Gas Fireplace Energy Use: How Much It Really Costs to Run One
Last Updated on May 14, 2025 by Chad Peterson
Why Energy Use Matters with Gas Fireplaces
Gas fireplace energy use can add up quickly. Learn how much gas your fireplace burns, what it costs per month, and how to make it more efficient.
Many of my customers see gas fireplaces as a cozy feature, not a major energy appliance. But depending on how often you use it, a gas fireplace can have a noticeable effect on your monthly gas bill.
Gas fireplaces burn gas to create real heat, not just visual flames. That means every hour of use adds to your total energy consumption, especially in colder months.
Because fireplaces are often used without much thought to efficiency, they can become silent energy drains. It’s easy to flip a switch for ambiance and forget it’s using the same fuel as your furnace or water heater.
Understanding how much energy your fireplace uses helps you make smarter choices. Whether it’s running it less, upgrading your controls, or improving efficiency, knowing the numbers puts you in control.
Gas Fireplace Energy Use by the Numbers
Gas fireplace energy use is measured in BTUs — British Thermal Units. Most residential gas fireplaces burn between 20,000 and 40,000 BTUs per hour, depending on the model and flame setting.
To make sense of those numbers, it helps to understand how BTUs relate to your gas bill. One therm equals 100,000 BTUs, and most utility companies charge by the therm. As of now, the average cost per therm in the U.S. is around $1.50.
Here’s a quick example:
A fireplace rated at 30,000 BTUs per hour uses 0.3 therms per hour. If you run it for 2 hours per day, that’s 0.6 therms per day.
If you run that fireplace for just 2 hours a day, you’ll burn through 0.6 therms daily. Multiply that over a 30-day month and you’ve used 18 therms total.
At an average rate of $1.50 per therm, that comes out to $27 per month. This is only for the fireplace — it doesn’t include your furnace or other gas appliances.
Factors That Affect Fireplace Energy Consumption
Not all gas fireplace energy use is measured in the same way. Several factors can impact how much gas your fireplace burns and how efficiently it heats a space.
Fireplace Size and BTU Rating
The size and BTU output of your fireplace directly affect energy use. A unit rated at 40,000 BTUs will naturally use more gas per hour than one rated at 20,000 BTUs.
Larger fireplaces are designed to heat bigger spaces, but that comes with higher fuel costs. Always check your unit’s BTU label or manual for details.
Vent Type (Vented vs. Ventless)
Vented fireplaces lose more heat through the flue, which reduces efficiency. These models often need to burn more gas to achieve the same level of room warmth.
Ventless fireplaces are generally more efficient because all the heat stays inside your home. However, they can raise indoor air quality concerns and are restricted in some areas.
Ventless Pros
Ventless Cons
Thermostat Or A Remote vs. On/Off Switch
A basic wall switch gives you zero control (other than on or off) over how long the fireplace runs. It’s easy to forget it’s on, which can waste gas over time.
Upgrading to a thermostat allows your fireplace to turn off automatically when the room reaches a set temperature. This prevents overheating and unnecessary fuel use.
Climate and Insulation
Colder climates naturally lead to more frequent fireplace use. The colder it is outside, the longer your fireplace needs to run to keep your home comfortable.
Poor insulation also makes a big difference. If heat escapes quickly through windows, walls, or ceilings, your fireplace has to work harder — and use more gas — to maintain warmth.
How to Make a Gas Fireplace More Efficient
If you like the comfort of a gas fireplace but want to keep costs down, a few simple changes can make a big difference. These improvements can help you get more heat using less gas.
Use a Thermostat Instead of a Wall Switch
A wall switch runs the fireplace at full blast until you manually turn it off. That often leads to overheating and wasted fuel.
Add a Blower or Circulation Fan
A blower helps distribute heat more evenly around the room. Without one, heat tends to collect near the fireplace and stay there.
Moving warm air out into the room means the fireplace doesn’t have to run as long. That reduces both runtime and energy use.
Make Sure the Fireplace Is Properly Sealed
Gas fireplaces should be sealed and vented according to the manufacturer’s specs. If there are air leaks in the vent connections or around the fireplace framing, heat can escape before it reaches the room.
Check that the glass panel is seated correctly and the vent pipe is sealed. Any leaks reduce efficiency and could affect safety.
Reduce Furnace Use When the Fireplace Is On
Since most fireplaces are in the main living area, let them do the heavy lifting. If you’re enjoying heat from the fireplace, reduce or shut off central heat in that zone using dampers, vents, or thermostat controls.
This doesn’t make the fireplace a true zone heater, but it keeps the furnace from working harder than necessary. That’s an easy way to lower total gas usage.
What to Compare It To (Electric Heaters, Furnaces, etc.)
To understand how gas fireplace energy use really affects efficiency, it helps to compare it to other common heating methods. That includes electric space heaters, gas furnaces, and even heat pumps.
Gas fireplaces cost around $0.30 to $0.50 per hour to operate, depending on BTU output and local gas rates. That adds up to about $15 to $50 per month with moderate use.
Electric space heaters generally cost more to run — often $0.50 to $0.75 per hour. Electricity is more expensive per BTU than natural gas in most areas.
A high-efficiency gas furnace usually costs less per BTU than a fireplace. Furnaces are designed to heat the whole home and operate with thermostats, zoning, and insulation in mind.
Heat pumps are among the most efficient, especially in milder climates. But their effectiveness drops in freezing weather, where gas heating still plays a valuable role.
The takeaway? Gas fireplaces are best used for comfort and supplemental heat, not as your primary heat source. They’re more efficient than electric heaters in many cases, but less so than a well-tuned furnace or heat pump.
Frequently Asked Questions
How much gas does a fireplace use per hour?
Most gas fireplaces use between 20,000 and 40,000 BTUs per hour. That’s about 0.2 to 0.4 therms per hour, depending on the size and flame setting.
Is it expensive to run a gas fireplace every day?
It depends on your gas rates and how long it runs. For 2 hours a day, a 30,000 BTU fireplace could cost about $25 to $30 per month.
Are ventless gas fireplaces safe to use?
Yes, if installed and used properly — but they must meet safety standards and may be restricted in some areas due to indoor air quality concerns.
How can I tell if my gas fireplace is energy efficient?
Check the BTU rating and if it has a blower or thermostat. Vented models lose more heat, while ventless ones retain nearly all the heat inside.
Does a gas fireplace use more gas than a furnace?
It depends on how long each system runs and their efficiency ratings. A furnace is designed to heat the entire home, while a fireplace heats just one room.
What’s the difference between a pilot light and electronic ignition?
A pilot light stays on continuously and uses a small amount of gas. Electronic ignition only fires when needed, which can reduce gas use.
Final Thoughts On A Gas Fireplace Energy Use
Gas fireplaces offer comfort, ambiance, and a quick way to warm up a living space. But they’re not without cost, especially if used regularly during colder months.
You can compare my data based on energy efficiency data from regional utility programs like Energy Trust of Oregon.
Understanding everything you can know about how much energy they use can help you avoid surprise increases on your gas bill. A typical unit can add $15 to $50 per month depending on usage and efficiency.
If you enjoy your fireplace often, small upgrades like a thermostat or blower can help reduce wasted fuel. It’s also smart to compare its cost to your furnace or other heat sources.
Used wisely, a gas fireplace can be a cozy and practical part of your home heating plan. The key is knowing what it really costs to run — and using that heat where it matters most.
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