Should Herndon switch to a heat pump?
In Herndon, the extra upfront cost technically comes back, just not before the equipment wears out. Against a like-for-like gas furnace and AC swap, going electric costs $3,500 more up front here (already netting out a $2,000 tax credit). Lower bills claw that back: about $224 saved annually, for a payback of roughly 15.6 years. Herndon's own numbers say this pencils out only in theory, not in practice.
The climate behind Herndon's payback figure
Herndon has a real but manageable winter — 3678 heating degree days a year against a 65°F base — and summers are hot enough that cooling matters as much as heating, at 1567 cooling degree days. 8.1°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 7°F on file. Worked through the model, that's a seasonal COP of 2.89 on the cold-climate unit fit for this climate. A cold-climate unit is the right call in Herndon — below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. These numbers come from WASHINGTON DULLES INTERNATION, the closest NOAA station, 4 miles out.
What it actually costs to run, year to year
Electricity use for heating alone comes out to about 3,223 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $756 a year. That compares with roughly 38 Mcf a year of gas at Herndon's 16.79 per-Mcf rate — about $980 a year — against a local electricity rate of 16.58¢/kWh. Priced as a standalone purchase rather than against a like-for-like replacement, equipment payback runs about 60.3 years, for a 15-year net position $139 behind.
The other scenario: no gas furnace to begin with
Plenty of homes in Herndon 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. The saving here runs about $1,125 a year, which recovers the extra $8,000 spent going electric in roughly 7.1 years.
How Herndon compares nationally
Ranked against the other 3206 cities covered, Herndon comes in at 1694 for heating severity — 1 would be the coldest place in the dataset — and 1594 by population, where 1 is largest. That's the middle third for winter severity among the cities covered here.
Deciding what's next in Herndon, VA
About 25,180 people live in Herndon, Virginia, and every number on this page is what a contractor would actually work from when quoting a system here — the point isn't to replace that quote, it's to tell you whether to bother asking for one. Here, there's no cost penalty to waiting until your current furnace or AC actually needs replacing.
Line up a few local HVAC quotes before you decide.
More on how this number was built
Every constant behind this page — the 2.89 seasonal COP, the degree-day corrections, the equipment costs — is documented in the methodology guide. Herndon's 8.1°F design temperature is below the 25°F line, which is why a cold-climate unit is the right call here — see what that changes in the cold-climate unit guide.