Union County, IA Insulation Payback
Union County attic insulation, by the numbers
DOE classifies Union County as climate zone 5, cold — a real winter that drives most of the annual energy bill here. 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 $1,924 a year in heating and cooling — a payback around 1.8 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,790 a year on the heating side, $133 on cooling. By estimated insulation savings, Union County lands in the 78th percentile nationally. Zone 5 alone covers 745 counties in this dataset, and Union County comes in 120th by savings. Iowa averages $1,985/year across the counties tracked here; Union County comes in 3% lower.
The climate data behind this
The heating and cooling degree days behind this estimate — 6,696 HDD and 831 CDD (base 65°F, 1991-2020 normals) — come from CRESTON 2 SW, IA US, the nearest NOAA station with published normals, 7.8 miles from Union County's center. Combined heating and cooling load puts Union County in the 80th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Union County sits in moisture regime A (humid), 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 $281/year saved (~8.1-year payback). Call this borderline rather than a clear win.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $3,480 figure above as a planning number for Union County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Union 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.