Brookings County, SD Insulation Payback
Brookings County attic insulation, by the numbers
DOE classifies Brookings County as climate zone 6, cold — a real winter that drives most of the annual energy bill here. 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 1.5 years at an estimated $2,324/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Brookings County
Split it out and it's roughly $2,240 a year on the heating side, $84 on cooling. By estimated insulation savings, Brookings County lands in the 94th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Brookings County comes in 80th by savings. South Dakota averages $2,162/year across the counties tracked here; Brookings County comes in 7% higher.
Brookings County's actual weather, not a national average
Brookings County's climate figures — 8,378 heating and 524 cooling degree days a year — are read from BROOKINGS 2 NE, SD US, 3.9 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Brookings County 189th nationally by total degree days — the 94th percentile. One local detail the R-value alone won't tell you: Brookings County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $339/year saved — roughly 6.7 years to break even. Worth doing on the numbers alone.
Quotes and materials for this job
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 Brookings County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Brookings 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.