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Window SHGC in Zone 3

user-6458536 | Posted in Energy Efficiency and Durability on

What is a reasonable goal for my windows’ solar heat gain coefficient (SHGC) in Zone 3. Obviously in Alabama, we want to minimize heat gain to save on A/C costs. I’m planning to use Weathershield clad windows.

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  1. GBA Editor
    Martin Holladay | | #1

    First of all, when comparing SHGC values, make sure that you are comparing the numbers on the NFRC label. This is the whole-window number (rather than the glazing-only number). You need to compare the NFRC numbers to get an apples-to-apples comparison.

    Building codes require that windows in your climate zone have a maximum SHGC of 0.25. That is also the maximum permitted SHGC for Energy Star windows in your climate zone. When it comes to SHGC, lower is better than higher in your climate zone.

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