Every heat pump quote in Tacoma lists two efficiency numbers, SEER2 and HSPF2, and most homeowners are told that bigger is better on both. That is true, but it hides the part that matters most here: in the Puget Sound climate, one of those numbers drives most of your electric bill and the other barely moves it. This guide explains what each rating measures, why heating efficiency dominates west of the Cascades, and how to turn an HSPF2 number into an estimate of real kWh for your own home.
What SEER2 and HSPF2 actually measure
Both ratings are seasonal averages from a Department of Energy test procedure that took effect in 2023. The 2 on the end means the newer test, which uses higher duct resistance to better match real homes. Both are expressed in BTUs of heating or cooling delivered per watt hour of electricity used.
| Rating | What it measures | How much it matters in Tacoma |
|---|---|---|
| SEER2 | Cooling output per unit of electricity over a cooling season | Low to moderate. Our cooling season is short, so small SEER2 gains move the bill very little. |
| HSPF2 | Heating output per unit of electricity over a heating season | High. Most of a Tacoma heat pump’s yearly run time is heating. |
| COP at 5°F or 17°F | Efficiency at one specific cold temperature | Moderate. Matters for cold snaps and for homes on exposed hills or near the water. |
| Capacity at 17°F | How much heat the unit can still make when it is cold | High for comfort. A unit that loses too much capacity leans on backup heat. |
Why heating efficiency dominates in the Puget Sound
Tacoma has a long, mild, damp heating season and a short cooling season. A typical South Sound home might call for heat from October into May, with most days sitting between the mid 30s and low 50s. Cooling is usually limited to a few weeks in July and August, plus the occasional heat dome.
That split means a heat pump in Pierce County spends most of its yearly run time heating. So moving from 7.5 to 9.5 HSPF2 changes the bill far more than moving from 15 to 18 SEER2.
The frost test is our weather
The HSPF2 test includes a frosting condition around 35°F with high humidity, where the outdoor coil ices up and the unit has to run defrost cycles. That is a typical Tacoma winter morning. Units with smart demand defrost and good low speed operation tend to hold up well here, which is one reason variable speed and ductless systems perform so well in our climate.
HSPF2 is rated for a different climate
The label number assumes a standard national climate region. Our winters are milder than that region, but damper and longer. In practice, a well installed variable speed heat pump in Tacoma often performs close to or a bit better than its label, while a single stage unit with leaky ducts can fall well short of it.
Estimate your own heating kWh from HSPF2
Because HSPF2 is BTUs per watt hour, the math is simple:
Yearly heating kWh = yearly heating load in BTU ÷ (HSPF2 × 1,000)
As an example, a 30 million BTU yearly heating load is in the range we see for a moderately insulated 1,800 square foot South Sound home. Your load will differ, and a Manual J calculation gives a real number for your house.
| HSPF2 | Estimated yearly heating electricity for a 30 million BTU load |
|---|---|
| 7.5 (federal minimum for split heat pumps) | About 4,000 kWh |
| 8.5 | About 3,530 kWh |
| 9.5 | About 3,160 kWh |
| 10.5 | About 2,860 kWh |
To turn kWh into dollars, multiply by the per kWh rate on your Tacoma Power, Puget Sound Energy, or Lakeview Light and Power bill. In this example, going from 7.5 to 9.5 HSPF2 saves roughly 840 kWh a year. Run the same math on SEER2 with our small cooling load and the difference is usually a fraction of that.
How to use the ratings when comparing quotes
- Compare HSPF2 first. In Tacoma it is the rating that tracks your bill.
- Check capacity at 17°F. A high HSPF2 unit that loses too much output in a cold snap will lean on resistance backup heat, which uses much more electricity.
- Use the AHRI matched rating. The rating belongs to a specific outdoor and indoor combination. Ask for the AHRI certificate number on the quote. You can look it up in the AHRI directory.
- Do not pay a lot extra for SEER2 alone. A small SEER2 bump rarely pays back here unless you run a lot of summer cooling.
- Remember the install. Duct leakage, refrigerant charge, and airflow can erase the difference between two ratings. Our heat pump sizing guide covers why right sizing matters as much as the label.
Frequently asked questions
Is SEER2 lower than SEER for the same unit?
Yes. The SEER2 test uses higher external static pressure to better reflect real ductwork, so the same equipment scores lower on the new scale. A unit that was about 15 SEER is roughly 14.3 SEER2. It did not get worse, the test got stricter.
What HSPF2 should I look for in Tacoma?
The federal minimum for split heat pumps is 7.5 HSPF2. Many good ducted systems land in the high 7s to mid 8s, and variable speed and ductless systems often reach 9 or higher. Look at HSPF2 together with capacity at 17°F, not by itself.
Does a higher SEER2 help with heat domes?
A little, but capacity matters more during a heat dome than seasonal efficiency. A properly sized variable speed unit will keep up better than an undersized high SEER2 unit.
Why does my bill not match the rating?
Ratings come from a standard lab test. Duct leakage, poor airflow, thermostat setbacks that trigger backup heat, and an oversized or undersized system all pull real performance below the label.
Want help reading a heat pump quote?
If you have a quote with SEER2 and HSPF2 numbers and are not sure what they mean for your house, GreenFlow Heating & Cooling can walk you through it. Call (253) 370-8641 or send us a message. You can also read about our heat pump installations.