San Francisco County, CA Insulation Payback
San Francisco County attic insulation, by the numbers
San Francisco County, California is zone 3 under DOE's climate map (Marine), which means mild, damp weather year-round with modest heating load and little cooling. An uninsulated attic there should be built up to R-49. Going from R-2 to the recommended R-49 costs roughly $2,820 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 3.2 years at an estimated $870/year saved. Topping up the attic pays for itself here.
The breakdown behind the number
Split it out and it's roughly $865 a year on the heating side, $5 on cooling. By estimated insulation savings, San Francisco County lands in the 8th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and San Francisco County comes in 664th by savings. California averages $1,056/year across the counties tracked here; San Francisco County comes in 18% lower.
Where these numbers come from
NOAA's SAN FRANCISCO OCEANSIDE, CA US station, 28.8 miles from San Francisco County, supplies the 3,260 HDD and 29 CDD this estimate runs on. By total degree days, San Francisco County sits at the 1th percentile nationally. One local detail the R-value alone won't tell you: San Francisco County sits in moisture regime C (marine), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $117/year saved — roughly 13.8 years to break even. Call this borderline rather than a clear win.
Quotes and materials for this job
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 San Francisco County's estimated $870/year on the line.
Where these figures come from
San Francisco 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.