Heat Pump Payback in Key West, FL
Should Key West switch to a heat pump?
Key West sits right on the fence, how long you'll own the house decides this one. $3,000 is what Key West would pay extra to go electric rather than replace the furnace and AC with the same again. Key West's residents would see roughly $369 a year back in running costs, putting the payback around 8.1 years. Whether that's worth it in Key West depends on how many years you expect to own the place.
Compare against another city
Key West is one of 3206 cities covered here, each run through the same model. Search another below.
Why Key West's climate drives this number
7 heating degree days pile up here every year, so Key West barely has a winter to speak of; the cooling side runs to 5375 cooling degree days, where summers are severe enough that cooling can dominate the annual bill. The 99% winter design temperature here, the cold snap equipment must be sized for, not the seasonal average, is 57.9°F, and the coldest daily reading in the 2024 station record was 55°F. That puts the seasonal coefficient of performance at 3.93 for the recommended standard unit. A standard ducted system is enough here; Key West's design temperature doesn't justify the cold-climate premium. Source: NOAA station Key West International Airpor, 1.4 miles from Key West, the closest one on record.
Key West's running-cost comparison, in dollars
Heating hardly figures in Key West: on a 2000-square-foot reference house the heat pump's roughly $708 yearly electric bill is nearly all cooling. With so little heating demand, a furnace in Key West would burn only about 0 Mcf a year ($25.48 per Mcf); almost all of the $1,077 yearly running cost of the current system is cooling, at 15.43¢/kWh. Any saving here is really a cooling-efficiency saving. Buying outright rather than at replacement time stretches payback to longer than the 15-year equipment life. Over 15 years, compared with a like-for-like replacement, the heat pump leaves you $2,533 ahead.
How sensitive Key West's result is to prices
Because the heat pump's better air conditioning saves more electricity than its heating uses, it stays cheaper to run than the current furnace and AC in Key West at any electricity price. When quotes arrive, compare the heat pump price with a like-for-like furnace and AC replacement: at $369 a year saved, a difference under $2,583 pays back within 7 years here, and under $3,690 within 10.
The other scenario: no gas furnace to begin with
Plenty of homes in Key West heat with electricity alone, no gas line involved. Swap the comparison to resistance heat instead of gas, and Key West's answer improves. Even against resistance heat, the running-cost gap here isn't enough to clear the $7,500 incremental cost within the equipment's 15-year life.
Key West against the rest of the country
Ranked against the other 3206 cities covered, Key West comes in at 3205 for heating severity, 1 would be the coldest place in the dataset, and 1589 by population, where 1 is largest. That's the mildest third of cities covered, where utility rates carry more of the answer than climate does.
Deciding what's next in Key West, FL
About 25,240 people live in Key West, Florida, 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.
More on how this number was built
The methodology guide walks through exactly how Key West's 3.93 seasonal COP and the rest of this page's numbers get built. Not every home in Key West has gas; the guide comparing a heat pump against electric baseboard covers that case separately.