Window Replacement Energy Payback
Enter how many windows, the glass area, the U-factor of the old and new windows and the price per window, pick your state, and see the energy difference per year and the years it takes to cover the cost.
Window replacement payback
G02Scenario A
Sets the electricity rate. Pick US average if you're not sure.
From EIA for US average. Use the rate on your bill if you know it.
Rate used: 18.4¢/kWh · US average · EIA reference 2025–26 · gas $1.55/therm · 4,500 heating degree-days · 1,300 cooling degree-days (data as of 2026-09-26) ·
Energy payback
$96.35 a year in energy against $10,800.00 installed.
- Savings per year (conduction + low-e)
- $96.35
- Total cost (cost per window × number)
- $10,800.00
- Payback
- More than 30 years
- Reading
- Energy savings rarely pay for new windows on their own; comfort, noise and home value are the case for them.
Estimate. Formula and sources are under “How it works”. Change any input; the result updates as you type.
2026 note: The federal 25C and 25D tax credits ended for installations after Dec 31, 2025. Our numbers use 2026 rules. State rebates, HEAR/HOMES programs and utility programs may still apply.
Formula
How it works
- Heat kept in per year (BTU) = glass area × (U old − U new) × heating degree-days × 24
- Heating difference = BTU ÷ 1,000,000 × the cost of 1 million BTU of gas heat (your state's price per therm, 90% efficient furnace)
- Cooling difference = glass area × (U old − U new) × cooling degree-days × 24, converted to kWh as BTU ÷ (SEER 14 × 1,000) and priced at your rate
- Low-e summer allowance = glass area × 0.15 kWh × your rate × (cooling degree-days ÷ 1,000), a simplified figure for the sun a low-e coating keeps out
- Estimated yearly difference = heating + cooling + low-e allowance
- Simple payback = number of windows × price per window ÷ yearly difference
The honest reading: energy alone rarely pays for new windows. Comfort, less noise and the home's value are the real reasons to replace them. The calculator shows the energy part so you can weigh it.
Sources: U-factor criteria from ENERGY STAR (2023, by zone); conduction U × A × ΔT × time (ASHRAE fundamentals); simplified solar heat gain for low-e glass; installed prices from HomeAdvisor 2026; degree-days from NOAA 1991–2020 normals; EIA electricity and natural gas prices.
Worked example
A worked example
Replacing 15 older double-pane windows (220 sq ft of glass) with U-0.28 windows in Texas is worth an estimated $85.69 a year in heating and cooling. At $850 a window, the job costs $12,750.00, a simple payback of about 149 years. Energy rarely pays for windows on its own; comfort, noise and the home's value are the argument.
Reference
By state, at the default inputs
Energy payback, with this page's default inputs and each state's reference prices (EIA reference 2025–26, data as of 2026-09-26).
| US average | More than 30 years | 18.4¢/kWh |
|---|---|---|
| Alabama | More than 30 years | 15.5¢/kWh |
| Alaska | More than 30 years | 25.0¢/kWh |
| Arizona | More than 30 years | 15.0¢/kWh |
| Arkansas | More than 30 years | 13.0¢/kWh |
| California | More than 30 years | 32.0¢/kWh |
| Colorado | More than 30 years | 16.0¢/kWh |
| Connecticut | More than 30 years | 30.0¢/kWh |
| Delaware | More than 30 years | 17.0¢/kWh |
| District of Columbia | More than 30 years | 19.0¢/kWh |
| Florida | More than 30 years | 15.0¢/kWh |
| Georgia | More than 30 years | 14.5¢/kWh |
| Hawaii | More than 30 years | 42.0¢/kWh |
| Idaho | More than 30 years | 12.0¢/kWh |
| Illinois | More than 30 years | 17.0¢/kWh |
| Indiana | More than 30 years | 15.5¢/kWh |
| Iowa | More than 30 years | 13.5¢/kWh |
| Kansas | More than 30 years | 14.5¢/kWh |
| Kentucky | More than 30 years | 13.0¢/kWh |
| Louisiana | More than 30 years | 12.5¢/kWh |
| Maine | More than 30 years | 26.0¢/kWh |
| Maryland | More than 30 years | 19.0¢/kWh |
| Massachusetts | More than 30 years | 29.0¢/kWh |
| Michigan | More than 30 years | 19.5¢/kWh |
| Minnesota | More than 30 years | 15.5¢/kWh |
| Mississippi | More than 30 years | 13.5¢/kWh |
| Missouri | More than 30 years | 13.0¢/kWh |
| Montana | More than 30 years | 13.0¢/kWh |
| Nebraska | More than 30 years | 12.0¢/kWh |
| Nevada | More than 30 years | 15.0¢/kWh |
| New Hampshire | More than 30 years | 27.0¢/kWh |
| New Jersey | More than 30 years | 22.0¢/kWh |
| New Mexico | More than 30 years | 15.0¢/kWh |
| New York | More than 30 years | 25.0¢/kWh |
| North Carolina | More than 30 years | 14.5¢/kWh |
| North Dakota | More than 30 years | 11.5¢/kWh |
| Ohio | More than 30 years | 16.5¢/kWh |
| Oklahoma | More than 30 years | 13.0¢/kWh |
| Oregon | More than 30 years | 14.5¢/kWh |
| Pennsylvania | More than 30 years | 18.5¢/kWh |
| Rhode Island | More than 30 years | 29.0¢/kWh |
| South Carolina | More than 30 years | 15.0¢/kWh |
| South Dakota | More than 30 years | 13.0¢/kWh |
| Tennessee | More than 30 years | 13.5¢/kWh |
| Texas | More than 30 years | 15.5¢/kWh |
| Utah | More than 30 years | 12.0¢/kWh |
| Vermont | More than 30 years | 22.0¢/kWh |
| Virginia | More than 30 years | 15.5¢/kWh |
| Washington | More than 30 years | 12.0¢/kWh |
| West Virginia | More than 30 years | 15.5¢/kWh |
| Wisconsin | More than 30 years | 17.5¢/kWh |
| Wyoming | More than 30 years | 12.5¢/kWh |
Questions
FAQ
Do new windows really save energy?
Some, and less than the ads suggest. With US-average climate and prices, replacing 12 older double-pane windows (180 sq ft) with U-0.28 windows is worth an estimated $84.87 a year, a 127-year payback at $900 a window. Replacing single pane gets much more: $263.09 a year, about 41 years.
Single pane to double pane: how much difference?
The biggest step there is. U drops from about 1.0 to 0.5 or lower, which halves the heat through the glass or better. In Minnesota, going from single pane to U-0.28 on 180 sq ft is worth about $327.30 a year, a 33-year payback on $10,800.
Is triple pane worth it?
Enter the triple-pane window's U-factor from its label and compare. Each step down in U moves fewer BTU than the step before, so the extra cost of triple pane usually takes longer to recover than the move to double pane did.
Why is the payback so long?
Windows are a small share of a home's wall and roof area, and the price is per window, not per BTU. In mild climates there are few heating degree-days to recover. Replace windows for comfort, noise or repairs, and use this number to see what energy adds to that decision.
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