Insulation payback for 2200 ft² from R-30 to R-30 in Zone 4 heating with a heat pump
| Existing R-value | R-30 |
|---|---|
| Target R-value | R-30 |
| Verdictmoney is better spent on air sealing | Already there |
- Area
- 2200 ft²
- Existing R-value
- 30
- Target R-value
- 30
- Climate zone
- Zone 4
- Heating fuel
- a heat pump
The saving
2200 ft² going from R-30 to R-30 in Zone 4 (4,700 heating degree days — Baltimore, St Louis, Seattle) cuts about 0 MMBTU a year of heat loss. On a heat pump that is 0 kWh of fuel, worth $0 a year.
Payback
DIY material comes to about $0, which pays back in ∞ years. Contractor-installed runs near $0 and pays back in ∞. Over twenty years the DIY cost returns 0 times over — insulation has no moving parts and does not wear out.
Why the last inch is nearly worthless
This is the part almost nobody calculates, and it changes decisions.
Savings follow the difference between two reciprocals, not the difference between two R-values. The first R-10 of this upgrade is worth $36 a year. The last R-10 is worth $36.
That is why "more R is always better" is bad advice. Past a point you are buying insulation whose payback is longer than the roof above it.
Climate is half the answer
The same job saves $0 in Zone 4. In Zone 6 at 7,900 HDD it would save $0; in Zone 2 at 1,500 HDD, $0. Advice written for one climate is simply wrong in another, and most insulation advice on the internet does not say which climate it was written for.
What is assumed
Fuel priced at the US average, and the relationship is linear — scale it for your own bill. Utility rates vary by more than a factor of two across the country, which is enough to move a ten-year payback either side of five.
Notes
- R-30 already meets the R-30 target, so there is no heat saving to pay for the work. Insulation past the point of diminishing returns is the most common way people spend money on efficiency and get nothing back.
- Air sealing is where the money goes next, and it is not a close call. Gaps around can lights, top plates, ducts and the attic hatch move heat by bulk air movement, which insulation does nothing about.
Nearby sizes
- Insulation payback for 2000 ft² from R-30 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 2400 ft² from R-30 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 1800 ft² from R-30 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 2600 ft² from R-30 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 2200 ft² from R-19 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 2200 ft² from R-11 to R-30 in Zone 4 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-38 in Zone 4 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-49 in Zone 4 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 3 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 5 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 2 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 6 heating with a heat pump
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 4 heating with electric resistance
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 4 heating with propane
- Insulation payback for 2200 ft² from R-30 to R-30 in Zone 4 heating with natural gas
Read more
- Finding Your IECC Climate Zone, and Why the Map Is Not the AnswerClimate zones are assigned by county, not by zip code. Where the two disagree, the county wins — and they disagree more often than you would expect.
- Zone 5 Attic Insulation: The Target, the Depth, and the Top-Up MathsZone 5 covers a large share of the country and sits right on the step where the code moved from R-49 to R-60. Which one applies to you is a local question.
- R-38 vs R-49 vs R-60: What Each Step Actually RemovesEach step up removes less than the one before it. Knowing how much less is the difference between a sensible upgrade and buying insulation you will never notice.
- R-Value by Climate Zone: Ceilings, Walls and Floors in One TableThe whole envelope in one table, plus the thing nobody says out loud — the edition your jurisdiction enforces may be two cycles behind the current one.