Rockville, MD: the heat pump payback math
The payback math works in Rockville on paper, past the equipment's own working life. Swap a failed furnace and AC for a heat pump rather than buying like-for-like, and the extra cost here runs $3,500 after a $2,000 federal tax credit. That premium is recovered through $119 of lower running costs every year, landing the payback clock at roughly 29.5 years. That's a technicality, not a recommendation, for anyone actually living in Rockville.
Rockville's weather, in the numbers that matter
3720 heating degree days pile up here every year, so Rockville has a real but manageable winter; the cooling side runs to 1541 cooling degree days, where summers are hot enough that cooling matters as much as heating. Sizing runs off the design temperature, not the average day: 14.9°F here (record low 12.9°F), which works out to a seasonal COP of 3.06 for the cold-climate class of unit this climate calls for. A cold-climate unit is the right call in Rockville — below 25°F design temperature, a standard heat pump leans hard on electric-resistance backup, which erases most of the savings. Source: NOAA station COLLEGE PARK AP, 14.4 miles from Rockville — the closest one on record.
Rockville's running-cost comparison, in dollars
A 2000-square-foot house here would pull roughly 3,078 heating kilowatt-hours annually on top of cooling, totalling about $929 a year on electricity. The gas furnace it replaces burns roughly 39 Mcf a year at 16.14 per Mcf here, for a running cost near $1,048 a year (electricity here runs 21.16¢/kWh). Buy it outright, not incrementally, and payback stretches to 113.9 years; over 15 years the net position sits $1,722 behind.
The other scenario: no gas furnace to begin with
Plenty of homes in Rockville heat with electricity alone, no gas line involved. Swap the comparison to resistance heat instead of gas, and Rockville's answer improves. The saving here runs about $1,486 a year, which recovers the extra $8,000 spent going electric in roughly 5.4 years.
Rockville against the rest of the country
Ranked against the other 3206 cities covered, Rockville comes in at 1660 for heating severity — 1 would be the coldest place in the dataset — and 570 by population, where 1 is largest. That's the middle third for winter severity among the cities covered here.
Next step for 68,417 people in Rockville
Rockville, Maryland is home to about 68,417 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 Rockville, nothing is lost by holding off until the current equipment genuinely fails.
Get quotes from local HVAC contractors before deciding.
Where Rockville's figure comes from
The methodology guide walks through exactly how Rockville's 3.06 seasonal COP and the rest of this page's numbers get built. At a 14.9°F design temperature, Rockville sits in cold-climate territory; the guide to that class of unit explains why.