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What is HSPF?

HSPF, or Heating Seasonal Performance Factor, is the measure of a heat pump’s overall energy efficiency during the heating season (fall and winter). Higher HSPF rated heat pumps are more energy efficient, which is a good thing for both the environment and your wallet!

Heat pumps with higher HSPF ratings can run more efficiently while using less energy, so they may cost you less each month in utility bills. Although the initial investment into a high HSPF-rated heat pump can seem a bit pricey, using a high-caliber heat pump that comes with many benefits should be a top priority for all homeowners.

So, what exactly is a high HSPF rating?

A high HSPF rating is anywhere between 9 HSPF and 10 HSPF. In 2015, the Department of Energy set a minimum HSPF standard of 8.2, but this number is expected to increase to a mandatory minimum of 8.8 HSPF for all heat pumps by 2023. These standards set by the DOE can help Americans save energy at home and on their utility bills.

How are HSPF ratings calculated?

HSPF ratings are calculated by dividing the total heating output during the fall and winter months (measured in BTUs or British Thermal Units) by the total watt-hours of energy consumed during these months (measured in kWh or kilowatt-hours). To convert kilowatt-hours to watt-hours, divide the kilowatt-hour figure by 1,000 because 1 kWh = 1,000 Wh (watt-hours).

That makes the equation to calculate HSPF: BTUs / (kWhs x 1,000) = HSPF

For example, if a heat pump uses 180,000,000 BTUs (an average amount for a colder winter climate) during a total of 20,000 kWhs in a heating season, HSPF would be calculated by:

HSPF = 180,000,000 BTUs/(20,000 kWh x 1,000)
HSPF = 180,000,000 BTUs/20,000,000
WhHSPF = 9 (an efficient heat pump)

HSPF vs. SEER rating

Heat pumps are more energy efficient than other heating devices like furnaces. Under ideal conditions, a heat pump can transfer 300% more energy than it consumes, while a high-efficiency gas furnace is about 95% efficient. Plus, since heat pumps perform both heating and cooling functions, they can be a great investment for homeowners. Because they can both heat and cool spaces, heat pumps boast both an HSPF and a SEER, or a Seasonal Energy Efficiency Rating. Minimum heat pump SEER ratings are 14 in the U.S. according to Appliance Standards.

When a heat pump is set to “heat,” it transfers heat into your home to warm it. HSPF measures the efficiency of this process. When a heat pump is set to “cool,” it extracts heat out of your home to cool it down. SEER measures the efficiency of this process.

You can find both the heat pump HSPF rating and the heat pump SEER rating on the Energy Guide sticker on your unit.

What’s the difference between these two?

While both HSPF and SEER are indicators of overall heat pump efficiency, they measure opposite things. The HSPF rating measures energy efficiency during heating months in the fall and winter, and SEER measures energy efficiency during cooling months in the spring and summer. Because a heat pump can perform two different functions, it needs two separate ratings to determine the efficiency of each function.

Which rating is more important?

The more important rating varies depending on the season. The HSPF rating measures energy efficiency during a heating season, so that will be more important during your colder, winter months. The SEER rating measures energy efficiency during a cooling season, so that number will be more beneficial during warmer, summer months.

HSPF rating is likely more important to you if you live in a region where wintry, cold weather lasts significantly longer than warm or humid temperatures. The opposite is true if you live in a part of the country where it’s hot and balmy much more than it’s cool or frigid.

How much can a higher HSPF save you?

A higher HSPF typically goes along with having a higher SEER and an overall more effective system. A smoothly working system can save you time and the stress of dealing with a malfunctioning heat pump, but it can also save you money.

When your heat pump meets the minimum requirements of a HSPF of 9.2 and a SEER of 16, it qualifies for an ENERGY STAR® certification. Homes that use a heat pump with an ENERGY STAR certification may be eligible for a government tax credit up to $300. If you want to apply to earn this credit, your heat pump must be in your existing home, which you must also use as your primary residence.

Buying a higher-rated heat pump may cost you more initially than a lower-rated alternative. Depending on its rating and what part of the country you live in, a high-rated HSPF heat pump (9+ HSPF) can cost anywhere from $1,000 to $2,000 more than a minimum standard-rated HSPF heat pump (8.2 HSPF). But, you could justify spending more with the potential money you save on energy bills.

How to calculate your savings

For example, let’s look at the difference between an 8.2 HSPF and a 9.2 HSPF-rated heat pump. First, let’s determine the difference in energy efficiency between these two heat pumps as a percentage. To do this, we can simply divide the higher HSPF-rated heat pump by the lower rated heat pump, then subtract one to get this number as a percentage.

In this case:

9.2 HSPF / 8.2 HSPF = 1.12
1.12 – 1 = 12%

This means, a 9.2 HSPF unit is going to use 12% less energy than an 8.2 HSPF unit.

Now, let’s think about your yearly heating bill. The amount you spend on heating per year varies based on the climate where you live. But let’s say that in your region it costs $2,600 to heat your home annually with an 8.2 HSPF-rated heat pump.

By upgrading to a 9.2 HSPF-rated heat pump, you’re getting a heat pump that is 12% more efficient and using 12% less energy.

12% of $2,600 = $312

Here, the higher-rated HSPF heat pump can save you $312 yearly on your heating energy bill. This, combined with the possibility of a $300 government tax credit, would make the initial cost of the higher-rated heat pump pay for itself in just over 2 years, while also helping the environment in the process.

Additional factors that can influence HSPF rating and heat pump efficiency


Heat pumps are “fit” to your home. During installation, an HVAC professional will determine the size of heat pump your home needs so that it can heat and cool efficiently based on square footage, number of rooms, and floors in the home.

If your heat pump is too small for the size of your home, it could be using more energy trying to heat or cool your home, but ultimately exert so much energy that it’s unable to complete the job. If your heat pump is too big for your home, it’s likely heating or cooling your home too fast, then rapidly turning on and off to repeat the process and keep your home at your desired temperature. The constant on-and-off cycle of the heat pump can use more energy than necessary, making the overall system less efficient.

To avoid installing the wrong size heat pump in your home, always leave sizing to an HVAC professional.


Your heat pump can provide heat to your home in all kinds of outdoor climates, but when the temperature outside drops below 25°F, it requires more energy to provide sufficient heat. A properly sized heat pump can heat a well-insulated home even in sub-zero temperatures. However, if you live in an older home in a climate that regularly drops below 25°F, many homeowners may prefer a hybrid heat pump to get the best comfort and efficiency from their system.

Need help?

A high HSPF rated heat pump can save homeowners time, money and help the environment in the process. If it’s time for you to purchase, replace, or upgrade your heat pump, Trane has you covered.

Contact a local dealer

Dealers can answer questions, help you find the right products for your home, and repair your system.

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Connect with our Customer Care team about your products, warranties, and dealer concerns.

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