Marion County, IN Insulation Payback
Marion County, IN: what topping up your attic actually costs
Marion County sits in IECC climate zone 5 (Cold) — a real winter that drives most of the annual energy bill here. 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 $1,677 a year in heating and cooling — a payback around 2.1 years. That's about as fast as attic paybacks get.
Heating vs. cooling in Marion County
The estimated savings split roughly $1,525/year heating, $152/year cooling. Out of every 100 US counties tracked here, Marion County's savings potential beats roughly 65 of them. Within zone 5 specifically, it ranks 524th of 745 counties by estimated savings. Indiana averages $1,634/year across the counties tracked here; Marion County comes in 3% higher.
The climate data behind this
The heating and cooling degree days behind this estimate — 5,704 HDD and 947 CDD (base 65°F, 1991-2020 normals) — come from INDIANAPOLIS SE SIDE, IN US, the nearest NOAA station with published normals, 5.8 miles from Marion County's center. That combined heating-and-cooling load ranks Marion County 1115th nationally by total degree days — the 65th percentile. Marion County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
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 $245/year saved — roughly 9.3 years to break even. This one is a genuine toss-up, not a clear yes.
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 Marion County's estimated $1,677/year on the line.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-60 is the target here specifically.