San Francisco / Millbrae
Millbrae has 22,689 residents (give or take 27) (ACS 2020-2024 5-year, table B01003, https://data.census.gov/table/ACSDT5Y2024.B01003?g=160XX00US0647486, checked 2026-10-19), about 6,941 people per square mile.
Millbrae is about 36 miles from the Census center point for San Francisco in a straight line and covers 3.269 square miles of land (Census 2024 Gazetteer internal points and land area, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/, checked 2026-10-19).
The quote form takes a ZIP code; for Millbrae that is 94030 (Census 2020 ZCTA to county subdivision and ZCTA to place relationship files, ZIP areas at least 20% inside the town, https://www2.census.gov/geo/docs/maps-data/data/rel2020/zcta520/tab20_zcta520_cousub20_natl.txt and https://www2.census.gov/geo/docs/maps-data/data/rel2020/zcta520/tab20_zcta520_place20_natl.txt, checked 2026-10-19).
6,941 people per square mile puts Millbrae in suburban density, where the outdoor unit usually sits in a side yard and the noise is not an issue for neighbors.
Of the 8,121 occupied homes in Millbrae, 63% heat with natural gas, 0% with heating oil, 32% with electricity and 1% with propane (ACS 2020-2024 5-year, table B25040, https://data.census.gov/table/ACSDT5Y2024.B25040?g=160XX00US0647486, checked 2026-10-19).
Gas heats 63% of Millbrae against electricity at 32%, and a cold-climate heat pump sized for this market replaces the gas system outright, so the usual quote is a whole-home install.
Millbrae has about the San Mateo County oil share of 0% and the same 32% electric share (ACS 2020-2024 5-year, table B25040, https://data.census.gov/table/ACSDT5Y2024.B25040?g=050XX00US06081, checked 2026-10-19).
Millbrae has 8,705 housing units, 6% built before 1940 and 77% before 1980, with 11% built in 2000 or later (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=160XX00US0647486, checked 2026-10-19).
Millbrae has 3 points fewer pre-1940 homes than San Mateo County as a whole (9%) (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=050XX00US06081, checked 2026-10-19).
The median Millbrae home was built in 1962 (ACS 2020-2024 5-year, table B25035, https://data.census.gov/table/ACSDT5Y2024.B25035?g=160XX00US0647486, checked 2026-10-19) and the median home has 5.4 rooms (ACS 2020-2024 5-year, table B25018, https://data.census.gov/table/ACSDT5Y2024.B25018?g=160XX00US0647486, checked 2026-10-19).
61% of Millbrae homes are single-family detached, 5% are in two- to four-unit buildings and 31% are in buildings of five or more units (ACS 2020-2024 5-year, table B25024, https://data.census.gov/table/ACSDT5Y2024.B25024?g=160XX00US0647486, checked 2026-10-19).
39% of Millbrae homes are rented (ACS 2020-2024 5-year, table B25003, https://data.census.gov/table/ACSDT5Y2024.B25003?g=160XX00US0647486, checked 2026-10-19), so beside the 61% detached houses there is a real share of jobs where the landlord, not the resident, signs the quote.
Millbrae has 6 points more detached houses than San Mateo County overall (55%) (ACS 2020-2024 5-year, table B25024, https://data.census.gov/table/ACSDT5Y2024.B25024?g=050XX00US06081, checked 2026-10-19).
77% of Millbrae homes were built before 1980 and only 11% in 2000 or later (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=160XX00US0647486, checked 2026-10-19), so most of the stock predates modern insulation codes; the installer's heat-loss calculation, not a square-footage rule, decides the tonnage.
No electric utility is on file for Millbrae on this door yet, so this page does not name one; the name on the bill decides which rebate path applies.
Median household income in Millbrae is $163,476 (ACS 2020-2024 5-year, table B19013, https://data.census.gov/table/ACSDT5Y2024.B19013?g=160XX00US0647486, checked 2026-10-19); many state and utility heat pump rebate programs set higher incentive tiers for income-qualifying households, so the household income on the application, not the town median, decides which level applies.
Heating design temperature: 29F. Source: ENERGY STAR Design Temperature Limit Reference Guide (2019 Edition), San Mateo County row, 99% heating, PDF pages 11 to 13 of 141 (Revised 11/11/2020), https://www.energystar.gov/sites/default/files/Design%20Temperature%20Limit%20Reference%20Guide%20(2019%20Ed)%20-%20ENERGY%20STAR%20Single-Family%20New%20Homes_Rev11.pdf, fetched 2026-10-19, 99%.
That 29F figure is the San Mateo County cold-day number a Millbrae heat pump is sized against, so ask the installer to show the system's heating output at 29F, not at the milder rating-label temperature.
Ask whether the quote is whole-home or partial-home, because with 63% of Millbrae on gas and 32% already electric the two paths carry different rebate figures and different sizing.
Ask for the heat-loss calculation room by room; the median Millbrae home has 5.4 rooms and was built around 1962, and the count of heads and the tonnage follow the rooms and the insulation, not the square footage.
The form on this page is the follow-up for Millbrae. The public number is the number the contractor quotes from.
No local contractor is named on this door for Millbrae yet. A request from this page goes to the first licensed shop that takes the door.