Sullivan County, IN Insulation Payback
Sullivan County attic insulation, by the numbers
Sullivan County sits in IECC climate zone 4 (Mixed-Humid) — real heating and real cooling seasons both, roughly balanced across the year. 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 $1,540 a year in heating and cooling — a payback around 2.3 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,348 a year on the heating side, $192 on cooling. By estimated insulation savings, Sullivan County lands in the 56th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Sullivan County comes in 113th by savings. Indiana averages $1,634/year across the counties tracked here; Sullivan County comes in 6% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 5,043 HDD and 1,193 CDD (base 65°F, 1991-2020 normals) — come from SHAKAMAK SP, IN US, the nearest NOAA station with published normals, 10.5 miles from Sullivan County's center. That combined heating-and-cooling load ranks Sullivan County 1366th nationally by total degree days — the 57th percentile. One local detail the R-value alone won't tell you: Sullivan County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
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 $225/year saved (~10.1-year payback). Call this borderline rather than a clear win.
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 Sullivan County's estimated $1,540/year on the line.
Where these figures come from
Sullivan 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.