Insulation R-Value Savings Calculator
Estimate your annual heating and cooling savings from upgrading your home's insulation.
Heat Flow Reduction vs. R-Value (from R-11 baseline)
| Target R-Value | Heat Flow Reduction | Save on $1,500 HVAC (25% attic) |
|---|---|---|
| R-19 | 42% | $158/yr |
| R-30 | 63% | $238/yr |
| R-38 | 71% | $266/yr |
| R-49 | 78% | $291/yr |
| R-60 | 82% | $306/yr |
Frequently Asked Questions
What is R-value and why does it matter?
R-value measures thermal resistance — how well an insulation material resists heat flow. Higher R-value = better insulation. Heat loss (or gain in summer) is inversely proportional to R-value: doubling R-value halves heat transfer. The DOE recommends R-38 to R-60 in attics for most US climate zones, but many existing homes have only R-11 to R-19.
How much can I save by upgrading attic insulation?
The DOE estimates that upgrading from R-11 to R-38 in an uninsulated attic saves 10–50% on heating and cooling costs, depending on climate. In cold climates (Zone 5–7), savings average 15–25% annually. For a home with $1,500/year in HVAC costs, that's $225–$375/year. Attic insulation upgrades typically pay back in 3–7 years.
What R-value do I need for my climate zone?
DOE recommendations by zone — Attic: Zone 1–2 (South): R-30 to R-49. Zone 3–4 (Mid): R-38 to R-60. Zone 5–8 (North): R-49 to R-60. Walls: R-13 to R-21. Floors over unheated space: R-19 to R-38. Check the DOE's climate zone map to find your zone, or enter your zip code on energystar.gov.
What type of insulation has the highest R-value per inch?
Closed-cell spray foam has the highest R-value per inch at R-6 to R-7/inch. Open-cell spray foam: R-3.5/inch. Rigid foam board: R-3.8 to R-6.5/inch. Fiberglass batts: R-2.2 to R-2.7/inch. Blown cellulose: R-3.2 to R-3.8/inch. Blown fiberglass: R-2.2 to R-2.9/inch. For attics, blown cellulose or fiberglass is most cost-effective.
Is adding more insulation always cost-effective?
There are diminishing returns. Going from R-0 to R-11 saves a lot; from R-38 to R-49 saves much less proportionally. The DOE formula shows that the percentage heat-flow reduction = (1 - R_old/R_new) × 100%. Upgrading from R-11 to R-38 reduces heat flow by 71%. Upgrading from R-38 to R-60 reduces it by only an additional 37% — so the second upgrade saves less.