Arroyo Municipio, PR Insulation Payback
Arroyo Municipio attic insulation, by the numbers
Arroyo Municipio sits in IECC climate zone 1 (Hot-Humid) — long, muggy summers and mild winters, where cooling dominates the energy bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-30. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-30 runs an estimated $1,680, and saves about $924 a year in heating and cooling — a payback around 1.8 years. Topping up the attic pays for itself fast here.
Where the savings come from
Split it out and it's roughly $0 a year on the heating side, $924 on cooling. By estimated insulation savings, Arroyo Municipio lands in the 11th percentile nationally. Zone 1 alone covers 81 counties in this dataset, and Arroyo Municipio comes in 3rd by savings. Puerto Rico averages $660/year across the counties tracked here; Arroyo Municipio comes in 40% higher.
Arroyo Municipio's actual weather, not a national average
The heating and cooling degree days behind this estimate — 0 HDD and 5,958 CDD (base 65°F, 1991-2020 normals) — come from GUAYAMA 2E, PR RQ, the nearest NOAA station with published normals, 3 miles from Arroyo Municipio's center. Combined heating and cooling load puts Arroyo Municipio in the 51th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Arroyo Municipio sits in moisture regime A (humid), which can affect the vapor-barrier choice.
If the attic isn't bare
Already have a few inches up there? Topping R-11 up to R-25 runs about $840 for about $101/year saved — roughly 8.3 years to break even. Call this borderline rather than a clear win.
Getting it done in Arroyo Municipio
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 Arroyo Municipio's estimated $924/year on the line.
Where these figures come from
Arroyo Municipio'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.