Northbrook, IL: the heat pump payback math
Northbrook is a place where a heat pump genuinely costs more to operate than the alternative. 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. Unfortunately the electric bill outweighs the gas bill it replaces by about $228 a year here, so the extra spend stays unrecovered. There's no spin on that: Northbrook's numbers say wait.
The climate behind Northbrook's payback figure
4991 heating degree days pile up here every year, so Northbrook has a real but manageable winter; the cooling side runs to 1020 cooling degree days, where summers are hot enough that cooling matters as much as heating. The 99% winter design temperature here — the cold snap equipment must be sized for, not the seasonal average — is -0.9°F, against a record low of -11°F. That puts the seasonal coefficient of performance at 2.68 for the recommended cold-climate unit. A cold-climate unit is the right call in Northbrook — 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 PALWAUKEE MUNICIPAL ARPT, the closest NOAA station, 3.6 miles out.
What it actually costs to run, year to year
A 2000-square-foot house here would pull roughly 4,716 heating kilowatt-hours annually on top of cooling, totalling about $1,065 a year on electricity. That compares with roughly 52 Mcf a year of gas at Northbrook's 11.25 per-Mcf rate — about $837 a year — against a local electricity rate of 19.06¢/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 $6,917 behind.
Electric resistance heat in Northbrook, compared
Not every home in Northbrook has gas service. Swap the comparison to resistance heat instead of gas, and Northbrook's answer improves. Switching saves about $1,596 a year here — a heat pump moving heat rather than generating it needs far less electricity than resistance coils — so the extra $8,000 spent up front comes back in about 5 years.
Northbrook against the rest of the country
Ranked against the other 3206 cities covered, Northbrook comes in at 718 for heating severity — 1 would be the coldest place in the dataset — and 1190 by population, where 1 is largest. That's the coldest third of the dataset, where climate does most of the work behind this figure.
Next step for 34,546 people in Northbrook
About 34,546 people live in Northbrook, 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.
Ask a local HVAC contractor for a quote before committing either way.
Reading further on this page's numbers
Nothing above is a black box: the methodology guide shows the full arithmetic behind Northbrook's 2.68 seasonal COP and payback figure. At a -0.9°F design temperature, Northbrook sits in cold-climate territory; the guide to that class of unit explains why.