Arapahoe County, CO Insulation Payback
Arapahoe County, CO: what topping up your attic actually costs
Arapahoe County sits in IECC climate zone 5 (Cold) — winters that dominate the energy bill, with cooling a minor factor. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-60. For an attic around 1,000 square feet, closing the gap from R-2 to R-60 costs around $3,480 and saves an estimated $1,827 a year — payback in roughly 1.9 years. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,718/year heating, $108/year cooling. Out of every 100 US counties tracked here, Arapahoe County's savings potential beats roughly 74 of them. Within zone 5 specifically, it ranks 252nd of 745 counties by estimated savings. Colorado averages $2,043/year across the counties tracked here; Arapahoe County comes in 11% lower.
Where these numbers come from
Arapahoe County's climate figures — 6,427 heating and 674 cooling degree days a year — are read from BYERS 5 ENE, CO US, 12.7 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Arapahoe County 845th nationally by total degree days — the 73th percentile. Arapahoe County falls in DOE's moisture regime B (dry), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
If Arapahoe 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 $266/year — payback about 8.6 years. This one is a genuine toss-up, not a clear yes.
Next steps for a Arapahoe County attic
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 Arapahoe County's estimated $1,827/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.