Heat Pump Payback in Joliet, IL
Should Joliet switch to a heat pump?
Joliet is a place where a heat pump genuinely costs more to operate than the alternative. Against a like-for-like gas furnace and AC swap, going electric costs $5,500 more up front here. Unfortunately the electric bill outweighs the gas bill it replaces by about $235 a year here, so the extra spend stays unrecovered. That's Joliet's own climate and rates talking, not a hedge or a caveat.
Checking a different city
Landed on Joliet by mistake, or want to compare it against somewhere else? Search the other 3206 cities below.
Joliet's weather, in the numbers that matter
Joliet has a real but manageable winter, 4733 heating degree days a year against a 65°F base, and summers are hot enough that cooling matters as much as heating, at 1089 cooling degree days. The 99% winter design temperature here, the cold snap equipment must be sized for, not the seasonal average, is -4.4°F, and the coldest daily reading in the 2024 station record was -10.3°F. That puts the seasonal coefficient of performance at 2.59 for the recommended cold-climate unit. A cold-climate unit is the right call in Joliet, below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. These numbers come from Joliet Regional Airport, the closest NOAA station, 1.5 miles out.
The yearly running costs in Joliet
Modelled on a typical 2000-square-foot house, the heat pump draws about 4,627 kWh a year to keep it warm, plus cooling, for a combined electric bill near $1,059 a year. Joliet's gas rate of $11.25 per Mcf, applied to the 49 Mcf a year the furnace burns, puts the current furnace-and-AC running cost near $824 a year, against 19.06¢ per kWh for electricity. Because the heat pump costs more to run here, the gap only widens with time: $9,031 behind after 15 years compared with replacing the furnace and AC like-for-like.
How sensitive Joliet's result is to prices
For the verdict in Joliet to flip, electricity would need to drop to about 13.4¢/kWh from 19.06¢, or gas climb past $16.03 per Mcf from $11.25. A utility offering a lower heat pump rate can change this. Until then, no quote price makes a heat pump pay back against gas in Joliet; the case for one here rests on comfort, cooling, or replacing electric heat instead.
The other scenario: no gas furnace to begin with
Not every home in Joliet has gas service. Swap the comparison to resistance heat instead of gas, and Joliet's answer improves. About $1,494 a year comes back this way, enough that the 6.7-year payback clears the $10,000 premium comfortably within the equipment's life.
Where Joliet ranks in this dataset
Among 3206 cities, Joliet's winter puts it at rank 997 for severity, while its size puts it at rank 179 for population, 1 in both cases being the extreme. 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 Joliet
Joliet, Illinois is home to about 151,837 people, and the figures above are the same ones a local HVAC contractor uses to size and quote a system, this site doesn't guess where a real quote would land, it just tells you whether it's worth asking for one. In Joliet, nothing is lost by holding off until the current equipment genuinely fails.
Ask a local HVAC contractor for a quote before committing either way.
More on how this number was built
Every constant behind this page, the 2.59 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. Joliet's -4.4°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.