Anne Arundel County, MD Insulation Payback
Anne Arundel County attic insulation, by the numbers
DOE classifies Anne Arundel County as climate zone 4, mixed-humid — heating load in winter and cooling load in summer, both worth taking seriously here. Its recommended attic R-value for bare joists is R-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 2.7 years at an estimated $1,300/year saved. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,036 a year on the heating side, $264 on cooling. By estimated insulation savings, Anne Arundel County lands in the 39th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Anne Arundel County comes in 580th by savings. Maryland averages $1,395/year across the counties tracked here; Anne Arundel County comes in 7% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 3,876 HDD and 1,643 CDD (base 65°F, 1991-2020 normals) — come from ANNAPOLIS POLICE BRKS, MD US, the nearest NOAA station with published normals, 2.9 miles from Anne Arundel County's center. Combined heating and cooling load puts Anne Arundel County in the 40th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Anne Arundel County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $190/year saved — roughly 12 years to break even. Call this borderline rather than a clear win.
Next steps for a Anne Arundel County attic
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 Anne Arundel County's estimated $1,300/year on the line.
Where these figures come from
Anne Arundel County's R-60 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-60 is the target here specifically.