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Sun Shade inside or outside

Steve95065 | Posted in General Questions on

Many places I see it recommended to close your drapes to keep the sun from heating up your house. Does this help? It seems to me that the heat is already inside the envelope. Wouldn’t putting a shade on the outside of the window do a much better job?

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  1. Expert Member
    Akos | | #1

    Generally with low E windows, once the heat is in the house you own it. Depending on the number of coatings and number of windows panes, low E coating reflect between 40% to 80% of the heat from the house. Interior shades do reduce heat load somewhat, but nowhere near as much as exterior shades.

    Also if your interior shutters are well sealed and insulated, you can end up with a situation where trap heat between the shade and the window you overheat the IGU.

    Exterior shading is the way to go. Overhangs and low SHGC windows are your friend.

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