SEER2 rates a heat pump’s seasonal cooling efficiency and HSPF2 its seasonal heating efficiency; higher numbers mean more heat moved per unit of electricity. In Sacramento both matter. SMUD’s rebate sets a floor of 15.2 SEER2 on two-stage systems, but whether a heat pump saves money over gas in winter is a heating question, and that is HSPF2’s territory.
Tule Sacramento Heat Pump designs and installs ducted heat pumps across the Sacramento region, with licensed and insured contractors doing the work. This guide explains what the ratings measure and how to read them against your own utility.
What each rating measures
Both ratings are seasonal averages from a standardized federal test, not a reading at one temperature.
SEER2: cooling
The Seasonal Energy Efficiency Ratio (the 2 marks the current test procedure) divides the cooling a system delivers over a modeled season, in Btu, by the electricity it uses, in watt-hours. It blends performance across a range of outdoor temperatures.
HSPF2: heating
The Heating Seasonal Performance Factor does the same for heating: seasonal heat output in Btu divided by watt-hours of electricity, including the energy used for defrost and any backup heat the test assumes.
EER2: the hot-afternoon number
Some equipment also lists EER2, measured at a single hot condition. Because SMUD’s highest summer price falls from 5 to 8 p.m. on weekdays, late in the hottest part of the day, EER2 says more than SEER2 about cost during those hours.
COP: the number that links them
The coefficient of performance is the simplest efficiency measure: heat delivered divided by electricity used, both in the same units. A COP of 3 delivers three units of heat for each unit of electricity. Electric resistance heat sits at 1.
Turning HSPF2 into a COP
One watt-hour equals 3.412 Btu, so dividing HSPF2 by 3.412 converts it to an approximate seasonal average COP. As arithmetic: an HSPF2 of 7.5 works out to about 2.2, and 8.5 to about 2.5. Sacramento’s valley-floor winters are milder than the rating’s reference climate, so actual average COP here can run higher, though frequent defrost cycles on foggy mornings pull it back down.
Comparing that with your utility
Working from published tariffs, the derived break-even COP against a 95% gas furnace is:
| Electric rate | Break-even COP vs 95% furnace |
|---|---|
| SMUD winter off-peak ($0.1285 per kWh) | About 1.41 |
| SMUD winter peak ($0.1776) | About 1.95 |
| Roseville Electric Tier 1 to Tier 2 | About 1.70 to 2.18 |
| PG&E E-ELEC winter off-peak to peak | About 3.13 to 3.52 |
| PG&E E-TOU-C winter off-peak | About 4.04 |
These use PG&E’s residential gas baseline rate and energy charges only, with fixed charges left out. In SMUD territory, nearly any modern heat pump clears the bar. In PG&E territory, the heating efficiency of the specific system and its installation decide the winter math. The heat pump vs gas furnace guide works through it.
Why HSPF2 deserves weight here
Sacramento sizes for the summer afternoon, but it heats for longer than it cools. NOAA’s 1991-2020 normals give Sacramento Executive Airport about 2,436 heating degree days a year against 1,292 cooling degree days; Auburn shows 2,813 and 1,453. Degree days measure how far and how long temperatures sit from a comfortable baseline, so a higher heating figure means more heating hours.
Cooling is concentrated, heating is spread out
The cooling season packs its load into roughly 76 days at 90°F or hotter at the airport station. Heating runs on many more mild-to-cool days. A system that is efficient in heating pays off over all of them, especially on SMUD power, where winter heating is where the savings over gas show up.
Ratings belong to a matched system
A rating is certified for a specific combination: outdoor unit, indoor coil or air handler, and sometimes a particular blower or control. Pair the same outdoor unit with a different coil and the rating changes.
What to check in a quote
- the model numbers of the outdoor unit and the indoor coil or air handler
- the certified SEER2 and HSPF2 for that exact pair
- whether the compressor is single-stage, two-stage or variable-speed
- that the indoor coil uses the same refrigerant as the outdoor unit
When the air handler or coil is not being replaced, ask how the rating was arrived at. Heat pump air handler replacement explains when the indoor side must change, and the quote comparison guide covers the rest of the checklist.
The label
A model’s yellow EnergyGuide label shows its ratings and can list states where federal regional efficiency standards bar its installation. Confirm the label shows the model may be installed in California.
Compressor type and the rating
Variable-speed compressors earn the highest ratings because they run at low output most of the time, where a heat pump is most efficient. Two-stage equipment sits in between. That difference also drives comfort: longer, gentler run times even out room temperatures through Sacramento’s long run of 90-degree days. SMUD reflects it in its rebate, paying $3,000 for variable-stage gas-to-electric systems and $2,000 for two-stage, while single-stage systems earn nothing. The variable-speed heat pump page explains the hardware.
Installation decides the real number
A rating assumes correct refrigerant charge, correct airflow and tight ducts. Miss them and the system underperforms its label.
- Airflow. Title 24 refrigerant charge verification assumes at least 300 cfm per ton. Restrictive returns or crushed ducts cut capacity and efficiency.
- Charge. Too much or too little refrigerant lowers output; heat pumps get charge verified in every climate zone.
- Ducts. Leakage to a hot attic wastes cooling before it reaches a room, which is why the ECC-Rater tests ducts on every change-out.
The permit and Title 24 guide covers those checks, and the sizing guide explains why an oversized high-SEER2 system can still disappoint.
Choosing a tier
For a SMUD home, a two-stage or variable-speed system at or above 15.2 SEER2 is the practical floor, since it qualifies for the rebate. For a PG&E-electric home, heating efficiency carries more weight because the break-even COP is higher. The electric bill guide runs seasonal costs by utility. To see matched options with their ratings for your house, call (916) 516-1454 or request an estimate.
