The Garage Heat Index

Every row below is the same garage — a 24×24 ft attached two-car garage, R-13 walls, one uninsulated steel door, average drafts — held at 50°F all winter, priced at each state's own current electricity, natural gas and propane rates. Only the climate (the state's population-primary weather station) and the fuel prices change from row to row. See the methodology page for the load, balance-point and cost formulas behind every figure here.

The Garage Heat Index

Electric and heat-pump prices are each state's current EIA residential rate; the heat pump column uses a reference 2.5CComputed by our enginecostsForSeasonalLoad() default heatPumpSeasonalCop — lib/planner/fuels.tsReport a problem seasonal COP, not a bin-by-bin simulation for a specific unit. Natural gas and propane assume a vented, 80% AFUE unit heater. A season here runs from whichever month the garage first needs continuous heat through whichever month it stops, computed from each station's own balance-point temperature — not a fixed calendar window, so it's longer in cold states and shorter in warm ones.

Why the same garage costs so differently by state

Two things move independently here: how cold it gets (the station's own design temperature and monthly averages) and what a kWh, therm or gallon costs locally. A mild state with expensive electricity and a cold state with cheap electricity can land on a similar number for very different reasons — the table separates the two so neither one hides in a single blended figure.