.52 per million BTU, and coal-fired systems are much less expensive, at $10.89 per million BTU.

But in the long run, the best place to spend your money is on insulation and sealing, along with a professionally designed and installed central heating system, so you don't need supplementary heat in the first place. Because none of these are perfect.