A Heat Pump Can Be More Than 100% Efficient. Yes, Really — Here’s How

When you’re trying to lower your utility bills, you might be tempted to reach for the thermostat.

That’s a good instinct. Setting your thermostat strategically can help reduce your heating or cooling costs, but it’s not the only way to spend less on energy. One big variable is built right into your HVAC system itself: energy efficiency.

“An efficient solution allows you to achieve the same outcome with less input,” explains Cristi Pedotto, the portfolio director for Trane and American Standard residential ducted equipment.

One of the most efficient heating and cooling solutions on the market these days is a heat pump. In some conditions, these units can actually reach above 100% efficiency — usually in the range of 200% to 400% — allowing you to receive more energy than you put in to begin with.

Here’s how that 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 how much energy you put into a system and how much you get out of it.

Let’s say you pay for a certain amount of gas to power a furnace in your home. As the system converts that gas to heat for your home, by burning it and then transferring the heat through ducts or radiators, some of it is lost along the way, essentially wasted. So the more heat you get from that unit of gas without losing it, the higher your furnace’s efficiency rating.

“Simply put, the more efficient we are with the energy we consume, the less energy we need” to heat the same home, Pedotto says.

What is the typical energy efficiency of a fossil-fuel heating system?

Traditional fossil-fuel heating systems can have a range of efficiency ratings, depending on the age of the equipment and the setup of your home.

A typical gas furnace, for example, is usually between 80% and 98% efficient. Pedotto says 80% is the minimum efficiency rating now required for furnaces sold in the U.S. — a threshold that will jump to 95% in 2028.

But that rating can be pushed lower in a couple of ways.

For example, if the heat from the furnace is then pushed through air ducts, the air can lose heat as it travels to a heating vent. That’s according to Gwendolyn van der Linden, a principal algorithm engineer at San Francisco heat pump startup Quilt. And the electricity used to power fans or blowers is not included in the standard efficiency calculations for a gas furnace, Pedotto says.

What is the typical efficiency of an electric heat pump?

When we discuss efficiency for electric heat pumps, we can use the measurement known as “coefficient of performance,” or COP. This measures the amount of electricity required to operate the system compared to how much energy (heat or cooling) is delivered to your home.

Even an older heat pump might have a COP of two, meaning it moves twice as much energy into your home as the energy it takes to operate. “It’s remarkable what it can do,” Pedotto says.

But newer heat pump systems can go even higher, van der Linden says. Her company’s model averages a COP of four, essentially 400% efficiency. 

In some extreme cold temperatures, however, a heat pump’s COP can actually drop below one, meaning it is below 100% efficient and uses more energy to operate than it is ultimately transferring into your home. Newer heat pumps can maintain efficiency at lower temperatures. Quilt’s model, for example, reports a COP of two at 5 degrees Fahrenheit.

How is it even possible to go above 100% efficiency?

The answer lies in the fundamental innovation of heat pumps. They don’t generate heat like a furnace would by burning gas. Rather, heat pumps simply move heat from one place to another.

In the winter, a heat pump extracts heat from the outside air (yes, there is some heat out there even in the dead of winter) and uses refrigerant to extract that energy and blow it into your home as hot air. As Pedotto explains, “You’re not creating heat, you’re grabbing it from the outside and transferring it inside.”

This allows heat pumps to have higher efficiency ratings: It often takes less energy to move heat than it does to create heat. 

The efficiency of a heat pump, however, does range depending on the outside temperature. If there’s a large difference between the desired indoor temperature and the current outdoor temperature (on a frigid winter day, for example), the heat pump has to work harder to extract heat from the outdoor air, and its efficiency will drop to the lower end.

But the opposite is also true. If it’s a mild winter day, there’s more heat energy floating around outside, which means the heat pump won’t work as hard to extract it.

Why energy efficiency matters for you

Most consumers will care about efficiency for a simple reason: It can lower their utility bills. The more efficient your HVAC system, the less energy you will need (to pay for) to keep your home at a comfortable temperature.

However, switching from a gas-powered system to an electric heat pump system (even with its sky-high efficiency) won’t always save you money. If you live in a state where gas prices are more favorable than electricity prices, or where you have many frigid winter days, it might actually be cheaper for you to run a gas-powered furnace.

Of course, price isn’t the only reason to switch. Burning less fossil fuel is good for the environment and can help reduce greenhouse gas emissions, even if it doesn’t immediately help your wallet.