Chapel Hill, NC: the heat pump payback math
This one's marginal in Chapel Hill: it only clears if you stay long enough. $3,500 is what Chapel Hill would pay extra to go electric rather than replace the furnace and AC with the same again, once the $2,000 federal credit is applied. Chapel Hill's residents would see roughly $245 a year back in running costs, putting the payback around 14.3 years. It's a genuine toss-up here — Chapel Hill's numbers don't point clearly either way.
Chapel Hill's weather, in the numbers that matter
3022 heating degree days pile up here every year, so Chapel Hill has a real but manageable winter; the cooling side runs to 1378 cooling degree days, where summers are hot enough that cooling matters as much as heating. 18.7°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 15.1°F on file. Worked through the model, that's a seasonal COP of 3.15 on the cold-climate unit fit for this climate. Below the 25°F line where a standard machine starts leaning on resistance backup, Chapel Hill sits firmly in cold-climate territory, so that's the class of unit priced here. Source: NOAA station DURHAM 11 W , 4.1 miles from Chapel Hill — the closest one on record.
What it actually costs to run, year to year
Modelled on a typical 2000-square-foot house, the heat pump draws about 2,429 kWh a year to keep it warm, plus cooling, for a combined electric bill near $538 a year. Chapel Hill's gas rate of 16.42 per Mcf, applied to the 31 Mcf a year the furnace burns, puts its running cost near $783 a year, against 14.93¢ per kWh for electricity. Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs about 55 years, for a 15-year net position $180 ahead.
Electric resistance heat in Chapel Hill, compared
Gas isn't universal in Chapel Hill — many houses run on electric heat already. Swap the comparison to resistance heat instead of gas, and Chapel Hill's answer improves. Switching saves about $871 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 9.2 years.
Chapel Hill against the rest of the country
Ranked against the other 3206 cities covered, Chapel Hill comes in at 1912 for heating severity — 1 would be the coldest place in the dataset — and 614 by population, where 1 is largest. That's the middle third for winter severity among the cities covered here.
Next step for 64,028 people in Chapel Hill
Chapel Hill, North Carolina is home to about 64,028 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 Chapel Hill, 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
Nothing above is a black box: the methodology guide shows the full arithmetic behind Chapel Hill's 3.15 seasonal COP and payback figure. At a 18.7°F design temperature, Chapel Hill sits in cold-climate territory; the guide to that class of unit explains why.