Sweetwater County, WY Insulation Payback
Sweetwater County attic insulation, by the numbers
DOE classifies Sweetwater County as climate zone 6, cold — winters that dominate the energy bill, with cooling a minor factor. Its recommended attic R-value for bare joists is R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $2,207 a year in heating and cooling — a payback around 1.6 years. Topping up the attic pays for itself fast here.
Where the savings come from
Split it out and it's roughly $2,156 a year on the heating side, $51 on cooling. By estimated insulation savings, Sweetwater County lands in the 90th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Sweetwater County comes in 179th by savings. Wyoming averages $2,161/year across the counties tracked here; Sweetwater County comes in 2% higher.
The climate data behind this
The heating and cooling degree days behind this estimate — 8,064 HDD and 319 CDD (base 65°F, 1991-2020 normals) — come from ROCK SPRINGS AP, WY US, the nearest NOAA station with published normals, 10.2 miles from Sweetwater County's center. By total degree days, Sweetwater County sits at the 90th percentile nationally. One local detail the R-value alone won't tell you: Sweetwater County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
The smaller top-up scenario
A shallower starting point changes the math: with R-11 already down, only the gap to R-49 needs filling, at roughly $2,280 for an estimated $322/year saved (~7.1-year payback). Worth doing on the numbers alone.
Getting it done in Sweetwater County
Get more than one quote before committing. Attic access and any needed air sealing move the price around, and most contractors won't take a job below roughly $600 regardless of size - worth asking upfront given Sweetwater County's estimated $2,207/year on the line.
Where these figures come from
Sweetwater County's R-60 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-60 is the target here specifically.