HSPF Rating: What Is a Good HSPF for Heat Pumps?

A good HSPF rating for a heat pump is 9.5 or higher under the old standard (approximately 8.1+ HSPF2 under the new standard), which translates to a seasonal heating COP of about 2.8. The federal minimum was 8.2 HSPF before the 2023 transition to HSPF2. Premium cold-climate heat pumps reached 12-13 HSPF, delivering nearly four times more heat than the electricity they consumed over a full winter season.

HSPF was replaced by HSPF2 on January 1, 2023, but millions of existing heat pumps still carry HSPF ratings. This guide explains what HSPF means, where your unit falls on the efficiency scale, and how to compare HSPF to the new HSPF2 standard.

What HSPF Measures

HSPF stands for Heating Seasonal Performance Factor. It calculates how many BTU of heat a heat pump delivers per watt-hour of electricity consumed over a standardized heating season.

HSPF = Total Heating Output (BTU) / Total Electrical Input (Wh)

An HSPF of 10 means the heat pump delivers 10 BTU of heat for every watt-hour of electricity. Dividing by 3.412 converts to COP: 10 HSPF = COP 2.93, meaning 293% heating efficiency.

The test uses DOE Climate Region IV (moderate climate) and includes defrost cycle energy use and supplemental electric heat strip activation during the coldest temperature bins.

HSPF Rating Scale

HSPF vs HSPF2

HSPF2 replaced HSPF on January 1, 2023. The key difference is the M1 test procedure with higher static pressure (0.5 in. w.c. vs 0.1 in. w.c.).

The conversion is less precise than SEER/SEER2 because heating tests involve defrost and strip heat that interact differently with static pressure changes.

How HSPF Affects Your Heating Bill

Annual Heating Cost = (Heating Load BTU) / HSPF x ($/kWh / 1,000)

Real-World Example

Example: A 3-ton heat pump heating a home in Nashville (4,000 HDD climate) at $0.14/kWh.

At HSPF 8.5: Annual cost = approximately $1,130

At HSPF 10.5: Annual cost = approximately $915

At HSPF 12.5: Annual cost = approximately $770

Upgrading from 8.5 to 12.5 HSPF saves about $360/year, or $5,400 over 15 years.

HSPF by Equipment Type

Mini-splits consistently achieve the highest HSPF ratings because they eliminate duct losses and use highly optimized inverter compressors.

When HSPF Matters Most

HSPF is most important in heating-dominated climates. If you live in a region where annual heating hours exceed cooling hours, HSPF (or HSPF2) is the more important efficiency number compared to SEER.

In Atlanta (2,800 HDD), heating and cooling costs are roughly balanced. In Minneapolis (7,900 HDD), heating costs dwarf cooling costs by 3-4x. For a Minneapolis heat pump owner, the difference between 8.5 and 12.5 HSPF can be $600-$800 per year.

In cooling-dominated climates like Miami or Phoenix, HSPF matters less because the heat pump rarely runs in heating mode. Focus on SEER2 instead.

Limitations of HSPF

HSPF has the same limitations as any seasonal metric. It's tested in DOE Region IV (moderate climate), so homes in very cold regions will see lower real-world efficiency. It includes an allowance for strip heat usage, but your actual strip usage may differ. It doesn't account for duct losses. And it's a composite number that masks the wide variation in efficiency between mild weather (very high COP) and bitter cold (low COP).

For a more nuanced picture of cold-weather performance, look for the manufacturer's published COP at 17 degrees F and 5 degrees F, or check if the unit meets the NEEP Cold Climate specification.

Key Takeaway

Key Takeaways

Good HSPF is 9.5+ (old standard) or 8.1+ HSPF2 (new standard). Excellent is 12+ HSPF / 10+ HSPF2.
HSPF = BTU of heat per watt-hour of electricity over a full heating season. Divide by 3.412 for COP.
HSPF was replaced by HSPF2 in January 2023. HSPF2 is roughly HSPF x 0.85.
Mini-splits achieve the highest HSPF (10-14) by eliminating duct losses.
In heating-dominated climates, HSPF matters more than SEER for your energy bill.
Each HSPF point saves roughly $50-$100/year depending on climate severity and electricity rate.
The federal minimum was 8.2 HSPF (now 7.5 HSPF2). ENERGY STAR requires 8.5+ HSPF / 8.1+ HSPF2.

CADR Rating Explained: How to Choose an Air Purifier by CADR

guide • 8 min read

EER Chart for Air Conditioners (Good, Average, Excellent)

reference • 7 min read

What Is EER Rating? Energy Efficiency Ratio Explained

explainer • 7 min read

EER vs SEER: What's the Difference Between These Ratings?