Published on December 17th, 2007 | by Stephanie Evans
Fireplaces for Home Heating
Fireplaces truly are ancient. A hearth with a stone or masonry chimney represents a first advance from a fire built on the dirt floor of a house with smoke slowly escaping through the rafters. We’ve made some progress since the invention of the fireplace, although in many houses that isn’t very evident!
A conventional fireplace is in reality an energy hole—not a space-heating device—since almost all of the air that it heats gets sucked up and escapes out through the chimney.
But there is still nothing that fully replaces fire as the focal point for a home. Fireplaces are an opportunity to design with beautiful permanent materials like tile, brick, and stone. And radiant heat (as opposed to forced-air) remains the most comfortable kind of space heating.
Today, ambiance and space heating are separable technologies. If all you require is a romantic flickering flame on a hearth, there are some new green options available. Likewise, if you are looking for a way to heat your home that doesn’t use fossil fuels, wood (one of the oldest biofuels around) can be a good choice—just don’t try to use a fireplace to do it!
Burning Wood Responsibly
Burning anything levies environmental consequences—there are no exceptions! Burning wood obviously produces smoke and destroys trees. Trees are a renewable resource when managed sustainably, but without strong legal oversight, they usually aren’t. If you want a glimpse of what uncontrolled forestry practices can produce, just take a look at China, Iceland, or Ireland—countries that were once heavily forested. And anyone who lives in an area where burning wood for heat is common can attest to the air pollution it can produce—if everyone used EPA-certified woodstoves, the pollution would be vastly reduced. For eco friendly wood burning tips, read 5 Steps to Becoming the Greenest Firewood User .
Does burning wood contribute to global warming? A good question and the answer is . . . not significantly. Global warming is almost entirely caused by the burning of fossil fuels, that releases CO2 into the atmosphere that otherwise would never be there. Burning wood speeds up, by some decades, the release of CO2 captured in trees that would be released anyway when the tree died and rotted. Clear-cutting and/or burning forests down does contribute to global warming though, mainly because it reduces the number of living trees that can take up CO2.
Home Fire Options
Your most environmentally sound choice in a home fire depends upon a number of factors, including:
- how cold a climate you live in
- how close you are to sources of firewood
- whether you need ambiance more than heat (or vice versa)
- whether you have an existing fireplace
A family in rural Minnesota will have different criteria than a bachelor in an Atlanta apartment. The higher your actual heating needs, the more useful you will find a slow-heat-release or timed-heat-release fire such as a pellet stove, masonry heater, or soapstone-clad stove (listed in descending order of efficiency). Although fossil-fuel stoves and fireplaces aren’t a green choice for heating needs, they could make sense for occasional ambiance, so they are included at the end of this article. We’ll outline your:
- Cordwood—existing fireplaces, energy-efficient fireplace inserts, manufactured fireplace logs, advanced combustion fireplaces, woodstoves, clad woodstoves, and masonry heaters
- Pellet stoves
- Ethanol gel fireplaces
Fossil Fuel Choices
- Gas fireplaces
- Electric fireplaces
This section includes: existing fireplaces, energy-efficient fireplace inserts, manufactured fireplace logs, advanced combustion fireplaces, wood stoves, and masonry heaters.
Existing fireplaces. They are often pretty, and they are invariably extremely hard to remove. The first thing is to stop up that big hole in your house. Get an insulating flue plug, an inflatable urethane pillow that stops the draft up your chimney. Some fireplaces can be made usable by installing an energy-efficient fireplace insert, essentially a wood or gas stove that fits into your fireplace and uses the existing chimney.
If you want to use your fireplace occasionally, burn artificial fireplace logs made from recycled wood waste from lumber milling (don’t forget to take your flue plug out first!). Look for manufactured logs that contain no paraffin, a petroleum product that emits toxins into the air when burned.
Advanced Combustion Fireplaces. A few new wood burning fireplaces are designed for enough energy efficiency that they are EPA certified. They tend to resemble fireplace inserts (an iron stove box with glass doors), but they possess a more integrated look since they are not retrofitted.
Wood Stoves. These are the most common wood space heaters. To decide whether a wood stove will heat your house, remember that radiant heat is direct heat. Unlike forced-air heat that is distributed via a ducting system, a wood heater must be placed in the main room you want to heat. Radiant heat doesn’t distribute very quickly through a house divided into many small rooms, even if they are above the stove (unless the flue passes through a room above the stove, radiating heat into that room). If you have a fairly open floor plan, wood heat works very well.
The EPA has established strict smoke emission limits for new wood stoves. Manufacturers have addressed this challenge in two ways, and each has its merits.
