As the chill of autumn nips the air, your thoughts are probably wandering to your basement. Will your furnace or boiler hold up this year? Will it keep your family warm? And how much will it cost you? While natural gas furnaces are the most-used heating method for homes in this country, they’re not the only option. And as more homeowners become conscious of the cost of heating their homes — to themselves and to the planet — a high-efficiency alternative is creeping up from behind.
The heat pump grows more popular every year, but from an energy- and cost-savings perspective, how do the two stack up to each other? Will you really save more with a heat pump? Are there trade-offs in performance and comfort? That’s what we’re here to find out.
To do so, we consulted Pearl Certification’s senior sustainability analyst, Kerry Harp, who gave us the rundown on the pros and cons of sticking with your furnace or boiler or switching to a heat pump. Yes, there is a clear winner; if you can’t take the suspense, feel free to skip to the end.
We’re starting off with a complex match-up. When it comes to the energy efficiency of your heating system, you need to compare input to output. In other words, for every British thermal unit (BTU) you put into your heating system, how many BTUs do you get out?
For furnaces or boilers that use natural gas, propane, or oil, this is measured in annual fuel utilization efficiency (AFUE) — the percentage of fuel put into your heating system that is turned into heat for your home. The higher the AFUE, the more efficient the system. Generally speaking, newer combustion furnaces and boilers have higher AFUE ratings than older ones. And electric furnaces, which produce heat via electrical resistance, are considered to be the least efficient heating systems.
“High-efficiency gas furnaces burn fuel to generate heat and provide an annual fuel utilization efficiency (AFUE) of around 90% to 98.5%,” says Harp. “They lose up to 10% of the heat energy through gas released up the flue.” In other words, for every BTU of fuel you put into a high-efficiency gas furnace, you get .9 to .985 BTUs in home heating energy.
Unlike combustion units, heat pumps use compression to create heat or to cool a space — the same principle used in refrigerators.
“Heat pump systems are more efficient because they do not actually generate heat; they just transfer it — needing less energy to operate,” says Harp.
There are two basic types of heat pumps — the air source is the most common. An air-source heat pump extracts and dissipates heat captured from the surrounding air. Ground-source heat pumps, also called geothermal heat pumps, tap the temperature difference between your home and the earth under it to provide a heat source. For every BTU of electricity your heat pump consumes, it produces two to three BTUs of heat energy. Which makes it, at a unit level, much more energy efficient than even a high-efficiency natural gas furnace.
When compared against the least efficient type of heating system, the difference is striking. “Air-source heat pumps can be up to 50% more efficient than an electric-resistant furnace,” says Harp.
What if you live in a region where temperatures dip below freezing in winter? Aren’t heat pumps not designed for cold climates? Not anymore! While heat pumps were originally designed to function best in milder climates, the U.S. Department of Energy (DOE) has been driving the development of heat pumps specifically designed for more extreme temperatures.
“The DOE sponsored the Residential Cold Climate Heat Pump Technology Challenge to accelerate the design and deployment of cold climate heat pump technologies,” says Harp. “The deployment phase of this program is targeted for 2024, but there are certain manufacturers that have already brought this technology to market.” (For more information on cold-climate heat pumps, check out our heat pump deep dive.)
Enough said, right? Heat pumps for the win! Well, for those homeowners who are interested not only in the nitty gritty of efficiency, it’s helpful to look at how electricity is generated for your homes. If you’re using clean energy sources like solar, hydroelectric, or wind, congratulations, your efficiency is top-of-the-line at the micro and macro level. Electricity generated from fossil fuels and transported to your home is much less efficient depending on the fuel source — there’s loss of energy during the process of creating electricity and loss of electricity on the way to your home. All the more reason to switch to clean energy from start to finish, particularly if you’re interested in fully electrifying your home.
That said, Harp and Pearl Certification continue to recommend switching to a heat pump system for both energy efficiency and some reasons we’ll get into below.
Comparing acquisition costs on heat pumps versus traditional finance systems reveals a trend in all things heating, ventilation, and air conditioning (HVAC): The more efficient systems tend to cost more up-front.
“Installation costs for an air-source heat pump are slightly more than a traditional furnace,” says Harp. “These costs depend on the size of the home, complexity of the system, and ductwork needed.”
Remember that heat pumps are a heating and cooling system in one, whereas with a furnace and air-conditioning system, you’re looking at two sets of operating costs. “Since a heat pump system is used for both heating and cooling,” says Harp, “there may be a reduction in overall HVAC costs for not having to install a central air-conditioning unit.”
