{
  "title": "Heat pumps at -30°C — chart data",
  "prepared": "2026-09-28",
  "notes": "Every figure below was read from the cited source. Temperatures converted °F→°C with (F-32)*5/9 and rounded to 0.1. Derived values (percentages, $/MMBtu) are computed from cited inputs; the formula is given.",
  "charts": {
    "cop_vs_temperature": {
      "caption": "Heating COP versus outdoor temperature: one manufacturer's published curve and measured field results",
      "manufacturer_curve": {
        "label": "Mitsubishi Zuba-Central PVA-A36AA4 / PUZ-HA36NHA5, maximum capacity, no auxiliary heat (manufacturer data)",
        "source": "https://www.mitsubishitechinfo.ca/sites/default/files/Zuba_36_Heating_Performance.pdf",
        "points": [
          {"tC": 8.3, "tF": 47, "cop": 3.49, "capacity_btuh": 40000},
          {"tC": 5.6, "tF": 42, "cop": 3.30, "capacity_btuh": 38000},
          {"tC": 2.8, "tF": 37, "cop": 3.28, "capacity_btuh": 38000},
          {"tC": 0.0, "tF": 32, "cop": 2.99, "capacity_btuh": 38000},
          {"tC": -2.8, "tF": 27, "cop": 2.60, "capacity_btuh": 38000},
          {"tC": -5.6, "tF": 22, "cop": 2.30, "capacity_btuh": 38000},
          {"tC": -8.3, "tF": 17, "cop": 2.06, "capacity_btuh": 38000},
          {"tC": -11.1, "tF": 12, "cop": 1.96, "capacity_btuh": 38000},
          {"tC": -13.9, "tF": 7, "cop": 1.86, "capacity_btuh": 38000},
          {"tC": -15.0, "tF": 5, "cop": 1.82, "capacity_btuh": 38000},
          {"tC": -16.7, "tF": 2, "cop": 1.75, "capacity_btuh": 36500},
          {"tC": -19.4, "tF": -3, "cop": 1.63, "capacity_btuh": 34000},
          {"tC": -22.2, "tF": -8, "cop": 1.50, "capacity_btuh": 31500},
          {"tC": -25.0, "tF": -13, "cop": 1.38, "capacity_btuh": 29000},
          {"tC": -30.0, "tF": -22, "cop": 1.26, "capacity_btuh": 26500}
        ],
        "minimum_capacity_row_at_minus30C": {"capacity_btuh": 12400, "cop": 2.01, "note": "Same table, minimum-capacity page: at low output the unit is more efficient"}
      },
      "field_points": [
        {"label": "DOE Cold Climate Heat Pump Challenge, 22 sites (US & Canada), median COP, heat-pump-only, 0 to 5°F bin", "tC": -16.4, "cop": 1.9, "source": "https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-37127.pdf"},
        {"label": "NRCan CCHT ducted cold-climate ASHP (2013), apparent COP at -21.1°C", "tC": -21.1, "cop": 1.5, "source": "https://natural-resources.canada.ca/maps-tools-publications/publications/cooling-heating-season-performance-assessment-cold-climate-air-source-heat-pump-canadian-centre-housing-technology"},
        {"label": "NRCan CCHT mini-split (2014), apparent COP at -15°C", "tC": -15.0, "cop": 2.3, "source": "https://natural-resources.canada.ca/maps-tools-publications/publications/cooling-heating-season-performance-assessment-mini-split-cold-climate-air-source-heat-pump-canadian-centre-housing-technology"},
        {"label": "NRCan CCHT mini-split (2014), COP 'close to 2.0' at -25°C", "tC": -25.0, "cop": 2.0, "source": "https://natural-resources.canada.ca/maps-tools-publications/publications/cooling-heating-season-performance-assessment-mini-split-cold-climate-air-source-heat-pump-canadian-centre-housing-technology"},
        {"label": "Minnesota CEE ductless Site 6, average daily COP for 0 to -13°F (plotted at bin midpoint)", "tC": -21.4, "cop": 1.7, "source": "https://www.mncee.org/sites/default/files/report-files/86417-Cold-Climate-Air-Source-Heat-Pump-(CARD-Final-Report-2018).pdf"},
        {"label": "Minnesota CEE ductless Site 8, average daily COP for 0 to -13°F (plotted at bin midpoint)", "tC": -21.4, "cop": 1.3, "source": "https://www.mncee.org/sites/default/files/report-files/86417-Cold-Climate-Air-Source-Heat-Pump-(CARD-Final-Report-2018).pdf"},
        {"label": "ORNL prototype (not a commercial product) at CCHRC Fairbanks, average system COP at -13°F", "tC": -25.0, "cop": 2.0, "source": "https://www.aceee.org/wp-content/uploads/2026/08/experimental-evaluation-of-a-high-performance-cold.pdf"},
        {"label": "ORNL prototype (not a commercial product) at CCHRC Fairbanks, average system COP at -27°F", "tC": -32.8, "cop": 1.8, "source": "https://www.aceee.org/wp-content/uploads/2026/08/experimental-evaluation-of-a-high-performance-cold.pdf"}
      ],
      "reference_lines": [
        {"label": "NEEP ccASHP v4.0 & ENERGY STAR Cold Climate minimum: COP >= 1.75 at 5°F (-15°C)", "cop": 1.75, "source": "https://neep.org/sites/default/files/media-files/cold_climate_air_source_heat_pump_specification_-_version_4.0_final.pdf"},
        {"label": "Electric resistance heat", "cop": 1.0}
