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Calcimator

Window Restoration vs Replace Calculator

Cost and tax credit impact for historic window treatment.

Inputs

Results

Restore + storms ($)

$21,000.00

≈ 11 gaming PCs

Replace all ($)$24,000.00
Restoration savings ($)$3,000.00
Replace payback (years)5
Potential HTC loss ($)$4,800.00
How to Use This Calculator
  1. Enter Number of windows and Restoration cost each ($) — this includes epoxy consolidation, reglaze, weatherstripping, and hardware.
  2. Enter Replacement cost each ($) for the installed cost of new windows sized to match historic openings.
  3. Add Storm window each ($) to the restoration option — interior storm windows add energy performance without harming historic character.
  4. Enter Energy savings/yr/window ($) from improved weather sealing and glazing to calculate the energy payback.
  5. Review Restore + storms total vs Replace all total — restoration is typically less expensive and preserves historic fabric.
  6. Check Potential HTC loss ($) — replacing original windows can jeopardize eligibility for the 20% Historic Tax Credit.

How the result changes with Number of windows

Number of windowsRestore + storms ($)
51$53,550.00
176$184,800.00
325$341,250.00
450$472,500.00

What each input means

Number of windows
Total number of historic windows.
Restoration cost each ($)
Cost to restore each window (epoxy repair, reglaze, weatherstrip).
Replacement cost each ($)
Cost for new replacement window and installation.
Storm window each ($)
Cost per interior or exterior storm window.
Energy savings/yr/window ($)
Annual energy savings per window from upgrade.

What each result means

Restore + storms ($)
Total cost to restore all windows and add storms.
Replace all ($)
Total cost to replace all windows.
Restoration savings ($)
Cost savings from restoration vs replacement.
Replace payback (years)
Years for replacement energy savings to offset extra cost.
Potential HTC loss ($)
Tax credit at risk if replacement disqualifies HTC.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Number of windows = 20, Restoration cost each ($) = 800, Replacement cost each ($) = 1200, Storm window each ($) = 250 = 5 input(s) provided
  2. Calculate Restore + storms
    Restore + storms = restoreTotalPerWindow * numWindows
    21000 = $21,000
  3. Calculate Replace all
    Replace all = replacementCostEach * numWindows
    24000 = $24,000
  4. Calculate Restoration savings
    Restoration savings = totalReplacementCost - totalRestorationCost
    3000 = $3,000

Engine last updated .

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