South Pasadena, CA: the heat pump payback math
South Pasadena clears a genuine payback here, inside a reasonable stretch of years. 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). Lower bills claw that back: about $323 saved annually, for a payback of roughly 3.1 years. That's a real payback, built from South Pasadena's own climate and utility rates, not a national guess.
The climate behind South Pasadena's payback figure
South Pasadena barely has a winter to speak of — 686 heating degree days a year against a 65°F base — and summers are hot enough that cooling matters as much as heating, at 2300 cooling degree days. 39.2°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 37.4°F on file. Worked through the model, that's a seasonal COP of 3.37 on the standard unit fit for this climate. A standard ducted system is enough here; South Pasadena's design temperature doesn't justify the cold-climate premium. These numbers come from EL MONTE AIRPORT, the closest NOAA station, 7.3 miles out.
The month-to-month numbers for South Pasadena
A 2000-square-foot house here would pull roughly 515 heating kilowatt-hours annually on top of cooling, totalling about $813 a year on electricity. South Pasadena's gas rate of 22.01 per Mcf, applied to the 7 Mcf a year the furnace burns, puts its running cost near $1,136 a year, against 32.83¢ per kWh for electricity. Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs about 34.1 years, for a 15-year net position $3,842 ahead.
If your home heats with electric baseboard instead of gas
Plenty of homes in South Pasadena heat with electricity alone, no gas line involved. Swap the comparison to resistance heat instead of gas, and South Pasadena's answer improves. Switching saves about $736 a year here — a heat pump moving heat rather than generating it needs far less electricity than resistance coils — so the extra $5,500 spent up front comes back in about 7.5 years.
South Pasadena against the rest of the country
Ranked against the other 3206 cities covered, South Pasadena comes in at 3009 for heating severity — 1 would be the coldest place in the dataset — and 1565 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.
What to do with this number in South Pasadena
About 25,656 people live in South Pasadena, 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, it's worth getting quotes before your current system fails, not after.
Ask a local HVAC contractor for a quote before committing either way.
Reading further on this page's numbers
Nothing above is a black box: the methodology guide shows the full arithmetic behind South Pasadena's 3.37 seasonal COP and payback figure. See what South Pasadena's figure looks like without the $2,000 federal credit in the guide to how that credit moves the payback window.