Heat Pump Payback in Seattle, WA
Seattle, WA: the heat pump payback math
In Seattle, the extra upfront cost technically comes back, just not before the equipment wears out. Against a like-for-like gas furnace and AC swap, going electric costs $5,500 more up front here. Lower bills claw that back: about $311 saved annually, for a payback of roughly 17.7 years. That's a technicality, not a recommendation, for anyone actually living in Seattle.
Compare against another city
Seattle is one of 3206 cities covered here, each run through the same model. Search another below.
Seattle's weather, in the numbers that matter
4232 heating degree days pile up here every year, so Seattle has a real but manageable winter; the cooling side runs to 365 cooling degree days, where summers add a moderate cooling load. 18°F is the figure equipment gets sized against here, the 99th-percentile cold snap, not an average day, with a low of 14°F in the 2024 station record. Worked through the model, that's a seasonal COP of 3.13 on the cold-climate unit fit for this climate. Seattle needs the cold-climate class of unit: past a 25°F design temperature a standard heat pump falls back on resistance backup often enough to eat the savings. Climate figures trace to the nearest NOAA station, Boeing Fld/King Co International AP, 6.6 miles from Seattle.
What it actually costs to run, year to year
A 2000-square-foot house here would pull roughly 3,424 heating kilowatt-hours annually on top of cooling, totalling about $533 a year on electricity. That compares with roughly 44 Mcf a year of gas at Seattle's $17.62 per-Mcf rate, about $844 a year with the old AC included, against a local electricity rate of 14.27¢/kWh. Priced as a standalone purchase, with a working furnace ripped out early, payback would take longer than the 15-year equipment life. Measured against the like-for-like replacement instead, a household here ends 15 years $833 behind.
How sensitive Seattle's result is to prices
Gas would only overtake the heat pump in Seattle if electricity rose past 23.8¢/kWh from 14.27¢, or gas fell under $10.56 per Mcf from $17.62. A useful quote test for Seattle: the heat pump is worth it within a decade if it costs less than $3,110 more than replacing the furnace and AC, and within 7 years if the gap is under $2,177.
If your home heats with electric baseboard instead of gas
Gas isn't universal in Seattle, many houses run on electric heat already. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. About $1,064 a year comes back this way, enough that the 9.4-year payback clears the $10,000 premium comfortably within the equipment's life.
Seattle against the rest of the country
Among 3206 cities, Seattle's winter puts it at rank 1387 for severity, while its size puts it at rank 18 for population, 1 in both cases being the extreme. That's the middle third for winter severity among the cities covered here.
Next step if you live in Seattle
Seattle, Washington is home to about 780,995 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 Seattle, nothing is lost by holding off until the current equipment genuinely fails.
Line up a few local HVAC quotes before you decide.
Where Seattle's figure comes from
Every constant behind this page, the 3.13 seasonal COP, the degree-day corrections, the equipment costs, is documented in the methodology guide. At a 18°F design temperature, Seattle sits in cold-climate territory; the guide to that class of unit explains why.