Is a heat pump worth it in Derby?
Derby is a place where a heat pump genuinely costs more to operate than the alternative. 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). Running costs here land $208 a year HIGHER than the furnace it replaces, so that premium is never recovered. There's no spin on that: Derby's numbers say wait.
The climate behind Derby's payback figure
Degree days tell the story here: Derby racks up 4517 heating degree days each year (base 65°F), and summers add a moderate cooling load, with 722 cooling degree days on the cooling side. 16.9°F is the figure equipment gets sized against here — the 99th-percentile cold snap, not an average day — with a record low of 10.8°F on file. Worked through the model, that's a seasonal COP of 3.11 on the cold-climate unit fit for this climate. Derby needs the cold-climate class of unit: past a 25°F design temperature a standard heat pump falls back on resistance backup often enough to eat the savings. These numbers come from NEW HAVEN, the closest NOAA station, 11 miles out.
Derby's running-cost comparison, in dollars
A 2000-square-foot house here would pull roughly 3,678 heating kilowatt-hours annually on top of cooling, totalling about $1,279 a year on electricity. That compares with roughly 47 Mcf a year of gas at Derby's 16.83 per-Mcf rate — about $1,070 a year — against a local electricity rate of 29.78¢/kWh. Looked at as a full purchase rather than an incremental one, payback here is longer than the 15-year equipment life, leaving the 15-year total $6,622 behind.
The other scenario: no gas furnace to begin with
Not every home in Derby has gas service. Swap the comparison to resistance heat instead of gas, and Derby's answer improves. The saving here runs about $2,406 a year, which recovers the extra $8,000 spent going electric in roughly 3.3 years.
How Derby compares nationally
Derby lands at position 1189 out of 3206 cities on heating severity (coldest is 1), and 2664 out of 3206 by population size (biggest is 1). That's the middle third for winter severity among the cities covered here.
What to do with this number in Derby
About 12,915 people live in Derby, Connecticut, 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 3.11 seasonal COP, the degree-day corrections, the equipment costs — is documented in the methodology guide. At a 16.9°F design temperature, Derby sits in cold-climate territory; the guide to that class of unit explains why.