With the range of heat pump systems comes a range of pricing as well. According to the DOE, “Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs may be returned in energy savings in 5 to 10 years, depending on the cost of energy and available incentives.” Incentives can look like federal and state energy efficiency tax credits and rebates from utility companies or manufacturers. With the passage of the Inflation Reduction Act, a further $9 billion will be available to homeowners for energy-efficient upgrades like heat pumps over the next eight to ten years. (We’ll be covering the specifics of those programs here, and in our newsletter and @greendoorapp on Facebook, Instagram, and Twitter in the coming months).
Another factor to consider is resale value. A study from Nature Energy indicates that homes equipped with heat pumps showed an increase in value of 4.1% to 7.3%. Between energy cost savings over time and an increase in value of the home, heat pumps tend to win the overall battle of the bill.
Since furnaces and boilers are only used during the cold months, they typically have a longer lifespan than heat pumps, depending on the models involved. Keep in mind that if you need cooling in addition to a furnace or boiler, you may need to replace your separate air-conditioning system more frequently. According to the National Association of Certified Home Inspectors (NACHI), the typical lifespan for these HVAC systems is as follows:
| Equipment | Lifespan |
|---|---|
| Furnace | 15-25 years |
| Boiler | 40 years |
| Air-source heat pump | 10-15 years |
| Geothermal heat pump | 20 years for the heat pump, 25-50 years for the ground loops |
| Central air-conditioning system | 7-15 years |
Whatever system gets the nod, keep in mind that annual maintenance is required for all types of HVAC systems and is critical to reaching or exceeding average life expectancy.
Furnaces, air conditioners, and heat pumps all rely on forced air to spread the warm or cool air through the house. Boilers pump warmed water into radiators or floor panels to provide radiant heat. Any time you burn fossil fuels, you produce carbon monoxide (CO), a dangerous gas, and a malfunctioning combustion heater can off-gas into your home. In the case of forced-air systems like furnaces, the gas may be sent through the duct work and into your rooms.
When it comes to indoor air quality, the heat pump is a safer choice, says Harp. “Good indoor air quality increases and the risk of CO leakage is eliminated when using heat pump technology due to the lack of burning fossil fuels,” says Harp. “Heat pumps run on electricity and do not produce CO, so there is no concern about dirty air from combustion or CO leakage.
“Unlike a furnace that periodically distributes warm air through a duct system via a blower fan, a heat pump is constantly moving air,” says Harp.
From a comfort perspective, many homeowners find the always-on flow of heat pumps to be more comfortable than the on-and-off blast of combustion systems. Additionally, the hot air of a combustion furnace can be very dry, while heat pumps, which move air rather than produce it, maintain a natural, more comfortable humidity level.
If you’ve paid any attention to what the U.S. Environmental Protection Agency (EPA) or Department of Energy (DOE) has had to say over the last several years, you’ll have heard about the benefits of switching from a furnace or boiler to a heat pump if you want to lower your carbon footprint.
Studies have shown that using heat pump technology has emission reductions of up to 53% for carbon dioxide and up to 67% for 20-year global warming potential compared to fossil fuel furnace systems.
“Fossil fuels used in heating are a large contributor to greenhouse gas (GHG) emissions,” says Harp. “As the electric grid continues to move toward decarbonization, transitioning to heat pump technology will help to reduce overall GHG emissions.”
As we mentioned earlier, paying attention to your energy consumption from its point of origin to your home can help illustrate your home’s true energy efficiency. Moving to clean energy sources can help bring down both your energy bills and your home’s emissions.
While the heat pump hits more of the high notes in the areas we discussed, ultimately, every home and its location are unique, and choosing between a heat pump or furnace means taking a hard look at a number of factors. When making a decision, be sure to ask yourself and your contractor:
What is my priority: energy efficiency, cost savings, emissions reduction, system life expectancy, indoor air quality and comfort, or resale value?
What is my budget for installation costs, including rebates and tax credits?
How quickly do I need to recoup my cost?
What fuels are locally available?
What’s the cost of electricity?
What fuels are used to generate electricity for my grid?
What are the highest and lowest temperatures for this climate?
Will the surrounding terrain affect installation?
At what temperature do I want to set my thermostat seasonally?
Is there an existing duct system?
Is there room for outdoor units?
Is there a conditioned space for a furnace and a flue?
Finding a qualified HVAC contractor with experience in energy efficiency can be a challenge. That’s why Pearl Certification created the free Green Door app, which enables you to bypass the search party and connect with a vetted Pearl Network contractor. Only contractors who meet the most stringent requirements in customer service, certification and licenses, and business best practices earn admittance. Sign up or login today to begin your journey to a more efficient, more comfortable, and healthier home.
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