Idaho Falls, ID: the heat pump payback math
Here in Idaho Falls, the honest answer is that a heat pump raises your annual running cost. 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). Unfortunately the electric bill outweighs the gas bill it replaces by about $220 a year here, so the extra spend stays unrecovered. There's no spin on that: Idaho Falls's numbers say wait.
Why Idaho Falls's climate drives this number
Degree days tell the story here: Idaho Falls racks up 6714 heating degree days each year (base 65°F), and summers add a moderate cooling load, with 545 cooling degree days on the cooling side. Sizing runs off the design temperature, not the average day: 0°F here (record low -14.1°F), which works out to a seasonal COP of 2.7 for the cold-climate class of unit this climate calls for. Idaho Falls 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. Source: NOAA station IDAHO FALLS REGIONAL ARPT, 2.5 miles from Idaho Falls — the closest one on record.
The month-to-month numbers for Idaho Falls
Electricity use for heating alone comes out to about 6,297 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $847 a year. The gas furnace it replaces burns roughly 70 Mcf a year at 7.69 per Mcf here, for a running cost near $626 a year (electricity here runs 12.52¢/kWh). Buy it outright, not incrementally, and payback stretches to beyond the 15-year equipment life; over 15 years the net position sits $6,805 behind.
The other scenario: no gas furnace to begin with
Gas isn't universal in Idaho Falls — 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 $1,370 a year comes back this way, enough that the 5.8-year payback clears the $8,000 premium comfortably within the equipment's life.
How Idaho Falls compares nationally
Idaho Falls lands at position 58 out of 3206 cities on heating severity (coldest is 1), and 559 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.
Deciding what's next in Idaho Falls, ID
About 69,523 people live in Idaho Falls, Idaho, 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.
Reading further on this page's numbers
The methodology guide walks through exactly how Idaho Falls's 2.7 seasonal COP and the rest of this page's numbers get built. Idaho Falls's 0°F design temperature falls on the cold side of the 25°F cutoff the cold-climate unit guide walks through.