Maui County, HI Insulation Payback
Maui County attic insulation, by the numbers
DOE classifies Maui County as climate zone 1, hot-humid — summers that stay hot and humid while winters barely register on the energy bill. Its recommended attic R-value for bare joists is R-30. For an attic around 1,000 square feet, closing the gap from R-2 to R-30 costs around $1,680 and saves an estimated $518 a year — payback in roughly 3.2 years. Topping up the attic pays for itself here.
The breakdown behind the number
Split it out and it's roughly $0 a year on the heating side, $518 on cooling. By estimated insulation savings, Maui County lands in the 1th percentile nationally. Zone 1 alone covers 81 counties in this dataset, and Maui County comes in 61st by savings. Hawaii averages $808/year across the counties tracked here; Maui County comes in 36% lower.
Maui County's actual weather, not a national average
NOAA's PUUKOLII 457.1, HI US station, 6.8 miles from Maui County, supplies the 1 HDD and 3,341 CDD this estimate runs on. Combined heating and cooling load puts Maui County in the 1th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Maui County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
If the attic isn't bare
If Maui County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-25. That smaller top-up costs around $840 and saves an estimated $57/year — payback about 14.9 years. Call this borderline rather than a clear win.
Quotes and materials for this job
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $1,680 as a starting estimate for a Maui County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Where these figures come from
Maui County's R-30 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-30 is the target here specifically.