Should Sussex switch to a heat pump?
In Sussex, a heat pump would cost more to run each year than what you have now. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $3,500 after a $2,000 federal tax credit. The heat pump would cost about $438 more a year to run than the furnace it replaces — a premium with no payback. There's no spin on that: Sussex's numbers say wait.
Why Sussex's climate drives this number
6294 heating degree days pile up here every year, so Sussex has a cold winter that leans hard on heating equipment; the cooling side runs to 394 cooling degree days, where summers add a moderate cooling load. The 99% winter design temperature here — the cold snap equipment must be sized for, not the seasonal average — is -5.8°F, against a record low of -11.2°F. That puts the seasonal coefficient of performance at 2.56 for the recommended cold-climate unit. A cold-climate unit is the right call in Sussex — below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station WAUKESHA COUNTY AIRPORT, 6.5 miles from Sussex — the closest one on record.
The month-to-month numbers for Sussex
Modelled on a typical 2000-square-foot house, the heat pump draws about 6,225 kWh a year to keep it warm, plus cooling, for a combined electric bill near $1,238 a year. The gas furnace it replaces burns roughly 66 Mcf a year at 10.74 per Mcf here, for a running cost near $800 a year (electricity here runs 18.87¢/kWh). Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs past the 15-year equipment life, for a 15-year net position $10,067 behind.
Electric resistance heat in Sussex, compared
Gas isn't universal in Sussex — many houses run on electric heat already. Swap the comparison to resistance heat instead of gas, and Sussex's answer improves. About $1,866 a year comes back this way, enough that the 4.3-year payback clears the $8,000 premium comfortably within the equipment's life.
How Sussex compares nationally
Sussex lands at position 122 out of 3206 cities on heating severity (coldest is 1), and 2715 out of 3206 by population size (biggest is 1). That's the coldest third of the dataset, where climate does most of the work behind this figure.
What to do with this number in Sussex
About 12,607 people live in Sussex, Wisconsin, and every number on this page is what a contractor would actually work from when quoting a system here — the point isn't to replace that quote, it's to tell you whether to bother asking for one. Here, there's no cost penalty to waiting until your current furnace or AC actually needs replacing.
Line up a few local HVAC quotes before you decide.
More on how this number was built
The methodology guide walks through exactly how Sussex's 2.56 seasonal COP and the rest of this page's numbers get built. Sussex's -5.8°F design temperature is below the 25°F line, which is why a cold-climate unit is the right call here — see what that changes in the cold-climate unit guide.