Is Your Fireplace Burning Through your Energy Bill?

Geoff Godwin
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leaking ductwork

Fireplace Efficiency Tips and Tricks for your Home

Few things are as enjoyable on a cold winter night as sitting next to a warm fire. But the reality is that you might be sending your energy bill up in smoke.  More than 100 million homes in North America are built with wood or gas burning fireplaces and nearly all of them can contribute to energy loss.

Putting a Damper on Your Energy Bills

The primary culprit in energy loss is the fireplace’s damper.  An open or unsealed damper in a well-insulated house can raise overall energy consumption by up to 30 percent, or nearly $200 per year. According to the Department of Energy, an average home spends approximately $600 per year for heating.

What’s more, between 80 and 90 percent of the heat produced by wood burned in an open fireplace is lost up the chimney. This means that for every $100 you spend on firewood, you get only $10 to $20 worth of heat. The rest goes up the chimney.

According to the U.S. Department of Energy, conventional fireplaces (wood or gas) are one of the most inefficient heat sources. All that warm air lost up the chimney must be replaced by cold air brought from outside and then reheated by the furnace.

Looking at the Big Picture

To put in perspective how much heat is lost, think about a basketball, which is approximately the size of one cubic foot of air.  A conventional fireplace exhausts as much as 24,000 cubic feet of air per hour.  So, it’s essentially like shooting 400 basketballs out your chimney every minute.  Basketballs aren’t cheap, and neither is wasted heat energy.

Take it From Us

Certainly fireplaces are a mainstay in many homes in the U.S. and while we don’t suggest deconstructing them, we do not recommend they be used as a primary heat source. The dampers should always be closed tightly when not in use, and it’s worth examining the damper seal annually to make sure it hasn’t worn down or bent, which could cause a leak. It’s also worth examining the seals around your doors and windows, which if not properly sealed, can be another site for heat to escape your home.

Is this going to make you more or less likely to have a fire this winter?

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13 thoughts on “Is Your Fireplace Burning Through your Energy Bill?”

  1. Hi I want to ask what happens when I modern wood stove is not in use.Does the house losing energy through the flue ?

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  3. Hello
    I just made a new classic white marble chimney. But the man who constructed it didn’t put a damper inside it. He said the damper is not important, it will break the marble of the chimney when the wood is burning.
    I want your clarification please because I really don’t know what to do!

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    • If the fireplace and central system are properly vented you can run both at the same time. Just be cognizant that as the fireplace vents through the chimney it will pull some of the heat generated by the furnace up the chimney.

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  7. These guys are a bunch of liars! In the winter where I live in the us it will get down to 20 and even 10 degrees and on extreme 0 degrees, we have 4 bedrooms in our house and it’s a two story, I’ll start burning wood around 3-4pm to make sure the fireplace is really hot by 7 or 8pm and our fireplace keeps the house in the high 60s low 70s throughout the night! These guys are feeding everyone a bunch of bull cause the heating companies want money, overall make a fire 3-4 hours before real cool or night so your fireplace gets really nice and warm and then enjoy! Don’t listen to these bafoons, I fact the guy writing this article is probably hanging out in his nice downtown apartment by his electric fireplace!

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  8. So what we’re saying here is that a fireplace should also have an air intake coming from the outside, directly into the fire pit to reduce air coming from outside into the home. And even better would be a wood stove since a lot more heat can get into the home that way.

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    • In Finland we’ve been doing them this way for a while in new builds, a supply air pipe is fitted from below the fireplace to the outside. There are dampers on the supply and exhaust side to reduce airflow when not in use. To retrofit this solution, modern chimneys can allow for supply air to be brought in via a separate channel in the chimney. Starting the fire with the retrofit chimney requires air from inside, but once the fire is burning hot you can switch to outside air and it burns nicely.

      A lot of people use fireplaces for around 80 percent of their heating needs. This requires a large fireplace that can reserve the heat into it and release it slowly into the air. The combustion gasses go through complex channels in the fireplace to get as much heat into the fireplace as possible.

      Another option for retrofitting that is becoming increasingly popular is to integrate it into your central heating by installing a large insulated water tank and a water-fireplace which directs the combustion gasses through a heat exchanger that heats the water. The heated water is the shunted into the central heating system via automation. The automation can handle the whole process. There are sensors in the chimney that start water pumps as soon as a fire is detected. There is also a fail safe that runs cold mains water through the heat exchanger if the water pump fails or there is an unexpected temperature rise.

      Most people burn two loads of wood, close the dampers and the fireplace should warm most of the home for the rest of the day by slowly radiating heat. Radiators are a just incase or for extremely cold spells. We do also have insane insulation requirements written into our codes, modern houses require 24″ of insulation in the roof, 10” in external walls and 8” under the slab. HVAC systems with heat exchangers that use the exhaust air to heat the supply air are also required for new builds. Most new builds are heated using geothermal heatpumps, or other kinds of heatpumps.

      It’s a hefty upfront investments but using 6kW of bought energy annually does make it worth while.

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  9. How about wood burning/potbelly stoves? I imagine those would give off more heat since the heat can escape from all around the stove.

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    • We recommend having a manual J calculation done to determine what your heat load requirement is. With that information you can then determine what size unit to purchase based on its heat output capacity in BTU’s. Most equipment takes into consideration all formed of energy transfer (radiant, conduction, and convection).

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