Harrison County, MS Insulation Payback
Is attic insulation worth it in Harrison County, MS?
Harrison County sits in IECC climate zone 2 (Hot-Humid) — summers that stay hot and humid while winters barely register on the energy bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building 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 3.4 years at an estimated $838/year saved. That is a solid payback as home upgrades go.
Heating vs. cooling in Harrison County
Heating accounts for about $400/year of that and cooling about $438/year — Harrison County needs both. Nationally, Harrison County ranks in the 6th percentile for insulation savings potential. Compared only against its own climate zone, Harrison County places 131st out of 233. Against Mississippi's own average of $1,022/year, Harrison County runs 18% below that.
Harrison County's actual weather, not a national average
NOAA's GULFPORT - BILOXI AP, MS US station, 0.4 miles from Harrison County, supplies the 1,507 HDD and 2,749 CDD this estimate runs on. By total degree days, Harrison County sits at the 5th percentile nationally. Its moisture regime is classified humid, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
If the attic isn't bare
A shallower starting point changes the math: with R-11 already down, only the gap to R-38 needs filling, at roughly $1,620 for an estimated $113/year saved (~14.4-year payback). Whether that is worth it depends on how long you plan to stay.
Getting it done in Harrison County
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 Harrison County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Harrison County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Harrison 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.