Should Plainfield switch to a heat pump?
In Plainfield, a heat pump would cost more to run each year than what you have now. Against a like-for-like gas furnace and AC swap, going electric costs $3,500 more up front here (already netting out a $2,000 tax credit). Running costs here land $250 a year HIGHER than the furnace it replaces, so that premium is never recovered. There's no spin on that: Plainfield's numbers say wait.
Why Plainfield's climate drives this number
Degree days tell the story here: Plainfield racks up 4951 heating degree days each year (base 65°F), and summers are hot enough that cooling matters as much as heating, with 1049 cooling degree days on the cooling side. -4°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of -13°F on file. Worked through the model, that's a seasonal COP of 2.6 on the cold-climate unit fit for this climate. Below the 25°F line where a standard machine starts leaning on resistance backup, Plainfield sits firmly in cold-climate territory, so that's the class of unit priced here. These numbers come from LEWIS UNIVERSITY AIRPORT, the closest NOAA station, 7.4 miles out.
Plainfield's running-cost comparison, in dollars
Modelled on a typical 2000-square-foot house, the heat pump draws about 4,822 kWh a year to keep it warm, plus cooling, for a combined electric bill near $1,090 a year. The gas furnace it replaces burns roughly 52 Mcf a year at 11.25 per Mcf here, for a running cost near $839 a year (electricity here runs 19.06¢/kWh). Looked at as a full purchase rather than an incremental one, payback here is longer than the 15-year equipment life, leaving the 15-year total $7,254 behind.
The other scenario: no gas furnace to begin with
Gas isn't universal in Plainfield — many houses run on electric heat already. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. The saving here runs about $1,559 a year, which recovers the extra $8,000 spent going electric in roughly 5.1 years.
Plainfield against the rest of the country
Plainfield lands at position 805 out of 3206 cities on heating severity (coldest is 1), and 837 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.
Next step for 48,881 people in Plainfield
About 48,881 people live in Plainfield, Illinois, 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.
Where Plainfield's figure comes from
Every constant behind this page — the 2.6 seasonal COP, the degree-day corrections, the equipment costs — is documented in the methodology guide. Plainfield's -4°F design temperature falls on the cold side of the 25°F cutoff the cold-climate unit guide walks through.