Half Moon Bay, CA: the heat pump payback math
Half Moon Bay is a place where a heat pump genuinely costs more to operate than the alternative. 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). Running costs here land $80 a year HIGHER than the furnace it replaces, so that premium is never recovered. That's Half Moon Bay's own climate and rates talking, not a hedge or a caveat.
Half Moon Bay's weather, in the numbers that matter
3680 heating degree days pile up here every year, so Half Moon Bay has a real but manageable winter; the cooling side runs to 5 cooling degree days, where summers rarely ask much of an air conditioner. 37.4°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 3.31 on the standard unit fit for this climate. Half Moon Bay's winters don't get cold enough to need the cold-climate premium — a standard unit holds up fine. Climate figures trace to the nearest NOAA station, HALF MOON BAY AIRPORT, 4.6 miles from Half Moon Bay.
The month-to-month numbers for Half Moon Bay
Electricity use for heating alone comes out to about 2,815 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $926 a year. That compares with roughly 38 Mcf a year of gas at Half Moon Bay's 22.01 per-Mcf rate — about $846 a year — against a local electricity rate of 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 $2,199 behind.
If your home heats with electric baseboard instead of gas
Plenty of homes in Half Moon Bay heat with electricity alone, no gas line involved. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. Switching saves about $2,136 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 2.6 years.
Half Moon Bay against the rest of the country
Among 3206 cities, Half Moon Bay's winter puts it at rank 1692 for severity, while its size puts it at rank 2923 for population — 1 in both cases being the extreme. That's the middle third for winter severity among the cities covered here.
Next step for 11,324 people in Half Moon Bay
Half Moon Bay, California is home to about 11,324 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 Half Moon Bay, nothing is lost by holding off until the current equipment genuinely fails.
Ask a local HVAC contractor for a quote before committing either way.
Where Half Moon Bay's figure comes from
The methodology guide walks through exactly how Half Moon Bay's 3.31 seasonal COP and the rest of this page's numbers get built. Half Moon Bay 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.