IECC Window U/SHGC Default Values
Instructions:
Review the methodology to make sure it aligns with your project's requirements.
Windows:
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Select Frame type
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Select the number of panes
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Select Clear or Tinted
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The U-Value, SHGC, and VT code default values will populate the results table.
Note: you can access NFRC's Certified Product Directory to search for your specific window's actual U-factors and SHGC values.
Doors:
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Enter the door type
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The code default U-factor value will populate the result box.
Default values from the 2021 IECC and the 2020 Florida Energy Conservation Code, Tables C303.1.3(1), (2) and (3). Use the NFRC-rated values on the window label when they are available; these defaults apply only when they are not.
Methodology:
NFRC U-Factor and SHGC values are critical when performing Cooling Load Calculations and Energy Code Compliance Calculations. New windows will have these values on their stickers. In the event that the windows no longer have an NFRC label affixed, the International Energy Conservation Code (IECC) and Florida Energy Conservation Code (FECC) provide default values U-Factor, SHGC values, and VT values. The values below are taken directly from the 2020 Florida Energy Conservation Code, Table C303.1.3(1) & (2), and the 2021 International Energy Conservation Code C303.1.3 (1) & (2) and show SHGC, U-Factor, and VT values for windows and doors:
| FRAME TYPE | WINDOW AND GLASS DOOR | SKYLIGHT | ||
|---|---|---|---|---|
| Single | Double | Single | Double | |
| Metal | 1.2 | 0.8 | 2 | 1.3 |
| Metal with Thermal Break | 1.1 | 0.65 | 1.9 | 1.1 |
| Nonmetal or Metal Clad | 0.95 | 0.55 | 1.75 | 1.05 |
| Glazed Block | 0.6 | |||
| DOOR TYPE | U-FACTOR |
|---|---|
| Uninsulated Metal | 1.2 |
| Insulated Metal (Rolling) | 0.9 |
| Insulated Metal (Other) | 0.6 |
| Wood | 0.5 |
| Insulated, nonmetal edge, max 45% glazing,any glazing double pane | 0.35 |
| SINGLE GLAZED | DOUBLE GLAZED | GLAZED BLOCK | |||
|---|---|---|---|---|---|
| Clear | Tinted | Clear | Tinted | ||
| SHGC | 0.8 | 0.7 | 0.7 | 0.6 | 0.6 |
| VT | 0.6 | 0.3 | 0.6 | 0.3 | 0.6 |
Example 1: You are performing a load calculation for an existing building. You do a site visit and see that the existing windows have metal frames and the single-pane glass has no tinting. What values should you use for the U-Factor, SHGC value, and VT value of the windows?
Find the U-Factor From Table C303.1.3(1) by looking up Metal Frame / Single Pane windows: U-Factor = 1.2
Find the SHGC and VT From Table C303.1.3(3) by looking up SINGLE GLAZED-Clear windows: SHGC = 0.8, VT = 0.6
Example 2: You are performing a load calculation for an existing building. You do a site visit and see that the existing doors are uninsulated and metal. What value should you use for the U-Factor?
Find the U-Factor From Table C303.1.3(2) by looking up Uninsulated Metal: U-Factor = 1.2
Example 3: Use Adicot's International Energy Conservation CodeWindow U-Factors & SHGC Default Values Calculator to solve the examples above:
