Greene County, IL Insulation Payback
Greene County attic insulation, by the numbers
DOE classifies Greene County as climate zone 5, cold — winters that dominate the energy bill, with cooling a minor factor. Its recommended attic R-value for bare joists is R-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 2.1 years at an estimated $1,642/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Greene County
Split it out and it's roughly $1,464 a year on the heating side, $178 on cooling. By estimated insulation savings, Greene County lands in the 62th percentile nationally. Zone 5 alone covers 745 counties in this dataset, and Greene County comes in 586th by savings. Illinois averages $1,642/year across the counties tracked here; Greene County comes in 0% higher.
Where these numbers come from
NOAA's WHITE HALL 1 E, IL US station, 5.9 miles from Greene County, supplies the 5,477 HDD and 1,107 CDD this estimate runs on. By total degree days, Greene County sits at the 63th percentile nationally. One local detail the R-value alone won't tell you: Greene County sits in moisture regime A (humid), 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 $240/year saved — roughly 9.5 years to break even. Call this borderline rather than a clear win.
Next steps for a Greene County attic
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 Greene County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Greene 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.