Bonneville County, ID Insulation Payback
Bonneville County attic insulation, by the numbers
Bonneville County sits in IECC climate zone 6 (Cold) — winters that dominate the energy bill, with cooling a minor factor. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to 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 $2,281 a year in heating and cooling — a payback around 1.5 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $2,259 a year on the heating side, $22 on cooling. By estimated insulation savings, Bonneville County lands in the 93th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Bonneville County comes in 108th by savings. Idaho averages $1,995/year across the counties tracked here; Bonneville County comes in 14% higher.
Where these numbers come from
NOAA's IDAHO FALLS 16 SE, ID US station, 8.9 miles from Bonneville County, supplies the 8,450 HDD and 136 CDD this estimate runs on. That combined heating-and-cooling load ranks Bonneville County 265th nationally by total degree days — the 92th percentile. One local detail the R-value alone won't tell you: Bonneville County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
If the attic isn't bare
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $333/year saved — roughly 6.9 years to break even. Worth doing on the numbers alone.
Quotes and materials for this job
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 Bonneville County's estimated $2,281/year on the line.
Where these figures come from
Bonneville 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.