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Calcimator

Window-to-Wall Ratio Calculator

Calculate window-to-wall ratio and check energy code compliance by climate zone with energy penalty estimates.

Inputs

sq ft
sq ft

Results

Window-to-Wall Ratio

25%

Max Allowed (Code)

30%

Code Compliant

1

Energy Penalty0%
How to Use This Calculator
  1. Enter Total Window Area in sq ft — the sum of all window rough openings.
  2. Enter Total Wall Area in sq ft — the gross exterior wall area above grade.
  3. Enter the ASHRAE Climate Zone (1 = hot tropical, 8 = subarctic) for code compliance checking.
  4. Review Window-to-Wall Ratio percentage and the Code Maximum Allowed for your climate zone.
  5. Check Code Compliance status and Energy Penalty percentage if over the allowable ratio.

How the result changes with Total Wall Area

Total Wall AreaWindow-to-Wall RatioMax Allowed (Code)Code Compliant
50,0011.2%30%1
175,0010.34%30%1
325,0000.18%30%1
450,0000.13%30%1

What each input means

Total Window Area
Sum of all window rough openings on the building.
Total Wall Area
Total gross exterior wall area above grade.
ASHRAE Climate Zone
ASHRAE climate zone (1=hot, 8=subarctic). Affects maximum allowed WWR.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Total Window Area = 600, Total Wall Area = 2400, ASHRAE Climate Zone = 4 = 3 input(s) provided
  2. Calculate Window-to-Wall Ratio
    Window-to-Wall Ratio
    25 = 25
  3. Calculate Max Allowed
    Max Allowed
    30 = 30
  4. Calculate Code Compliant
    Code Compliant
    1 = 1
  5. Calculate Energy Penalty
    Energy Penalty
    0 = 0

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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