Energy efficient fireplace

Home heating alternatives with a touch of class

An energy efficient fireplace, woodstove or pellet stove, can be an excellent supplemental heat source in your home, or, if your living space is small, well-insulated, and has good airflow, such as a country cabin, a fireplace or woodstove can meet all your heating needs. And there’s nothing quite like the glow of a fire to make your home feel welcoming and cosy. We have had a high-efficiency woodstove insert in our living room for over a decade, and it throws off a phenomenal amount of heat with just a log or two of well cured hardwood.

Before we get into the main fuels for an energy efficient fireplace, let’s clear up the difference between a fireplace, a fireplace insert, and a stove when referring to woodstoves and pellet stoves.

A conventional fireplace in an older home typically consists of a masonry enclosure and chimney, including a hearth, and a decorative mantel above and to both sides of the enclosure. Conventional fireplaces may not have any protection between the fireplace enclosure and the room, or may have tempered glass doors to prevent sparks from travelling from the fire into the room, but the glass covering the fire is there only for protection, not for efficiency. Most conventional fireplaces burn wood, but fossil gas fireplaces are also found in some homes built in the 1950’s through 1980’s. A conventional fireplace is not typically an energy efficient fireplace because there is too much airflow between the room and the firebox, and the burning of the fire tends to draw quite a bit of the warm air from inside the room up the chimney.

A fireplace insert is a sealed firebox that is designed to slide into an existing fireplace. A fireplace insert is almost always an energy efficient fireplace because the sealed combustion chamber prevents the fire from drawing large amounts of indoor air to the outside. Fireplace inserts burn firewood, fossil gas, or pellet fuel.

A woodstove or pellet stove is a sealed firebox that stands on its own in a room, rather than inside a fireplace. These stoves may have a decorative casing and glass doors to allow you to enjoy the sight of the fire, or they may be purely functional with the combustion chamber hidden by solid metal doors. Utility stoves are useful for warming a basement or small cabin where low cost is more important than aesthetics.

Fuel choices

Your choice of fuel will depend on the relative importance of cost, convenience, and environmental considerations. One of the advantages of an energy efficient fireplace is that you can heat your home (or a part of it) with a renewable fuel source such as firewood, wood pellets, or some types of grain. I strongly recommend against installing a fossil gas (what some people incorrectly call “natural gas”) fireplace. While firewood, pellets, and grain are carbon neutral, fossil gas is a contributor to climate change, including not only the CO2 emitted when the fire burns, but methane emissions upstream due to leakage at the oil or gas well and in the distribution system.

Pellet stoves

Pellet stoves burn pellets of compressed wood or other biomass to produce heat. Early models in the 1980s typically had a very small combustion chamber which made for an unattractive and boxy (but warm) addition to the living room, while models available today range from pellet furnaces and boilers, to elegant free-standing pellet stoves or energy efficient fireplace inserts suitable for a living room. Pellet stoves slowly and automatically feed their fuel from the hopper (storage container) into a burn-pot, requiring little effort to adjust the flame and no effort to feed the fuel (other than keeping the hopper loaded).

Some pellet stoves can burn other biomass than pellets, such as corn or wheat, and many farmers have taken to heating their farmhouse with a small part of their corn crop. Many pellet stove manufacturers actually favor a blend of corn and wood pellets for energy efficient fireplace burning.

Pellet stoves are definitely easier to operate than woodstoves, because loading the hopper can be a much faster, cleaner, safer operation than hauling logs in from outside, stacking them near the wood fireplace or woodstove, and then feeding them in one or two at a time through the day. Most pellet stoves can start up on their own based on thermostatic controls, and some can even be operated by remote controls.

One of the risks of heating with a wood-fired energy efficient fireplace is the build-up of creosote in the chimney or exhaust pipe for the stove; this tarry black substance is the leading cause of chimney fires, and is the reason anyone who heats with wood needs to have their chimney or exhaust pipe cleaned every year. The burning of pellets does not produce creosote, only a fine fly-ash which stays in the unit itself. Pellets produce typically one to four pounds of ash for every hundred pounds of pellets burned, with the higher quality pellets at the 1% level.

While woodstoves may draw air from the room they are located in into the stove to oxygenate the fire, pellet stoves need specially sealed input and exhaust pipes. The exhaust pipes are important to prevent the exhaust gases from being blown into the living area, because of the higher air pressure that the combustion blower produces. This means installation must be done by an experienced, qualified pellet stove installer, but one advantage is that, unlike a woodstove, a pellet stove can be installed in a place where vertical venting is not possible. (A small amount of vertical draft is beneficial but not essential.)

It’s best to provide an outside air intake for any sealed energy efficient fireplace, both to avoid creating negative air pressure in the home, and to ensure the unit operates efficiently. When any combustion-based heating device burns the indoor air as the source of oxygen, you are just drawing the warm air from inside into the combustion chamber and then out the flue, which merely draws colder air into your home through drafts.

