How We Estimate Heat Pump Running Costs

This page explains exactly how Heat Pump Atlas produces every number on the site, so you can judge how much weight to give it.

1. Equipment data

All performance figures come from the ENERGY STAR Certified Heat Pumps dataset published by the U.S. EPA (public domain). Each record is one certified combination of an outdoor unit and an indoor unit. For each outdoor model we aggregate all of its certified pairings and report:

  • SEER2 range: lowest and highest certified value across pairings.
  • EER2, HSPF2, capacities and COP at 5°F: the highest certified value across pairings.
  • Pairings: how many indoor-unit combinations are certified.

Because capacities and HSPF2 are maxima, a specific pairing quoted to you may be somewhat lower. Always confirm with the AHRI reference number of your exact system.

2. Twin (rebadged) models

Two listings are treated as the same equipment when they share the same certifying ENERGY STAR partner and identical values for product type, cooling capacity, heating capacity at 47°F, 17°F and 5°F, minimum and maximum SEER2, HSPF2, compressor staging and refrigerant.

3. Electricity prices

State residential prices are from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A (latest month: August 2026, preliminary). Monthly prices fluctuate seasonally; enter the price from your own bill for the most accurate result.

4. Climate hours

Each state is assigned planning values for equivalent full-load heating hours and cooling hours, based on its broad climate zone. These are deliberately simple, rounded assumptions meant to make states comparable — not a substitute for a professional load calculation. Every calculator lets you override them.

5. The cost formula

Heating kWh = heating capacity at 47°F (BTU/h) × heating hours ÷ (HSPF2 × 1,000)
Cooling kWh = cooling capacity (BTU/h) × cooling hours ÷ (minimum SEER2 × 1,000)
Annual cost = (heating kWh + cooling kWh) × price per kWh

This mirrors the approach used by the federal ENERGY STAR savings calculators. It assumes the unit is correctly sized for the home. HSPF2 already accounts for typical backup resistance heat in the DOE test climate; in very cold regions actual heating costs can be higher than estimated, which is why we highlight 5°F capacity separately.

6. 3-ton normalised cost

For rankings we also compute what each model would cost to run if it served a 36,000 BTU/h load, using the same formula. This removes the effect of unit size so models can be compared on efficiency alone.

7. Percentiles

Statements such as "better than 72% of models" compare a value with all 308 outdoor units currently in our database.

Limitations

  • Estimates are not quotes, guarantees or engineering advice.
  • Installation quality, ductwork, thermostat settings and occupant behaviour can change real-world costs substantially.
  • Our database currently covers a curated selection of widely sold models; it does not include every certified product.

Found an error? Tell us and we will correct it.