The Residential Energy Consumption Survey reveals that almost 50% of American homes have a gas furnace, and that number is even higher if you limit that survey to just states and regions with cold climates. Electric furnaces and heat pumps, on the other hand, are present in about 30% of homes, which is a number that has trended up over the past two decades. One reason for that trend is that electric furnaces are often touted as the most energy-efficient option. But is it really that simple?
The question, “Are electric furnaces efficient?” is common in the HVAC world. There is a degree of confusion among many consumers, and one reason is that the term energy efficiency is often ambiguous. In a scientific sense, energy efficiency is the ratio between energy input and useful output. In this sense, electric furnaces are very efficient. But when a consumer asks about energy efficiency, they are often really asking about cost-effectiveness, and that question requires a much more complex answer.
Annual Fuel Utilization Efficiency
Annual fuel utilization efficiency — often abbreviated AFUE — is a metric that measures the thermal efficiency of furnaces and other heating equipment. Standard natural gas furnaces have an AFUE between 78% and 84%. If a gas-burning furnace has an 81% AFUE, it means that 19% of the gas burned is lost and thus not converted into heat.
All electric furnaces have a 100% AFUE. That means that 100% of the electricity used is transferred into heat. But to compare the AFUE of an electric furnace to the AFUE of a gas furnace is like comparing apples to oranges. This is where the confusion comes in and why the answer is much bigger than just comparing efficiency metrics.
Electric vs. Gas Furnaces
Both gas and electric furnaces are types of forced-air heating. Both receive a signal from a thermostat and when to start and stop producing heat.
When a gas unit receives that signal, it will ignite its main burner via a pilot light, which is a small flame that burns all the time. The furnace then uses its heat exchanger to transfer heat from the burner to the air that will be distributed throughout the home. An electric furnace does not have a pilot light or a burner. Instead, it has an electric heat exchanger.
While an electric furnace is technically more thermally efficient than a gas furnace, it is not more heat efficient due to the nature of its design. Gas furnaces are often described as providing a more forceful or powerful heat, and many people notice that gas heat feels warmer than electric heat. The reason for this is that gas furnaces heat the air to between 120 and 140 degrees Fahrenheit.
An electric furnace, however, only heats the air to about 95 degrees — below body temperature. That is enough to warm your home, but it means that a gas furnace will heat a home faster, will not need to run for as long or as often, and is less prone to energy losses as the heated air is circulated through the ducts.
Upfront and Operational Costs
Electric furnaces are generally less expensive than gas furnaces. This varies from region to region, but the total cost of a gas furnace — equipment plus installation and assuming that no conversion is required — will be 1.5 to 2.5 times greater than an electric furnace.
The cost of operating a gas furnace is much less, however, and that is because natural gas is cheaper than electricity. Your heating bill can be as much as 30% higher with an electric furnace, which more than offsets the higher upfront cost.
This aspect of the comparison gets even more interesting when you consider lifespan. Electric furnaces are expected to last 10 years and can last up to 20 years with regular maintenance. Gas furnaces are expected to last 20 years and can last up to 30 with cleaning and tune-ups.
So, while electric furnaces cost less initially, they actually have a much higher total cost of ownership. Due to that longer lifespan, gas furnaces generally have longer and more robust warranties as well.
Indoor Air Quality
One of the attractive aspects of an electric furnace is that it is safer and cleaner. Burning natural gas is messy. Gas-heated air has a smell to it whereas electric-heated air does not. Carbon monoxide is a by-product of burning natural gas.
You should schedule seasonal maintenance for both electric and gas furnaces, but it is particularly important with gas furnaces due to the health risks involved. This is not to say that electric furnaces do not create pollution. They do but to a much lesser degree.
Sizing any furnace is important, but sizing an electric furnace is more difficult. Factors include not just the square footage of your home but also the layout and the climate zone you live in. It is important to involve a professional in the unit choice to ensure that you select the proper characteristics.
An improperly sized furnace will be inefficient, and it will not last as long. This is true even for a furnace that is too large for its home because this leads to short cycling and thus additional wear and tear.
High-efficiency furnaces have been around since the 1980s, and the technology has improved greatly in the 40 years since. They are becoming quite popular, and for this reason, customers often ask if there is such a thing as high-efficiency electric furnaces.
The answer to that question is no. As for the reason why not, let us refer back to the AFUE section. Electric furnaces have a 100% AFUE. Standard natural gas furnaces have an AFUE between 78% and 84%, but high-efficiency gas furnaces have an AFUE between 90% and 97%.
Are Electric Furnaces Energy Efficient? It’s Relative!
Yes, electric furnaces are energy efficient, but whether they are energy efficient for you depends on a number of factors. As a general rule, gas furnaces are more efficient in cold northern climates, and electric furnaces can be efficient over the long term in warmer southern climates where they are not used as much.
There is also the matter of the natural gas connection. If you do not have one, the conversion is an additional and not insignificant cost. However, if you plan to live in your home for the life of the furnace, the conversion will more than pay for itself.
Your Furnace Experts in Central Pennsylvania and Northern Maryland
Is it time to replace your old furnace? HB McClure would love to help! In fact, the HB Home Service Team has been installing, replacing, maintaining, and repairing furnaces since 1914. We have a location in Harrisburg, Pennsylvania, that serves Carlisle, Harrisburg, Hershey, York, and the neighboring communities and another in Randallstown, Maryland, that serves Carroll, Baltimore, Howard, and the surrounding areas.
Our team works with all types of gas and electric heating equipment. We also install, maintain, and repair cooling equipment and are available for plumbing service and repair. Call HB McClure today with any questions or to schedule an appointment!