Arlington / Mount Vernon
Mount Vernon has 13,122 residents (give or take 1,088) (ACS 2020-2024 5-year, table B01003, https://data.census.gov/table/ACSDT5Y2024.B01003?g=160XX00US5154144, checked 2026-10-19), about 2,511 people per square mile.
Mount Vernon is about 11 miles from the Census center point for Arlington in a straight line and covers 5.225 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 Mount Vernon that is 22309 (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).
Of the 4,850 occupied homes in Mount Vernon, 61% heat with natural gas, 6% with heating oil, 30% with electricity and 0% with propane (ACS 2020-2024 5-year, table B25040, https://data.census.gov/table/ACSDT5Y2024.B25040?g=160XX00US5154144, checked 2026-10-19).
Gas heats 61% of Mount Vernon against electricity at 30%, so most quotes here are a partial-home system that carries the shoulder seasons and the summer while the gas furnace handles the coldest nights, or a whole-home system when the house is ready for it.
Mount Vernon has 5 points more oil heat than Fairfax County as a whole, where 1% of homes burn oil, and 12 points less electric heat than the county's 42% (ACS 2020-2024 5-year, table B25040, https://data.census.gov/table/ACSDT5Y2024.B25040?g=050XX00US51059, checked 2026-10-19).
Mount Vernon has 4,973 housing units, 1% built before 1940 and 70% before 1980, with 13% built in 2000 or later (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=160XX00US5154144, checked 2026-10-19).
Mount Vernon has 7 points fewer homes built after 2000 than the county's 20% (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=050XX00US51059, checked 2026-10-19).
The median Mount Vernon home was built in 1968 (ACS 2020-2024 5-year, table B25035, https://data.census.gov/table/ACSDT5Y2024.B25035?g=160XX00US5154144, checked 2026-10-19) and the median home has 7.8 rooms (ACS 2020-2024 5-year, table B25018, https://data.census.gov/table/ACSDT5Y2024.B25018?g=160XX00US5154144, checked 2026-10-19).
74% of Mount Vernon homes are single-family detached, 3% are in two- to four-unit buildings and 13% are in buildings of five or more units (ACS 2020-2024 5-year, table B25024, https://data.census.gov/table/ACSDT5Y2024.B25024?g=160XX00US5154144, checked 2026-10-19).
With 74% detached houses and 3% in small multi-family buildings, a Mount Vernon quote is usually one or two outdoor units with ducted or ductless heads sized room by room. With 27% of Mount Vernon homes rented (ACS 2020-2024 5-year, table B25003, https://data.census.gov/table/ACSDT5Y2024.B25003?g=160XX00US5154144, checked 2026-10-19), the landlord signs the quote in many of them.
Mount Vernon has 28 points more detached houses than Fairfax County overall (46%) and 16 points fewer five-plus-unit buildings than the county's 29% (ACS 2020-2024 5-year, table B25024, https://data.census.gov/table/ACSDT5Y2024.B25024?g=050XX00US51059, checked 2026-10-19).
70% of Mount Vernon homes were built before 1980 and only 13% in 2000 or later (ACS 2020-2024 5-year, table B25034, https://data.census.gov/table/ACSDT5Y2024.B25034?g=160XX00US5154144, 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 Mount Vernon 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 Mount Vernon is $163,750 (ACS 2020-2024 5-year, table B19013, https://data.census.gov/table/ACSDT5Y2024.B19013?g=160XX00US5154144, 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: 14F. Source: ENERGY STAR Design Temperature Limit Reference Guide (2019 Edition), Fairfax County row, 99% heating, PDF pages 127 to 133 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 14F figure is the Fairfax County cold-day number a Mount Vernon heat pump is sized against, so ask the installer to show the system's heating output at 14F, not at the milder rating-label temperature.
Ask whether the quote is whole-home or partial-home, because with 61% of Mount Vernon on gas and 30% already electric the two paths carry different rebate figures and different sizing.
Ask for the heat-loss calculation room by room; the median Mount Vernon home has 7.8 rooms and was built around 1968, 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 Mount Vernon. The public number is the number the contractor quotes from.
No local contractor is named on this door for Mount Vernon yet. A request from this page goes to the first licensed shop that takes the door.