When it comes to energy-efficiency, you may find a wide range depending on size and model. Gas fireplaces use between 40,000 and 85,000 BTUs, are 90% efficient at converting energy to heat, and cost around $10 a month to run.
Electric fireplaces have an output that is based on the electric current. The average 120v outlet will produce just over 5000 BTUs, which comes to around $25 a year to run.
*With that being said, an electric heater will not warm the room as well as a gas fireplace. With a gas fireplace, you can actually heat the room without an additional heater. With an electric fireplace, you will likely have another heat source running, which will add to the cost saved.
Electric fireplaces are easier to install than a gas-burning fireplace. A gas fireplace requires that a plumber runs a gas line to the fireplace, and a small vent is needed for most models. Non-venting units are available if you are unable to run a vent. The unit is then set in place and hooked up. Keep in mind that if you do not have a gas line, or are in an area where gas does not run, you will need to use propane.
Electric fireplaces simply plug into where they will be used. If you do not have an outlet there, it is a simple process to have one installed, and then the unit can be placed. Electric fireplaces can be portable, meaning you can move them around with you as you need them, or they can be wall mounted, for a better appearance. Wall mounted units are usually designed to recess into the wall, so you may need a carpenter or a handyman to help move some studs in the wall to accommodate the box. Installing the box once the wall is ready is usually a fast process and takes just a few minutes.
Either should be installed by a trained professional if an outlet or gas line needs to be installed first. Otherwise, most homeowners can set up an electric unit by themselves, while a gas fireplace will need professional assistance every time.
Gas fireplaces are considered low maintenance when compared to wood-burning fireplaces, but they do require some yearly maintenance. The vent must be inspected annually and cleaned as needed. Valves should also be checked for leaks and to make sure they are operating properly.
The biggest problem we found with electric fireplaces is that due to complicated nature of the electronics inside, paired with heat, they tend to break down much quicker than gas fireplaces. when something inevitably goes wrong, it is very difficult to diagnose, and even more difficult to get the parts. If we were able to figure out what part needed replaced, we would have to order it from China so fixing anything was a massive ordeal.
Gas fireplaces become hot very quickly. While they are generally considered safe, the glass doors that house the unit can become hot enough to burn if they are touched. Like any gas appliance, a gas leak may occur if the unit is not maintained properly, which can cause significant health problems and a fire hazard if not detected and dealt with quickly. Most units have a gas shut off valve in this event.
Electric units have fewer safety concerns, but like any space heater, they may cause electrical fires if they become damaged. Most new units have automatic shut-off features that kick in if the unit becomes overheated, helping to prevent fires.
Gas fireplaces are considered efficient because they convert up to 90% of their energy into heat. However, gas is a non-renewable resource, and burning it releases some particles into the atmosphere. Gas is considered clean-burning and while it does not produce harmful levels of carbon dioxide within the home, it does produce some CO2, which is released into the atmosphere.
Electric fireplaces use less energy and do not directly release particles into the air, but the process of producing electricity to power the unit may produce CO2 gas as well. This depends on the energy mix and how it is produced. Electricity may be a non-renewable resource depending on where you are located and your power utility.