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      Data and methodology

      Every number on this site comes from a public U.S. government source. Here is exactly which ones, and what we do with them.

      Heat pump ratings

      Source: the ENERGY STAR Certified Heat Pumps dataset published by the U.S. Environmental Protection Agency. It covers ducted split systems, single-package units and mini- and multi-split systems certified to the ENERGY STAR Air-Source Heat Pump specification. The last download, on October 12, 2026, contained 284,895 certified combinations.

      • Records are grouped by outdoor unit model number. Each indoor-unit (and furnace) combination becomes a “matchup” on that model's page.
      • Headline figures show the best certified matchup: the highest SEER2 and EER2 of that matchup, and the highest HSPF2, 5°F capacity and 5°F COP across matchups.
      • Models listed only for the Canadian market are excluded.
      • A trailing asterisk in a model number is a manufacturer wildcard and is dropped from page titles.
      • Brand names that differ only in capitalization or punctuation are merged. When the same outdoor unit is certified under several brands, it gets one page listing every brand.

      Size classes and rankings

      Mini-splits are grouped by the nominal BTU size closest to their median certified cooling capacity (6,000 to 60,000 BTU). Ducted and packaged systems are grouped by the nearest half ton. Within each class, models are ranked by SEER2, with HSPF2 as the tie-breaker.

      Climate data for cities

      City pages use the NOAA 1991-2020 U.S. Climate Normals from the nearest first-order weather station (usually the main airport, within 60 km): annual and monthly heating and cooling degree days, the average number of nights at or below 0°F, 10°F, 20°F and 32°F, days at or above 90°F and 100°F, and average winter lows and summer highs. Cities are the 272 largest U.S. cities by Census Bureau population estimates, plus at least three per state. State figures are population-weighted averages of those cities.

      Full-load hours, which drive the cost estimates, are derived from degree days: heating hours = 0.4 × heating degree days and cooling hours = 0.7 × cooling degree days, calibrated against DOE/AHRI climate-region assumptions. A city is flagged as needing a cold-climate model when it averages five or more nights a year at or below 0°F, twenty or more at or below 20°F, or over 6,000 heating degree days.

      Energy prices

      • Electricity: average residential price by state, U.S. EIA Electric Power Monthly table 5.6.B (12 months to July 2026).
      • Natural gas: average residential price by state, U.S. EIA (2025), converted at 10.37 therms per thousand cubic feet.
      • Propane and heating oil: U.S. EIA weekly residential prices (week of 2026-10-05). States not covered by the EIA survey use the national median.

      Running cost and savings

      Heat pump electricity = capacity × hours ÷ (rating × 1,000), separately for cooling (SEER2) and heating (HSPF2). The current system is costed on the same heat delivered: gas at 100,000 BTU per therm, propane at 91,452 BTU per gallon and heating oil at 138,500 BTU per gallon, each divided by the furnace efficiency (AFUE); electric resistance at 3,412 BTU per kWh. Payback is the installed price minus rebates, divided by the yearly saving. Monthly costs follow each month's share of heating and cooling degree days. Very cold hours that need backup heat are not modelled.

      Sizing

      The size calculator uses the ENERGY STAR room air conditioner sizing table for cooling, adjusted for climate, sun exposure, occupants and kitchens, and a heating load per square foot that rises with heating degree days and falls with better insulation. It is a starting point; a Manual J load calculation by an installer is the reliable method for a whole house.

      Update schedule

      Data is downloaded again and every page rebuilt once a week. New certifications typically appear within seven days of being published by ENERGY STAR.

      Limits

      Certified ratings come from standardized lab tests. Real-world efficiency depends on installation quality, ductwork, sizing and climate. Always confirm the exact matchup and its AHRI reference number with your installer.