Pima County, AZ Insulation Payback
Is attic insulation worth it in Pima County, AZ?
DOE classifies Pima County as climate zone 2, hot-dry — intense summer heat with low humidity, where attic radiant heat gain is the main driver. Its recommended attic R-value for bare joists is R-49. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-49 runs an estimated $2,820, and saves about $1,157 a year in heating and cooling — a payback around 2.4 years. Few home upgrades pay back that quickly.
Heating vs. cooling in Pima County
Heating accounts for about $1,059/year of that and cooling about $98/year — Pima County needs both. Nationally, Pima County ranks in the 28th percentile for insulation savings potential. Compared only against its own climate zone, Pima County places 1st out of 233. Against Arizona's own average of $1,149/year, Pima County runs 1% above that.
Where these numbers come from
NOAA's KITT PEAK, AZ US station, 15.9 miles from Pima County, supplies the 3,992 HDD and 616 CDD this estimate runs on. That combined heating-and-cooling load ranks Pima County 2725th nationally by total degree days — the 14th percentile. Its moisture regime is classified dry, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $156/year saved — roughly 10.4 years to break even. Whether that is worth it depends on how long you plan to stay.
Getting it done in Pima County
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 Pima County's estimated $1,157/year on the line.
Pima County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Pima County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.