Saline County, IL Insulation Payback
Saline County attic insulation, by the numbers
DOE classifies Saline County as climate zone 4, mixed-humid — a genuine mix of cold winters and humid summers, with neither one dominating the bill. Its recommended attic R-value for bare joists is R-60. For an attic around 1,000 square feet, closing the gap from R-2 to R-60 costs around $3,480 and saves an estimated $1,394 a year — payback in roughly 2.5 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,149 a year on the heating side, $244 on cooling. By estimated insulation savings, Saline County lands in the 45th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Saline County comes in 401st by savings. Illinois averages $1,642/year across the counties tracked here; Saline County comes in 15% lower.
The climate data behind this
NOAA's HARRISBURG, IL US station, 1.3 miles from Saline County, supplies the 4,299 HDD and 1,522 CDD this estimate runs on. That combined heating-and-cooling load ranks Saline County 1656th nationally by total degree days — the 48th percentile. One local detail the R-value alone won't tell you: Saline County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
If Saline County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $203/year — payback about 11.2 years. Call this borderline rather than a clear win.
Getting it done in Saline County
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 Saline County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Saline 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.