If you're trying to reduce your utility bills, you might be tempted to reach for the thermostat.
That's a good instinct. Set your thermostat strategically can help reduce your heating or cooling costs, but it's not the only way to spend less energy. One big variable is built right into your HVAC system itself: energy efficiency.
“An efficient solution allows you to achieve the same result with less effort,” explains Cristi Pedotto, portfolio director for residential duct equipment for Trane and American Standard.
One of the most efficient heating and cooling solutions on the market today is a heat pump. Under certain conditions, these devices can actually achieve over 100% efficiency – usually in the range of 200% to 400% – giving you more energy than you originally put in.
Here's how it works and why heat pumps are such an efficient way to heat and cool your home.
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What is energy efficiency?
Energy efficiency is a way of measuring the relationship between the amount of energy you put into a system and the amount you get out of it.
Let's say you pay a certain amount of gas to run a furnace in your home. Because the system converts this gas into heat for your home by burning it and then transferring the heat via ducts or radiators, some of it is lost along the way, essentially wasted. So the more heat you get from this gas unit without losing it, the higher the efficiency of your oven.
“Simply put, the more efficient we are with the energy we use, the less energy we need” to heat the same house, Pedotto says.
What is the typical energy efficiency of a fossil fuel heating system?
Traditional fossil fuel heating systems can have varying levels of efficiency depending on the age of the equipment and your home's setup.
When deciding between a heat pump and fossil fuel generators like a furnace, there are several things to consider.
For example, a typical gas furnace typically has an efficiency between 80% and 98%. Pedotto says 80% is the minimum efficiency now required for furnaces sold in the U.S. — a threshold that will rise to 95% in 2028.
However, this rating can be lowered in various ways.
For example, if heat from the furnace is then passed through air ducts, the air can lose heat on its way to a heating vent. That's according to Gwendolyn van der Linden, a senior algorithm engineer at a heat pump startup in San Francisco Ceiling. And the electricity used to power fans or blowers is not included in standard efficiency calculations for a gas furnace, says Pedotto.
|
Special feature |
Fossil fuel heating system (gas furnace) |
Electric heat pump |
|
Efficiency measurement |
Annual Fuel Utilization Efficiency (AFUE) |
Coefficient of performance (COP) |
|
Typical efficiency range |
80% to 98% (AFUE) |
100% to 400% (COP from 2 to 4) |
|
mechanism |
Generates heat by burning gas |
Moves heat from one place to another (removes heat from outside air). |
|
Why it can exceed 100% |
The efficiency cannot exceed 100% because heat is generated |
Moves energy rather than creating it, requiring less electrical energy to be supplied than the thermal energy delivered. |
|
Minimum Efficiency (USA) |
80% (required minimum for new ovens, expected to rise to 95% by 2028) |
Older models can deliver a COP of 2 (200% efficiency). The Department of Energy states that the minimum value for newer models is 3.1 COP |
|
Efficiency caveats |
Efficiency may be lower due to heat loss in the air ducts or power consumption for fans/blowers |
In extremely cold temperatures, efficiency may decrease (COP may fall below one/100% efficiency). Newer models are better at maintaining efficiency |
What is the typical efficiency of an electric heat pump?
When we talk about the efficiency of electric heat pumps, we can use the measurement known as “Coefficient of Performance” or COP. This measures the amount of electricity required to run the system compared to how much energy (heating or cooling) is delivered to your home.
Even an older heat pump can have a COP of two, meaning it is moving twice as much energy into your home as it needs to run. “It’s remarkable what it can do,” says Pedotto.
But newer heat pump systems can go even further, says van der Linden. Their company's model has an average COP of four, which is essentially 400% efficient.
However, in some extremely cold temperatures, a heat pump's COP can actually drop below one, meaning it is less than 100% efficient and uses more energy to operate than it ultimately transfers to your home. Newer heat pumps can maintain their efficiency even at lower temperatures. For example, Quilt's model reports a COP of two at 5 degrees Fahrenheit.
How is it even possible to achieve an efficiency of over 100%?
Getting a heat pump can help you with your electric bill, but you could also end up with a hefty bill from an electrician if you need a new panel or better electric service.
The answer lies in the fundamental innovation of heat pumps. They do not produce heat like a stove that burns gas. Rather simply heat pumps move Heat from one place to another.
In the winter, a heat pump extracts heat from the outside air (yes, that exists). some (They heat you up even in the dead of winter out there) and use refrigerants to extract that energy and blow it into your home as hot air. As Pedotto explains, “You don’t generate heat, you absorb it from the outside and transfer it inside.”
This enables heat pumps to be more efficient: heat transfer often requires less energy than heat generation.
However, the efficiency of a heat pump varies depending on the outside temperature. When there is a large difference between the desired indoor temperature and the current outdoor temperature (e.g. on a cold winter day), the heat pump has to work harder to extract heat from the outside air and its efficiency drops to a lower level.
But the opposite is also the case. If it's a mild winter day, there's more heat energy floating around outside, meaning the heat pump doesn't have to work as hard to extract it.
Why energy efficiency is important to you
Most consumers value efficiency for one simple reason: it can reduce their electricity bills. The more efficient your HVAC system is, the less energy you have to pay to keep your home at a comfortable temperature.
However, switching from a gas-powered system to an electric heat pump system (even with its extremely high efficiency) is not possible always Save money. If you live in a state where gas prices are cheaper than electricity prices or where there are a lot of cold winter days, it may actually be cheaper for you to run a gas-powered furnace.
Of course, price isn't the only reason to switch. Burning less fossil fuels is good for the environment and can help reduce greenhouse gas emissions, even if it doesn't immediately help your wallet.