Mountain View, CA: the heat pump payback math
In Mountain View, a heat pump would cost more to run each year than what you have now. Against a like-for-like gas furnace and AC swap, going electric costs $1,000 more up front here (already netting out a $2,000 tax credit). The heat pump would cost about $2 more a year to run than the furnace it replaces — a premium with no payback. There's no spin on that: Mountain View's numbers say wait.
The climate behind Mountain View's payback figure
Degree days tell the story here: Mountain View racks up 2250 heating degree days each year (base 65°F), and summers add a moderate cooling load, with 387 cooling degree days on the cooling side. 35.6°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 35.6°F on file. Worked through the model, that's a seasonal COP of 3.26 on the standard unit fit for this climate. A standard ducted system is enough here; Mountain View's design temperature doesn't justify the cold-climate premium. Climate figures trace to the nearest NOAA station, MOFFETT FEDERAL AIRFIELD, 1.8 miles from Mountain View.
What it actually costs to run, year to year
Modelled on a typical 2000-square-foot house, the heat pump draws about 1,748 kWh a year to keep it warm, plus cooling, for a combined electric bill near $682 a year. That compares with roughly 23 Mcf a year of gas at Mountain View's 22.01 per-Mcf rate — about $680 a year — against a local electricity rate of 32.83¢/kWh. Looked at as a full purchase rather than an incremental one, payback here is longer than the 15-year equipment life, leaving the 15-year total $1,025 behind.
The other scenario: no gas furnace to begin with
Plenty of homes in Mountain View heat with electricity alone, no gas line involved. Swap the comparison to resistance heat instead of gas, and Mountain View's answer improves. The saving here runs about $1,353 a year, which recovers the extra $5,500 spent going electric in roughly 4.1 years.
How Mountain View compares nationally
Among 3206 cities, Mountain View's winter puts it at rank 2304 for severity, while its size puts it at rank 410 for population — 1 in both cases being the extreme. That's the mildest third of cities covered, where utility rates carry more of the answer than climate does.
What to do with this number in Mountain View
About 87,316 people live in Mountain View, California, 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.
Where Mountain View's figure comes from
The methodology guide walks through exactly how Mountain View's 3.26 seasonal COP and the rest of this page's numbers get built. The guide on cities that never pay back covers exactly Mountain View's situation: a genuinely higher annual running cost, not a slow one.