Hillsborough County, NH Insulation Payback
Is attic insulation worth it in Hillsborough County, NH?
Hillsborough County sits in IECC climate zone 5 (Cold) — a real winter that drives most of the annual energy bill here. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $1,913 a year in heating and cooling — a payback around 1.8 years. Few home upgrades pay back that quickly.
The breakdown behind the number
Heating accounts for about $1,825/year of that and cooling about $88/year — Hillsborough County needs both. Nationally, Hillsborough County ranks in the 78th percentile for insulation savings potential. Compared only against its own climate zone, Hillsborough County places 131st out of 745. Against New Hampshire's own average of $2,071/year, Hillsborough County runs 8% below that.
Hillsborough County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 6,825 HDD and 546 CDD (base 65°F, 1991-2020 normals) — come from MILFORD, NH US, the nearest NOAA station with published normals, 6.2 miles from Hillsborough County's center. By total degree days, Hillsborough County sits at the 78th 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.
The smaller top-up scenario
A shallower starting point changes the math: with R-11 already down, only the gap to R-49 needs filling, at roughly $2,280 for an estimated $279/year saved (~8.2-year payback). Whether that is worth it depends on how long you plan to stay.
Next steps for a Hillsborough County attic
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $3,480 as a starting estimate for a Hillsborough County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Hillsborough County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Hillsborough 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.