If you’re in the market for a new heat pump, finding one that’s as energy efficient as possible is an important consideration, especially when you factor in that heating and cooling account for around 48 percent of the energy used in a typical household. To do that, look to the heat pump’s Heating Seasonal Performance (HSPF) rating.
Inspired by the oil crisis of 1973, the Air Conditioning, Heating and Refrigeration Institute (AHRI) developed the HSPF for measuring the energy efficiency of heat pumps. The Energy Policy and Conservation Act (EPCA) of 1975 was enacted to help reduce energy consumption. Subsequent amendments to this act gave the Department of Energy (DOE) the authority to devise energy efficiency standards for various appliances, and eventually led to the HSPF rating for heat pump efficiency becoming the national standard.
Today, the HSPF rating is largely used to determine a heat pump’s energy-saving potential for cost and environmental impact.
According to Mark Woodruff, Senior Product Manager of Ducted Outdoor Products for Trane Residential and American Standard Heating & Air Conditioning, HSPF is “a ratio of the heat output to electricity use over an average heating season, and the higher the HSPF the greater the energy efficiency.”
Specifically, it tells you how much heat energy, measured in British Thermal Units (BTUs), a heat pump will produce for every kilowatt-hour (kWh) of energy consumed to generate heat. For example, a heat pump with an HSPF rating of 8.2 will output 8.2 BTUs for every kWh of input. In practical terms, the HSPF gives you an idea of the impact a heat pump has on your heating bill.
A new heat pump’s HSPF rating can range from 8.2 to 13. While the current minimum standard established by the DOE is 8.2, it is set to rise to 8.8 in 2023.
“When shopping for a new heating system, efficiency is of utmost importance,” says Woodruff. “An efficient system not only lowers your energy costs, it will also lower your impact on the environment.”
Because of the HSPF and related standards, American homes are consuming fewer fossil fuels today than in the 1970s, despite having more and larger energy-consuming appliances and devices. This translates into saving 2.52 quadrillion BTUs created from fossil fuels. Americans collectively have saved $2.5 to $12.2 billion on their energy bills since the standards were established.
To determine the exact differences in energy efficiency between HSPF ratings, it’s helpful to convert HSPF to a percentage. To do this, start by dividing the HSPF number by 3.414 (the amount of BTUs in one kWh of electricity). This number is how many BTUs of heat energy is output for every BTU-worth of energy input. That number can then be converted into a percentage.
For example, a heat pump with an HSPF of 8.2 outputs 2.4 times (or 240 percent) the amount of BTUs than the energy it consumes, because 8.2 divided by 3.414 is 2.4. And a heat pump with an HSPF of 9 outputs 2.63 times (263 percent) the amount of BTUs than the energy it consumes, because 9 divided by 3.414 is 2.63.
Once you’ve determined how efficient each HSFP rating is, you can calculate the differences in energy efficiency by subtracting one figure from the other. So a heat pump with an HSPF rating of 9 is 23 percent more energy efficient than one with an HSPF rating of 8.2, because 263 percent (the percentage of efficiency for an HSFP 9 heat pump) minus 240 percent (the percentage of efficiency for an HSPF 8.2 heat pump) is 23 percent.
Heat pumps with higher HSPF ratings are typically more expensive, so you need to determine if what you’ll save on your heating bill is worth the higher upfront cost. This will largely depend on your climate, and how much energy is required to heat your home per year.
As an example, a 9 HSPF heat pump that’s 23 percent more efficient than an 8.2 HSPF heat pump may cost $1,000 more. So if you live in a cold climate, and it costs $2,460 to heat your home for a year with an 8.2 HSPF heat pump, and a 9 HPSF only costs you $2,000, the $460 annual savings will quickly pay off. On the other hand, the savings to your heating bill will take significantly longer to pay off if you live in a warmer climate that doesn’t require as much heat.
However, you may still be interested in a higher HSPF heat pump if your primary concern is reducing your carbon footprint. “Saving a few dollars every month on energy costs is something every homeowner can appreciate,” Woodruff says. “And if you could lower your home’s heating bill and lessen your impact on the environment at the same time, it’s a win-win.”