San Bernardino County, CA Insulation Payback
San Bernardino County attic insulation, by the numbers
San Bernardino County sits in IECC climate zone 3 (Hot-Dry) — scorching, dry summers where heat radiating straight through the roof does most of the damage. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-49. For an attic around 1,000 square feet, closing the gap from R-2 to R-49 costs around $2,820 and saves an estimated $1,088 a year — payback in roughly 2.6 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $484 a year on the heating side, $604 on cooling. By estimated insulation savings, San Bernardino County lands in the 24th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and San Bernardino County comes in 265th by savings. California averages $1,056/year across the counties tracked here; San Bernardino County comes in 3% higher.
The climate data behind this
The heating and cooling degree days behind this estimate — 1,823 HDD and 3,789 CDD (base 65°F, 1991-2020 normals) — come from BAKER, CA US, the nearest NOAA station with published normals, 29.7 miles from San Bernardino County's center. By total degree days, San Bernardino County sits at the 42th percentile nationally. One local detail the R-value alone won't tell you: San Bernardino County sits in moisture regime B (dry), 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-38 runs about $1,620 for about $146/year saved — roughly 11.1 years to break even. Call this borderline rather than a clear win.
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 $2,820 figure above as a planning number for San Bernardino County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
San Bernardino County's R-49 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-49 is the target here specifically.