      ]
    },
    "capacity_vs_temperature": {
      "caption": "Maximum heating output of one 3-ton cold-climate unit vs. an illustrative house heat-loss line",
      "unit_source": "https://www.mitsubishitechinfo.ca/sites/default/files/Zuba_36_Heating_Performance.pdf",
      "unit_points_ref": "see cop_vs_temperature.manufacturer_curve.points[].capacity_btuh",
      "capacity_as_pct_of_47F_output": [
        {"tC": -15.0, "pct": 95.0},
        {"tC": -25.0, "pct": 72.5},
        {"tC": -30.0, "pct": 66.3}
      ],
      "pct_formula": "capacity_btuh / 40000 * 100",
      "illustrative_load_line": {
        "ASSUMPTION": true,
        "description": "Hypothetical house: 0 Btu/h at 18°C rising linearly to 36,000 Btu/h at -30°C. Not from a source; drawn only to show what a balance point is.",
        "points": [{"tC": 18, "btuh": 0}, {"tC": -30, "btuh": 36000}]
      },
      "lockouts": [
        {"model": "Mitsubishi PVA-A36AA7 / PUZ-HA36NKA (newer Zuba-Central submittal)", "heating_thermal_lockout_C": -30, "restart_C": -25, "source": "https://www.mitsubishitechinfo.ca/sites/default/files/SB_PVA-A36AA7_PUZ-HA36NKA_202401.pdf"},
        {"model": "Mitsubishi MSZ-FS12NA / MUZ-FS12NAH (ductless)", "heating_thermal_lockout_C": -28, "restart_C": -26, "max_capacity_btuh_at_minus25C": 11000, "cop_at_minus25C": 1.92, "max_capacity_btuh_at_minus15C": 14690, "cop_at_minus15C": 2.25, "source": "http://www.mitsubishitechinfo.ca/sites/default/files/SB_MSZ-FS12NA-U1_MUZ-FS12NAH-U1_202401.pdf"}
      ]
    },
    "operating_cost_worked_example": {
      "caption": "Cost to deliver 1 million Btu (MMBtu) of heat, Minnesota prices, 2025-26 heating season",
      "formula": "$/MMBtu delivered = price per unit / (MMBtu per unit) / efficiency (AFUE or COP)",
      "inputs": {
        "electricity_usd_per_kwh": {"value": 0.1625, "period": "Minnesota residential, year-to-date Jan-Jul 2026", "source": "https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_b"},
        "natural_gas_usd_per_mcf": {"value": 10.65, "period": "Simple mean of Minnesota residential monthly prices Oct 2025-Mar 2026 (10.04, 7.99, 9.43, 11.17, 13.03, 12.24)", "source": "https://www.eia.gov/dnav/ng/hist/n3010mn3m.htm"},
        "propane_usd_per_gal": {"value": 1.951, "period": "Mean of 26 weekly Minnesota residential prices, 6 Oct 2025-30 Mar 2026", "source": "https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPLLPA_PRS_SMN_DPG&f=W"},
        "heating_oil_usd_per_gal": {"value": 3.628, "period": "Mean of 26 weekly Minnesota residential prices, 6 Oct 2025-30 Mar 2026", "source": "https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPD2F_PRS_SMN_DPG&f=W"},
        "heat_content": {"kwh_btu": 3412, "cubic_foot_gas_btu": 1036, "gallon_heating_oil_btu": 138500, "gallon_propane_btu": 91452, "source": "https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php"},
        "efficiencies": {
          "gas_and_propane_furnace_afue": {"value": 0.97, "basis": "ENERGY STAR U.S. North gas furnace criterion", "source": "https://www.energystar.gov/products/furnaces/key_product_criteria"},
          "oil_furnace_afue": {"value": 0.87, "basis": "ENERGY STAR oil furnace criterion", "source": "https://www.energystar.gov/products/furnaces/key_product_criteria"},
          "electric_resistance_cop": {"value": 1.0, "basis": "by definition"},
          "heat_pump_seasonal_cop_low": {"value": 1.9, "basis": "Low end of the modeled annual heat-pump COP range (1.9-2.1) for Minnesota cities, CEE 2018", "source": "https://www.mncee.org/sites/default/files/report-files/86417-Cold-Climate-Air-Source-Heat-Pump-(CARD-Final-Report-2018).pdf"},
          "heat_pump_seasonal_cop_high": {"value": 2.5, "basis": "Rounded down from measured weather-normalized annual heat-pump-only COPs of 2.51-2.78, CEE 2018", "source": "https://www.mncee.org/sites/default/files/report-files/86417-Cold-Climate-Air-Source-Heat-Pump-(CARD-Final-Report-2018).pdf"}
        }
      },
      "results_usd_per_mmbtu_delivered": [
        {"system": "Natural gas furnace, 97% AFUE", "value": 10.60},
        {"system": "Heat pump, seasonal COP 2.5", "value": 19.05},
        {"system": "Propane furnace, 97% AFUE", "value": 21.99},
        {"system": "Heat pump, seasonal COP 1.9", "value": 25.07},
        {"system": "Oil furnace, 87% AFUE", "value": 30.11},
        {"system": "Electric resistance (baseboard / furnace)", "value": 47.63}
      ],
      "break_even_heat_pump_cop": {"vs_gas": 4.49, "vs_propane": 2.17, "vs_oil": 1.58, "formula": "electricity $/MMBtu / competitor $/MMBtu delivered"}
    }
  }
}