Woodstoves and wood fireplace inserts

Sealed woodstoves and energy efficient fireplace inserts are an effective way of reducing your fossil fule based heating or electric heating costs if you have access to a cheap or free supply of high quality firewood. I have an uncle whose only heat sources are electric baseboard heaters, and a woodstove fireplace insert in his basement recreation room; he heats his home practically for free, because he’s retired and has time to scrounge for high quality scrap hardwood, most of which consists of oak spacers from the stacks of hardwood flooring sold by local dealers. (Note – do not burn hardwood flooring itself – the urethane or varnish coating can releases carcinogens when burned.)

For an energy efficient fireplace insert or woodstove to be energy efficient, it needs to satisfy a number of conditions:

• The unit needs to be sealed, with a damper to let you control the flow of air into the unit.
• Ideally it should draw its intake air from outside, to avoid creating negative pressure or cold drafts in your living space, and to avoid drawing warm indoor air up the chimney.
• There needs to be an adequate system of heat distribution in your home, for example, ceiling fans, or furnace / air conditioner heating ducts and a blower that can circulate air around the home
• Where heating ducts and a blower are used, you need a cold air return on each floor.
• The wood should be of high quality – preferably hardwood such as maple, birch, oak, or beech. If you have lighter hardwoods such as poplar or basswood, save it for the shoulder season.
• The energy cost, or delivery cost, of shipping the wood needs to be factored into the equation. If you had to drive an hour out of town in your pickup truck to get a load of firewood, don’t forget to include the gas, and wear and tear on your vehicle, in how you calculate the price of heating your home with firewood. (Also, be aware that transporting firewood between different regions, townships or counties may be prohibited in some areas, to fight the spread of highly invasive pests such as emerald ash borers,)

For a complete source of information on wood stoves and wood heating information visit this wood stove website, Wood-Stove.org.

Fossil gas fireplaces

A fossil gas fireplace is typically an aesthetic choice: if you want to have an energy efficient fireplace in a living room, recreation room or bedroom because it looks nice, and you don’t want the trouble or mess of loading it with firewood, then a natural gas fireplace may make you feel you’ve achieved that aesthetic goal. But given the climate emergency we all need to be doing everything possible to reduce our fossil gas consumption, so I really don’t recommend them. The only reason I can see these days to install a fossil gas fireplace is if you are switching from a furnace to an air-source heat pump, and you want to use the gas fireplace for supplementary heat on the coldest days. It’s better to use a heat pump 90% of the time, and supplement with a gas fireplace when it’s really cold or when you want to heat just the living room, but it’s generally accepted in the climate research community that we need to stop using all fossil fuels right now to avoid the catastrophic impacts of climate change, so we shouldn’t be adding anything new to our colletion of fossil fuel consuming devices in the home.

If you already have an old low-efficiency furnace or boiler (below 80%), or a mid-efficiency furnace or boiler (80-89%), I would recommend replacing that with a high efficiency heat pump, rather than buying a natural gas fireplace to supplement your existing fossil fuel based heating – because the overall energy savings will be greater and you’ll be doing the planet a favor.

Meanwhile, an open fireplace fed by fossil gas, such as the ones in some homes built in the 60’s and 70’s, is not efficient at all, and instead serves to draw heat up the chimney and pull cold outside air in through cracks and gaps in the walls. Such fireplaces are pretty to look at when the fire is burning, but the best way to save energy here is to leave them off as much as possible, and ideally remove them.

Electric fireplaces

An electric fireplace can be a nice addition to a room where there isn’t a built-in fireplace. Since electric fireplaces heat with electricity, they are by definition 100% energy efficient – at converting electricity to heat. That doesn’t make them ideal – a heat pump can be 4-5 times more efficient than that at converting electricity to heat – but there are several benefits to electric fireplaces over any combustion fireplace:

• No risk of carbon monoxide poisining
• No need to feed the fireplace any fuel such as pellets or firewood
• No CO2 emissions
• No need for any venting of intake air or exhaust air
• Very easy to install

We installed an electric fireplace in our bedroom several years ago and it’s an attractive sight to read by at bedtime, as well as a good source of heat for those extra cold nights, or for nights when we’re going to bed after the setback thermostat for the house has already lowered the temperature. While it’s easy to sleep in cooler temperatures, it can be hard to get to sleep while you’re trying to get warm.

Stay comfortable and save energy

One of the best things about an energy efficient fireplace is that you can stay cosy and warm in the area of your house where the fireplace is located, while allowing rooms that are less frequently used to stay a little cooler. Selective heating of only the rooms you actively occupy is a great way to save energy. Remember that the heat in your house is continually escaping through walls, windows, attic ceilings, and air gaps throughout the house; the fewer rooms you keep heated to your comfort temperature, the less heat there is to escape. And if you have a very well-insulated modern home, it’s even possible to heat the entire home with nothing more than an energy efficient fireplace. Particularly if you have access to a cheap or cash-free source of renewable fuel, these fireplaces can provide comfort and a pleasing aesthetic with very little expense.