Wisconsin · NOAA station KMKE
Heating with a mini-split in Milwaukee, WI
The short answer
In Milwaukee, a median ENERGY STAR cold-climate mini-split heating a 24,000 BTU/h design load should cost about $1,264 a year: $638 more than natural gas (90% efficient), and 61% less than electric resistance. The 99% design temperature is 4°F, so capacity at 5°F matters here.
The winter you are actually buying for
This is Milwaukee's average year of hourly temperatures from 2015 through 2024 (87,641 readings at General Mitchell International Ap, 100% of all hours). The dashed line is the 99% design temperature: only 1% of hours are colder.
What it costs, by fuel
Mini-split modeled as a median certified cold-climate unit sized to cover the load at 4°F. Seasonal efficiency in Milwaukee's weather: COP 2.54. In 97 hours a year the load exceeds capacity and the estimate adds electric backup.
Three house sizes
| Design load | Heat pump | Gas | Oil | Propane | Resistance | Seasonal COP | Systems that cover it |
|---|---|---|---|---|---|---|---|
| 12,000 BTU/h | $632 | $313 | $726 | $614 | $1,609 | 2.54 | 10,935 of 14,941 |
| 24,000 BTU/h | $1,264 | $626 | $1,452 | $1,227 | $3,217 | 2.54 | 5,303 of 14,941 |
| 36,000 BTU/h | $1,896 | $940 | $2,178 | $1,841 | $4,826 | 2.54 | 2,457 of 14,941 |
The last column counts ENERGY STAR cold-climate systems whose published 5°F and 47°F capacities, joined by a straight line, still reach the design load at Milwaukee's 4°F. How sizing works.
Not a quote. Real bills depend on insulation, thermostat habits, installation and your own Manual J. Use this to decide whether a heat pump is worth pricing, then get two local quotes.
Questions people ask
Will a mini-split work in Milwaukee in winter?
Yes, if it is a cold-climate model. Milwaukee's 99% design temperature from 2015–2024 hourly data is 4°F, and the lowest hour recorded was -21°F. The median ENERGY STAR cold-climate unit keeps 88% of its 47°F heating capacity at 5°F. Hours per year at or below 5°F in Milwaukee: 97.
Is a heat pump cheaper than natural gas in Milwaukee?
At a 24,000 BTU/h design load, we estimate $1,264 a year with a median cold-climate mini-split versus $626 for natural gas at 90% efficiency, using 18.79¢/kWh electricity and 2024 Wisconsin fuel prices. That is $638 more than natural gas.
How big a mini-split do I need in Milwaukee?
Size to your home's heat loss at 4°F, not to square feet. For a 24,000 BTU/h load, a unit shaped like the median certified system needs about 27,265 BTU/h of 47°F capacity. 5,303 of the 14,941 certified systems cover that load at 4°F.