Millbrae, CA: the heat pump payback math

Here in Millbrae, 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 $1,000 more up front here (already netting out a $2,000 tax credit). Unfortunately the electric bill outweighs the gas bill it replaces by about $30 a year here, so the extra spend stays unrecovered. That's Millbrae's own climate and rates talking, not a hedge or a caveat.

How cold Millbrae actually gets

2665 heating degree days pile up here every year, so Millbrae 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. 39.9°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 35.1°F on file. Worked through the model, that's a seasonal COP of 3.39 on the standard unit fit for this climate. Millbrae's winters don't get cold enough to need the cold-climate premium — a standard unit holds up fine. These numbers come from SAN FRANCISCO INTERNATIONAL A, the closest NOAA station, 2.5 miles out.

Millbrae's running-cost comparison, in dollars

A 2000-square-foot house here would pull roughly 1,991 heating kilowatt-hours annually on top of cooling, totalling about $679 a year on electricity. That compares with roughly 28 Mcf a year of gas at Millbrae's 22.01 per-Mcf rate — about $649 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 $1,443 behind.

If your home heats with electric baseboard instead of gas

Plenty of homes in Millbrae heat with electricity alone, no gas line involved. 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 Millbrae compares nationally

Ranked against the other 3206 cities covered, Millbrae comes in at 2062 for heating severity — 1 would be the coldest place in the dataset — and 1697 by population, where 1 is largest. That's the middle third for winter severity among the cities covered here.

Deciding what's next in Millbrae, CA

Millbrae, California is home to about 23,321 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 Millbrae, nothing is lost by holding off until the current equipment genuinely fails.

Get quotes from local HVAC contractors before deciding.

Where Millbrae's figure comes from

Every constant behind this page — the 3.39 seasonal COP, the degree-day corrections, the equipment costs — is documented in the methodology guide. Millbrae 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.