- In the catalytic approach, smoke is passed through a converter within the stove, which burns the gases in the smoke. Catalytic wood stoves can produce long, evenly emitted heat, but they must be managed well to get the most efficiency and longest lifespan from the converter. With care, the catalytic converter can last up to six seasons before requiring a replacement, but over-firing, lack of regular cleaning, or burning anything other than dry hardwood can reduce this to two seasons.
- Non-catalytic wood stoves use firebox insulation, baffles, and special air intakes to create combustion efficiency. They can’t produce the even heat of catalytic wood stoves but they are easier to maintain, more forgiving about what they can burn, and they do not have an expensive catalyst to periodically replace. Read more about wood stoves at woodheat.org.
Soapstone stoves are iron stoves with soapstone cladding. Because soapstone retains heat much longer than iron, these stoves have some of the advantages of the long heat release of masonry stoves.
Masonry heaters, sometimes called Russian fireplaces or Finnish fireplaces, are the most efficient (90%) and least polluting woodburning space heating devices. They resemble conventional fireplaces in exterior appearance and are characterized by:
- long twisting interior smoke channels
- tight-fitting doors
- considerable thermal mass (which can be brick, stone, tile, concrete, or a combination of these)
- a firebox lined with refractory materials that can withstand temperatures of over 2,000 degrees F
A small hot fire built once or twice a day heats the masonry via the smoke channels—the heat is then slowly released over a period of twelve to twenty hours. Masonry heaters can double as solar thermal mass if they are built where winter sunlight can strike them. They can be adapted to burn almost any solid fuel.
Masonry heaters are available as prefabricated units, though most are site-built. They range from the size of a wood stove to covering an entire wall. They do have the disadvantage of not being able to provide a quick source of heat. If you have low heating needs, remember that they also cool off extremely slowly even if the weather changes. Read more about masonry heaters at the Masonry Heater Association of North America Web site.
Pellet stoves are extremely efficient burners (beating any wood heater), and because they emit so little air pollution, they are exempt from EPA air-quality certification! Their fuel is rabbit-food-sized pellets made from lumber mill wastes like sawdust and bark, crop wastes like corn cobs, and recycled paper—no trees are sacrificed to heat your house with a pellet stove. They are available as free-standing stoves or fireplace inserts, or even as furnaces and boilers.
Pellet stoves have fuel hoppers that automatically feed pellets a few at a time into the combustion chamber, so the feed rate determines the heat output. Normally the hopper is loaded once a day. Some models have thermostats and computers that control the feed rate. The fuel is considerably easier and much cleaner to store and handle than cordwood. Since the burn is so complete, creosote build-up in the flue is minimal, which reduces the hazard of a chimney fire.
On the down side, pellet stoves are more complex and have more components to break down than wood stoves or masonry heaters. Electricity is required to run the fans, controls, and feeders—about 100 kilowatt-hours and month. If there is a power failure, the stove is useless without generator back-up. Photovoltaic cells might be a good adjunct to a pellet stove. The Deptartment of Energy has an excellent overview of various wood and pellet space heaters.
Ethanol Gel Fireplace
Ethanol Gel Fireplaces are also extremely portable and require no venting, as they are smokeless and their only byproducts are water vapor and a small amount of CO2. They use environmentally friendly ethanol derived from biological sources like corn or sugarcane. Although they produce a real flame, they are not considered space heating devices. Gel fireplaces are the greenest way to put a fire on your hearth, and they’re available in the highest of high fashion designs.
Gas Fireplaces provide radiant heat and a hearth flame without the bother and mess of wood. Although they do use fossil fuels—either natural gas or propane—and hence cannot be termed the “best” green alternative, a new, efficient gas fireplace is certainly greener than an energy-wasting, air-polluting conventional wood fireplace. There is a very wide variety of sizes and aesthetic choices in gas fireplaces, and considerably more leeway in terms of venting than that offered by wood heat appliances. Choose a gas fireplace with the highest efficiency rating, called AFUE (Annual Fuel Utilization Rating), that you can find.
Electric Fireplaces take up very little space and can thus be used even in the tiniest apartment. They are portable and require zero venting and almost no maintenance. They use common incandescent light bulbs and colored metal reflectors to create the illusion of flames. Some come with heaters as well. If you don’t turn on the heater, they don’t use much wattage, so they are an economical solution if all you’re after is the appearance of a flame. However, electric heat is a poor solution for all but the very smallest of rooms. Even if it is “clean” at your end, it is generally produced by burning fossil fuels somewhere out of sight.
There’s just nothing to beat a fire on the hearth for emotional satisfaction! Even though the old fireplace—which was little more than a hole to the sky—should be retired, somewhere there is an alternative that works for your budget, your needs, and the needs of our planet.