Hillsborough, CA: the heat pump payback math
Hillsborough is a place where a heat pump genuinely costs more to operate than the alternative. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $1,000 after a $2,000 federal tax credit. The heat pump would cost about $30 more a year to run than the furnace it replaces — a premium with no payback. That's Hillsborough's own climate and rates talking, not a hedge or a caveat.
How cold Hillsborough actually gets
2665 heating degree days pile up here every year, so Hillsborough has a mild winter by US standards; the cooling side runs to 90 cooling degree days, where summers rarely ask much of an air conditioner. The 99% winter design temperature here — the cold snap equipment must be sized for, not the seasonal average — is 39.9°F, against a record low of 35.1°F. That puts the seasonal coefficient of performance at 3.39 for the recommended standard unit. Hillsborough's winters don't get cold enough to need the cold-climate premium — a standard unit holds up fine. Source: NOAA station SAN FRANCISCO INTERNATIONAL A, 4.4 miles from Hillsborough — the closest one on record.
Hillsborough's running-cost comparison, in dollars
Electricity use for heating alone comes out to about 1,991 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $679 a year. The gas furnace it replaces burns roughly 28 Mcf a year at 22.01 per Mcf here, for a running cost near $649 a year (electricity here runs 32.83¢/kWh). Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs past the 15-year equipment life, for a 15-year net position $1,443 behind.
The other scenario: no gas furnace to begin with
Gas isn't universal in Hillsborough — many houses run on electric heat already. Against electric-resistance heat — baseboard or an electric furnace, both 100% efficient but still just resistance — the case for switching gets stronger here. The saving here runs about $1,575 a year, which recovers the extra $5,500 spent going electric in roughly 3.5 years.
How Hillsborough compares nationally
Hillsborough lands at position 2063 out of 3206 cities on heating severity (coldest is 1), and 2952 out of 3206 by population size (biggest is 1). That's the middle third for winter severity among the cities covered here.
Next step for 11,171 people in Hillsborough
Hillsborough, California is home to about 11,171 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 Hillsborough, nothing is lost by holding off until the current equipment genuinely fails.
Get quotes from local HVAC contractors before deciding.
Reading further on this page's numbers
The methodology guide walks through exactly how Hillsborough's 3.39 seasonal COP and the rest of this page's numbers get built. Hillsborough is one of the cities where running costs land higher every year, not just slower to pay back — the guide to where this happens lays out why.