Logan County, IL Insulation Payback
Is attic insulation worth it in Logan County, IL?
Logan County, Illinois is zone 5 under DOE's climate map (Cold), which means a real winter that drives most of the annual energy bill here. An uninsulated attic there should be built 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 $1,667 a year in heating and cooling — a payback around 2.1 years. Few home upgrades pay back that quickly.
Heating vs. cooling in Logan County
Heating accounts for about $1,504/year of that and cooling about $163/year — Logan County needs both. Nationally, Logan County ranks in the 64th percentile for insulation savings potential. Compared only against its own climate zone, Logan County places 538th out of 745. Against Illinois's own average of $1,642/year, Logan County runs 2% above that.
Logan County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 5,624 HDD and 1,015 CDD (base 65°F, 1991-2020 normals) — come from LINCOLN, IL US, the nearest NOAA station with published normals, 2.1 miles from Logan County's center. By total degree days, Logan County sits at the 65th percentile nationally. Its moisture regime is classified humid, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
Already have some insulation?
If Logan 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 $243/year — payback about 9.4 years. Whether that is worth it depends on how long you plan to stay.
Getting it done in Logan 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 Logan County's estimated $1,667/year on the line.
Logan County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Logan County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.